built-in add -p: add support for the same config settings as the Perl version

This is the final leg of the journey to a fully built-in git add: the git add -i and git add -p modes were re-implemented in C, but they lacked support for a couple of config settings.

The one that sticks out most is the interactive.singleKey setting: it was particularly hard to get to work, especially on Windows.

It also seems to be the setting that is incomplete already in the Perl version of the interactive add command: while the name of the config setting suggests that it applies to all of the interactive add, including the main loop of git add --interactive and to the file selections in that command, it does not. Only the git add --patch mode respects that setting.

As it is outside the purpose of the conversion of git-add--interactive.perl to C, we will leave that loose end for some future date.

Johannes Schindelin (9):
built-in add -p: support interactive.diffFilter
built-in add -p: handle diff.algorithm
terminal: make the code of disable_echo() reusable
terminal: accommodate Git for Windows' default terminal
terminal: add a new function to read a single keystroke built-in add -p: respect the interactive.singlekey config setting built-in add -p: handle Escape sequences in interactive.singlekey mode built-in add -p: handle Escape sequences more efficiently
ci: include the built-in git add -i in the linux-gcc job

 add-interactive.c         |  19 +++
 add-interactive.h         |   4 +
 add-patch.c               |  57 ++++++++-
 ci/run-build-and-tests.sh |   1 +
 compat/terminal.c         | 249 +++++++++++++++++++++++++++++++++++++-
 compat/terminal.h         |   3 +
 6 files changed, 325 insertions(+), 8 deletions(-)

base-commit: 2d4b85ddc76af3e703e6e3a6a72319b5e79c2d8b
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-175%2Fdscho%2Fadd-p-in-c-config-settings-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-175/dscho/add-p-in-c-config-settings-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/175

gitgitgadget

From: Johannes Schindelin <[email protected]>

The Perl version supports post-processing the colored diff (that is generated in addition to the uncolored diff, intended to offer a prettier user experience) by a command configured via that config setting, and now the built-in version does that, too.

---
 add-interactive.c | 12 ++++++++++++
 add-interactive.h |  3 +++
 add-patch.c       | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 48 insertions(+)

index 0e753d2acc..00c3bc9a1b 100644
@@ -52,6 +52,17 @@ void init_add_i_state(struct add_i_state *s, struct repository *r)
 		diff_get_color(s->use_color, DIFF_FILE_OLD));
 	init_color(r, s, "new", s->file_new_color,
 		diff_get_color(s->use_color, DIFF_FILE_NEW));
+
+	FREE_AND_NULL(s->interactive_diff_filter);
+	git_config_get_string("interactive.difffilter",
+			      &s->interactive_diff_filter);
+}
+
+void clear_add_i_state(struct add_i_state *s)
+{
+	FREE_AND_NULL(s->interactive_diff_filter);
+	memset(s, 0, sizeof(*s));
+	s->use_color = -1;
 }
 
 /*

@@ -1149,6 +1160,7 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 	strbuf_release(&print_file_item_data.worktree);
 	strbuf_release(&header);
 	prefix_item_list_clear(&commands);
+	clear_add_i_state(&s);
 
 	return res;
 }

index 4895ed1df5..7299cf6e04 100644
@@ -15,9 +15,12 @@ struct add_i_state {
 	char context_color[COLOR_MAXLEN];
 	char file_old_color[COLOR_MAXLEN];
 	char file_new_color[COLOR_MAXLEN];
+
+	char *interactive_diff_filter;
 };
 
 void init_add_i_state(struct add_i_state *s, struct repository *r);
+void clear_add_i_state(struct add_i_state *s);
 
 struct repository;
 struct pathspec;

index 2ad18dc3cb..73bf2caca2 100644
@@ -397,6 +397,7 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 
 	if (want_color_fd(1, -1)) {
 		struct child_process colored_cp = CHILD_PROCESS_INIT;
+		const char *diff_filter = s->s.interactive_diff_filter;
 
 		setup_child_process(s, &colored_cp, NULL);
 		xsnprintf((char *)args.argv[color_arg_index], 8, "--color");

@@ -406,6 +407,24 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 		argv_array_clear(&args);
 		if (res)
 			return error(_("could not parse colored diff"));
+
+		if (diff_filter) {
+			struct child_process filter_cp = CHILD_PROCESS_INIT;
+
+			setup_child_process(s, &filter_cp,
+					    diff_filter, NULL);
+			filter_cp.git_cmd = 0;
+			filter_cp.use_shell = 1;
+			strbuf_reset(&s->buf);
+			if (pipe_command(&filter_cp,
+					 colored->buf, colored->len,
+					 &s->buf, colored->len,
+					 NULL, 0) < 0)
+				return error(_("failed to run '%s'"),
+					     diff_filter);
+			strbuf_swap(colored, &s->buf);
+		}
+
 		strbuf_complete_line(colored);
 		colored_p = colored->buf;
 		colored_pend = colored_p + colored->len;

@@ -530,6 +549,9 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 						   colored_pend - colored_p);
 			if (colored_eol)
 				colored_p = colored_eol + 1;
+			else if (p != pend)
+				/* colored shorter than non-colored? */
+				goto mismatched_output;
 			else
 				colored_p = colored_pend;
 

@@ -554,6 +576,15 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 		 */
 		hunk->splittable_into++;
 
+	/* non-colored shorter than colored? */
+	if (colored_p != colored_pend) {
+mismatched_output:
+		error(_("mismatched output from interactive.diffFilter"));
+		advise(_("Your filter must maintain a one-to-one correspondence\n"
+			 "between its input and output lines."));
+		return -1;
+	}
+
 	return 0;
 }
 

@@ -1611,6 +1642,7 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	    parse_diff(&s, ps) < 0) {
 		strbuf_release(&s.plain);
 		strbuf_release(&s.colored);
+		clear_add_i_state(&s.s);
 		return -1;
 	}
 

@@ -1629,5 +1661,6 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	strbuf_release(&s.buf);
 	strbuf_release(&s.plain);
 	strbuf_release(&s.colored);
+	clear_add_i_state(&s.s);
 	return 0;
 }

gitgitgadget

From: Johannes Schindelin <[email protected]>

The Perl version of git add -p reads the config setting diff.algorithm and if set, uses it to generate the diff using the specified algorithm.

This patch ports that functionality to the C version.

Note: just like git-add--interactive.perl, we do _not_ respect this config setting in git add -i's diff command, but _only_ in the patch command.

---
 add-interactive.c | 5 +++++
 add-interactive.h | 2 +-
 add-patch.c       | 3 +++
 3 files changed, 9 insertions(+), 1 deletion(-)

index 00c3bc9a1b..77762d75d6 100644
@@ -56,11 +56,16 @@ void init_add_i_state(struct add_i_state *s, struct repository *r)
 	FREE_AND_NULL(s->interactive_diff_filter);
 	git_config_get_string("interactive.difffilter",
 			      &s->interactive_diff_filter);
+
+	FREE_AND_NULL(s->interactive_diff_algorithm);
+	git_config_get_string("diff.algorithm",
+			      &s->interactive_diff_algorithm);
 }
 
 void clear_add_i_state(struct add_i_state *s)
 {
 	FREE_AND_NULL(s->interactive_diff_filter);
+	FREE_AND_NULL(s->interactive_diff_algorithm);
 	memset(s, 0, sizeof(*s));
 	s->use_color = -1;
 }

index 7299cf6e04..21389851aa 100644
@@ -16,7 +16,7 @@ struct add_i_state {
 	char file_old_color[COLOR_MAXLEN];
 	char file_new_color[COLOR_MAXLEN];
 
-	char *interactive_diff_filter;
+	char *interactive_diff_filter, *interactive_diff_algorithm;
 };
 
 void init_add_i_state(struct add_i_state *s, struct repository *r);

index 73bf2caca2..fdfaa76c3c 100644
@@ -359,6 +359,7 @@ static int is_octal(const char *p, size_t len)
 static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 {
 	struct argv_array args = ARGV_ARRAY_INIT;
+	const char *diff_algorithm = s->s.interactive_diff_algorithm;
 	struct strbuf *plain = &s->plain, *colored = NULL;
 	struct child_process cp = CHILD_PROCESS_INIT;
 	char *p, *pend, *colored_p = NULL, *colored_pend = NULL, marker = '\0';

@@ -368,6 +369,8 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 	int res;
 
 	argv_array_pushv(&args, s->mode->diff);
+	if (diff_algorithm)
+		argv_array_pushf(&args, "--diff-algorithm=%s", diff_algorithm);
 	if (s->revision) {
 		struct object_id oid;
 		argv_array_push(&args,

gitgitgadget

From: Johannes Schindelin <[email protected]>

We are about to introduce the function enable_non_canonical(), which shares almost the complete code with disable_echo().

Let's prepare for that, by refactoring out that shared code.

---
 compat/terminal.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

index fa13ee672d..1fb40b3a0a 100644
@@ -32,7 +32,7 @@ static void restore_term(void)
 	term_fd = -1;
 }
 
-static int disable_echo(void)
+static int disable_bits(tcflag_t bits)
 {
 	struct termios t;
 

@@ -43,7 +43,7 @@ static int disable_echo(void)
 	old_term = t;
 	sigchain_push_common(restore_term_on_signal);
 
-	t.c_lflag &= ~ECHO;
+	t.c_lflag &= ~bits;
 	if (!tcsetattr(term_fd, TCSAFLUSH, &t))
 		return 0;
 

@@ -53,6 +53,11 @@ static int disable_echo(void)
 	return -1;
 }
 
+static int disable_echo(void)
+{
+	return disable_bits(ECHO);
+}
+
 #elif defined(GIT_WINDOWS_NATIVE)
 
 #define INPUT_PATH "CONIN$"

@@ -72,7 +77,7 @@ static void restore_term(void)
 	hconin = INVALID_HANDLE_VALUE;
 }
 
-static int disable_echo(void)
+static int disable_bits(DWORD bits)
 {
 	hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE,
 	    FILE_SHARE_READ, NULL, OPEN_EXISTING,

@@ -82,7 +87,7 @@ static int disable_echo(void)
 
 	GetConsoleMode(hconin, &cmode);
 	sigchain_push_common(restore_term_on_signal);
-	if (!SetConsoleMode(hconin, cmode & (~ENABLE_ECHO_INPUT))) {
+	if (!SetConsoleMode(hconin, cmode & ~bits)) {
 		CloseHandle(hconin);
 		hconin = INVALID_HANDLE_VALUE;
 		return -1;

@@ -91,6 +96,12 @@ static int disable_echo(void)
 	return 0;
 }
 
+static int disable_echo(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT);
+}
+
+
 #endif
 
 #ifndef FORCE_TEXT

gitgitgadget

From: Johannes Schindelin <[email protected]>

Git for Windows' Git Bash runs in MinTTY by default, which does not have a Win32 Console instance, but uses MSYS2 pseudo terminals instead.

This is a problem, as Git for Windows does not want to use the MSYS2 emulation layer for Git itself, and therefore has no direct way to interact with that pseudo terminal.

As a workaround, use the stty utility (which is included in Git for Windows, and which *is* an MSYS2 program, so it knows how to deal with the pseudo terminal).

Note: If Git runs in a regular CMD or PowerShell window, there *is* a regular Win32 Console to work with. This is not a problem for the MSYS2 stty: it copes with this scenario just fine.

Also note that we introduce support for more bits than would be necessary for a mere disable_echo() here, in preparation for the upcoming enable_non_canonical() function.

---
 compat/terminal.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

index 1fb40b3a0a..16e9949da1 100644
@@ -2,6 +2,8 @@
 #include "compat/terminal.h"
 #include "sigchain.h"
 #include "strbuf.h"
+#include "run-command.h"
+#include "string-list.h"
 
 #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE)
 

@@ -64,11 +66,28 @@ static int disable_echo(void)
 #define OUTPUT_PATH "CONOUT$"
 #define FORCE_TEXT "t"
 
+static int use_stty = 1;
+static struct string_list stty_restore = STRING_LIST_INIT_DUP;
 static HANDLE hconin = INVALID_HANDLE_VALUE;
 static DWORD cmode;
 
 static void restore_term(void)
 {
+	if (use_stty) {
+		int i;
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		if (stty_restore.nr == 0)
+			return;
+
+		argv_array_push(&cp.args, "stty");
+		for (i = 0; i < stty_restore.nr; i++)
+			argv_array_push(&cp.args, stty_restore.items[i].string);
+		run_command(&cp);
+		string_list_clear(&stty_restore, 0);
+		return;
+	}
+
 	if (hconin == INVALID_HANDLE_VALUE)
 		return;
 

@@ -79,6 +98,37 @@ static void restore_term(void)
 
 static int disable_bits(DWORD bits)
 {
+	if (use_stty) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		argv_array_push(&cp.args, "stty");
+
+		if (bits & ENABLE_LINE_INPUT) {
+			string_list_append(&stty_restore, "icanon");
+			argv_array_push(&cp.args, "-icanon");
+		}
+
+		if (bits & ENABLE_ECHO_INPUT) {
+			string_list_append(&stty_restore, "echo");
+			argv_array_push(&cp.args, "-echo");
+		}
+
+		if (bits & ENABLE_PROCESSED_INPUT) {
+			string_list_append(&stty_restore, "-ignbrk");
+			string_list_append(&stty_restore, "intr");
+			string_list_append(&stty_restore, "^c");
+			argv_array_push(&cp.args, "ignbrk");
+			argv_array_push(&cp.args, "intr");
+			argv_array_push(&cp.args, "");
+		}
+
+		if (run_command(&cp) == 0)
+			return 0;
+
+		/* `stty` could not be executed; access the Console directly */
+		use_stty = 0;
+	}
+
 	hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE,
 	    FILE_SHARE_READ, NULL, OPEN_EXISTING,
 	    FILE_ATTRIBUTE_NORMAL, NULL);

gitgitgadget

From: Johannes Schindelin <[email protected]>

Typically, input on the command-line is line-based. It is actually not really easy to get single characters (or better put: keystrokes).

We provide two implementations here:

- One that handles /dev/tty based systems as well as native Windows. The former uses the tcsetattr() function to put the terminal into "raw mode", which allows us to read individual keystrokes, one by one. The latter uses stty.exe to do the same, falling back to direct Win32 Console access.

Thanks to the refactoring leading up to this commit, this is a single function, with the platform-specific details hidden away in conditionally-compiled code blocks.

- A fall-back which simply punts and reads back an entire line.

Note that the function writes the keystroke into an strbuf rather than a char, in preparation for reading Escape sequences (e.g. when the user hit an arrow key). This is also required for UTF-8 sequences in case the keystroke corresponds to a non-ASCII letter.

---
 compat/terminal.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++
 compat/terminal.h |  3 +++
 2 files changed, 58 insertions(+)

index 16e9949da1..1b2564042a 100644
@@ -60,6 +60,11 @@ static int disable_echo(void)
 	return disable_bits(ECHO);
 }
 
+static int enable_non_canonical(void)
+{
+	return disable_bits(ICANON | ECHO);
+}
+
 #elif defined(GIT_WINDOWS_NATIVE)
 
 #define INPUT_PATH "CONIN$"

@@ -151,6 +156,10 @@ static int disable_echo(void)
 	return disable_bits(ENABLE_ECHO_INPUT);
 }
 
+static int enable_non_canonical(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
+}
 
 #endif
 

@@ -198,6 +207,33 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return buf.buf;
 }
 
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	int ch;
+
+	if (warning_displayed || enable_non_canonical() < 0) {
+		if (!warning_displayed) {
+			warning("reading single keystrokes not supported on "
+				"this platform; reading line instead");
+			warning_displayed = 1;
+		}
+
+		return strbuf_getline(buf, stdin);
+	}
+
+	strbuf_reset(buf);
+	ch = getchar();
+	if (ch == EOF) {
+		restore_term();
+		return EOF;
+	}
+
+	strbuf_addch(buf, ch);
+	restore_term();
+	return 0;
+}
+
 #else
 
 char *git_terminal_prompt(const char *prompt, int echo)

@@ -205,4 +241,23 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return getpass(prompt);
 }
 
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	const char *res;
+
+	if (!warning_displayed) {
+		warning("reading single keystrokes not supported on this "
+			"platform; reading line instead");
+		warning_displayed = 1;
+	}
+
+	res = getpass("");
+	strbuf_reset(buf);
+	if (!res)
+		return EOF;
+	strbuf_addstr(buf, res);
+	return 0;
+}
+
 #endif

index 97db7cd69d..a9d52b8464 100644
@@ -3,4 +3,7 @@
 
 char *git_terminal_prompt(const char *prompt, int echo);
 
+/* Read a single keystroke, without echoing it to the terminal */
+int read_key_without_echo(struct strbuf *buf);
+
 #endif /* COMPAT_TERMINAL_H */

gitgitgadget

From: Johannes Schindelin <[email protected]>

The Perl version of git add -p supports this config setting to allow users to input commands via single characters (as opposed to having to press the <Enter> key afterwards).

This is an opt-in feature because it requires Perl packages (Term::ReadKey and Term::Cap, where it tries to handle an absence of the latter package gracefully) to work. Note that at least on Ubuntu, that Perl package is not installed by default (it needs to be installed via sudo apt-get install libterm-readkey-perl), so this feature is probably not used a whole lot.

In C, we obviously do not have these packages available, but we just introduced read_single_keystroke() that is similar to what Term::ReadKey provides, and we use that here.

---
 add-interactive.c |  2 ++
 add-interactive.h |  1 +
 add-patch.c       | 21 +++++++++++++++++----
 3 files changed, 20 insertions(+), 4 deletions(-)

index 77762d75d6..01a2f92f0c 100644
@@ -60,6 +60,8 @@ void init_add_i_state(struct add_i_state *s, struct repository *r)
 	FREE_AND_NULL(s->interactive_diff_algorithm);
 	git_config_get_string("diff.algorithm",
 			      &s->interactive_diff_algorithm);
+
+	git_config_get_bool("interactive.singlekey", &s->use_single_key);
 }
 
 void clear_add_i_state(struct add_i_state *s)

index 21389851aa..3450359685 100644
@@ -16,6 +16,7 @@ struct add_i_state {
 	char file_old_color[COLOR_MAXLEN];
 	char file_new_color[COLOR_MAXLEN];
 
+	int use_single_key;
 	char *interactive_diff_filter, *interactive_diff_algorithm;
 };
 

index fdfaa76c3c..ef0469d398 100644
@@ -6,6 +6,7 @@
 #include "pathspec.h"
 #include "color.h"
 #include "diff.h"
+#include "compat/terminal.h"
 
 enum prompt_mode_type {
 	PROMPT_MODE_CHANGE = 0, PROMPT_DELETION, PROMPT_HUNK

@@ -1148,14 +1149,27 @@ static int run_apply_check(struct add_p_state *s,
 	return 0;
 }
 
+static int read_single_character(struct add_p_state *s)
+{
+	if (s->s.use_single_key) {
+		int res = read_key_without_echo(&s->answer);
+		printf("%s\n", res == EOF ? "" : s->answer.buf);
+		return res;
+	}
+
+	if (strbuf_getline(&s->answer, stdin) == EOF)
+		return EOF;
+	strbuf_trim_trailing_newline(&s->answer);
+	return 0;
+}
+
 static int prompt_yesno(struct add_p_state *s, const char *prompt)
 {
 	for (;;) {
 		color_fprintf(stdout, s->s.prompt_color, "%s", _(prompt));
 		fflush(stdout);
-		if (strbuf_getline(&s->answer, stdin) == EOF)
+		if (read_single_character(s) == EOF)
 			return -1;
-		strbuf_trim_trailing_newline(&s->answer);
 		switch (tolower(s->answer.buf[0])) {
 		case 'n': return 0;
 		case 'y': return 1;

@@ -1395,9 +1409,8 @@ static int patch_update_file(struct add_p_state *s,
 			      _(s->mode->prompt_mode[prompt_mode_type]),
 			      s->buf.buf);
 		fflush(stdout);
-		if (strbuf_getline(&s->answer, stdin) == EOF)
+		if (read_single_character(s) == EOF)
 			break;
-		strbuf_trim_trailing_newline(&s->answer);
 
 		if (!s->answer.len)
 			continue;

gitgitgadget

From: Johannes Schindelin <[email protected]>

This recapitulates part of b5cc003253c8 (add -i: ignore terminal escape sequences, 2011-05-17):

add -i: ignore terminal escape sequences

On the author's terminal, the up-arrow input sequence is ^[[A, and thus fat-fingering an up-arrow into 'git checkout -p' is quite
dangerous: git-add--interactive.perl will ignore the ^[ and [ characters and happily treat A as "discard everything".

As a band-aid fix, use Term::Cap to get all terminal capabilities. Then use the heuristic that any capability value that starts with ^[ (i.e., \e in perl) must be a key input sequence. Finally, given an input that starts with ^[, read more characters until we have read a full escape sequence, then return that to the caller. We use a timeout of 0.5 seconds on the subsequent reads to avoid getting stuck if the user actually input a lone ^[.

Since none of the currently recognized keys start with ^[, the net result is that the sequence as a whole will be ignored and the help displayed.

Note that we leave part for later which uses "Term::Cap to get all terminal capabilities", for several reasons:

1. it is actually not really necessary, as the timeout of 0.5 seconds should be plenty sufficient to catch Escape sequences,

2. it is cleaner to keep the change to special-case Escape sequences separate from the change that reads all terminal capabilities to speed things up, and

3. in practice, relying on the terminal capabilities is a bit overrated, as the information could be incomplete, or plain wrong. For example, in this developer's tmux sessions, the terminal capabilities claim that the "cursor up" sequence is ^[M, but the actual sequence produced by the "cursor up" key is ^[[A.

---
 compat/terminal.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

index 1b2564042a..b7f58d1781 100644
@@ -161,6 +161,37 @@ static int enable_non_canonical(void)
 	return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
 }
 
+/*
+ * Override `getchar()`, as the default implementation does not use
+ * `ReadFile()`.
+ *
+ * This poses a problem when we want to see whether the standard
+ * input has more characters, as the default of Git for Windows is to start the
+ * Bash in a MinTTY, which uses a named pipe to emulate a pty, in which case
+ * our `poll()` emulation calls `PeekNamedPipe()`, which seems to require
+ * `ReadFile()` to be called first to work properly (it only reports 0
+ * available bytes, otherwise).
+ *
+ * So let's just override `getchar()` with a version backed by `ReadFile()` and
+ * go our merry ways from here.
+ */
+static int mingw_getchar(void)
+{
+	DWORD read = 0;
+	unsigned char ch;
+
+	if (!ReadFile(GetStdHandle(STD_INPUT_HANDLE), &ch, 1, &read, NULL))
+		return EOF;
+
+	if (!read) {
+		error("Unexpected 0 read");
+		return EOF;
+	}
+
+	return ch;
+}
+#define getchar mingw_getchar
+
 #endif
 
 #ifndef FORCE_TEXT

@@ -228,8 +259,31 @@ int read_key_without_echo(struct strbuf *buf)
 		restore_term();
 		return EOF;
 	}
-
 	strbuf_addch(buf, ch);
+
+	if (ch == '\033' /* ESC */) {
+		/*
+		 * We are most likely looking at an Escape sequence. Let's try
+		 * to read more bytes, waiting at most half a second, assuming
+		 * that the sequence is complete if we did not receive any byte
+		 * within that time.
+		 *
+		 * Start by replacing the Escape byte with ^[ */
+		strbuf_splice(buf, buf->len - 1, 1, "^[", 2);
+
+		for (;;) {
+			struct pollfd pfd = { .fd = 0, .events = POLLIN };
+
+			if (poll(&pfd, 1, 500) < 1)
+				break;
+
+			ch = getchar();
+			if (ch == EOF)
+				return 0;
+			strbuf_addch(buf, ch);
+		}
+	}
+
 	restore_term();
 	return 0;
 }

gitgitgadget

From: Johannes Schindelin <[email protected]>

When interactive.singlekey = true, we react immediately to keystrokes, even to Escape sequences (e.g. when pressing a cursor key).

The problem with Escape sequences is that we do not really know when they are done, and as a heuristic we poll standard input for half a second to make sure that we got all of it.

While waiting half a second is not asking for a whole lot, it can become quite annoying over time, therefore with this patch, we read the terminal capabilities (if available) and extract known Escape sequences from there, then stop polling immediately when we detected that the user pressed a key that generated such a known sequence.

This recapitulates the remaining part of b5cc003253c8 (add -i: ignore terminal escape sequences, 2011-05-17).

Note: We do *not* query the terminal capabilities directly. That would either require a lot of platform-specific code, or it would require linking to a library such as ncurses.

Linking to a library in the built-ins is something we try very hard to avoid (we even kicked the libcurl dependency to a non-built-in remote helper, just to shave off a tiny fraction of a second from Git's startup time). And the platform-specific code would be a maintenance nightmare.

Even worse: in Git for Windows' case, we would need to query MSYS2 pseudo terminals, which git.exe simply cannot do (because it is intentionally *not* an MSYS2 program).

To address this, we simply spawn infocmp -L -1 and parse its output (which works even in Git for Windows, because that helper is included in the end-user facing installations).

This is done only once, as in the Perl version, but it is done only when the first Escape sequence is encountered, not upon startup of git add -i; This saves on startup time, yet makes reacting to the first Escape sequence slightly more sluggish. But it allows us to keep the terminal-related code encapsulated in the compat/terminal.c file.

---
 compat/terminal.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

index b7f58d1781..35bca03d14 100644
@@ -4,6 +4,7 @@
 #include "strbuf.h"
 #include "run-command.h"
 #include "string-list.h"
+#include "hashmap.h"
 
 #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE)
 

@@ -238,6 +239,71 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return buf.buf;
 }
 
+/*
+ * The `is_known_escape_sequence()` function returns 1 if the passed string
+ * corresponds to an Escape sequence that the terminal capabilities contains.
+ *
+ * To avoid depending on ncurses or other platform-specific libraries, we rely
+ * on the presence of the `infocmp` executable to do the job for us (failing
+ * silently if the program is not available or refused to run).
+ */
+struct escape_sequence_entry {
+	struct hashmap_entry entry;
+	char sequence[FLEX_ARRAY];
+};
+
+static int sequence_entry_cmp(const void *hashmap_cmp_fn_data,
+			      const struct escape_sequence_entry *e1,
+			      const struct escape_sequence_entry *e2,
+			      const void *keydata)
+{
+	return strcmp(e1->sequence, keydata ? keydata : e2->sequence);
+}
+
+static int is_known_escape_sequence(const char *sequence)
+{
+	static struct hashmap sequences;
+	static int initialized;
+
+	if (!initialized) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+		struct strbuf buf = STRBUF_INIT;
+		char *p, *eol;
+
+		hashmap_init(&sequences, (hashmap_cmp_fn)sequence_entry_cmp,
+			     NULL, 0);
+
+		argv_array_pushl(&cp.args, "infocmp", "-L", "-1", NULL);
+		if (pipe_command(&cp, NULL, 0, &buf, 0, NULL, 0))
+			strbuf_setlen(&buf, 0);
+
+		for (eol = p = buf.buf; *p; p = eol + 1) {
+			p = strchr(p, '=');
+			if (!p)
+				break;
+			p++;
+			eol = strchrnul(p, '\n');
+
+			if (starts_with(p, "\\E")) {
+				char *comma = memchr(p, ',', eol - p);
+				struct escape_sequence_entry *e;
+
+				p[0] = '^';
+				p[1] = '[';
+				FLEX_ALLOC_MEM(e, sequence, p, comma - p);
+				hashmap_entry_init(&e->entry,
+						   strhash(e->sequence));
+				hashmap_add(&sequences, &e->entry);
+			}
+			if (!*eol)
+				break;
+		}
+		initialized = 1;
+	}
+
+	return !!hashmap_get_from_hash(&sequences, strhash(sequence), sequence);
+}
+
 int read_key_without_echo(struct strbuf *buf)
 {
 	static int warning_displayed;

@@ -271,7 +337,12 @@ int read_key_without_echo(struct strbuf *buf)
 		 * Start by replacing the Escape byte with ^[ */
 		strbuf_splice(buf, buf->len - 1, 1, "^[", 2);
 
-		for (;;) {
+		/*
+		 * Query the terminal capabilities once about all the Escape
+		 * sequences it knows about, so that we can avoid waiting for
+		 * half a second when we know that the sequence is complete.
+		 */
+		while (!is_known_escape_sequence(buf->buf)) {
 			struct pollfd pfd = { .fd = 0, .events = POLLIN };
 
 			if (poll(&pfd, 1, 500) < 1)

gitgitgadget

From: Johannes Schindelin <[email protected]>

This job runs the test suite twice, once in regular mode, and once with a whole slew of GIT_TEST_* variables set.

Now that the built-in version of git add --interactive is feature-complete, let's also throw GIT_TEST_MULTI_PACK_INDEX into that fray.

---
 ci/run-build-and-tests.sh | 1 +
 1 file changed, 1 insertion(+)

index ff0ef7f08e..4df54c4efe 100755
@@ -20,6 +20,7 @@ linux-gcc)
 	export GIT_TEST_OE_DELTA_SIZE=5
 	export GIT_TEST_COMMIT_GRAPH=1
 	export GIT_TEST_MULTI_PACK_INDEX=1
+	export GIT_TEST_ADD_I_USE_BUILTIN=1
 	make test
 	;;
 linux-gcc-4.8)

gitgitgadget

GIT_TEST_MULTI_PACK_INDEX? ;)

Hi Gábor,

Whoops. Copy/paste fail.

Fixed in v2,
Dscho

"Johannes Schindelin via GitGitGadget" <[email protected]>

Huh?

Hi Junio,

Right. This is so obvious a copy/edit fail, but don't you know, I read through these patches multiple times and still failed to notice...

Fixed in v2,
Dscho

"Johannes Schindelin via GitGitGadget" <[email protected]>

It is not generally helpful to those who reads this list to use a commit that is not part of history leading to my 'pu' or 'next' as the base.

I am guessing that it will build on top of the "use add -i/p from more commands" series, so I'll try to apply these on top there, but I wonder if it would help readers if we had some extra comments for human consumption next to "base-commit:" line (similar to the other stuff like Published-As added by GGG), perhaps in a format similar to the one we use to refer to random commits, e.g.

    base-commit: 2d4b85ddc76af3e703e6e3a6a72319b5e79c2d8b
    # commit --interactive: make it work with the built-in `add -i`, 2019-12-17

perhaps?

I think there was only one spot that needed adjusting to the newer iteration of the js/patch-mode-in-others-in-c series.

This may have started as "there are some configuration variables that are ignored in the C version, fix them" and that may be why the pull-request branch says "config-settings", but overall, I think the bulk of the change ends up being a "how would we implement the annoying-to-implement-portably single-key behaviour".

I think it is a mistake to write the lower-level terminal access code without using established libraries (or write it with a higher level abstraction offered by scripting languages like Perl and Pythnon), and I would personally take, given a choice between accepting such maintenance/porting liability and dropping of single-key behaviour, the latter in any second.

I wonder if it makes sense to split this series into two so that the early and easier part for leftover config bits can graduate separately early in the next cycle, instead of letting the parts that tackles the terminal nightmare (note that the problem being nightmare is not the fault of this topic) which would inevitably take more time to stabilize take the remainder of the series hostage to it.

Thanks.

I've no opinion on the implementation or maintenance work.

But as a heavy user of git add -p with interactive.singlekey I'd like to keep this feature in Git. It makes using git add -p a lot more comfortable for me.

Regards
Simon

+ privacy is necessary
+ using gnupg http://gnupg.org
+ public key id: 0x92FEFDB7E44C32F9

Hi Junio,

I wondered about the same two things: whether to use an established library, and whether to split off the patches for the config settings.

Alas, I did not find any established library that I could use on Windows, so there is _already_ a precedent for doing it the way my patches do it. And if we already have to e.g. spawn infocmp and poll to catch Escape sequences for Windows, my reasoning went: why not just do it for all platforms? This simplifies the overall complexity of the patches, as we do not have to do _too_ different things for Windows vs non-Windows.

About the config settings, sure, they could be split off, but for me this patch series really is about getting the built-in to reach parity with the Perl script version of git add -i/git add -p.

In short, I really would like to keep the overall direction of this patch series intact.

Ciao,
Dscho

Hi Junio,

Right, but it _was_ part of pu. I based it directly on an earlier version of js/patch-mode-in-others-in-c.

This is actually the output of git format-patch --base=.... I agree that your suggestion makes sense, and just like you suggested in another recent mail, it would probably make sense for git format-patch to learn that trick and for GitGitGadget to simply be just one of the users.

Ciao,
Dscho

This is the final leg of the journey to a fully built-in git add: the git add -i and git add -p modes were re-implemented in C, but they lacked support for a couple of config settings.

The one that sticks out most is the interactive.singleKey setting: it was particularly hard to get to work, especially on Windows.

It also seems to be the setting that is incomplete already in the Perl version of the interactive add command: while the name of the config setting suggests that it applies to all of the interactive add, including the main loop of git add --interactive and to the file selections in that command, it does not. Only the git add --patch mode respects that setting.

As it is outside the purpose of the conversion of git-add--interactive.perl to C, we will leave that loose end for some future date.

Changes since v1:

* Fixed the commit message where a copy/paste fail made it talk about another GIT_TEST_* variable than the GIT_TEST_ADD_I_USE_BUILTIN one.

Johannes Schindelin (9):
built-in add -p: support interactive.diffFilter
built-in add -p: handle diff.algorithm
terminal: make the code of disable_echo() reusable
terminal: accommodate Git for Windows' default terminal
terminal: add a new function to read a single keystroke built-in add -p: respect the interactive.singlekey config setting built-in add -p: handle Escape sequences in interactive.singlekey mode built-in add -p: handle Escape sequences more efficiently
ci: include the built-in git add -i in the linux-gcc job

 add-interactive.c         |  19 +++
 add-interactive.h         |   4 +
 add-patch.c               |  57 ++++++++-
 ci/run-build-and-tests.sh |   1 +
 compat/terminal.c         | 249 +++++++++++++++++++++++++++++++++++++-
 compat/terminal.h         |   3 +
 6 files changed, 325 insertions(+), 8 deletions(-)

base-commit: c480eeb574e649a19f27dc09a994e45f9b2c2622
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-175%2Fdscho%2Fadd-p-in-c-config-settings-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-175/dscho/add-p-in-c-config-settings-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/175

Range-diff vs v1:

  1:  a7355776d6 =  1:  f45ff08bd0 built-in add -p: support interactive.diffFilter
  2:  74958419f6 !  2:  e9c4a13cbf built-in add -p: handle diff.algorithm
     @@ -62,7 +62,7 @@
      @@
       	int res;
       
     - 	argv_array_pushv(&args, s->mode->diff);
     + 	argv_array_pushv(&args, s->mode->diff_cmd);
      +	if (diff_algorithm)
      +		argv_array_pushf(&args, "--diff-algorithm=%s", diff_algorithm);
       	if (s->revision) {
  3:  7631c1ea8c =  3:  e643554dba terminal: make the code of disable_echo() reusable
  4:  a77fa914da =  4:  bd2306c5d5 terminal: accommodate Git for Windows' default terminal
  5:  3996d7997a =  5:  190fb4f5e9 terminal: add a new function to read a single keystroke
  6:  6d6794089d !  6:  167dfa37dd built-in add -p: respect the `interactive.singlekey` config setting
     @@ -54,7 +54,7 @@
      +#include "compat/terminal.h"
       
       enum prompt_mode_type {
     - 	PROMPT_MODE_CHANGE = 0, PROMPT_DELETION, PROMPT_HUNK
     + 	PROMPT_MODE_CHANGE = 0, PROMPT_DELETION, PROMPT_HUNK,
      @@
       	return 0;
       }
  7:  fd5a129776 =  7:  32067bebe8 built-in add -p: handle Escape sequences in interactive.singlekey mode
  8:  af9b598738 =  8:  703719ffce built-in add -p: handle Escape sequences more efficiently
  9:  9719604a1f !  9:  23a3a47b01 ci: include the built-in `git add -i` in the `linux-gcc` job

@@ -6,8 +6,8 @@
a whole slew of GIT_TEST_* variables set.

Now that the built-in version of git add --interactive is
- feature-complete, let's also throw GIT_TEST_MULTI_PACK_INDEX into that
- fray.
+ feature-complete, let's also throw GIT_TEST_ADD_I_USE_BUILTIN into
+ that fray.

gitgitgadget

From: Johannes Schindelin <[email protected]>

The Perl version supports post-processing the colored diff (that is generated in addition to the uncolored diff, intended to offer a prettier user experience) by a command configured via that config setting, and now the built-in version does that, too.

---
 add-interactive.c | 12 ++++++++++++
 add-interactive.h |  3 +++
 add-patch.c       | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 48 insertions(+)

index a5bb14f2f4..1786ea29c4 100644
@@ -52,6 +52,17 @@ void init_add_i_state(struct add_i_state *s, struct repository *r)
 		diff_get_color(s->use_color, DIFF_FILE_OLD));
 	init_color(r, s, "new", s->file_new_color,
 		diff_get_color(s->use_color, DIFF_FILE_NEW));
+
+	FREE_AND_NULL(s->interactive_diff_filter);
+	git_config_get_string("interactive.difffilter",
+			      &s->interactive_diff_filter);
+}
+
+void clear_add_i_state(struct add_i_state *s)
+{
+	FREE_AND_NULL(s->interactive_diff_filter);
+	memset(s, 0, sizeof(*s));
+	s->use_color = -1;
 }
 
 /*

@@ -1149,6 +1160,7 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 	strbuf_release(&print_file_item_data.worktree);
 	strbuf_release(&header);
 	prefix_item_list_clear(&commands);
+	clear_add_i_state(&s);
 
 	return res;
 }

index b2f23479c5..46c73867ad 100644
@@ -15,9 +15,12 @@ struct add_i_state {
 	char context_color[COLOR_MAXLEN];
 	char file_old_color[COLOR_MAXLEN];
 	char file_new_color[COLOR_MAXLEN];
+
+	char *interactive_diff_filter;
 };
 
 void init_add_i_state(struct add_i_state *s, struct repository *r);
+void clear_add_i_state(struct add_i_state *s);
 
 struct repository;
 struct pathspec;

index 46c6c183d5..78bde41df0 100644
@@ -398,6 +398,7 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 
 	if (want_color_fd(1, -1)) {
 		struct child_process colored_cp = CHILD_PROCESS_INIT;
+		const char *diff_filter = s->s.interactive_diff_filter;
 
 		setup_child_process(s, &colored_cp, NULL);
 		xsnprintf((char *)args.argv[color_arg_index], 8, "--color");

@@ -407,6 +408,24 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 		argv_array_clear(&args);
 		if (res)
 			return error(_("could not parse colored diff"));
+
+		if (diff_filter) {
+			struct child_process filter_cp = CHILD_PROCESS_INIT;
+
+			setup_child_process(s, &filter_cp,
+					    diff_filter, NULL);
+			filter_cp.git_cmd = 0;
+			filter_cp.use_shell = 1;
+			strbuf_reset(&s->buf);
+			if (pipe_command(&filter_cp,
+					 colored->buf, colored->len,
+					 &s->buf, colored->len,
+					 NULL, 0) < 0)
+				return error(_("failed to run '%s'"),
+					     diff_filter);
+			strbuf_swap(colored, &s->buf);
+		}
+
 		strbuf_complete_line(colored);
 		colored_p = colored->buf;
 		colored_pend = colored_p + colored->len;

@@ -531,6 +550,9 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 						   colored_pend - colored_p);
 			if (colored_eol)
 				colored_p = colored_eol + 1;
+			else if (p != pend)
+				/* colored shorter than non-colored? */
+				goto mismatched_output;
 			else
 				colored_p = colored_pend;
 

@@ -555,6 +577,15 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 		 */
 		hunk->splittable_into++;
 
+	/* non-colored shorter than colored? */
+	if (colored_p != colored_pend) {
+mismatched_output:
+		error(_("mismatched output from interactive.diffFilter"));
+		advise(_("Your filter must maintain a one-to-one correspondence\n"
+			 "between its input and output lines."));
+		return -1;
+	}
+
 	return 0;
 }
 

@@ -1612,6 +1643,7 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	    parse_diff(&s, ps) < 0) {
 		strbuf_release(&s.plain);
 		strbuf_release(&s.colored);
+		clear_add_i_state(&s.s);
 		return -1;
 	}
 

@@ -1630,5 +1662,6 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	strbuf_release(&s.buf);
 	strbuf_release(&s.plain);
 	strbuf_release(&s.colored);
+	clear_add_i_state(&s.s);
 	return 0;
 }

gitgitgadget

So this patch makes the test 'detect bogus diffFilter output' in 't3701-add-interactive.sh' succeed with the builtin interactive add, but I stumbled upon a test failure caused by SIGPIPE in an experimental Travis CI s390x build:

expecting success of 3701.49 'detect bogus diffFilter output':

          git reset --hard &&
  
          echo content >test &&
          test_config interactive.diffFilter "echo too-short" &&
          printf y >y &&
          test_must_fail force_color git add -p <y

+ git reset --hard
HEAD is now at 6ee5ee5 test
+ echo content
+ test_config interactive.diffFilter echo too-short
+ printf y
+ test_must_fail force_color git add -p
test_must_fail: died by signal 13: force_color git add -p
error: last command exited with $?=1

Turns out it's a general issue, and

  GIT_TEST_ADD_I_USE_BUILTIN=1 ./t3701-add-interactive.sh -r 39,49 --stress

fails within 10 seconds on my Linux box, whereas the scripted 'add -p' managed to survive a couple hundred repetitions.

Hi Gábor,

You're right, of course. And I had let that slip for too long, as I saw it sporadically happen in the Azure Pipeline, too.

This took quite a while to figure out, and I won't claim that I understand _all_ the details: I _think_ that stdin being so short "breaks the pipe" and interferes with add -p's normal operation, so I needed to explicitly use the sigchain feature to ignore SIGPIPE during add -p's main loop.

Thanks,
Dscho

From: Johannes Schindelin <[email protected]>

The Perl version of git add -p reads the config setting diff.algorithm and if set, uses it to generate the diff using the specified algorithm.

This patch ports that functionality to the C version.

Note: just like git-add--interactive.perl, we do _not_ respect this config setting in git add -i's diff command, but _only_ in the patch command.

---
 add-interactive.c | 5 +++++
 add-interactive.h | 2 +-
 add-patch.c       | 3 +++
 3 files changed, 9 insertions(+), 1 deletion(-)

index 1786ea29c4..9e4bcb382c 100644
@@ -56,11 +56,16 @@ void init_add_i_state(struct add_i_state *s, struct repository *r)
 	FREE_AND_NULL(s->interactive_diff_filter);
 	git_config_get_string("interactive.difffilter",
 			      &s->interactive_diff_filter);
+
+	FREE_AND_NULL(s->interactive_diff_algorithm);
+	git_config_get_string("diff.algorithm",
+			      &s->interactive_diff_algorithm);
 }
 
 void clear_add_i_state(struct add_i_state *s)
 {
 	FREE_AND_NULL(s->interactive_diff_filter);
+	FREE_AND_NULL(s->interactive_diff_algorithm);
 	memset(s, 0, sizeof(*s));
 	s->use_color = -1;
 }

index 46c73867ad..923efaf527 100644
@@ -16,7 +16,7 @@ struct add_i_state {
 	char file_old_color[COLOR_MAXLEN];
 	char file_new_color[COLOR_MAXLEN];
 
-	char *interactive_diff_filter;
+	char *interactive_diff_filter, *interactive_diff_algorithm;
 };
 
 void init_add_i_state(struct add_i_state *s, struct repository *r);

index 78bde41df0..8f2ee8688b 100644
@@ -360,6 +360,7 @@ static int is_octal(const char *p, size_t len)
 static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 {
 	struct argv_array args = ARGV_ARRAY_INIT;
+	const char *diff_algorithm = s->s.interactive_diff_algorithm;
 	struct strbuf *plain = &s->plain, *colored = NULL;
 	struct child_process cp = CHILD_PROCESS_INIT;
 	char *p, *pend, *colored_p = NULL, *colored_pend = NULL, marker = '\0';

@@ -369,6 +370,8 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 	int res;
 
 	argv_array_pushv(&args, s->mode->diff_cmd);
+	if (diff_algorithm)
+		argv_array_pushf(&args, "--diff-algorithm=%s", diff_algorithm);
 	if (s->revision) {
 		struct object_id oid;
 		argv_array_push(&args,

gitgitgadget

From: Johannes Schindelin <[email protected]>

We are about to introduce the function enable_non_canonical(), which shares almost the complete code with disable_echo().

Let's prepare for that, by refactoring out that shared code.

---
 compat/terminal.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

index fa13ee672d..1fb40b3a0a 100644
@@ -32,7 +32,7 @@ static void restore_term(void)
 	term_fd = -1;
 }
 
-static int disable_echo(void)
+static int disable_bits(tcflag_t bits)
 {
 	struct termios t;
 

@@ -43,7 +43,7 @@ static int disable_echo(void)
 	old_term = t;
 	sigchain_push_common(restore_term_on_signal);
 
-	t.c_lflag &= ~ECHO;
+	t.c_lflag &= ~bits;
 	if (!tcsetattr(term_fd, TCSAFLUSH, &t))
 		return 0;
 

@@ -53,6 +53,11 @@ static int disable_echo(void)
 	return -1;
 }
 
+static int disable_echo(void)
+{
+	return disable_bits(ECHO);
+}
+
 #elif defined(GIT_WINDOWS_NATIVE)
 
 #define INPUT_PATH "CONIN$"

@@ -72,7 +77,7 @@ static void restore_term(void)
 	hconin = INVALID_HANDLE_VALUE;
 }
 
-static int disable_echo(void)
+static int disable_bits(DWORD bits)
 {
 	hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE,
 	    FILE_SHARE_READ, NULL, OPEN_EXISTING,

@@ -82,7 +87,7 @@ static int disable_echo(void)
 
 	GetConsoleMode(hconin, &cmode);
 	sigchain_push_common(restore_term_on_signal);
-	if (!SetConsoleMode(hconin, cmode & (~ENABLE_ECHO_INPUT))) {
+	if (!SetConsoleMode(hconin, cmode & ~bits)) {
 		CloseHandle(hconin);
 		hconin = INVALID_HANDLE_VALUE;
 		return -1;

@@ -91,6 +96,12 @@ static int disable_echo(void)
 	return 0;
 }
 
+static int disable_echo(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT);
+}
+
+
 #endif
 
 #ifndef FORCE_TEXT

gitgitgadget

From: Johannes Schindelin <[email protected]>

Git for Windows' Git Bash runs in MinTTY by default, which does not have a Win32 Console instance, but uses MSYS2 pseudo terminals instead.

This is a problem, as Git for Windows does not want to use the MSYS2 emulation layer for Git itself, and therefore has no direct way to interact with that pseudo terminal.

As a workaround, use the stty utility (which is included in Git for Windows, and which *is* an MSYS2 program, so it knows how to deal with the pseudo terminal).

Note: If Git runs in a regular CMD or PowerShell window, there *is* a regular Win32 Console to work with. This is not a problem for the MSYS2 stty: it copes with this scenario just fine.

Also note that we introduce support for more bits than would be necessary for a mere disable_echo() here, in preparation for the upcoming enable_non_canonical() function.

---
 compat/terminal.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

index 1fb40b3a0a..16e9949da1 100644
@@ -2,6 +2,8 @@
 #include "compat/terminal.h"
 #include "sigchain.h"
 #include "strbuf.h"
+#include "run-command.h"
+#include "string-list.h"
 
 #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE)
 

@@ -64,11 +66,28 @@ static int disable_echo(void)
 #define OUTPUT_PATH "CONOUT$"
 #define FORCE_TEXT "t"
 
+static int use_stty = 1;
+static struct string_list stty_restore = STRING_LIST_INIT_DUP;
 static HANDLE hconin = INVALID_HANDLE_VALUE;
 static DWORD cmode;
 
 static void restore_term(void)
 {
+	if (use_stty) {
+		int i;
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		if (stty_restore.nr == 0)
+			return;
+
+		argv_array_push(&cp.args, "stty");
+		for (i = 0; i < stty_restore.nr; i++)
+			argv_array_push(&cp.args, stty_restore.items[i].string);
+		run_command(&cp);
+		string_list_clear(&stty_restore, 0);
+		return;
+	}
+
 	if (hconin == INVALID_HANDLE_VALUE)
 		return;
 

@@ -79,6 +98,37 @@ static void restore_term(void)
 
 static int disable_bits(DWORD bits)
 {
+	if (use_stty) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		argv_array_push(&cp.args, "stty");
+
+		if (bits & ENABLE_LINE_INPUT) {
+			string_list_append(&stty_restore, "icanon");
+			argv_array_push(&cp.args, "-icanon");
+		}
+
+		if (bits & ENABLE_ECHO_INPUT) {
+			string_list_append(&stty_restore, "echo");
+			argv_array_push(&cp.args, "-echo");
+		}
+
+		if (bits & ENABLE_PROCESSED_INPUT) {
+			string_list_append(&stty_restore, "-ignbrk");
+			string_list_append(&stty_restore, "intr");
+			string_list_append(&stty_restore, "^c");
+			argv_array_push(&cp.args, "ignbrk");
+			argv_array_push(&cp.args, "intr");
+			argv_array_push(&cp.args, "");
+		}
+
+		if (run_command(&cp) == 0)
+			return 0;
+
+		/* `stty` could not be executed; access the Console directly */
+		use_stty = 0;
+	}
+
 	hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE,
 	    FILE_SHARE_READ, NULL, OPEN_EXISTING,
 	    FILE_ATTRIBUTE_NORMAL, NULL);

gitgitgadget

From: Johannes Schindelin <[email protected]>

Typically, input on the command-line is line-based. It is actually not really easy to get single characters (or better put: keystrokes).

We provide two implementations here:

- One that handles /dev/tty based systems as well as native Windows. The former uses the tcsetattr() function to put the terminal into "raw mode", which allows us to read individual keystrokes, one by one. The latter uses stty.exe to do the same, falling back to direct Win32 Console access.

Thanks to the refactoring leading up to this commit, this is a single function, with the platform-specific details hidden away in conditionally-compiled code blocks.

- A fall-back which simply punts and reads back an entire line.

Note that the function writes the keystroke into an strbuf rather than a char, in preparation for reading Escape sequences (e.g. when the user hit an arrow key). This is also required for UTF-8 sequences in case the keystroke corresponds to a non-ASCII letter.

---
 compat/terminal.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++
 compat/terminal.h |  3 +++
 2 files changed, 58 insertions(+)

index 16e9949da1..1b2564042a 100644
@@ -60,6 +60,11 @@ static int disable_echo(void)
 	return disable_bits(ECHO);
 }
 
+static int enable_non_canonical(void)
+{
+	return disable_bits(ICANON | ECHO);
+}
+
 #elif defined(GIT_WINDOWS_NATIVE)
 
 #define INPUT_PATH "CONIN$"

@@ -151,6 +156,10 @@ static int disable_echo(void)
 	return disable_bits(ENABLE_ECHO_INPUT);
 }
 
+static int enable_non_canonical(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
+}
 
 #endif
 

@@ -198,6 +207,33 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return buf.buf;
 }
 
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	int ch;
+
+	if (warning_displayed || enable_non_canonical() < 0) {
+		if (!warning_displayed) {
+			warning("reading single keystrokes not supported on "
+				"this platform; reading line instead");
+			warning_displayed = 1;
+		}
+
+		return strbuf_getline(buf, stdin);
+	}
+
+	strbuf_reset(buf);
+	ch = getchar();
+	if (ch == EOF) {
+		restore_term();
+		return EOF;
+	}
+
+	strbuf_addch(buf, ch);
+	restore_term();
+	return 0;
+}
+
 #else
 
 char *git_terminal_prompt(const char *prompt, int echo)

@@ -205,4 +241,23 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return getpass(prompt);
 }
 
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	const char *res;
+
+	if (!warning_displayed) {
+		warning("reading single keystrokes not supported on this "
+			"platform; reading line instead");
+		warning_displayed = 1;
+	}
+
+	res = getpass("");
+	strbuf_reset(buf);
+	if (!res)
+		return EOF;
+	strbuf_addstr(buf, res);
+	return 0;
+}
+
 #endif

index 97db7cd69d..a9d52b8464 100644
@@ -3,4 +3,7 @@
 
 char *git_terminal_prompt(const char *prompt, int echo);
 
+/* Read a single keystroke, without echoing it to the terminal */
+int read_key_without_echo(struct strbuf *buf);
+
 #endif /* COMPAT_TERMINAL_H */

gitgitgadget

From: Johannes Schindelin <[email protected]>

The Perl version of git add -p supports this config setting to allow users to input commands via single characters (as opposed to having to press the <Enter> key afterwards).

This is an opt-in feature because it requires Perl packages (Term::ReadKey and Term::Cap, where it tries to handle an absence of the latter package gracefully) to work. Note that at least on Ubuntu, that Perl package is not installed by default (it needs to be installed via sudo apt-get install libterm-readkey-perl), so this feature is probably not used a whole lot.

In C, we obviously do not have these packages available, but we just introduced read_single_keystroke() that is similar to what Term::ReadKey provides, and we use that here.

---
 add-interactive.c |  2 ++
 add-interactive.h |  1 +
 add-patch.c       | 21 +++++++++++++++++----
 3 files changed, 20 insertions(+), 4 deletions(-)

index 9e4bcb382c..39c3896494 100644
@@ -60,6 +60,8 @@ void init_add_i_state(struct add_i_state *s, struct repository *r)
 	FREE_AND_NULL(s->interactive_diff_algorithm);
 	git_config_get_string("diff.algorithm",
 			      &s->interactive_diff_algorithm);
+
+	git_config_get_bool("interactive.singlekey", &s->use_single_key);
 }
 
 void clear_add_i_state(struct add_i_state *s)

index 923efaf527..693f125e8e 100644
@@ -16,6 +16,7 @@ struct add_i_state {
 	char file_old_color[COLOR_MAXLEN];
 	char file_new_color[COLOR_MAXLEN];
 
+	int use_single_key;
 	char *interactive_diff_filter, *interactive_diff_algorithm;
 };
 

index 8f2ee8688b..d8dafa8168 100644
@@ -6,6 +6,7 @@
 #include "pathspec.h"
 #include "color.h"
 #include "diff.h"
+#include "compat/terminal.h"
 
 enum prompt_mode_type {
 	PROMPT_MODE_CHANGE = 0, PROMPT_DELETION, PROMPT_HUNK,

@@ -1149,14 +1150,27 @@ static int run_apply_check(struct add_p_state *s,
 	return 0;
 }
 
+static int read_single_character(struct add_p_state *s)
+{
+	if (s->s.use_single_key) {
+		int res = read_key_without_echo(&s->answer);
+		printf("%s\n", res == EOF ? "" : s->answer.buf);
+		return res;
+	}
+
+	if (strbuf_getline(&s->answer, stdin) == EOF)
+		return EOF;
+	strbuf_trim_trailing_newline(&s->answer);
+	return 0;
+}
+
 static int prompt_yesno(struct add_p_state *s, const char *prompt)
 {
 	for (;;) {
 		color_fprintf(stdout, s->s.prompt_color, "%s", _(prompt));
 		fflush(stdout);
-		if (strbuf_getline(&s->answer, stdin) == EOF)
+		if (read_single_character(s) == EOF)
 			return -1;
-		strbuf_trim_trailing_newline(&s->answer);
 		switch (tolower(s->answer.buf[0])) {
 		case 'n': return 0;
 		case 'y': return 1;

@@ -1396,9 +1410,8 @@ static int patch_update_file(struct add_p_state *s,
 			      _(s->mode->prompt_mode[prompt_mode_type]),
 			      s->buf.buf);
 		fflush(stdout);
-		if (strbuf_getline(&s->answer, stdin) == EOF)
+		if (read_single_character(s) == EOF)
 			break;
-		strbuf_trim_trailing_newline(&s->answer);
 
 		if (!s->answer.len)
 			continue;

gitgitgadget

From: Johannes Schindelin <[email protected]>

This recapitulates part of b5cc003253c8 (add -i: ignore terminal escape sequences, 2011-05-17):

add -i: ignore terminal escape sequences

On the author's terminal, the up-arrow input sequence is ^[[A, and thus fat-fingering an up-arrow into 'git checkout -p' is quite
dangerous: git-add--interactive.perl will ignore the ^[ and [ characters and happily treat A as "discard everything".

As a band-aid fix, use Term::Cap to get all terminal capabilities. Then use the heuristic that any capability value that starts with ^[ (i.e., \e in perl) must be a key input sequence. Finally, given an input that starts with ^[, read more characters until we have read a full escape sequence, then return that to the caller. We use a timeout of 0.5 seconds on the subsequent reads to avoid getting stuck if the user actually input a lone ^[.

Since none of the currently recognized keys start with ^[, the net result is that the sequence as a whole will be ignored and the help displayed.

Note that we leave part for later which uses "Term::Cap to get all terminal capabilities", for several reasons:

1. it is actually not really necessary, as the timeout of 0.5 seconds should be plenty sufficient to catch Escape sequences,

2. it is cleaner to keep the change to special-case Escape sequences separate from the change that reads all terminal capabilities to speed things up, and

3. in practice, relying on the terminal capabilities is a bit overrated, as the information could be incomplete, or plain wrong. For example, in this developer's tmux sessions, the terminal capabilities claim that the "cursor up" sequence is ^[M, but the actual sequence produced by the "cursor up" key is ^[[A.

---
 compat/terminal.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

index 1b2564042a..b7f58d1781 100644
@@ -161,6 +161,37 @@ static int enable_non_canonical(void)
 	return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
 }
 
+/*
+ * Override `getchar()`, as the default implementation does not use
+ * `ReadFile()`.
+ *
+ * This poses a problem when we want to see whether the standard
+ * input has more characters, as the default of Git for Windows is to start the
+ * Bash in a MinTTY, which uses a named pipe to emulate a pty, in which case
+ * our `poll()` emulation calls `PeekNamedPipe()`, which seems to require
+ * `ReadFile()` to be called first to work properly (it only reports 0
+ * available bytes, otherwise).
+ *
+ * So let's just override `getchar()` with a version backed by `ReadFile()` and
+ * go our merry ways from here.
+ */
+static int mingw_getchar(void)
+{
+	DWORD read = 0;
+	unsigned char ch;
+
+	if (!ReadFile(GetStdHandle(STD_INPUT_HANDLE), &ch, 1, &read, NULL))
+		return EOF;
+
+	if (!read) {
+		error("Unexpected 0 read");
+		return EOF;
+	}
+
+	return ch;
+}
+#define getchar mingw_getchar
+
 #endif
 
 #ifndef FORCE_TEXT

@@ -228,8 +259,31 @@ int read_key_without_echo(struct strbuf *buf)
 		restore_term();
 		return EOF;
 	}
-
 	strbuf_addch(buf, ch);
+
+	if (ch == '\033' /* ESC */) {
+		/*
+		 * We are most likely looking at an Escape sequence. Let's try
+		 * to read more bytes, waiting at most half a second, assuming
+		 * that the sequence is complete if we did not receive any byte
+		 * within that time.
+		 *
+		 * Start by replacing the Escape byte with ^[ */
+		strbuf_splice(buf, buf->len - 1, 1, "^[", 2);
+
+		for (;;) {
+			struct pollfd pfd = { .fd = 0, .events = POLLIN };
+
+			if (poll(&pfd, 1, 500) < 1)
+				break;
+
+			ch = getchar();
+			if (ch == EOF)
+				return 0;
+			strbuf_addch(buf, ch);
+		}
+	}
+
 	restore_term();
 	return 0;
 }

gitgitgadget

From: Johannes Schindelin <[email protected]>

When interactive.singlekey = true, we react immediately to keystrokes, even to Escape sequences (e.g. when pressing a cursor key).

The problem with Escape sequences is that we do not really know when they are done, and as a heuristic we poll standard input for half a second to make sure that we got all of it.

While waiting half a second is not asking for a whole lot, it can become quite annoying over time, therefore with this patch, we read the terminal capabilities (if available) and extract known Escape sequences from there, then stop polling immediately when we detected that the user pressed a key that generated such a known sequence.

This recapitulates the remaining part of b5cc003253c8 (add -i: ignore terminal escape sequences, 2011-05-17).

Note: We do *not* query the terminal capabilities directly. That would either require a lot of platform-specific code, or it would require linking to a library such as ncurses.

Linking to a library in the built-ins is something we try very hard to avoid (we even kicked the libcurl dependency to a non-built-in remote helper, just to shave off a tiny fraction of a second from Git's startup time). And the platform-specific code would be a maintenance nightmare.

Even worse: in Git for Windows' case, we would need to query MSYS2 pseudo terminals, which git.exe simply cannot do (because it is intentionally *not* an MSYS2 program).

To address this, we simply spawn infocmp -L -1 and parse its output (which works even in Git for Windows, because that helper is included in the end-user facing installations).

This is done only once, as in the Perl version, but it is done only when the first Escape sequence is encountered, not upon startup of git add -i; This saves on startup time, yet makes reacting to the first Escape sequence slightly more sluggish. But it allows us to keep the terminal-related code encapsulated in the compat/terminal.c file.

---
 compat/terminal.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

index b7f58d1781..35bca03d14 100644
@@ -4,6 +4,7 @@
 #include "strbuf.h"
 #include "run-command.h"
 #include "string-list.h"
+#include "hashmap.h"
 
 #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE)
 

@@ -238,6 +239,71 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return buf.buf;
 }
 
+/*
+ * The `is_known_escape_sequence()` function returns 1 if the passed string
+ * corresponds to an Escape sequence that the terminal capabilities contains.
+ *
+ * To avoid depending on ncurses or other platform-specific libraries, we rely
+ * on the presence of the `infocmp` executable to do the job for us (failing
+ * silently if the program is not available or refused to run).
+ */
+struct escape_sequence_entry {
+	struct hashmap_entry entry;
+	char sequence[FLEX_ARRAY];
+};
+
+static int sequence_entry_cmp(const void *hashmap_cmp_fn_data,
+			      const struct escape_sequence_entry *e1,
+			      const struct escape_sequence_entry *e2,
+			      const void *keydata)
+{
+	return strcmp(e1->sequence, keydata ? keydata : e2->sequence);
+}
+
+static int is_known_escape_sequence(const char *sequence)
+{
+	static struct hashmap sequences;
+	static int initialized;
+
+	if (!initialized) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+		struct strbuf buf = STRBUF_INIT;
+		char *p, *eol;
+
+		hashmap_init(&sequences, (hashmap_cmp_fn)sequence_entry_cmp,
+			     NULL, 0);
+
+		argv_array_pushl(&cp.args, "infocmp", "-L", "-1", NULL);
+		if (pipe_command(&cp, NULL, 0, &buf, 0, NULL, 0))
+			strbuf_setlen(&buf, 0);
+
+		for (eol = p = buf.buf; *p; p = eol + 1) {
+			p = strchr(p, '=');
+			if (!p)
+				break;
+			p++;
+			eol = strchrnul(p, '\n');
+
+			if (starts_with(p, "\\E")) {
+				char *comma = memchr(p, ',', eol - p);
+				struct escape_sequence_entry *e;
+
+				p[0] = '^';
+				p[1] = '[';
+				FLEX_ALLOC_MEM(e, sequence, p, comma - p);
+				hashmap_entry_init(&e->entry,
+						   strhash(e->sequence));
+				hashmap_add(&sequences, &e->entry);
+			}
+			if (!*eol)
+				break;
+		}
+		initialized = 1;
+	}
+
+	return !!hashmap_get_from_hash(&sequences, strhash(sequence), sequence);
+}
+
 int read_key_without_echo(struct strbuf *buf)
 {
 	static int warning_displayed;

@@ -271,7 +337,12 @@ int read_key_without_echo(struct strbuf *buf)
 		 * Start by replacing the Escape byte with ^[ */
 		strbuf_splice(buf, buf->len - 1, 1, "^[", 2);
 
-		for (;;) {
+		/*
+		 * Query the terminal capabilities once about all the Escape
+		 * sequences it knows about, so that we can avoid waiting for
+		 * half a second when we know that the sequence is complete.
+		 */
+		while (!is_known_escape_sequence(buf->buf)) {
 			struct pollfd pfd = { .fd = 0, .events = POLLIN };
 
 			if (poll(&pfd, 1, 500) < 1)

gitgitgadget

From: Johannes Schindelin <[email protected]>

This job runs the test suite twice, once in regular mode, and once with a whole slew of GIT_TEST_* variables set.

Now that the built-in version of git add --interactive is feature-complete, let's also throw GIT_TEST_ADD_I_USE_BUILTIN into that fray.

---
 ci/run-build-and-tests.sh | 1 +
 1 file changed, 1 insertion(+)

index ff0ef7f08e..4df54c4efe 100755
@@ -20,6 +20,7 @@ linux-gcc)
 	export GIT_TEST_OE_DELTA_SIZE=5
 	export GIT_TEST_COMMIT_GRAPH=1
 	export GIT_TEST_MULTI_PACK_INDEX=1
+	export GIT_TEST_ADD_I_USE_BUILTIN=1
 	make test
 	;;
 linux-gcc-4.8)

gitgitgadget

Hi Stolee,

Thank you for catching this!

It makes me wonder whether the test-coverage builds should use some sed invocation on the ci/run-build-and-tests.sh script, though, so that you do not have to edit the Azure Pipelines definition manually all the time?

Ciao,
Dscho

"Johannes Schindelin via GitGitGadget" <[email protected]>

This matches what is queued (with a hand-fix while queuing), so I'll keep it, together with the older author dates.

Thanks.

This is the final leg of the journey to a fully built-in git add: the git add -i and git add -p modes were re-implemented in C, but they lacked support for a couple of config settings.

The one that sticks out most is the interactive.singleKey setting: it was particularly hard to get to work, especially on Windows.

It also seems to be the setting that is incomplete already in the Perl version of the interactive add command: while the name of the config setting suggests that it applies to all of the interactive add, including the main loop of git add --interactive and to the file selections in that command, it does not. Only the git add --patch mode respects that setting.

As it is outside the purpose of the conversion of git-add--interactive.perl to C, we will leave that loose end for some future date.

Changes since v2:

* Fixed the SIGPIPE issue pointed out by Gábor Szeder.

Changes since v1:

* Fixed the commit message where a copy/paste fail made it talk about another GIT_TEST_* variable than the GIT_TEST_ADD_I_USE_BUILTIN one.

Johannes Schindelin (10):
built-in add -i/-p: treat SIGPIPE as EOF
built-in add -p: support interactive.diffFilter
built-in add -p: handle diff.algorithm
terminal: make the code of disable_echo() reusable
terminal: accommodate Git for Windows' default terminal
terminal: add a new function to read a single keystroke built-in add -p: respect the interactive.singlekey config setting built-in add -p: handle Escape sequences in interactive.singlekey mode built-in add -p: handle Escape sequences more efficiently
ci: include the built-in git add -i in the linux-gcc job

 add-interactive.c         |  22 ++++
 add-interactive.h         |   4 +
 add-patch.c               |  61 +++++++++-
 ci/run-build-and-tests.sh |   1 +
 compat/terminal.c         | 249 +++++++++++++++++++++++++++++++++++++-
 compat/terminal.h         |   3 +
 6 files changed, 332 insertions(+), 8 deletions(-)

base-commit: c480eeb574e649a19f27dc09a994e45f9b2c2622
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-175%2Fdscho%2Fadd-p-in-c-config-settings-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-175/dscho/add-p-in-c-config-settings-v3
Pull-Request: https://github.com/gitgitgadget/git/pull/175

Range-diff vs v2:

  -:  ---------- >  1:  5e258a8d2b built-in add -i/-p: treat SIGPIPE as EOF
  1:  f45ff08bd0 !  2:  2a5951ecfe built-in add -p: support interactive.diffFilter
     @@ -35,9 +35,9 @@
       	strbuf_release(&header);
       	prefix_item_list_clear(&commands);
      +	clear_add_i_state(&s);
     + 	sigchain_pop(SIGPIPE);
       
       	return res;
     - }
      
       diff --git a/add-interactive.h b/add-interactive.h
       --- a/add-interactive.h
     @@ -123,13 +123,14 @@
       		strbuf_release(&s.plain);
       		strbuf_release(&s.colored);
      +		clear_add_i_state(&s.s);
     + 		sigchain_pop(SIGPIPE);
       		return -1;
       	}
     - 
      @@
       	strbuf_release(&s.buf);
       	strbuf_release(&s.plain);
       	strbuf_release(&s.colored);
      +	clear_add_i_state(&s.s);
     + 	sigchain_pop(SIGPIPE);
       	return 0;
       }
  2:  e9c4a13cbf =  3:  a2bce01818 built-in add -p: handle diff.algorithm
  3:  e643554dba =  4:  be40a37c0c terminal: make the code of disable_echo() reusable
  4:  bd2306c5d5 =  5:  233f23791c terminal: accommodate Git for Windows' default terminal
  5:  190fb4f5e9 =  6:  74593b5115 terminal: add a new function to read a single keystroke
  6:  167dfa37dd !  7:  197fe1e14a built-in add -p: respect the `interactive.singlekey` config setting
     @@ -48,9 +48,9 @@
       --- a/add-patch.c
       +++ b/add-patch.c
      @@
     - #include "pathspec.h"
       #include "color.h"
       #include "diff.h"
     + #include "sigchain.h"
      +#include "compat/terminal.h"
       
       enum prompt_mode_type {
  7:  32067bebe8 =  8:  9ab381d539 built-in add -p: handle Escape sequences in interactive.singlekey mode
  8:  703719ffce =  9:  bdb6268b8b built-in add -p: handle Escape sequences more efficiently
  9:  23a3a47b01 = 10:  c4195969a6 ci: include the built-in `git add -i` in the `linux-gcc` job

gitgitgadget

From: Johannes Schindelin <[email protected]>

As noticed by Gábor Szeder, if we want to run git add -p with redirected input through test_must_fail in the test suite, we must expect that a SIGPIPE can happen due to stdin coming to its end.

The appropriate action here is to ignore that signal and treat it as a regular end-of-file, otherwise the test will fail. In preparation for such a test, introduce precisely this handling of SIGPIPE into the built-in version of git add -p.

For good measure, teach the built-in git add -i the same trick: it _also_ runs a loop waiting for input, and can receive a SIGPIPE just the same (and wants to treat it as end-of-file, too).

---
 add-interactive.c | 3 +++
 add-patch.c       | 4 ++++
 2 files changed, 7 insertions(+)

index a5bb14f2f4..3ff8400ea4 100644
@@ -9,6 +9,7 @@
 #include "lockfile.h"
 #include "dir.h"
 #include "run-command.h"
+#include "sigchain.h"
 
 static void init_color(struct repository *r, struct add_i_state *s,
 		       const char *slot_name, char *dst,

@@ -1097,6 +1098,7 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 			->util = util;
 	}
 
+	sigchain_push(SIGPIPE, SIG_IGN);
 	init_add_i_state(&s, r);
 
 	/*

@@ -1149,6 +1151,7 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 	strbuf_release(&print_file_item_data.worktree);
 	strbuf_release(&header);
 	prefix_item_list_clear(&commands);
+	sigchain_pop(SIGPIPE);
 
 	return res;
 }

index 46c6c183d5..9a3beed72e 100644
@@ -6,6 +6,7 @@
 #include "pathspec.h"
 #include "color.h"
 #include "diff.h"
+#include "sigchain.h"
 
 enum prompt_mode_type {
 	PROMPT_MODE_CHANGE = 0, PROMPT_DELETION, PROMPT_HUNK,

@@ -1578,6 +1579,7 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	};
 	size_t i, binary_count = 0;
 
+	sigchain_push(SIGPIPE, SIG_IGN);
 	init_add_i_state(&s.s, r);
 
 	if (mode == ADD_P_STASH)

@@ -1612,6 +1614,7 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	    parse_diff(&s, ps) < 0) {
 		strbuf_release(&s.plain);
 		strbuf_release(&s.colored);
+		sigchain_pop(SIGPIPE);
 		return -1;
 	}
 

@@ -1630,5 +1633,6 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	strbuf_release(&s.buf);
 	strbuf_release(&s.plain);
 	strbuf_release(&s.colored);
+	sigchain_pop(SIGPIPE);
 	return 0;
 }

gitgitgadget

I don't think this issue is related to the redirected input: I modified that flaky test to send "unlimited" data to 'git add's stdin, i.e.:

/usr/bin/yes | test_must_fail force_color git add -p

and the test with --stress still failed with SIGPIPE all the same and just as fast.

After looking into it, the issue seems to be sending data to the broken diffFilter process. So in that test the diff is "filtered" through 'echo too-short', which exits real fast, and doesn't read its standard input at all (well, apart from e.g. the usual kernel buffering that might happen on a pipe between the two processes). Making sure that the diffFilter process reads all the data before exiting, i.e. changing it to:

test_config interactive.diffFilter "cat >/dev/null ; echo too-short" &&

made the test reliable, with over 2000 --stress repetitions, and that with only a single "y" on 'git add's stdin.

Now, merely tweaking the test is clearly insufficient, because we not only want the test to be realiable, but we want 'git add' to die gracefully when users out there mess up their configuration.

Ignoring SIGPIPE can surely accomplish that, but I'm not sure about the scope. I mean your patch seems to ignore SIGPIPE basically for almost the whole 'git add -(i|p)' process, but perhaps it should be limited only to the surroundings of the pipe_command() call running the diffFilter, and be done as part of the next patch adding the 'if (diff_filter)' block.

Furthermore, I'm worried that by simply ignoring SIGPIPE we might just ignore a more fundamental issue in pipe_command(): shouldn't that function be smart enough not to write() to a fd that has no one on the other side to read it in the first place?!

So, when the diffFilter process exits unexpectedly early, then the poll() call in pipe_command() -> pump_io() -> pump_io_round() returns with success and usually sets 'revents' for the child process' stdin to 12 (i.e. 'POLLOUT | POLLERR'; gah, how I hate unnamed constants :). Unfortunately, at that point we don't take any special action on POLLERR, but call xwrite() to try to write to the dead fd anyway, which then promptly triggers SIGPIPE. (This is what usually happens when stepping through the statements of those functions in a debugger, and the diffFilter process has all the time in the world to exit.)

We could handle POLLERR with a patch like this:

--- >8 ---

Subject: run-command: handle POLLERR in pump_io_round() to reduce risk of SIGPIPE

index 3449db319b..57093f0acc 100644
@@ -1416,25 +1416,31 @@ static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
 	if (poll(pfd, pollsize, -1) < 0) {
 		if (errno == EINTR)
 			return 1;
 		die_errno("poll failed");
 	}
 
 	for (i = 0; i < nr; i++) {
 		struct io_pump *io = &slots[i];
 
 		if (io->fd < 0)
 			continue;
 
-		if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
+		if (io->pfd->revents & POLLERR) {
+			io->error = ECONNRESET;  /* What should we report to the caller? */
+			close(io->fd);
+			io->fd = -1;
+			continue;
+		}
+		if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLNVAL)))
 			continue;
 
 		if (io->type == POLLOUT) {
 			ssize_t len = xwrite(io->fd,
 					     io->u.out.buf, io->u.out.len);
 			if (len < 0) {
 				io->error = errno;
 				close(io->fd);
 				io->fd = -1;
 			} else {
 				io->u.out.buf += len;
 				io->u.out.len -= len;

--- >8 ---

Unfortunately #1, this changes the error 'git add -p' dies with from:

error: mismatched output from interactive.diffFilter

to:

error: failed to run 'echo too-short'

It might affect other commands as well, but FWIW the test suite doesn't catch any.

Unfortunately #2, the above patch doesn't completely eliminates the SIGPIPE, but only (greatly) reduces its probability. It is possible that:

- poll() returns with success and indicating a writable fd without

    any error, i.e. 'revents = 4'.

- the bogus diffFilter exits, closing its stdin.

- 'git add' attempts to xwrite() to the now closed fd, and triggers a SIGPIPE right away.

This happens much rarer, 'GIT_TEST_ADD_I_USE_BUILTIN=1 ./t3701-add-interactive.sh -r 39,49 --stress-jobs=<4*nr-of-cores> --stress' tends to take over 200 repetitions. The patch below reproduces it fairly reliably by adding two strategically-placed sleep()s, with a bit of extra debug output:

--- >8 ---

index d8dafa8168..0fd017bbd3 100644
@@ -421,6 +421,7 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 			filter_cp.git_cmd = 0;
 			filter_cp.use_shell = 1;
 			strbuf_reset(&s->buf);
+			fprintf(stderr, "about to run diffFilter\n");
 			if (pipe_command(&filter_cp,
 					 colored->buf, colored->len,
 					 &s->buf, colored->len,

index 57093f0acc..49ae88a922 100644
@@ -1419,6 +1419,7 @@ static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
 		die_errno("poll failed");
 	}
 
+	sleep(2);
 	for (i = 0; i < nr; i++) {
 		struct io_pump *io = &slots[i];
 

@@ -1435,8 +1436,11 @@ static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
 			continue;
 
 		if (io->type == POLLOUT) {
-			ssize_t len = xwrite(io->fd,
+			ssize_t len;
+			fprintf(stderr, "attempting to xwrite() %lu bytes to a fd with revents flags 0x%hx\n", io->u.out.len, io->pfd->revents);
+			len = xwrite(io->fd,
 					     io->u.out.buf, io->u.out.len);
+			fprintf(stderr, "after xwrite()\n");
 			if (len < 0) {
 				io->error = errno;
 				close(io->fd);

index 12ee321707..acffc9af37 100755
@@ -561,7 +561,7 @@ test_expect_success 'detect bogus diffFilter output' '
 	git reset --hard &&
 
 	echo content >test &&
-	test_config interactive.diffFilter "echo too-short" &&
+	test_config interactive.diffFilter "sleep 1 ; echo too-short" &&
 	printf y >y &&
 	test_must_fail force_color git add -p <y
 '

--- >8 ---

and 'GIT_TEST_ADD_I_USE_BUILTIN=1 ./t3701-add-interactive.sh -r 39,49' fails with:

+ test_must_fail force_color git add -p
about to run diffFilter
attempting to xwrite() 224 bytes to a fd with revents flags 0x4
test_must_fail: died by signal 13: force_color git add -p

I don't understand why we get SIGPIPE right away instead of some error that we can act upon (ECONNRESET?). FWIW, it fails the same way not only on my box, but on Travis CI's Linux and OSX images as well.

https://travis-ci.org/szeder/git/jobs/636446843#L2937

Cc'ing Peff for all things SIGPIPE :) who also happens to be the author of both pipe_command() and that now flaky test.

Yeah, I agree the test should be changed. What you wrote above was my first thought, too, but I think "sed 1d" is actually a more realistic test (and is shorter and one fewer process).

I also agree that it would be nice to deal with this for real-world cases. I suspect it's not something that would come up a lot, though.

The scope there is probably OK in practice. In my opinion SIGPIPE is usually _not_ what the behavior we want. If we're carefully checking our write() return values, then we'd get EPIPE in such an instance and behave appropriately. And if we're not checking our write() return values, that's generally a bug that ought to be fixed.

The big exception is when we are writing copious output to stdout (or the pager) via printf() or similar, and want to die rather than continue writing output nobody will see. But I don't think git-add really counts as generating a lot of output, where EPIPE could prevent us from doing useless work (unlike, say, git-log).

Maybe. As you noted below, checking for POLLERR is racy. Seeing that we "can" write to an fd and doing it to discover what write() returns (whether error or not) doesn't seem like the worst strategy. If the caller cares about pipe death, then it needs to be handling SIGPIPE anyway.

I really wish there was a way to set a handler for SIGPIPE that tells _which_ descriptor caused it. Because I think logic like "die if it was fd 1, ignore and let write() return EPIPE otherwise" is the behavior we'd like. But I don't think there's a portable way to do so.

I've been tempted to say that we should just ignore SIGPIPE everywhere, and convert even copious-output programs like git-log to just check for errors (they could probably even just check ferror(stdout) for each commit we output, if we didn't want to touch every printf call).

-Peff

I am not sure what we are aiming for. Are we making sure the command behaves well in the hands of end users, who may write a script that consumes only early parts of the input that is needed for its use and stops reading, or are we just aiming to claim "all our tests pass"? I was hoping that we would be doing the former, and I would understand if the suggestion were "sed 1q" for that exact reason.

IOW, shouldn't we be fixing the part that drives the external process, so that the test "passes" even with such a "broken" filter?

Yes, and I was hoping that we do not have to touch the test if we did the latter.

Yeah, I share that temptation.

The original motivation for this test (and the code that fixes it) was diff-so-fancy, which read all of the input but didn't have a 1:1 line correspondence in the output (IIRC it condensed some particular lines, like rename from/to into a single line).

And I think most sane filters would end up reading all of the content. Or a misconfiguration would cause them to read nothing at all.

So something like "sed 1d" is more representative of a real filter. If we want to test SIGPIPE, then the current one that reads _nothing_ is the most torturous. But "sed 1q" is neither realistic (if that's what we're going for) nor the hardest thing we can throw at the code (if that's what we want).

Hmm. My recollection was that you were more of a fan of SIGPIPE than I am. But if you agree, then maybe the time has come for action. :)

-Peff

Hi Gábor,

Ouch. Thank you for investigating. For my education, how did you debug this? I could not find a way to identify *what* caused that SIGPIPE...

Ah, my diff filter simply ignores the stdin... That's easy enough to fix, and since real-world diff filters probably won't just blatantly ignore the input, I think it is legitimate to change the test.

I think it is sufficient to tweak the test, but I agree that a better error message might be good when users out there mess up their configuration.

Right. Very heavy-handed, and probably inviting unwanted side effects.

Hmm. My first impression is that the error message could be a bit better, but that it is probably a good thing to have. It would have helped _me_ understand the issue at hand.

Isn't it buffered?

In any case, I would take the above-mentioned patch, even if it makes it "only" less likely to hit SIGPIPE.

I'll go with Peff's suggestion to use sed 1d instead of echo too-short.

Thanks,
Dscho

Doh', because it's a pipe, not a socket, that's why. pipe(7):

"If all file descriptors referring to the read end of a pipe have
been closed, then a write(2) will cause a SIGPIPE signal to be generated for the calling process."

So ECONNRESET is definitely not the right error to set on POLLERR, though I'm still not sure what the right one would be (perhaps EPIPE?).

Yes, if SIGPIPE is ignored, then that write() would produce EPIPE. So if you're trying to emulate it via POLLERR, that would be accurate. Of course it could fail for _other_ reasons, and I don't think we'd know what those are without actually calling write(). Practically speaking, though, if we know it's a pipe with a valid descriptor then any error is basically equivalent to EPIPE (we don't care how, but for whatever reason we couldn't write to the other end).

-Peff

From: Johannes Schindelin <[email protected]>

The Perl version supports post-processing the colored diff (that is generated in addition to the uncolored diff, intended to offer a prettier user experience) by a command configured via that config setting, and now the built-in version does that, too.

---
 add-interactive.c | 12 ++++++++++++
 add-interactive.h |  3 +++
 add-patch.c       | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 48 insertions(+)

index 3ff8400ea4..b36e5d97d8 100644
@@ -53,6 +53,17 @@ void init_add_i_state(struct add_i_state *s, struct repository *r)
 		diff_get_color(s->use_color, DIFF_FILE_OLD));
 	init_color(r, s, "new", s->file_new_color,
 		diff_get_color(s->use_color, DIFF_FILE_NEW));
+
+	FREE_AND_NULL(s->interactive_diff_filter);
+	git_config_get_string("interactive.difffilter",
+			      &s->interactive_diff_filter);
+}
+
+void clear_add_i_state(struct add_i_state *s)
+{
+	FREE_AND_NULL(s->interactive_diff_filter);
+	memset(s, 0, sizeof(*s));
+	s->use_color = -1;
 }
 
 /*

@@ -1151,6 +1162,7 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 	strbuf_release(&print_file_item_data.worktree);
 	strbuf_release(&header);
 	prefix_item_list_clear(&commands);
+	clear_add_i_state(&s);
 	sigchain_pop(SIGPIPE);
 
 	return res;

index b2f23479c5..46c73867ad 100644
@@ -15,9 +15,12 @@ struct add_i_state {
 	char context_color[COLOR_MAXLEN];
 	char file_old_color[COLOR_MAXLEN];
 	char file_new_color[COLOR_MAXLEN];
+
+	char *interactive_diff_filter;
 };
 
 void init_add_i_state(struct add_i_state *s, struct repository *r);
+void clear_add_i_state(struct add_i_state *s);
 
 struct repository;
 struct pathspec;

index 9a3beed72e..7d6015229c 100644
@@ -399,6 +399,7 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 
 	if (want_color_fd(1, -1)) {
 		struct child_process colored_cp = CHILD_PROCESS_INIT;
+		const char *diff_filter = s->s.interactive_diff_filter;
 
 		setup_child_process(s, &colored_cp, NULL);
 		xsnprintf((char *)args.argv[color_arg_index], 8, "--color");

@@ -408,6 +409,24 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 		argv_array_clear(&args);
 		if (res)
 			return error(_("could not parse colored diff"));
+
+		if (diff_filter) {
+			struct child_process filter_cp = CHILD_PROCESS_INIT;
+
+			setup_child_process(s, &filter_cp,
+					    diff_filter, NULL);
+			filter_cp.git_cmd = 0;
+			filter_cp.use_shell = 1;
+			strbuf_reset(&s->buf);
+			if (pipe_command(&filter_cp,
+					 colored->buf, colored->len,
+					 &s->buf, colored->len,
+					 NULL, 0) < 0)
+				return error(_("failed to run '%s'"),
+					     diff_filter);
+			strbuf_swap(colored, &s->buf);
+		}
+
 		strbuf_complete_line(colored);
 		colored_p = colored->buf;
 		colored_pend = colored_p + colored->len;

@@ -532,6 +551,9 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 						   colored_pend - colored_p);
 			if (colored_eol)
 				colored_p = colored_eol + 1;
+			else if (p != pend)
+				/* colored shorter than non-colored? */
+				goto mismatched_output;
 			else
 				colored_p = colored_pend;
 

@@ -556,6 +578,15 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 		 */
 		hunk->splittable_into++;
 
+	/* non-colored shorter than colored? */
+	if (colored_p != colored_pend) {
+mismatched_output:
+		error(_("mismatched output from interactive.diffFilter"));
+		advise(_("Your filter must maintain a one-to-one correspondence\n"
+			 "between its input and output lines."));
+		return -1;
+	}
+
 	return 0;
 }
 

@@ -1614,6 +1645,7 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	    parse_diff(&s, ps) < 0) {
 		strbuf_release(&s.plain);
 		strbuf_release(&s.colored);
+		clear_add_i_state(&s.s);
 		sigchain_pop(SIGPIPE);
 		return -1;
 	}

@@ -1633,6 +1665,7 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	strbuf_release(&s.buf);
 	strbuf_release(&s.plain);
 	strbuf_release(&s.colored);
+	clear_add_i_state(&s.s);
 	sigchain_pop(SIGPIPE);
 	return 0;
 }

gitgitgadget

From: Johannes Schindelin <[email protected]>

The Perl version of git add -p reads the config setting diff.algorithm and if set, uses it to generate the diff using the specified algorithm.

This patch ports that functionality to the C version.

Note: just like git-add--interactive.perl, we do _not_ respect this config setting in git add -i's diff command, but _only_ in the patch command.

---
 add-interactive.c | 5 +++++
 add-interactive.h | 2 +-
 add-patch.c       | 3 +++
 3 files changed, 9 insertions(+), 1 deletion(-)

index b36e5d97d8..e3cc30ad24 100644
@@ -57,11 +57,16 @@ void init_add_i_state(struct add_i_state *s, struct repository *r)
 	FREE_AND_NULL(s->interactive_diff_filter);
 	git_config_get_string("interactive.difffilter",
 			      &s->interactive_diff_filter);
+
+	FREE_AND_NULL(s->interactive_diff_algorithm);
+	git_config_get_string("diff.algorithm",
+			      &s->interactive_diff_algorithm);
 }
 
 void clear_add_i_state(struct add_i_state *s)
 {
 	FREE_AND_NULL(s->interactive_diff_filter);
+	FREE_AND_NULL(s->interactive_diff_algorithm);
 	memset(s, 0, sizeof(*s));
 	s->use_color = -1;
 }

index 46c73867ad..923efaf527 100644
@@ -16,7 +16,7 @@ struct add_i_state {
 	char file_old_color[COLOR_MAXLEN];
 	char file_new_color[COLOR_MAXLEN];
 
-	char *interactive_diff_filter;
+	char *interactive_diff_filter, *interactive_diff_algorithm;
 };
 
 void init_add_i_state(struct add_i_state *s, struct repository *r);

index 7d6015229c..736bcb4aa7 100644
@@ -361,6 +361,7 @@ static int is_octal(const char *p, size_t len)
 static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 {
 	struct argv_array args = ARGV_ARRAY_INIT;
+	const char *diff_algorithm = s->s.interactive_diff_algorithm;
 	struct strbuf *plain = &s->plain, *colored = NULL;
 	struct child_process cp = CHILD_PROCESS_INIT;
 	char *p, *pend, *colored_p = NULL, *colored_pend = NULL, marker = '\0';

@@ -370,6 +371,8 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 	int res;
 
 	argv_array_pushv(&args, s->mode->diff_cmd);
+	if (diff_algorithm)
+		argv_array_pushf(&args, "--diff-algorithm=%s", diff_algorithm);
 	if (s->revision) {
 		struct object_id oid;
 		argv_array_push(&args,

gitgitgadget

From: Johannes Schindelin <[email protected]>

We are about to introduce the function enable_non_canonical(), which shares almost the complete code with disable_echo().

Let's prepare for that, by refactoring out that shared code.

---
 compat/terminal.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

index fa13ee672d..1fb40b3a0a 100644
@@ -32,7 +32,7 @@ static void restore_term(void)
 	term_fd = -1;
 }
 
-static int disable_echo(void)
+static int disable_bits(tcflag_t bits)
 {
 	struct termios t;
 

@@ -43,7 +43,7 @@ static int disable_echo(void)
 	old_term = t;
 	sigchain_push_common(restore_term_on_signal);
 
-	t.c_lflag &= ~ECHO;
+	t.c_lflag &= ~bits;
 	if (!tcsetattr(term_fd, TCSAFLUSH, &t))
 		return 0;
 

@@ -53,6 +53,11 @@ static int disable_echo(void)
 	return -1;
 }
 
+static int disable_echo(void)
+{
+	return disable_bits(ECHO);
+}
+
 #elif defined(GIT_WINDOWS_NATIVE)
 
 #define INPUT_PATH "CONIN$"

@@ -72,7 +77,7 @@ static void restore_term(void)
 	hconin = INVALID_HANDLE_VALUE;
 }
 
-static int disable_echo(void)
+static int disable_bits(DWORD bits)
 {
 	hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE,
 	    FILE_SHARE_READ, NULL, OPEN_EXISTING,

@@ -82,7 +87,7 @@ static int disable_echo(void)
 
 	GetConsoleMode(hconin, &cmode);
 	sigchain_push_common(restore_term_on_signal);
-	if (!SetConsoleMode(hconin, cmode & (~ENABLE_ECHO_INPUT))) {
+	if (!SetConsoleMode(hconin, cmode & ~bits)) {
 		CloseHandle(hconin);
 		hconin = INVALID_HANDLE_VALUE;
 		return -1;

@@ -91,6 +96,12 @@ static int disable_echo(void)
 	return 0;
 }
 
+static int disable_echo(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT);
+}
+
+
 #endif
 
 #ifndef FORCE_TEXT

gitgitgadget

From: Johannes Schindelin <[email protected]>

Git for Windows' Git Bash runs in MinTTY by default, which does not have a Win32 Console instance, but uses MSYS2 pseudo terminals instead.

This is a problem, as Git for Windows does not want to use the MSYS2 emulation layer for Git itself, and therefore has no direct way to interact with that pseudo terminal.

As a workaround, use the stty utility (which is included in Git for Windows, and which *is* an MSYS2 program, so it knows how to deal with the pseudo terminal).

Note: If Git runs in a regular CMD or PowerShell window, there *is* a regular Win32 Console to work with. This is not a problem for the MSYS2 stty: it copes with this scenario just fine.

Also note that we introduce support for more bits than would be necessary for a mere disable_echo() here, in preparation for the upcoming enable_non_canonical() function.

---
 compat/terminal.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

index 1fb40b3a0a..16e9949da1 100644
@@ -2,6 +2,8 @@
 #include "compat/terminal.h"
 #include "sigchain.h"
 #include "strbuf.h"
+#include "run-command.h"
+#include "string-list.h"
 
 #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE)
 

@@ -64,11 +66,28 @@ static int disable_echo(void)
 #define OUTPUT_PATH "CONOUT$"
 #define FORCE_TEXT "t"
 
+static int use_stty = 1;
+static struct string_list stty_restore = STRING_LIST_INIT_DUP;
 static HANDLE hconin = INVALID_HANDLE_VALUE;
 static DWORD cmode;
 
 static void restore_term(void)
 {
+	if (use_stty) {
+		int i;
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		if (stty_restore.nr == 0)
+			return;
+
+		argv_array_push(&cp.args, "stty");
+		for (i = 0; i < stty_restore.nr; i++)
+			argv_array_push(&cp.args, stty_restore.items[i].string);
+		run_command(&cp);
+		string_list_clear(&stty_restore, 0);
+		return;
+	}
+
 	if (hconin == INVALID_HANDLE_VALUE)
 		return;
 

@@ -79,6 +98,37 @@ static void restore_term(void)
 
 static int disable_bits(DWORD bits)
 {
+	if (use_stty) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		argv_array_push(&cp.args, "stty");
+
+		if (bits & ENABLE_LINE_INPUT) {
+			string_list_append(&stty_restore, "icanon");
+			argv_array_push(&cp.args, "-icanon");
+		}
+
+		if (bits & ENABLE_ECHO_INPUT) {
+			string_list_append(&stty_restore, "echo");
+			argv_array_push(&cp.args, "-echo");
+		}
+
+		if (bits & ENABLE_PROCESSED_INPUT) {
+			string_list_append(&stty_restore, "-ignbrk");
+			string_list_append(&stty_restore, "intr");
+			string_list_append(&stty_restore, "^c");
+			argv_array_push(&cp.args, "ignbrk");
+			argv_array_push(&cp.args, "intr");
+			argv_array_push(&cp.args, "");
+		}
+
+		if (run_command(&cp) == 0)
+			return 0;
+
+		/* `stty` could not be executed; access the Console directly */
+		use_stty = 0;
+	}
+
 	hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE,
 	    FILE_SHARE_READ, NULL, OPEN_EXISTING,
 	    FILE_ATTRIBUTE_NORMAL, NULL);

gitgitgadget

From: Johannes Schindelin <[email protected]>

Typically, input on the command-line is line-based. It is actually not really easy to get single characters (or better put: keystrokes).

We provide two implementations here:

- One that handles /dev/tty based systems as well as native Windows. The former uses the tcsetattr() function to put the terminal into "raw mode", which allows us to read individual keystrokes, one by one. The latter uses stty.exe to do the same, falling back to direct Win32 Console access.

Thanks to the refactoring leading up to this commit, this is a single function, with the platform-specific details hidden away in conditionally-compiled code blocks.

- A fall-back which simply punts and reads back an entire line.

Note that the function writes the keystroke into an strbuf rather than a char, in preparation for reading Escape sequences (e.g. when the user hit an arrow key). This is also required for UTF-8 sequences in case the keystroke corresponds to a non-ASCII letter.

---
 compat/terminal.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++
 compat/terminal.h |  3 +++
 2 files changed, 58 insertions(+)

index 16e9949da1..1b2564042a 100644
@@ -60,6 +60,11 @@ static int disable_echo(void)
 	return disable_bits(ECHO);
 }
 
+static int enable_non_canonical(void)
+{
+	return disable_bits(ICANON | ECHO);
+}
+
 #elif defined(GIT_WINDOWS_NATIVE)
 
 #define INPUT_PATH "CONIN$"

@@ -151,6 +156,10 @@ static int disable_echo(void)
 	return disable_bits(ENABLE_ECHO_INPUT);
 }
 
+static int enable_non_canonical(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
+}
 
 #endif
 

@@ -198,6 +207,33 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return buf.buf;
 }
 
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	int ch;
+
+	if (warning_displayed || enable_non_canonical() < 0) {
+		if (!warning_displayed) {
+			warning("reading single keystrokes not supported on "
+				"this platform; reading line instead");
+			warning_displayed = 1;
+		}
+
+		return strbuf_getline(buf, stdin);
+	}
+
+	strbuf_reset(buf);
+	ch = getchar();
+	if (ch == EOF) {
+		restore_term();
+		return EOF;
+	}
+
+	strbuf_addch(buf, ch);
+	restore_term();
+	return 0;
+}
+
 #else
 
 char *git_terminal_prompt(const char *prompt, int echo)

@@ -205,4 +241,23 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return getpass(prompt);
 }
 
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	const char *res;
+
+	if (!warning_displayed) {
+		warning("reading single keystrokes not supported on this "
+			"platform; reading line instead");
+		warning_displayed = 1;
+	}
+
+	res = getpass("");
+	strbuf_reset(buf);
+	if (!res)
+		return EOF;
+	strbuf_addstr(buf, res);
+	return 0;
+}
+
 #endif

index 97db7cd69d..a9d52b8464 100644
@@ -3,4 +3,7 @@
 
 char *git_terminal_prompt(const char *prompt, int echo);
 
+/* Read a single keystroke, without echoing it to the terminal */
+int read_key_without_echo(struct strbuf *buf);
+
 #endif /* COMPAT_TERMINAL_H */

gitgitgadget

From: Johannes Schindelin <[email protected]>

The Perl version of git add -p supports this config setting to allow users to input commands via single characters (as opposed to having to press the <Enter> key afterwards).

This is an opt-in feature because it requires Perl packages (Term::ReadKey and Term::Cap, where it tries to handle an absence of the latter package gracefully) to work. Note that at least on Ubuntu, that Perl package is not installed by default (it needs to be installed via sudo apt-get install libterm-readkey-perl), so this feature is probably not used a whole lot.

In C, we obviously do not have these packages available, but we just introduced read_single_keystroke() that is similar to what Term::ReadKey provides, and we use that here.

---
 add-interactive.c |  2 ++
 add-interactive.h |  1 +
 add-patch.c       | 21 +++++++++++++++++----
 3 files changed, 20 insertions(+), 4 deletions(-)

index e3cc30ad24..bb6acf5ef6 100644
@@ -61,6 +61,8 @@ void init_add_i_state(struct add_i_state *s, struct repository *r)
 	FREE_AND_NULL(s->interactive_diff_algorithm);
 	git_config_get_string("diff.algorithm",
 			      &s->interactive_diff_algorithm);
+
+	git_config_get_bool("interactive.singlekey", &s->use_single_key);
 }
 
 void clear_add_i_state(struct add_i_state *s)

index 923efaf527..693f125e8e 100644
@@ -16,6 +16,7 @@ struct add_i_state {
 	char file_old_color[COLOR_MAXLEN];
 	char file_new_color[COLOR_MAXLEN];
 
+	int use_single_key;
 	char *interactive_diff_filter, *interactive_diff_algorithm;
 };
 

index 736bcb4aa7..67741128a8 100644
@@ -7,6 +7,7 @@
 #include "color.h"
 #include "diff.h"
 #include "sigchain.h"
+#include "compat/terminal.h"
 
 enum prompt_mode_type {
 	PROMPT_MODE_CHANGE = 0, PROMPT_DELETION, PROMPT_HUNK,

@@ -1150,14 +1151,27 @@ static int run_apply_check(struct add_p_state *s,
 	return 0;
 }
 
+static int read_single_character(struct add_p_state *s)
+{
+	if (s->s.use_single_key) {
+		int res = read_key_without_echo(&s->answer);
+		printf("%s\n", res == EOF ? "" : s->answer.buf);
+		return res;
+	}
+
+	if (strbuf_getline(&s->answer, stdin) == EOF)
+		return EOF;
+	strbuf_trim_trailing_newline(&s->answer);
+	return 0;
+}
+
 static int prompt_yesno(struct add_p_state *s, const char *prompt)
 {
 	for (;;) {
 		color_fprintf(stdout, s->s.prompt_color, "%s", _(prompt));
 		fflush(stdout);
-		if (strbuf_getline(&s->answer, stdin) == EOF)
+		if (read_single_character(s) == EOF)
 			return -1;
-		strbuf_trim_trailing_newline(&s->answer);
 		switch (tolower(s->answer.buf[0])) {
 		case 'n': return 0;
 		case 'y': return 1;

@@ -1397,9 +1411,8 @@ static int patch_update_file(struct add_p_state *s,
 			      _(s->mode->prompt_mode[prompt_mode_type]),
 			      s->buf.buf);
 		fflush(stdout);
-		if (strbuf_getline(&s->answer, stdin) == EOF)
+		if (read_single_character(s) == EOF)
 			break;
-		strbuf_trim_trailing_newline(&s->answer);
 
 		if (!s->answer.len)
 			continue;

gitgitgadget

From: Johannes Schindelin <[email protected]>

This recapitulates part of b5cc003253c8 (add -i: ignore terminal escape sequences, 2011-05-17):

add -i: ignore terminal escape sequences

On the author's terminal, the up-arrow input sequence is ^[[A, and thus fat-fingering an up-arrow into 'git checkout -p' is quite
dangerous: git-add--interactive.perl will ignore the ^[ and [ characters and happily treat A as "discard everything".

As a band-aid fix, use Term::Cap to get all terminal capabilities. Then use the heuristic that any capability value that starts with ^[ (i.e., \e in perl) must be a key input sequence. Finally, given an input that starts with ^[, read more characters until we have read a full escape sequence, then return that to the caller. We use a timeout of 0.5 seconds on the subsequent reads to avoid getting stuck if the user actually input a lone ^[.

Since none of the currently recognized keys start with ^[, the net result is that the sequence as a whole will be ignored and the help displayed.

Note that we leave part for later which uses "Term::Cap to get all terminal capabilities", for several reasons:

1. it is actually not really necessary, as the timeout of 0.5 seconds should be plenty sufficient to catch Escape sequences,

2. it is cleaner to keep the change to special-case Escape sequences separate from the change that reads all terminal capabilities to speed things up, and

3. in practice, relying on the terminal capabilities is a bit overrated, as the information could be incomplete, or plain wrong. For example, in this developer's tmux sessions, the terminal capabilities claim that the "cursor up" sequence is ^[M, but the actual sequence produced by the "cursor up" key is ^[[A.

---
 compat/terminal.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

index 1b2564042a..b7f58d1781 100644
@@ -161,6 +161,37 @@ static int enable_non_canonical(void)
 	return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
 }
 
+/*
+ * Override `getchar()`, as the default implementation does not use
+ * `ReadFile()`.
+ *
+ * This poses a problem when we want to see whether the standard
+ * input has more characters, as the default of Git for Windows is to start the
+ * Bash in a MinTTY, which uses a named pipe to emulate a pty, in which case
+ * our `poll()` emulation calls `PeekNamedPipe()`, which seems to require
+ * `ReadFile()` to be called first to work properly (it only reports 0
+ * available bytes, otherwise).
+ *
+ * So let's just override `getchar()` with a version backed by `ReadFile()` and
+ * go our merry ways from here.
+ */
+static int mingw_getchar(void)
+{
+	DWORD read = 0;
+	unsigned char ch;
+
+	if (!ReadFile(GetStdHandle(STD_INPUT_HANDLE), &ch, 1, &read, NULL))
+		return EOF;
+
+	if (!read) {
+		error("Unexpected 0 read");
+		return EOF;
+	}
+
+	return ch;
+}
+#define getchar mingw_getchar
+
 #endif
 
 #ifndef FORCE_TEXT

@@ -228,8 +259,31 @@ int read_key_without_echo(struct strbuf *buf)
 		restore_term();
 		return EOF;
 	}
-
 	strbuf_addch(buf, ch);
+
+	if (ch == '\033' /* ESC */) {
+		/*
+		 * We are most likely looking at an Escape sequence. Let's try
+		 * to read more bytes, waiting at most half a second, assuming
+		 * that the sequence is complete if we did not receive any byte
+		 * within that time.
+		 *
+		 * Start by replacing the Escape byte with ^[ */
+		strbuf_splice(buf, buf->len - 1, 1, "^[", 2);
+
+		for (;;) {
+			struct pollfd pfd = { .fd = 0, .events = POLLIN };
+
+			if (poll(&pfd, 1, 500) < 1)
+				break;
+
+			ch = getchar();
+			if (ch == EOF)
+				return 0;
+			strbuf_addch(buf, ch);
+		}
+	}
+
 	restore_term();
 	return 0;
 }

gitgitgadget

From: Johannes Schindelin <[email protected]>

When interactive.singlekey = true, we react immediately to keystrokes, even to Escape sequences (e.g. when pressing a cursor key).

The problem with Escape sequences is that we do not really know when they are done, and as a heuristic we poll standard input for half a second to make sure that we got all of it.

While waiting half a second is not asking for a whole lot, it can become quite annoying over time, therefore with this patch, we read the terminal capabilities (if available) and extract known Escape sequences from there, then stop polling immediately when we detected that the user pressed a key that generated such a known sequence.

This recapitulates the remaining part of b5cc003253c8 (add -i: ignore terminal escape sequences, 2011-05-17).

Note: We do *not* query the terminal capabilities directly. That would either require a lot of platform-specific code, or it would require linking to a library such as ncurses.

Linking to a library in the built-ins is something we try very hard to avoid (we even kicked the libcurl dependency to a non-built-in remote helper, just to shave off a tiny fraction of a second from Git's startup time). And the platform-specific code would be a maintenance nightmare.

Even worse: in Git for Windows' case, we would need to query MSYS2 pseudo terminals, which git.exe simply cannot do (because it is intentionally *not* an MSYS2 program).

To address this, we simply spawn infocmp -L -1 and parse its output (which works even in Git for Windows, because that helper is included in the end-user facing installations).

This is done only once, as in the Perl version, but it is done only when the first Escape sequence is encountered, not upon startup of git add -i; This saves on startup time, yet makes reacting to the first Escape sequence slightly more sluggish. But it allows us to keep the terminal-related code encapsulated in the compat/terminal.c file.

---
 compat/terminal.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

index b7f58d1781..35bca03d14 100644
@@ -4,6 +4,7 @@
 #include "strbuf.h"
 #include "run-command.h"
 #include "string-list.h"
+#include "hashmap.h"
 
 #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE)
 

@@ -238,6 +239,71 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return buf.buf;
 }
 
+/*
+ * The `is_known_escape_sequence()` function returns 1 if the passed string
+ * corresponds to an Escape sequence that the terminal capabilities contains.
+ *
+ * To avoid depending on ncurses or other platform-specific libraries, we rely
+ * on the presence of the `infocmp` executable to do the job for us (failing
+ * silently if the program is not available or refused to run).
+ */
+struct escape_sequence_entry {
+	struct hashmap_entry entry;
+	char sequence[FLEX_ARRAY];
+};
+
+static int sequence_entry_cmp(const void *hashmap_cmp_fn_data,
+			      const struct escape_sequence_entry *e1,
+			      const struct escape_sequence_entry *e2,
+			      const void *keydata)
+{
+	return strcmp(e1->sequence, keydata ? keydata : e2->sequence);
+}
+
+static int is_known_escape_sequence(const char *sequence)
+{
+	static struct hashmap sequences;
+	static int initialized;
+
+	if (!initialized) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+		struct strbuf buf = STRBUF_INIT;
+		char *p, *eol;
+
+		hashmap_init(&sequences, (hashmap_cmp_fn)sequence_entry_cmp,
+			     NULL, 0);
+
+		argv_array_pushl(&cp.args, "infocmp", "-L", "-1", NULL);
+		if (pipe_command(&cp, NULL, 0, &buf, 0, NULL, 0))
+			strbuf_setlen(&buf, 0);
+
+		for (eol = p = buf.buf; *p; p = eol + 1) {
+			p = strchr(p, '=');
+			if (!p)
+				break;
+			p++;
+			eol = strchrnul(p, '\n');
+
+			if (starts_with(p, "\\E")) {
+				char *comma = memchr(p, ',', eol - p);
+				struct escape_sequence_entry *e;
+
+				p[0] = '^';
+				p[1] = '[';
+				FLEX_ALLOC_MEM(e, sequence, p, comma - p);
+				hashmap_entry_init(&e->entry,
+						   strhash(e->sequence));
+				hashmap_add(&sequences, &e->entry);
+			}
+			if (!*eol)
+				break;
+		}
+		initialized = 1;
+	}
+
+	return !!hashmap_get_from_hash(&sequences, strhash(sequence), sequence);
+}
+
 int read_key_without_echo(struct strbuf *buf)
 {
 	static int warning_displayed;

@@ -271,7 +337,12 @@ int read_key_without_echo(struct strbuf *buf)
 		 * Start by replacing the Escape byte with ^[ */
 		strbuf_splice(buf, buf->len - 1, 1, "^[", 2);
 
-		for (;;) {
+		/*
+		 * Query the terminal capabilities once about all the Escape
+		 * sequences it knows about, so that we can avoid waiting for
+		 * half a second when we know that the sequence is complete.
+		 */
+		while (!is_known_escape_sequence(buf->buf)) {
 			struct pollfd pfd = { .fd = 0, .events = POLLIN };
 
 			if (poll(&pfd, 1, 500) < 1)

gitgitgadget

From: Johannes Schindelin <[email protected]>

This job runs the test suite twice, once in regular mode, and once with a whole slew of GIT_TEST_* variables set.

Now that the built-in version of git add --interactive is feature-complete, let's also throw GIT_TEST_ADD_I_USE_BUILTIN into that fray.

---
 ci/run-build-and-tests.sh | 1 +
 1 file changed, 1 insertion(+)

index ff0ef7f08e..4df54c4efe 100755
@@ -20,6 +20,7 @@ linux-gcc)
 	export GIT_TEST_OE_DELTA_SIZE=5
 	export GIT_TEST_COMMIT_GRAPH=1
 	export GIT_TEST_MULTI_PACK_INDEX=1
+	export GIT_TEST_ADD_I_USE_BUILTIN=1
 	make test
 	;;
 linux-gcc-4.8)

gitgitgadget

This is the final leg of the journey to a fully built-in git add: the git add -i and git add -p modes were re-implemented in C, but they lacked support for a couple of config settings.

The one that sticks out most is the interactive.singleKey setting: it was particularly hard to get to work, especially on Windows.

It also seems to be the setting that is incomplete already in the Perl version of the interactive add command: while the name of the config setting suggests that it applies to all of the interactive add, including the main loop of git add --interactive and to the file selections in that command, it does not. Only the git add --patch mode respects that setting.

As it is outside the purpose of the conversion of git-add--interactive.perl to C, we will leave that loose end for some future date.

Changes since v3:

* Reverted that heavy-handed SIGPIPE handling.
* Instead, changed the diffFilter test case to process the standard input instead of ignoring it.

(The range diff between v2 and v4 actually only shows the new patch 1/10 "t3701: adjust difffilter test".)

Changes since v2:

* Fixed the SIGPIPE issue pointed out by Gábor Szeder.

Changes since v1:

* Fixed the commit message where a copy/paste fail made it talk about another GIT_TEST_* variable than the GIT_TEST_ADD_I_USE_BUILTIN one.

Johannes Schindelin (10):
t3701: adjust difffilter test
built-in add -p: support interactive.diffFilter
built-in add -p: handle diff.algorithm
terminal: make the code of disable_echo() reusable
terminal: accommodate Git for Windows' default terminal
terminal: add a new function to read a single keystroke built-in add -p: respect the interactive.singlekey config setting built-in add -p: handle Escape sequences in interactive.singlekey mode built-in add -p: handle Escape sequences more efficiently
ci: include the built-in git add -i in the linux-gcc job

 add-interactive.c          |  19 +++
 add-interactive.h          |   4 +
 add-patch.c                |  57 ++++++++-
 ci/run-build-and-tests.sh  |   1 +
 compat/terminal.c          | 249 ++++++++++++++++++++++++++++++++++++-
 compat/terminal.h          |   3 +
 t/t3701-add-interactive.sh |   2 +-
 7 files changed, 326 insertions(+), 9 deletions(-)

base-commit: c480eeb574e649a19f27dc09a994e45f9b2c2622
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-175%2Fdscho%2Fadd-p-in-c-config-settings-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-175/dscho/add-p-in-c-config-settings-v4
Pull-Request: https://github.com/gitgitgadget/git/pull/175

Range-diff vs v3:

  1:  5e258a8d2b <  -:  ---------- built-in add -i/-p: treat SIGPIPE as EOF
  -:  ---------- >  1:  e12df77e8a t3701: adjust difffilter test
  2:  2a5951ecfe !  2:  413a87bd79 built-in add -p: support interactive.diffFilter
     @@ -35,9 +35,9 @@
       	strbuf_release(&header);
       	prefix_item_list_clear(&commands);
      +	clear_add_i_state(&s);
     - 	sigchain_pop(SIGPIPE);
       
       	return res;
     + }
      
       diff --git a/add-interactive.h b/add-interactive.h
       --- a/add-interactive.h
     @@ -123,14 +123,13 @@
       		strbuf_release(&s.plain);
       		strbuf_release(&s.colored);
      +		clear_add_i_state(&s.s);
     - 		sigchain_pop(SIGPIPE);
       		return -1;
       	}
     + 
      @@
       	strbuf_release(&s.buf);
       	strbuf_release(&s.plain);
       	strbuf_release(&s.colored);
      +	clear_add_i_state(&s.s);
     - 	sigchain_pop(SIGPIPE);
       	return 0;
       }
  3:  a2bce01818 =  3:  062c624547 built-in add -p: handle diff.algorithm
  4:  be40a37c0c =  4:  09a8946303 terminal: make the code of disable_echo() reusable
  5:  233f23791c =  5:  a81304cb76 terminal: accommodate Git for Windows' default terminal
  6:  74593b5115 =  6:  8d9c703f3b terminal: add a new function to read a single keystroke
  7:  197fe1e14a !  7:  8ed4487ae4 built-in add -p: respect the `interactive.singlekey` config setting
     @@ -48,9 +48,9 @@
       --- a/add-patch.c
       +++ b/add-patch.c
      @@
     + #include "pathspec.h"
       #include "color.h"
       #include "diff.h"
     - #include "sigchain.h"
      +#include "compat/terminal.h"
       
       enum prompt_mode_type {
  8:  9ab381d539 =  8:  cdc609f8fa built-in add -p: handle Escape sequences in interactive.singlekey mode
  9:  bdb6268b8b =  9:  80b0f2528d built-in add -p: handle Escape sequences more efficiently
 10:  c4195969a6 = 10:  7ab7ec62d0 ci: include the built-in `git add -i` in the `linux-gcc` job

gitgitgadget

From: Johannes Schindelin <[email protected]>

In 42f7d45428e (add--interactive: detect bogus diffFilter output, 2018-03-03), we added a test case that verifies that the diffFilter feature complains appropriately when the output is too short.

In preparation for the upcoming change where the built-in add -p is taught to respect that setting, let's adjust that test a little. The problem is that echo too-short is configured as diffFilter, and it does not read the stdin. When calling it through pipe_command(), it is therefore possible that we try to feed the diff to it while it is no longer listening, and we receive a SIGPIPE.

The Perl code apparently handles this in a way similar to an end-of-file, but taking a step back, we realize that a diffFilter that does not even _look_ at its standard input is very unrealistic. The entire point of this feature is to transform the diff, not to ignore it altogether.

So let's modify the test case to reflect that insight: instead of printing some bogus text, let's use a diffFilter that deletes the first line of the diff instead.

This still tests for the same thing, but it does not confuse the built-in add -p with that SIGPIPE.

---
 t/t3701-add-interactive.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 12ee321707..ac43f835a5 100755
@@ -561,7 +561,7 @@ test_expect_success 'detect bogus diffFilter output' '
 	git reset --hard &&
 
 	echo content >test &&
-	test_config interactive.diffFilter "echo too-short" &&
+	test_config interactive.diffFilter "sed 1d" &&
 	printf y >y &&
 	test_must_fail force_color git add -p <y
 '