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authorHeba Waly <heba.waly@gmail.com>2019-10-23 05:30:52 (GMT)
committerJunio C Hamano <gitster@pobox.com>2019-10-24 02:14:08 (GMT)
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config: move documentation to config.h
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 <heba.waly@gmail.com> Reviewed-by: Emily Shaffer <emilyshaffer@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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-config API
-==========
-
-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.
-
-Basic Config Querying
----------------------
-
-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).
-
-The `config_with_options` function 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. It takes two extra parameters:
-
-`config_source`::
-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_options` in `config.h` for details. As an example: regular `git_config`
-sets `opts.respect_includes` to `1` by default.
-
-Reading Specific Files
-----------------------
-
-To read a specific file in git-config format, use
-`git_config_from_file`. This takes the same callback and data parameters
-as `git_config`.
-
-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.
-
-`int git_config_get_value(const char *key, const char **value)`::
-
- 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.
-
-`const struct string_list *git_config_get_value_multi(const char *key)`::
-
- 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.
-
-`void git_config_clear(void)`::
-
- Resets and invalidates the config cache.
-
-The config API also provides type specific API functions which do conversion
-as well as retrieval for the queried variable, including:
-
-`int git_config_get_int(const char *key, int *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_ulong(const char *key, unsigned long *dest)`::
-
- Similar to `git_config_get_int` but for unsigned longs.
-
-`int git_config_get_bool(const char *key, int *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_or_int(const char *key, int *is_bool, 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_maybe_bool(const char *key, int *dest)`::
-
- Similar to `git_config_get_bool`, except that it returns -1 on error
- rather than dying.
-
-`int git_config_get_string_const(const char *key, const char **dest)`::
-
- 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 char *key, 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_pathname(const char *key, const char **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.
-
-`git_die_config(const char *key, const char *err, ...)`::
-
- 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`.
-
-`void git_die_config_linenr(const char *key, const char *filename, int linenr)`::
-
- 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.
-
-See test-config.c for usage examples.
-
-Value Parsing Helpers
----------------------
-
-To aid in parsing string values, the config API provides callbacks with
-a number of helper functions, including:
-
-`git_config_int`::
-Parse the string to an integer, including unit factors. Dies on error;
-otherwise, returns the parsed result.
-
-`git_config_ulong`::
-Identical to `git_config_int`, but for unsigned longs.
-
-`git_config_bool`::
-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.
-
-`git_config_bool_or_int`::
-Same as `git_config_bool`, except that integers are returned as-is, and
-an `is_bool` flag is unset.
-
-`git_parse_maybe_bool`::
-Same as `git_config_bool`, except that it returns -1 on error rather
-than dying.
-
-`git_config_string`::
-Allocates and copies the value string into the `dest` parameter; if no
-string is given, prints an error message and returns -1.
-
-`git_config_pathname`::
-Similar to `git_config_string`, but expands `~` or `~user` into the
-user's home directory when found at the beginning of the path.
-
-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.
-
-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, including:
-
-`void git_configset_init(struct config_set *cs)`::
-
- Initializes the config_set `cs`.
-
-`int git_configset_add_file(struct config_set *cs, const char *filename)`::
-
- 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_get_value(struct config_set *cs, const char *key, const char **value)`::
-
- 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.
-
-`const struct string_list *git_configset_get_value_multi(struct config_set *cs, const char *key)`::
-
- 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.
-
-`void git_configset_clear(struct config_set *cs)`::
-
- Clears `config_set` structure, removes all saved variable-value pairs.
-
-In addition to above functions, the `config_set` API provides type specific
-functions in the vein of `git_config_get_int` and family but with an extra
-parameter, pointer to struct `config_set`.
-They all behave similarly to the `git_config_get*()` family described in
-"Querying For Specific Variables" above.
-
-Writing Config Files
---------------------
-
-Git gives multiple entry points in the Config API to write config values to
-files namely `git_config_set_in_file` and `git_config_set`, which write to
-a specific config file or to `.git/config` respectively. They both take a
-key/value pair as parameter.
-In the end they both call `git_config_set_multivar_in_file` which 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.
-
-Also, there are functions `git_config_rename_section` and
-`git_config_rename_section_in_file` with parameters `old_name` and `new_name`
-for renaming or removing sections in the config files. If NULL is passed
-through `new_name` parameter, the section will be removed from the config file.