grep: fix multibyte regex handling under macOS

From: Diomidis Spinellis <[email protected]>

The 2013 commit 29de20504e9 fixed t0070-fundamental.sh under Darwin (macOS) by adopting Git's regex library. However, this library is compiled with NO_MBSUPPORT, which causes git-grep to work incorrectly on multibyte (e.g. UTF-8) files. Current macOS versions pass t0070-fundamental.sh with the native macOS regex library, which also supports multibyte characters.

Adjust the Makefile to use the native regex library, and call setlocale(3) to set CTYPE according to the user's preference. The setlocale(3) call is required on all platforms, but in platforms supporting gettext(3), setlocale(3) is called as a side-effect of initializing gettext(3).

To avoid running the new tests on platforms still using the compatibility library, which is compiled without multibyte support, store the corresponding NO_REGEX setting in the GIT-BUILD-OPTIONS file. This makes it available to the test scripts. In addition, adjust the test-tool regex command to work with multibyte regexes to further test a platform's support for them.

---
grep: fix multibyte regex handling under macOS

The 2013 commit 29de20504e9 fixed t0070-fundamental.sh under Darwin (macOS) by adopting Git's regex library. However, this library is compiled with NO_MBSUPPORT, which causes git-grep to work incorrectly on multibyte (e.g. UTF-8) files. Current macOS versions pass t0070-fundamental.sh with the native macOS regex library, which also supports multibyte characters.

Adjust the Makefile to use the native regex library, and call setlocale(3) to set CTYPE according to the user's preference. The setlocale(3) call is required on all platforms, but in platforms supporting gettext(3), setlocale(3) is called as a side-effect of initializing gettext(3).

To avoid running the new tests on platforms still using the compatibility library, which is compiled without multibyte support, store the corresponding NO_REGEX setting in the GIT-BUILD-OPTIONS file. This makes it available to the test scripts. In addition, adjust the test-tool regex command to work with multibyte regexes to further test a platform's support for them.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1313%2Fdspinellis%2Ffix-macos-mb-grep-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1313/dspinellis/fix-macos-mb-grep-v1
Pull-Request: https://github.com/git/git/pull/1313

 Makefile                  |  2 +-
 grep.c                    |  6 +++++-
 t/helper/test-regex.c     |  2 ++
 t/t7818-grep-multibyte.sh | 34 ++++++++++++++++++++++++++++++++++
 4 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100755 t/t7818-grep-multibyte.sh

index 04d0fd1fe60..d1a98257150 100644
@@ -1427,7 +1427,6 @@ ifeq ($(uname_S),Darwin)
 		APPLE_COMMON_CRYPTO = YesPlease
 		COMPAT_CFLAGS += -DAPPLE_COMMON_CRYPTO
 	endif
-	NO_REGEX = YesPlease
 	PTHREAD_LIBS =
 endif
 

@@ -2970,6 +2969,7 @@ GIT-BUILD-OPTIONS: FORCE
 	@echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@+
 	@echo NO_PTHREADS=\''$(subst ','\'',$(subst ','\'',$(NO_PTHREADS)))'\' >>$@+
 	@echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@+
+	@echo NO_REGEX=\''$(subst ','\'',$(subst ','\'',$(NO_REGEX)))'\' >>$@+
 	@echo NO_UNIX_SOCKETS=\''$(subst ','\'',$(subst ','\'',$(NO_UNIX_SOCKETS)))'\' >>$@+
 	@echo PAGER_ENV=\''$(subst ','\'',$(subst ','\'',$(PAGER_ENV)))'\' >>$@+
 	@echo DC_SHA1=\''$(subst ','\'',$(subst ','\'',$(DC_SHA1)))'\' >>$@+

index 82eb7da1022..c31657c3da3 100644
@@ -10,6 +10,8 @@
 #include "quote.h"
 #include "help.h"
 
+#include <locale.h>
+
 static int grep_source_load(struct grep_source *gs);
 static int grep_source_is_binary(struct grep_source *gs,
 				 struct index_state *istate);

@@ -707,8 +709,10 @@ static struct grep_expr *grep_splice_or(struct grep_expr *x, struct grep_expr *y
 void compile_grep_patterns(struct grep_opt *opt)
 {
 	struct grep_pat *p;
-	struct grep_expr *header_expr = prep_header_patterns(opt);
+	struct grep_expr *header_expr;
 
+	setlocale(LC_CTYPE, "");
+	header_expr = prep_header_patterns(opt);
 	for (p = opt->pattern_list; p; p = p->next) {
 		switch (p->token) {
 		case GREP_PATTERN: /* atom */

index d6f28ca8d14..ae4d7854abd 100644
@@ -1,5 +1,6 @@
 #include "test-tool.h"
 #include "gettext.h"
+#include <locale.h>
 
 struct reg_flag {
 	const char *name;

@@ -85,6 +86,7 @@ int cmd__regex(int argc, const char **argv)
 	}
 	git_setup_gettext();
 
+	setlocale(LC_CTYPE, "");
 	ret = regcomp(&r, pat, flags);
 	if (ret) {
 		if (silent)

new file mode 100755
index 00000000000..72129880fac
@@ -0,0 +1,34 @@
+#!/bin/sh
+
+test_description='grep multibyte characters'
+
+. ./test-lib.sh
+
+# Multibyte regex search is only supported with a native regex library
+# that supports them.
+# (The included library is compiled with NO_MBSUPPORT) and only if it
+test -z "$NO_REGEX" &&
+  LC_ALL=en_US.UTF-8 test-tool regex '^.$' '¿' &&
+  test_set_prereq MB_REGEX
+
+if ! test_have_prereq MB_REGEX
+then
+  skip_all='multibyte grep tests; Git compiled with NO_REGEX, NO_MBSUPPORT'
+  test_done
+fi
+
+test_expect_success 'setup' '
+	test_write_lines "¿" >file &&
+	git add file &&
+	LC_ALL="en_US.UTF-8" &&
+	export LC_ALL
+'
+test_expect_success 'grep exactly one char in single-char multibyte file' '
+	git grep "^.$"
+'
+
+test_expect_code 1 'grep two chars in single-char multibyte file' '
+	git grep ".."
+'
+
+test_done

base-commit: ad60dddad72dfb8367bd695028b5b8dc6c33661b

gitgitgadget

Thank you for pointing this out. I posted an update that fixes this.

Diomidis

From: Diomidis Spinellis <[email protected]>

The 2013 commit 29de20504e9 fixed t0070-fundamental.sh under Darwin (macOS) by adopting Git's regex library. However, this library is compiled with NO_MBSUPPORT, which causes git-grep to work incorrectly on multibyte (e.g. UTF-8) files. Current macOS versions pass t0070-fundamental.sh with the native macOS regex library, which also supports multibyte characters.

Adjust the Makefile to use the native regex library, and call setlocale(3) to set CTYPE according to the user's preference. The setlocale(3) call is required on all platforms, but in platforms supporting gettext(3), setlocale(3) is called as a side-effect of initializing gettext(3).

To avoid running the new tests on platforms still using the compatibility library, which is compiled without multibyte support, store the corresponding NO_REGEX setting in the GIT-BUILD-OPTIONS file. This makes it available to the test scripts. In addition, adjust the test-tool regex command to work with multibyte regexes to further test a platform's support for them.

---
grep: fix multibyte regex handling under macOS

The 2013 commit 29de20504e9 fixed t0070-fundamental.sh under Darwin (macOS) by adopting Git's regex library. However, this library is compiled with NO_MBSUPPORT, which causes git-grep to work incorrectly on multibyte (e.g. UTF-8) files. Current macOS versions pass t0070-fundamental.sh with the native macOS regex library, which also supports multibyte characters.

Adjust the Makefile to use the native regex library, and call setlocale(3) to set CTYPE according to the user's preference. The setlocale(3) call is required on all platforms, but in platforms supporting gettext(3), setlocale(3) is called as a side-effect of initializing gettext(3).

To avoid running the new tests on platforms still using the compatibility library, which is compiled without multibyte support, store the corresponding NO_REGEX setting in the GIT-BUILD-OPTIONS file. This makes it available to the test scripts. In addition, adjust the test-tool regex command to work with multibyte regexes to further test a platform's support for them.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1313%2Fdspinellis%2Ffix-macos-mb-grep-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1313/dspinellis/fix-macos-mb-grep-v2
Pull-Request: https://github.com/git/git/pull/1313

Range-diff vs v1:

1: d29b93537f4 ! 1: 1d390b493c1 grep: fix multibyte regex handling under macOS
@@ t/t7818-grep-multibyte.sh (new)
+. ./test-lib.sh
+
+# Multibyte regex search is only supported with a native regex library
-+# that supports them.
-+# (The included library is compiled with NO_MBSUPPORT) and only if it ++# that supports it.
++# (The supplied compatibility library is compiled with NO_MBSUPPORT.)
+test -z "$NO_REGEX" &&
+ LC_ALL=en_US.UTF-8 test-tool regex '^.$' '¿' &&
+ test_set_prereq MB_REGEX

 Makefile                  |  2 +-
 grep.c                    |  6 +++++-
 t/helper/test-regex.c     |  2 ++
 t/t7818-grep-multibyte.sh | 34 ++++++++++++++++++++++++++++++++++
 4 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100755 t/t7818-grep-multibyte.sh

index 04d0fd1fe60..d1a98257150 100644
@@ -1427,7 +1427,6 @@ ifeq ($(uname_S),Darwin)
 		APPLE_COMMON_CRYPTO = YesPlease
 		COMPAT_CFLAGS += -DAPPLE_COMMON_CRYPTO
 	endif
-	NO_REGEX = YesPlease
 	PTHREAD_LIBS =
 endif
 

@@ -2970,6 +2969,7 @@ GIT-BUILD-OPTIONS: FORCE
 	@echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@+
 	@echo NO_PTHREADS=\''$(subst ','\'',$(subst ','\'',$(NO_PTHREADS)))'\' >>$@+
 	@echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@+
+	@echo NO_REGEX=\''$(subst ','\'',$(subst ','\'',$(NO_REGEX)))'\' >>$@+
 	@echo NO_UNIX_SOCKETS=\''$(subst ','\'',$(subst ','\'',$(NO_UNIX_SOCKETS)))'\' >>$@+
 	@echo PAGER_ENV=\''$(subst ','\'',$(subst ','\'',$(PAGER_ENV)))'\' >>$@+
 	@echo DC_SHA1=\''$(subst ','\'',$(subst ','\'',$(DC_SHA1)))'\' >>$@+

index 82eb7da1022..c31657c3da3 100644
@@ -10,6 +10,8 @@
 #include "quote.h"
 #include "help.h"
 
+#include <locale.h>
+
 static int grep_source_load(struct grep_source *gs);
 static int grep_source_is_binary(struct grep_source *gs,
 				 struct index_state *istate);

@@ -707,8 +709,10 @@ static struct grep_expr *grep_splice_or(struct grep_expr *x, struct grep_expr *y
 void compile_grep_patterns(struct grep_opt *opt)
 {
 	struct grep_pat *p;
-	struct grep_expr *header_expr = prep_header_patterns(opt);
+	struct grep_expr *header_expr;
 
+	setlocale(LC_CTYPE, "");
+	header_expr = prep_header_patterns(opt);
 	for (p = opt->pattern_list; p; p = p->next) {
 		switch (p->token) {
 		case GREP_PATTERN: /* atom */

index d6f28ca8d14..ae4d7854abd 100644
@@ -1,5 +1,6 @@
 #include "test-tool.h"
 #include "gettext.h"
+#include <locale.h>
 
 struct reg_flag {
 	const char *name;

@@ -85,6 +86,7 @@ int cmd__regex(int argc, const char **argv)
 	}
 	git_setup_gettext();
 
+	setlocale(LC_CTYPE, "");
 	ret = regcomp(&r, pat, flags);
 	if (ret) {
 		if (silent)

new file mode 100755
index 00000000000..6cffcb33e26
@@ -0,0 +1,34 @@
+#!/bin/sh
+
+test_description='grep multibyte characters'
+
+. ./test-lib.sh
+
+# Multibyte regex search is only supported with a native regex library
+# that supports it.
+# (The supplied compatibility library is compiled with NO_MBSUPPORT.)
+test -z "$NO_REGEX" &&
+  LC_ALL=en_US.UTF-8 test-tool regex '^.$' '¿' &&
+  test_set_prereq MB_REGEX
+
+if ! test_have_prereq MB_REGEX
+then
+  skip_all='multibyte grep tests; Git compiled with NO_REGEX, NO_MBSUPPORT'
+  test_done
+fi
+
+test_expect_success 'setup' '
+	test_write_lines "¿" >file &&
+	git add file &&
+	LC_ALL="en_US.UTF-8" &&
+	export LC_ALL
+'
+test_expect_success 'grep exactly one char in single-char multibyte file' '
+	git grep "^.$"
+'
+
+test_expect_code 1 'grep two chars in single-char multibyte file' '
+	git grep ".."
+'
+
+test_done

base-commit: ad60dddad72dfb8367bd695028b5b8dc6c33661b

gitgitgadget

"Diomidis Spinellis via GitGitGadget" <[email protected]>

Very nice to see the last sentence in that paragraph.

This part, from here ...

... up to here does not need a separate sign-off. It is primarily to describe what got changed between v1 and this version. The changes can be seen in range-diff, and in some cases what the range-diff shows is sufficient to understand the difference, but it is better to either (1) supply explanation in your own words, or (2) omit almost duplicate description.

[...]

Apologies for this. I was led to believe that gitgitgadget would seamlessly interface between GitHub's pull request and the Git project's email workflow, but I don't see this happening. Not sure if this is due to a fault in gitgitgadget or due to my misuse of it. I think gitgitgadget expects users not to squash their subsequent commits. In any case, I'm switching to git-send-mail, which provides more visibility and control of the process.

I was also surprised to see a $(uname) conditional in the Makefile. I prefer to finish the macOS grep UTF-8 bug fix before discussing related house cleaning.

Thank you for clarifying the division of responsibility among files. I changed the fix accordingly.

I believe that grep was working by accident on other platforms, thanks to setlocale calls made in gettext.c. I don't think grep should depend on the implementation of gettext. Thankfully, according to test results, it turns out that we can now globally initialize the CTYPE locale, making its state available both to gettext.c and grep.c.