config: add documentation to config.h

From: Heba Waly <[email protected]>

This commit is copying and summarizing the documentation from documentation/technical/api-config.txt to comments in config.h

+ * A config callback function takes three parameters:
+ *
+ * - the name of the parsed variable. This is in canonical "flat" form: the

+ *   section, subsection, and variable segments will be separated by dots,
+ *   and the section and variable segments will be all lowercase. E.g.,
+ *   `core.ignorecase`, `diff.SomeType.textconv`.

+ *
+ * - the value of the found variable, as a string. If the variable had no
+ * value specified, the value will be NULL (typically this means it
+ * should be interpreted as boolean true).
+ *
+ * - a void pointer passed in by the caller of the config API; this can
+ * contain callback-specific data
+ *
+ * A config callback should return 0 for success, or -1 if the variable
+ * could not be parsed properly.
+ */

config.h +1 -0

+
 struct object_id;
 
 /* git_config_parse_key() returns these negated: */

Quoted 5 lines

From: Heba Waly <[email protected]>

This commit is copying and summarizing the documentation from documentation/technical/api-config.txt to comments in config.h

Thanks for this commit!

As for your commit message, as far as I know, the idea is to move the documentation, not to copy it. Also, write this in imperative form, e.g.:

Move the documentation from Documentation/technical/api-config.txt into config.h.

Also change the title of the commit message accordingly, e.g.:

config: move documentation to header file

Also, include the deletion of api-config.txt in this commit.

If you are doing any summarizing, describe what summarizing you are doing in the commit message too.

Quoted 20 lines

+ * A config callback function takes three parameters:
+ *
+ * - the name of the parsed variable. This is in canonical "flat" form: the

+ *   section, subsection, and variable segments will be separated by dots,
+ *   and the section and variable segments will be all lowercase. E.g.,
+ *   `core.ignorecase`, `diff.SomeType.textconv`.

+ *
+ * - the value of the found variable, as a string. If the variable had no
+ * value specified, the value will be NULL (typically this means it
+ * should be interpreted as boolean true).
+ *
+ * - a void pointer passed in by the caller of the config API; this can
+ * contain callback-specific data
+ *
+ * A config callback should return 0 for success, or -1 if the variable
+ * could not be parsed properly.
+ */
+
struct object_id;

config.h struct config_options { · line 109

Quoted 5 lines

/* git_config_parse_key() returns these negated: */

config.h +0 -0

@@ -73,6 +107,11 @@ struct config_options {
 
 typedef int (*config_fn_t)(const char *, const char *, void *);
 int git_default_config(const char *, const char *, void *);

The config callback is config_fn_t so that documentation should be placed above that typedef.

Other than that, this looks good to me. The result is perhaps not as tidy as we would like (especially with some functions being documented and others not) but I think, anyway, that a verbatim movement should be done in one commit (this one) and improvements, in a subsequent commit.

From: Heba Waly <[email protected]>

This commit is copying and summarizing the documentation from documentation/technical/api-config.txt to comments in config.h

Signed-off-by Heba Waly <[email protected]>

---
 config.h | 327 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 327 insertions(+)

config.h +53 -0

index f0ed464004..fa999a2ba0 100644
@@ -4,6 +4,40 @@
 #include "hashmap.h"
 #include "string-list.h"
 
+
+/**
+ * The config API gives callers a way to access Git configuration files
+ * (and files which have the same syntax). See linkgit:git-config[1] for a
+ * discussion of the config file syntax.
+ *
+ * General Usage
+ * -------------
+ *
+ * Config files are parsed linearly, and each variable found is passed to a
+ * caller-provided callback function. The callback function is responsible
+ * for any actions to be taken on the config option, and is free to ignore
+ * some options. It is not uncommon for the configuration to be parsed
+ * several times during the run of a Git program, with different callbacks
+ * picking out different variables useful to themselves.
+ *
+ * A config callback function takes three parameters:
+ *
+ * - the name of the parsed variable. This is in canonical "flat" form: the
+ *   section, subsection, and variable segments will be separated by dots,
+ *   and the section and variable segments will be all lowercase. E.g.,
+ *   `core.ignorecase`, `diff.SomeType.textconv`.
+ *
+ * - the value of the found variable, as a string. If the variable had no
+ *   value specified, the value will be NULL (typically this means it
+ *   should be interpreted as boolean true).
+ *
+ * - a void pointer passed in by the caller of the config API; this can
+ *   contain callback-specific data
+ *
+ * A config callback should return 0 for success, or -1 if the variable
+ * could not be parsed properly.
+ */
+
 struct object_id;
 
 /* git_config_parse_key() returns these negated: */

@@ -73,6 +107,11 @@ struct config_options {
 
 typedef int (*config_fn_t)(const char *, const char *, void *);
 int git_default_config(const char *, const char *, void *);
+
+/**
+ * Read a specific file in git-config format.
+ * This function takes the same callback and data parameters as `git_config`.
+ */
 int git_config_from_file(config_fn_t fn, const char *, void *);
 int git_config_from_file_with_options(config_fn_t fn, const char *,
 				      void *,

@@ -88,33 +127,152 @@ void git_config_push_parameter(const char *text);
 int git_config_from_parameters(config_fn_t fn, void *data);
 void read_early_config(config_fn_t cb, void *data);
 void read_very_early_config(config_fn_t cb, void *data);
+
+/**
+ * Most programs will simply want to look up variables in all config files
+ * that Git knows about, using the normal precedence rules. To do this,
+ * call `git_config` with a callback function and void data pointer.
+ *
+ * `git_config` will read all config sources in order of increasing
+ * priority. Thus a callback should typically overwrite previously-seen
+ * entries with new ones (e.g., if both the user-wide `~/.gitconfig` and
+ * repo-specific `.git/config` contain `color.ui`, the config machinery
+ * will first feed the user-wide one to the callback, and then the
+ * repo-specific one; by overwriting, the higher-priority repo-specific
+ * value is left at the end).
+ */
 void git_config(config_fn_t fn, void *);

config.h +7 -0

+ * If this parameter is non-NULL, it specifies the source to parse for
+ * configuration, rather than looking in the usual files. See `struct
+ * git_config_source` in `config.h` for details. Regular `git_config` defaults
+ * to `NULL`.
+ *
+ * `opts`::
+ * Specify options to adjust the behavior of parsing config files. See `struct

config.h +30 -0

+ */
+
 int git_parse_ssize_t(const char *, ssize_t *);
 int git_parse_ulong(const char *, unsigned long *);
+
+/**
+ * Same as `git_config_bool`, except that it returns -1 on error rather
+ * than dying.
+ */
 int git_parse_maybe_bool(const char *);
+
+/**
+ * Parse the string to an integer, including unit factors. Dies on error;
+ * otherwise, returns the parsed result.
+ */
 int git_config_int(const char *, const char *);
 int64_t git_config_int64(const char *, const char *);
+
+/**
+ * Identical to `git_config_int`, but for unsigned longs.
+ */
 unsigned long git_config_ulong(const char *, const char *);
 ssize_t git_config_ssize_t(const char *, const char *);
+
+/**
+ * Same as `git_config_bool`, except that integers are returned as-is, and
+ * an `is_bool` flag is unset.
+ */
 int git_config_bool_or_int(const char *, const char *, int *);
+
+/**
+ * Parse a string into a boolean value, respecting keywords like "true" and
+ * "false". Integer values are converted into true/false values (when they
+ * are non-zero or zero, respectively). Other values cause a die(). If
+ * parsing is successful, the return value is the result.
+ */
 int git_config_bool(const char *, const char *);
+
+/**

config.h +204 -0

 void git_config_set_in_file(const char *, const char *, const char *);
 int git_config_set_gently(const char *, const char *);
+
+/**
+ * write config values to `.git/config`
+ * takes a key/value pair as parameter.
+ */
 void git_config_set(const char *, const char *);
 int git_config_parse_key(const char *, char **, int *);
 int git_config_key_is_valid(const char *key);
 int git_config_set_multivar_gently(const char *, const char *, const char *, int);
 void git_config_set_multivar(const char *, const char *, const char *, int);
 int git_config_set_multivar_in_file_gently(const char *, const char *, const char *, const char *, int);
+
+/**
+ * takes four parameters:
+ *
+ * - the name of the file, as a string, to which key/value pairs will be written.
+ *
+ * - the name of key, as a string. This is in canonical "flat" form: the section,
+ *   subsection, and variable segments will be separated by dots, and the section
+ *   and variable segments will be all lowercase.
+ *   E.g., `core.ignorecase`, `diff.SomeType.textconv`.
+ *
+ * - the value of the variable, as a string. If value is equal to NULL, it will
+ *   remove the matching key from the config file.
+ *
+ * - the value regex, as a string. It will disregard key/value pairs where value
+ *   does not match.
+ *
+ * - a multi_replace value, as an int. If value is equal to zero, nothing or only
+ *   one matching key/value is replaced, else all matching key/values (regardless
+ *   how many) are removed, before the new pair is written.
+ *
+ * It returns 0 on success.
+ */
 void git_config_set_multivar_in_file(const char *, const char *, const char *, const char *, int);
+
+/**
+ * rename or remove sections in the config file
+ * parameters `old_name` and `new_name`
+ * If NULL is passed through `new_name` parameter,
+ * the section will be removed from the config file.
+ */
 int git_config_rename_section(const char *, const char *);
 int git_config_rename_section_in_file(const char *, const char *, const char *);
 int git_config_copy_section(const char *, const char *);

@@ -142,6 +300,30 @@ enum config_scope current_config_scope(void);
 const char *current_config_origin_type(void);
 const char *current_config_name(void);
 
+/**
+ * Include Directives
+ * ------------------
+ *
+ * By default, the config parser does not respect include directives.
+ * However, a caller can use the special `git_config_include` wrapper
+ * callback to support them. To do so, you simply wrap your "real" callback
+ * function and data pointer in a `struct config_include_data`, and pass
+ * the wrapper to the regular config-reading functions. For example:
+ *
+ * -------------------------------------------
+ * int read_file_with_include(const char *file, config_fn_t fn, void *data)
+ * {
+ * struct config_include_data inc = CONFIG_INCLUDE_INIT;
+ * inc.fn = fn;
+ * inc.data = data;
+ * return git_config_from_file(git_config_include, file, &inc);
+ * }
+ * -------------------------------------------
+ *
+ * `git_config` respects includes automatically. The lower-level
+ * `git_config_from_file` does not.
+ *
+ */
 struct config_include_data {
 	int depth;
 	config_fn_t fn;

@@ -169,6 +351,33 @@ int parse_config_key(const char *var,
 		     const char **subsection, int *subsection_len,
 		     const char **key);
 
+/**
+ * Custom Configsets
+ * -----------------
+ *
+ * A `config_set` can be used to construct an in-memory cache for
+ * config-like files that the caller specifies (i.e., files like `.gitmodules`,
+ * `~/.gitconfig` etc.). For example,
+ *
+ * ----------------------------------------
+ * struct config_set gm_config;
+ * git_configset_init(&gm_config);
+ * int b;
+ * //we add config files to the config_set
+ * git_configset_add_file(&gm_config, ".gitmodules");
+ * git_configset_add_file(&gm_config, ".gitmodules_alt");
+ *
+ * if (!git_configset_get_bool(gm_config, "submodule.frotz.ignore", &b)) {
+ * //hack hack hack
+ * }
+ *
+ * when we are done with the configset:
+ * git_configset_clear(&gm_config);
+ * ----------------------------------------
+ *
+ * Configset API provides functions for the above mentioned work flow
+ */
+
 struct config_set_element {
 	struct hashmap_entry ent;
 	char *key;

@@ -197,15 +406,45 @@ struct config_set {
 	struct configset_list list;
 };
 
+/**
+ * Initializes the config_set `cs`.
+ */
 void git_configset_init(struct config_set *cs);
+
+/**
+ * Parses the file and adds the variable-value pairs to the `config_set`,
+ * dies if there is an error in parsing the file. Returns 0 on success, or
+ * -1 if the file does not exist or is inaccessible. The user has to decide
+ * if he wants to free the incomplete configset or continue using it when
+ * the function returns -1.
+ */
 int git_configset_add_file(struct config_set *cs, const char *filename);
+
+/**
+ * Finds and returns the value list, sorted in order of increasing priority
+ * for the configuration variable `key` and config set `cs`. When the
+ * configuration variable `key` is not found, returns NULL. The caller
+ * should not free or modify the returned pointer, as it is owned by the cache.
+ */
 const struct string_list *git_configset_get_value_multi(struct config_set *cs, const char *key);
+
+/**
+ * Clears `config_set` structure, removes all saved variable-value pairs.
+ */
 void git_configset_clear(struct config_set *cs);
 
 /*
  * These functions return 1 if not found, and 0 if found, leaving the found
  * value in the 'dest' pointer.
  */
+
+/*
+ * Finds the highest-priority value for the configuration variable `key`
+ * and config set `cs`, stores the pointer to it in `value` and returns 0.
+ * When the configuration variable `key` is not found, returns 1 without
+ * touching `value`. The caller should not free or modify `value`, as it
+ * is owned by the cache.
+ */
 int git_configset_get_value(struct config_set *cs, const char *key, const char **dest);
 int git_configset_get_string_const(struct config_set *cs, const char *key, const char **dest);
 int git_configset_get_string(struct config_set *cs, const char *key, char **dest);

@@ -240,16 +479,92 @@ int repo_config_get_maybe_bool(struct repository *repo,
 int repo_config_get_pathname(struct repository *repo,
 			     const char *key, const char **dest);
 
+/**
+ * Querying For Specific Variables
+ * -------------------------------
+ *
+ * For programs wanting to query for specific variables in a non-callback
+ * manner, the config API provides two functions `git_config_get_value`
+ * and `git_config_get_value_multi`. They both read values from an internal
+ * cache generated previously from reading the config files.
+ */
+
+/**
+ * Finds the highest-priority value for the configuration variable `key`,
+ * stores the pointer to it in `value` and returns 0. When the
+ * configuration variable `key` is not found, returns 1 without touching
+ * `value`. The caller should not free or modify `value`, as it is owned
+ * by the cache.
+ */
 int git_config_get_value(const char *key, const char **value);
+
+/**
+ * Finds and returns the value list, sorted in order of increasing priority
+ * for the configuration variable `key`. When the configuration variable
+ * `key` is not found, returns NULL. The caller should not free or modify
+ * the returned pointer, as it is owned by the cache.
+ */
 const struct string_list *git_config_get_value_multi(const char *key);
+
+/**
+ * Resets and invalidates the config cache.
+ */
 void git_config_clear(void);
+
+/**
+ * Allocates and copies the retrieved string into the `dest` parameter for
+ * the configuration variable `key`; if NULL string is given, prints an
+ * error message and returns -1. When the configuration variable `key` is
+ * not found, returns 1 without touching `dest`.
+ */
 int git_config_get_string_const(const char *key, const char **dest);
+
+/**
+ * Similar to `git_config_get_string_const`, except that retrieved value
+ * copied into the `dest` parameter is a mutable string.
+ */
 int git_config_get_string(const char *key, char **dest);
+
+/**
+ * Finds and parses the value to an integer for the configuration variable
+ * `key`. Dies on error; otherwise, stores the value of the parsed integer in
+ * `dest` and returns 0. When the configuration variable `key` is not found,
+ * returns 1 without touching `dest`.
+ */
 int git_config_get_int(const char *key, int *dest);
+
+/**
+ * Similar to `git_config_get_int` but for unsigned longs.
+ */
 int git_config_get_ulong(const char *key, unsigned long *dest);
+
+/**
+ * Finds and parses the value into a boolean value, for the configuration
+ * variable `key` respecting keywords like "true" and "false". Integer
+ * values are converted into true/false values (when they are non-zero or
+ * zero, respectively). Other values cause a die(). If parsing is successful,
+ * stores the value of the parsed result in `dest` and returns 0. When the
+ * configuration variable `key` is not found, returns 1 without touching
+ * `dest`.
+ */
 int git_config_get_bool(const char *key, int *dest);
+
+/**
+ * Similar to `git_config_get_bool`, except that integers are copied as-is,
+ * and `is_bool` flag is unset.
+ */
 int git_config_get_bool_or_int(const char *key, int *is_bool, int *dest);
+
+/**
+ * Similar to `git_config_get_bool`, except that it returns -1 on error
+ * rather than dying.
+ */
 int git_config_get_maybe_bool(const char *key, int *dest);
+
+/**
+ * Similar to `git_config_get_string`, but expands `~` or `~user` into
+ * the user's home directory when found at the beginning of the path.
+ */
 int git_config_get_pathname(const char *key, const char **dest);
 int git_config_get_index_threads(int *dest);
 int git_config_get_untracked_cache(void);

@@ -270,7 +585,19 @@ struct key_value_info {
 	enum config_scope scope;
 };
 
+/**
+ * First prints the error message specified by the caller in `err` and then
+ * dies printing the line number and the file name of the highest priority
+ * value for the configuration variable `key`.
+ */
 NORETURN void git_die_config(const char *key, const char *err, ...) __attribute__((format(printf, 2, 3)));
+
+/**
+ * Helper function which formats the die error message according to the
+ * parameters entered. Used by `git_die_config()`. It can be used by callers
+ * handling `git_config_get_value_multi()` to print the correct error message
+ * for the desired value.
+ */
 NORETURN void git_die_config_linenr(const char *key, const char *filename, int linenr);
 
 #define LOOKUP_CONFIG(mapping, var) \

Signature · 1 line

gitgitgadget

Quoted 1 line · Heba Waly via GitGitGadget

From: Heba Waly <[email protected]>

Hi Heba,

Thanks for the patch!

I'd like to highlight to the community that this is an Outreachy applicant and microproject. Heba, when you send the next version, I think you can add [Outreachy] manually to the PR subject line - that should draw the attention of those in the community who are invested in helping Outreachy applicants.

Quoted 3 lines

This commit is copying and summarizing the documentation from documentation/technical/api-config.txt to comments in config.h

I think in the GitGitGadget PR you've got some great comments from Dscho about how to format your commit message; please take a look at those and feel free to reach out to me if you're still not sure what's missing or not.

Quoted 1 line

Signed-off-by Heba Waly <[email protected]>

One thing I miss in this change is the removal of the contents of Documentation/technical/api-config.txt (or maybe the removal of the file itself). I'd prefer to see at least for api-config.txt to say something like "Please refer to comments in 'config.h'"; or, more drastically, for api-config.txt to be removed entirely.

Having both pieces of documentation standing independently means that someone who's trying to add new information about the config API won't know where to add it; eventually they'll add something to config.h but not api-config.txt, or vice versa, and the two documents will go out of sync. So we want to move the documentation, rather than copy it.

Plus, having the removed doc as part of this change means I can more easily look at where the lines of content are coming from and see if you made any significant changes from the old contents of api-config.txt. Having a smaller amount of change to review means your review will be quicker - I don't feel as strong a need to check the grammar, spelling, etc, because that text has already been reviewed before, and can just make sure that the placement of each piece of documentation makes sense.

Quoted 88 lines

---
 config.h | 327 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 327 insertions(+)

config.h +60 -0

index f0ed464004..fa999a2ba0 100644
@@ -4,6 +4,40 @@
 #include "hashmap.h"
 #include "string-list.h"
 
+
+/**
+ * The config API gives callers a way to access Git configuration files
+ * (and files which have the same syntax). See linkgit:git-config[1] for a
+ * discussion of the config file syntax.
+ *
+ * General Usage
+ * -------------
+ *
+ * Config files are parsed linearly, and each variable found is passed to a
+ * caller-provided callback function. The callback function is responsible
+ * for any actions to be taken on the config option, and is free to ignore
+ * some options. It is not uncommon for the configuration to be parsed
+ * several times during the run of a Git program, with different callbacks
+ * picking out different variables useful to themselves.
+ *
+ * A config callback function takes three parameters:
+ *
+ * - the name of the parsed variable. This is in canonical "flat" form: the
+ *   section, subsection, and variable segments will be separated by dots,
+ *   and the section and variable segments will be all lowercase. E.g.,
+ *   `core.ignorecase`, `diff.SomeType.textconv`.
+ *
+ * - the value of the found variable, as a string. If the variable had no
+ *   value specified, the value will be NULL (typically this means it
+ *   should be interpreted as boolean true).
+ *
+ * - a void pointer passed in by the caller of the config API; this can
+ *   contain callback-specific data
+ *
+ * A config callback should return 0 for success, or -1 if the variable
+ * could not be parsed properly.
+ */
+
 struct object_id;
 
 /* git_config_parse_key() returns these negated: */

@@ -73,6 +107,11 @@ struct config_options {
 
 typedef int (*config_fn_t)(const char *, const char *, void *);
 int git_default_config(const char *, const char *, void *);
+
+/**
+ * Read a specific file in git-config format.
+ * This function takes the same callback and data parameters as `git_config`.
+ */
 int git_config_from_file(config_fn_t fn, const char *, void *);
 int git_config_from_file_with_options(config_fn_t fn, const char *,
                                    void *,

@@ -88,33 +127,152 @@ void git_config_push_parameter(const char *text);
 int git_config_from_parameters(config_fn_t fn, void *data);
 void read_early_config(config_fn_t cb, void *data);
 void read_very_early_config(config_fn_t cb, void *data);
+
+/**
+ * Most programs will simply want to look up variables in all config files
+ * that Git knows about, using the normal precedence rules. To do this,
+ * call `git_config` with a callback function and void data pointer.
+ *
+ * `git_config` will read all config sources in order of increasing
+ * priority. Thus a callback should typically overwrite previously-seen
+ * entries with new ones (e.g., if both the user-wide `~/.gitconfig` and
+ * repo-specific `.git/config` contain `color.ui`, the config machinery
+ * will first feed the user-wide one to the callback, and then the
+ * repo-specific one; by overwriting, the higher-priority repo-specific
+ * value is left at the end).
+ */
 void git_config(config_fn_t fn, void *);
+
+/**
+ * Lets the caller examine config while adjusting some of the default
+ * behavior of `git_config`. It should almost never be used by "regular"
+ * Git code that is looking up configuration variables.
+ * It is intended for advanced callers like `git-config`, which are
+ * intentionally tweaking the normal config-lookup process.

config.h void git_config_push_parameter(const char *text); · line 154

Quoted 3 lines

config.h +3 -0

+ * It takes two extra parameters:
+ *
+ * `config_source`::

I think the wonky trailing "::" is for generating manpages/HTML out of the asciidoc from the original api-config.txt. I expect it's OK to remove them throughout this change and format this in a way that makes more sense for comments which won't be converted into anything else.

Quoted 7 lines

config.h +7 -0

+ * If this parameter is non-NULL, it specifies the source to parse for
+ * configuration, rather than looking in the usual files. See `struct
+ * git_config_source` in `config.h` for details. Regular `git_config` defaults
+ * to `NULL`.
+ *
+ * `opts`::
+ * Specify options to adjust the behavior of parsing config files. See `struct

config.h void git_config_push_parameter(const char *text); · line 171

Quoted 10 lines

config.h +7 -0

+ * config_options` in `config.h` for details. As an example: regular `git_config`
+ * sets `opts.respect_includes` to `1` by default.
+ */
 int config_with_options(config_fn_t fn, void *,
                      struct git_config_source *config_source,
                      const struct config_options *opts);
+
+/**
+ * Value Parsing Helpers
+ * ---------------------

It may not make sense to have the header here in the middle of the doc.

I wonder whether we need the headers at all anymore; or, whether it makes more sense to put this header in the long comment at the top with just the list of function names (so someone knows where to look), and leave the per-function explanations inline with the function they describe?

config.h void git_config_push_parameter(const char *text); · line 174

Quoted 3 lines

config.h +3 -0

+ *
+ * To aid in parsing string values, the config API provides callbacks with
+ * a number of helper functions

In the copy paste, this lost some ending punctuation. I'd advocate ending this with ":" to indicate "we are about to give the list of those functions". Although, I wonder whether it makes more sense to rephrase this into something like "The following helper functions aid in parsing string values:"? Not sure.

Quoted 46 lines

config.h +36 -0

+ */
+
 int git_parse_ssize_t(const char *, ssize_t *);
 int git_parse_ulong(const char *, unsigned long *);
+
+/**
+ * Same as `git_config_bool`, except that it returns -1 on error rather
+ * than dying.
+ */
 int git_parse_maybe_bool(const char *);
+
+/**
+ * Parse the string to an integer, including unit factors. Dies on error;
+ * otherwise, returns the parsed result.
+ */
 int git_config_int(const char *, const char *);
 int64_t git_config_int64(const char *, const char *);
+
+/**
+ * Identical to `git_config_int`, but for unsigned longs.
+ */
 unsigned long git_config_ulong(const char *, const char *);
 ssize_t git_config_ssize_t(const char *, const char *);
+
+/**
+ * Same as `git_config_bool`, except that integers are returned as-is, and
+ * an `is_bool` flag is unset.
+ */
 int git_config_bool_or_int(const char *, const char *, int *);
+
+/**
+ * Parse a string into a boolean value, respecting keywords like "true" and
+ * "false". Integer values are converted into true/false values (when they
+ * are non-zero or zero, respectively). Other values cause a die(). If
+ * parsing is successful, the return value is the result.
+ */
 int git_config_bool(const char *, const char *);
+
+/**
+ * Allocates and copies the value string into the `dest` parameter; if no
+ * string is given, prints an error message and returns -1.
+ */
 int git_config_string(const char **, const char *, const char *);
+
+/**
+ * Similar to `git_config_string`, but expands `~` or `~user` into the

config.h void git_config_push_parameter(const char *text); · line 223

Quoted 3 lines

config.h +2 -0

+ * user's home directory when found at the beginning of the path.
+ */
 int git_config_pathname(const char **, const char *, const char *);

I might like to see another space under this function so it's clear that the description isn't talking about expiry, color, or set_in_file_gently. There are other places where this comment applies, too.

Quoted 4 lines

config.h +1 -0

 int git_config_expiry_date(timestamp_t *, const char *, const char *);
 int git_config_color(char *, const char *, const char *);
 int git_config_set_in_file_gently(const char *, const char *, const char *);
+

config.h void git_config_push_parameter(const char *text); · line 231

Quoted 4 lines

config.h +4 -0

+/**
+ * write config values to a specific config file
+ * takes a key/value pair as parameter.
+ */

You could reflow this comment and some others so that they extend closer to the end of the 80c line width; in some cases you can condense the comment to a single line this way :)

Quoted 270 lines

config.h +204 -0

 void git_config_set_in_file(const char *, const char *, const char *);
 int git_config_set_gently(const char *, const char *);
+
+/**
+ * write config values to `.git/config`
+ * takes a key/value pair as parameter.
+ */
 void git_config_set(const char *, const char *);
 int git_config_parse_key(const char *, char **, int *);
 int git_config_key_is_valid(const char *key);
 int git_config_set_multivar_gently(const char *, const char *, const char *, int);
 void git_config_set_multivar(const char *, const char *, const char *, int);
 int git_config_set_multivar_in_file_gently(const char *, const char *, const char *, const char *, int);
+
+/**
+ * takes four parameters:
+ *
+ * - the name of the file, as a string, to which key/value pairs will be written.
+ *
+ * - the name of key, as a string. This is in canonical "flat" form: the section,
+ *   subsection, and variable segments will be separated by dots, and the section
+ *   and variable segments will be all lowercase.
+ *   E.g., `core.ignorecase`, `diff.SomeType.textconv`.
+ *
+ * - the value of the variable, as a string. If value is equal to NULL, it will
+ *   remove the matching key from the config file.
+ *
+ * - the value regex, as a string. It will disregard key/value pairs where value
+ *   does not match.
+ *
+ * - a multi_replace value, as an int. If value is equal to zero, nothing or only
+ *   one matching key/value is replaced, else all matching key/values (regardless
+ *   how many) are removed, before the new pair is written.
+ *
+ * It returns 0 on success.
+ */
 void git_config_set_multivar_in_file(const char *, const char *, const char *, const char *, int);
+
+/**
+ * rename or remove sections in the config file
+ * parameters `old_name` and `new_name`
+ * If NULL is passed through `new_name` parameter,
+ * the section will be removed from the config file.
+ */
 int git_config_rename_section(const char *, const char *);
 int git_config_rename_section_in_file(const char *, const char *, const char *);
 int git_config_copy_section(const char *, const char *);

@@ -142,6 +300,30 @@ enum config_scope current_config_scope(void);
 const char *current_config_origin_type(void);
 const char *current_config_name(void);
 
+/**
+ * Include Directives
+ * ------------------
+ *
+ * By default, the config parser does not respect include directives.
+ * However, a caller can use the special `git_config_include` wrapper
+ * callback to support them. To do so, you simply wrap your "real" callback
+ * function and data pointer in a `struct config_include_data`, and pass
+ * the wrapper to the regular config-reading functions. For example:
+ *
+ * -------------------------------------------
+ * int read_file_with_include(const char *file, config_fn_t fn, void *data)
+ * {
+ * struct config_include_data inc = CONFIG_INCLUDE_INIT;
+ * inc.fn = fn;
+ * inc.data = data;
+ * return git_config_from_file(git_config_include, file, &inc);
+ * }
+ * -------------------------------------------
+ *
+ * `git_config` respects includes automatically. The lower-level
+ * `git_config_from_file` does not.
+ *
+ */
 struct config_include_data {
      int depth;
      config_fn_t fn;

@@ -169,6 +351,33 @@ int parse_config_key(const char *var,
                   const char **subsection, int *subsection_len,
                   const char **key);
 
+/**
+ * Custom Configsets
+ * -----------------
+ *
+ * A `config_set` can be used to construct an in-memory cache for
+ * config-like files that the caller specifies (i.e., files like `.gitmodules`,
+ * `~/.gitconfig` etc.). For example,
+ *
+ * ----------------------------------------
+ * struct config_set gm_config;
+ * git_configset_init(&gm_config);
+ * int b;
+ * //we add config files to the config_set
+ * git_configset_add_file(&gm_config, ".gitmodules");
+ * git_configset_add_file(&gm_config, ".gitmodules_alt");
+ *
+ * if (!git_configset_get_bool(gm_config, "submodule.frotz.ignore", &b)) {
+ * //hack hack hack
+ * }
+ *
+ * when we are done with the configset:
+ * git_configset_clear(&gm_config);
+ * ----------------------------------------
+ *
+ * Configset API provides functions for the above mentioned work flow
+ */
+
 struct config_set_element {
      struct hashmap_entry ent;
      char *key;

@@ -197,15 +406,45 @@ struct config_set {
      struct configset_list list;
 };
 
+/**
+ * Initializes the config_set `cs`.
+ */
 void git_configset_init(struct config_set *cs);
+
+/**
+ * Parses the file and adds the variable-value pairs to the `config_set`,
+ * dies if there is an error in parsing the file. Returns 0 on success, or
+ * -1 if the file does not exist or is inaccessible. The user has to decide
+ * if he wants to free the incomplete configset or continue using it when
+ * the function returns -1.
+ */
 int git_configset_add_file(struct config_set *cs, const char *filename);
+
+/**
+ * Finds and returns the value list, sorted in order of increasing priority
+ * for the configuration variable `key` and config set `cs`. When the
+ * configuration variable `key` is not found, returns NULL. The caller
+ * should not free or modify the returned pointer, as it is owned by the cache.
+ */
 const struct string_list *git_configset_get_value_multi(struct config_set *cs, const char *key);
+
+/**
+ * Clears `config_set` structure, removes all saved variable-value pairs.
+ */
 void git_configset_clear(struct config_set *cs);
 
 /*
  * These functions return 1 if not found, and 0 if found, leaving the found
  * value in the 'dest' pointer.
  */
+
+/*
+ * Finds the highest-priority value for the configuration variable `key`
+ * and config set `cs`, stores the pointer to it in `value` and returns 0.
+ * When the configuration variable `key` is not found, returns 1 without
+ * touching `value`. The caller should not free or modify `value`, as it
+ * is owned by the cache.
+ */
 int git_configset_get_value(struct config_set *cs, const char *key, const char **dest);
 int git_configset_get_string_const(struct config_set *cs, const char *key, const char **dest);
 int git_configset_get_string(struct config_set *cs, const char *key, char **dest);

@@ -240,16 +479,92 @@ int repo_config_get_maybe_bool(struct repository *repo,
 int repo_config_get_pathname(struct repository *repo,
                           const char *key, const char **dest);
 
+/**
+ * Querying For Specific Variables
+ * -------------------------------
+ *
+ * For programs wanting to query for specific variables in a non-callback
+ * manner, the config API provides two functions `git_config_get_value`
+ * and `git_config_get_value_multi`. They both read values from an internal
+ * cache generated previously from reading the config files.
+ */
+
+/**
+ * Finds the highest-priority value for the configuration variable `key`,
+ * stores the pointer to it in `value` and returns 0. When the
+ * configuration variable `key` is not found, returns 1 without touching
+ * `value`. The caller should not free or modify `value`, as it is owned
+ * by the cache.
+ */
 int git_config_get_value(const char *key, const char **value);
+
+/**
+ * Finds and returns the value list, sorted in order of increasing priority
+ * for the configuration variable `key`. When the configuration variable
+ * `key` is not found, returns NULL. The caller should not free or modify
+ * the returned pointer, as it is owned by the cache.
+ */
 const struct string_list *git_config_get_value_multi(const char *key);
+
+/**
+ * Resets and invalidates the config cache.
+ */
 void git_config_clear(void);
+
+/**
+ * Allocates and copies the retrieved string into the `dest` parameter for
+ * the configuration variable `key`; if NULL string is given, prints an
+ * error message and returns -1. When the configuration variable `key` is
+ * not found, returns 1 without touching `dest`.
+ */
 int git_config_get_string_const(const char *key, const char **dest);
+
+/**
+ * Similar to `git_config_get_string_const`, except that retrieved value
+ * copied into the `dest` parameter is a mutable string.
+ */
 int git_config_get_string(const char *key, char **dest);
+
+/**
+ * Finds and parses the value to an integer for the configuration variable
+ * `key`. Dies on error; otherwise, stores the value of the parsed integer in
+ * `dest` and returns 0. When the configuration variable `key` is not found,
+ * returns 1 without touching `dest`.
+ */
 int git_config_get_int(const char *key, int *dest);
+
+/**
+ * Similar to `git_config_get_int` but for unsigned longs.
+ */
 int git_config_get_ulong(const char *key, unsigned long *dest);
+
+/**
+ * Finds and parses the value into a boolean value, for the configuration
+ * variable `key` respecting keywords like "true" and "false". Integer
+ * values are converted into true/false values (when they are non-zero or
+ * zero, respectively). Other values cause a die(). If parsing is successful,
+ * stores the value of the parsed result in `dest` and returns 0. When the
+ * configuration variable `key` is not found, returns 1 without touching
+ * `dest`.
+ */
 int git_config_get_bool(const char *key, int *dest);
+
+/**
+ * Similar to `git_config_get_bool`, except that integers are copied as-is,
+ * and `is_bool` flag is unset.
+ */
 int git_config_get_bool_or_int(const char *key, int *is_bool, int *dest);
+
+/**
+ * Similar to `git_config_get_bool`, except that it returns -1 on error
+ * rather than dying.
+ */
 int git_config_get_maybe_bool(const char *key, int *dest);
+
+/**
+ * Similar to `git_config_get_string`, but expands `~` or `~user` into
+ * the user's home directory when found at the beginning of the path.
+ */
 int git_config_get_pathname(const char *key, const char **dest);
 int git_config_get_index_threads(int *dest);
 int git_config_get_untracked_cache(void);

@@ -270,7 +585,19 @@ struct key_value_info {
      enum config_scope scope;
 };
 
+/**
+ * First prints the error message specified by the caller in `err` and then
+ * dies printing the line number and the file name of the highest priority
+ * value for the configuration variable `key`.
+ */
 NORETURN void git_die_config(const char *key, const char *err, ...) __attribute__((format(printf, 2, 3)));
+
+/**
+ * Helper function which formats the die error message according to the
+ * parameters entered. Used by `git_die_config()`. It can be used by callers
+ * handling `git_config_get_value_multi()` to print the correct error message
+ * for the desired value.
+ */
 NORETURN void git_die_config_linenr(const char *key, const char *filename, int linenr);
 

Quoted 3 lines

config.h +0 -1

 #define LOOKUP_CONFIG(mapping, var) \
--

gitgitgadget

I made a couple of smallish comments about general formatting, but I'm also interested to know whether you were able to move the entire contents of api-config.txt across to here. Was there anything that you couldn't find a place for?

Thanks a lot for this change, and congrats on getting your first review out! Welcome! :)

- Emily

Quoted 8 lines · Emily Shaffer

Quoted 1 line · Heba Waly via GitGitGadget

From: Heba Waly <[email protected]>

Hi Heba,

Thanks for the patch!

Quoted 5 lines

I'd like to highlight to the community that this is an Outreachy applicant and microproject. Heba, when you send the next version, I think you can add [Outreachy] manually to the PR subject line - that should draw the attention of those in the community who are invested in helping Outreachy applicants.

Good idea! I wanted to add it to the email subject but as I decided to use gitgadget
I had no control over the subject.

Quoted 8 lines

Quoted 3 lines

This commit is copying and summarizing the documentation from documentation/technical/api-config.txt to comments in config.h

I think in the GitGitGadget PR you've got some great comments from Dscho about how to format your commit message; please take a look at those and feel free to reach out to me if you're still not sure what's missing or not.

Will do.

Quoted 8 lines

Quoted 1 line

Signed-off-by Heba Waly <[email protected]>

One thing I miss in this change is the removal of the contents of Documentation/technical/api-config.txt (or maybe the removal of the file itself). I'd prefer to see at least for api-config.txt to say something like "Please refer to comments in 'config.h'"; or, more drastically, for api-config.txt to be removed entirely.

Quoted 5 lines

Having both pieces of documentation standing independently means that someone who's trying to add new information about the config API won't know where to add it; eventually they'll add something to config.h but not api-config.txt, or vice versa, and the two documents will go out of sync. So we want to move the documentation, rather than copy it.

That makes sense, thanks for the explanation.
I wasn't sure if it should be removed or not so I decided to leave it until I'm asked otherwise.
So I assume api-config.html will be removed too?

Quoted 7 lines

config.h void git_config_push_parameter(const char *text); · line 171

Quoted 4 lines

config.h +4 -0

+
+/**
+ * Value Parsing Helpers
+ * ---------------------

It may not make sense to have the header here in the middle of the doc.

Quoted 5 lines

I wonder whether we need the headers at all anymore; or, whether it makes more sense to put this header in the long comment at the top with just the list of function names (so someone knows where to look), and leave the per-function explanations inline with the function they describe?

I see your point Emily, but in the CodingGuidelines file it was advised to refer to strbuf.h
as a model for documentation, I noticed that strbuf.h used headers this way so I decided
to replicate that.

Quoted 4 lines

I made a couple of smallish comments about general formatting, but I'm also interested to know whether you were able to move the entire contents of api-config.txt across to here. Was there anything that you couldn't find a place for?

Yes, everything is moved.

Quoted 5 lines

Thanks a lot for this change, and congrats on getting your first review out! Welcome! :)

- Emily

Thanks a lot Emily for the detailed and helpful feedback!

Heba

From: Heba Waly <[email protected]>

Move the documentation from Documentation/technical/api-config.txt into config.h

Quoted 4 lines

...
+/**
+ * The config API gives callers a way to access Git configuration files
+ * (and files which have the same syntax). See linkgit:git-config[1] for a

Ah, here's another place where the Asciidoc link isn't going to do anything anymore.

Otherwise I didn't still see anything jumping out. When the commit message is cleaned up I'm ready to add my Reviewed-by line.

Quoted 4 lines · Heba Waly via GitGitGadget

From: Heba Waly <[email protected]>

Move the documentation from Documentation/technical/api-config.txt into config.h

This is still a little thin for what we usually want from commit messages. Try to imagine that five years from now, you find this commit by running git blame on config.h and then examining the commit which introduced all these comments with git show <commit-id> - what would you want to know?

Typically we want to know "why" the change was made, because the diff shows "what". We can see from the diff that you're moving comments from A to B, but if you explain why you did so (not "because my Outreachy mentor told me to" ;) but "because it is useful to see usage information next to code" or "this is best practice as described by blah blah") - I wouldn't be able to know that reasoning just from looking at your diff.

Quoted 9 lines

config.h +0 -0

index f0ed464004..02f78ffc2b 100644
@@ -4,6 +4,23 @@
 #include "hashmap.h"
 #include "string-list.h"
 

config.h line 10

Quoted 4 lines

config.h +4 -0

+
+/**
+ * The config API gives callers a way to access Git configuration files
+ * (and files which have the same syntax). See linkgit:git-config[1] for a

Ah, here's another place where the Asciidoc link isn't going to do anything anymore.

Otherwise I didn't still see anything jumping out. When the commit message is cleaned up I'm ready to add my Reviewed-by line.

- Emily

From: Heba Waly <[email protected]>

Move the documentation from Documentation/technical/api-config.txt into config.h as it's easier for the developers to find the usage information beside the code instead of looking for it in another doc file, also documentation/technical/api-config.txt is removed because the information it has is now redundant and it'll be hard to keep it up to date and syncronized with the documentation in config.h

Signed-off-by Heba Waly <[email protected]>

Quoted 9 lines · Heba Waly via GitGitGadget

From: Heba Waly <[email protected]>

Move the documentation from Documentation/technical/api-config.txt into config.h as it's easier for the developers to find the usage information beside the code instead of looking for it in another doc file, also documentation/technical/api-config.txt is removed because the information it has is now redundant and it'll be hard to keep it up to date and syncronized with the documentation in config.h

Quoted 1 line

Signed-off-by Heba Waly <[email protected]>

Reviewed-by Emily Shaffer <[email protected]>

Thanks for the effort, Heba. (I guess you are an expert on git-config now!)