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Diffstat (limited to 'Documentation/technical')
| -rw-r--r-- | Documentation/technical/api-config.txt | 319 |
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diff --git a/Documentation/technical/api-config.txt b/Documentation/technical/api-config.txt deleted file mode 100644 index 7d20716c32..0000000000 --- a/Documentation/technical/api-config.txt +++ /dev/null @@ -1,319 +0,0 @@ -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. |