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add config_set API for caching config-like files
Currently `git_config()` uses a callback mechanism and file rereads for config values. Due to this approach, it is not uncommon for the config files to be parsed several times during the run of a git program, with different callbacks picking out different variables useful to themselves. Add a `config_set`, that can be used to construct an in-memory cache for config-like files that the caller specifies (i.e., files like `.gitmodules`, `~/.gitconfig` etc.). Add two external functions `git_configset_get_value` and `git_configset_get_value_multi` for querying from the config sets. `git_configset_get_value` follows `last one wins` semantic (i.e. if there are multiple matches for the queried key in the files of the configset the value returned will be the last entry in `value_list`). `git_configset_get_value_multi` returns a list of values sorted in order of increasing priority (i.e. last match will be at the end of the list). Add type specific query functions like `git_configset_get_bool` and similar. Add a default `config_set`, `the_config_set` to cache all key-value pairs read from usual config files (repo specific .git/config, user wide ~/.gitconfig, XDG config and the global /etc/gitconfig). `the_config_set` is populated using `git_config()`. Add two external functions `git_config_get_value` and `git_config_get_value_multi` for querying in a non-callback manner from `the_config_set`. Also, add type specific query functions that are implemented as a thin wrapper around the `config_set` API. Signed-off-by: Matthieu Moy <[email protected]> Signed-off-by: Tanay Abhra <[email protected]> Signed-off-by: Junio C Hamano <[email protected]>
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‎Documentation/technical/api-config.txt

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@@ -77,6 +77,86 @@ To read a specific file in git-config format, use
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`git_config_from_file`. This takes the same callback and data parameters
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as `git_config`.
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Querying For Specific Variables
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-------------------------------
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For programs wanting to query for specific variables in a non-callback
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manner, the config API provides two functions `git_config_get_value`
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and `git_config_get_value_multi`. They both read values from an internal
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cache generated previously from reading the config files.
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`int git_config_get_value(const char *key, const char **value)`::
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Finds the highest-priority value for the configuration variable `key`,
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stores the pointer to it in `value` and returns 0. When the
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configuration variable `key` is not found, returns 1 without touching
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`value`. The caller should not free or modify `value`, as it is owned
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by the cache.
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`const struct string_list *git_config_get_value_multi(const char *key)`::
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Finds and returns the value list, sorted in order of increasing priority
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for the configuration variable `key`. When the configuration variable
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`key` is not found, returns NULL. The caller should not free or modify
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the returned pointer, as it is owned by the cache.
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`void git_config_clear(void)`::
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Resets and invalidates the config cache.
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The config API also provides type specific API functions which do conversion
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as well as retrieval for the queried variable, including:
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`int git_config_get_int(const char *key, int *dest)`::
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Finds and parses the value to an integer for the configuration variable
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`key`. Dies on error; otherwise, stores the value of the parsed integer in
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`dest` and returns 0. When the configuration variable `key` is not found,
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returns 1 without touching `dest`.
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`int git_config_get_ulong(const char *key, unsigned long *dest)`::
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Similar to `git_config_get_int` but for unsigned longs.
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`int git_config_get_bool(const char *key, int *dest)`::
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Finds and parses the value into a boolean value, for the configuration
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variable `key` respecting keywords like "true" and "false". Integer
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values are converted into true/false values (when they are non-zero or
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zero, respectively). Other values cause a die(). If parsing is successful,
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stores the value of the parsed result in `dest` and returns 0. When the
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configuration variable `key` is not found, returns 1 without touching
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`dest`.
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`int git_config_get_bool_or_int(const char *key, int *is_bool, int *dest)`::
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Similar to `git_config_get_bool`, except that integers are copied as-is,
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and `is_bool` flag is unset.
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`int git_config_get_maybe_bool(const char *key, int *dest)`::
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Similar to `git_config_get_bool`, except that it returns -1 on error
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rather than dying.
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`int git_config_get_string_const(const char *key, const char **dest)`::
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Allocates and copies the retrieved string into the `dest` parameter for
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the configuration variable `key`; if NULL string is given, prints an
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error message and returns -1. When the configuration variable `key` is
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not found, returns 1 without touching `dest`.
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`int git_config_get_string(const char *key, char **dest)`::
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Similar to `git_config_get_string_const`, except that retrieved value
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copied into the `dest` parameter is a mutable string.
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`int git_config_get_pathname(const char *key, const char **dest)`::
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Similar to `git_config_get_string`, but expands `~` or `~user` into
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the user's home directory when found at the beginning of the path.
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See test-config.c for usage examples.
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Value Parsing Helpers
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---------------------
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@@ -134,6 +214,68 @@ int read_file_with_include(const char *file, config_fn_t fn, void *data)
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`git_config` respects includes automatically. The lower-level
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`git_config_from_file` does not.
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Custom Configsets
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-----------------
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A `config_set` can be used to construct an in-memory cache for
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config-like files that the caller specifies (i.e., files like `.gitmodules`,
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`~/.gitconfig` etc.). For example,
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---------------------------------------
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struct config_set gm_config;
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git_configset_init(&gm_config);
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int b;
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/* we add config files to the config_set */
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git_configset_add_file(&gm_config, ".gitmodules");
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git_configset_add_file(&gm_config, ".gitmodules_alt");
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if (!git_configset_get_bool(gm_config, "submodule.frotz.ignore", &b)) {
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/* hack hack hack */
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}
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/* when we are done with the configset */
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git_configset_clear(&gm_config);
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----------------------------------------
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Configset API provides functions for the above mentioned work flow, including:
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`void git_configset_init(struct config_set *cs)`::
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Initializes the config_set `cs`.
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`int git_configset_add_file(struct config_set *cs, const char *filename)`::
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Parses the file and adds the variable-value pairs to the `config_set`,
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dies if there is an error in parsing the file. Returns 0 on success, or
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-1 if the file does not exist or is inaccessible. The user has to decide
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if he wants to free the incomplete configset or continue using it when
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the function returns -1.
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`int git_configset_get_value(struct config_set *cs, const char *key, const char **value)`::
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Finds the highest-priority value for the configuration variable `key`
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and config set `cs`, stores the pointer to it in `value` and returns 0.
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When the configuration variable `key` is not found, returns 1 without
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touching `value`. The caller should not free or modify `value`, as it
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is owned by the cache.
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`const struct string_list *git_configset_get_value_multi(struct config_set *cs, const char *key)`::
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Finds and returns the value list, sorted in order of increasing priority
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for the configuration variable `key` and config set `cs`. When the
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configuration variable `key` is not found, returns NULL. The caller
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should not free or modify the returned pointer, as it is owned by the cache.
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`void git_configset_clear(struct config_set *cs)`::
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Clears `config_set` structure, removes all saved variable-value pairs.
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In addition to above functions, the `config_set` API provides type specific
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functions in the vein of `git_config_get_int` and family but with an extra
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parameter, pointer to struct `config_set`.
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They all behave similarly to the `git_config_get*()` family described in
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"Querying For Specific Variables" above.
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Writing Config Files
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--------------------
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‎cache.h

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@@ -1351,6 +1351,38 @@ extern int parse_config_key(const char *var,
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const char **subsection, int *subsection_len,
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const char **key);
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struct config_set {
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struct hashmap config_hash;
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int hash_initialized;
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};
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extern void git_configset_init(struct config_set *cs);
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extern int git_configset_add_file(struct config_set *cs, const char *filename);
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extern int git_configset_get_value(struct config_set *cs, const char *key, const char **value);
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extern const struct string_list *git_configset_get_value_multi(struct config_set *cs, const char *key);
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extern void git_configset_clear(struct config_set *cs);
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extern int git_configset_get_string_const(struct config_set *cs, const char *key, const char **dest);
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extern int git_configset_get_string(struct config_set *cs, const char *key, char **dest);
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extern int git_configset_get_int(struct config_set *cs, const char *key, int *dest);
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extern int git_configset_get_ulong(struct config_set *cs, const char *key, unsigned long *dest);
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extern int git_configset_get_bool(struct config_set *cs, const char *key, int *dest);
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extern int git_configset_get_bool_or_int(struct config_set *cs, const char *key, int *is_bool, int *dest);
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extern int git_configset_get_maybe_bool(struct config_set *cs, const char *key, int *dest);
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extern int git_configset_get_pathname(struct config_set *cs, const char *key, const char **dest);
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extern int git_config_get_value(const char *key, const char **value);
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extern const struct string_list *git_config_get_value_multi(const char *key);
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extern void git_config_clear(void);
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extern void git_config_iter(config_fn_t fn, void *data);
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extern int git_config_get_string_const(const char *key, const char **dest);
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extern int git_config_get_string(const char *key, char **dest);
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extern int git_config_get_int(const char *key, int *dest);
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extern int git_config_get_ulong(const char *key, unsigned long *dest);
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extern int git_config_get_bool(const char *key, int *dest);
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extern int git_config_get_bool_or_int(const char *key, int *is_bool, int *dest);
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extern int git_config_get_maybe_bool(const char *key, int *dest);
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extern int git_config_get_pathname(const char *key, const char **dest);
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extern int committer_ident_sufficiently_given(void);
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extern int author_ident_sufficiently_given(void);
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