141 lines
5.2 KiB
Plaintext
141 lines
5.2 KiB
Plaintext
config API
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==========
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The config API gives callers a way to access git configuration files
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(and files which have the same syntax). See linkgit:git-config[1] for a
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discussion of the config file syntax.
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General Usage
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-------------
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Config files are parsed linearly, and each variable found is passed to a
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caller-provided callback function. The callback function is responsible
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for any actions to be taken on the config option, and is free to ignore
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some options. It is not uncommon for the configuration to be parsed
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several times during the run of a git program, with different callbacks
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picking out different variables useful to themselves.
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A config callback function takes three parameters:
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- the name of the parsed variable. This is in canonical "flat" form: the
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section, subsection, and variable segments will be separated by dots,
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and the section and variable segments will be all lowercase. E.g.,
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`core.ignorecase`, `diff.SomeType.textconv`.
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- the value of the found variable, as a string. If the variable had no
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value specified, the value will be NULL (typically this means it
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should be interpreted as boolean true).
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- a void pointer passed in by the caller of the config API; this can
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contain callback-specific data
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A config callback should return 0 for success, or -1 if the variable
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could not be parsed properly.
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Basic Config Querying
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---------------------
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Most programs will simply want to look up variables in all config files
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that git knows about, using the normal precedence rules. To do this,
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call `git_config` with a callback function and void data pointer.
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`git_config` will read all config sources in order of increasing
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priority. Thus a callback should typically overwrite previously-seen
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entries with new ones (e.g., if both the user-wide `~/.gitconfig` and
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repo-specific `.git/config` contain `color.ui`, the config machinery
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will first feed the user-wide one to the callback, and then the
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repo-specific one; by overwriting, the higher-priority repo-specific
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value is left at the end).
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The `git_config_with_options` function lets the caller examine config
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while adjusting some of the default behavior of `git_config`. It should
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almost never be used by "regular" git code that is looking up
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configuration variables. It is intended for advanced callers like
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`git-config`, which are intentionally tweaking the normal config-lookup
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process. It takes two extra parameters:
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`filename`::
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If this parameter is non-NULL, it specifies the name of a file to
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parse for configuration, rather than looking in the usual files. Regular
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`git_config` defaults to `NULL`.
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`respect_includes`::
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Specify whether include directives should be followed in parsed files.
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Regular `git_config` defaults to `1`.
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There is a special version of `git_config` called `git_config_early`.
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This version takes an additional parameter to specify the repository
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config, instead of having it looked up via `git_path`. This is useful
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early in a git program before the repository has been found. Unless
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you're working with early setup code, you probably don't want to use
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this.
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Reading Specific Files
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----------------------
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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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Value Parsing Helpers
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---------------------
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To aid in parsing string values, the config API provides callbacks with
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a number of helper functions, including:
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`git_config_int`::
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Parse the string to an integer, including unit factors. Dies on error;
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otherwise, returns the parsed result.
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`git_config_ulong`::
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Identical to `git_config_int`, but for unsigned longs.
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`git_config_bool`::
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Parse a string into a boolean value, respecting keywords like "true" and
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"false". Integer values are converted into true/false values (when they
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are non-zero or zero, respectively). Other values cause a die(). If
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parsing is successful, the return value is the result.
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`git_config_bool_or_int`::
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Same as `git_config_bool`, except that integers are returned as-is, and
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an `is_bool` flag is unset.
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`git_config_maybe_bool`::
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Same as `git_config_bool`, except that it returns -1 on error rather
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than dying.
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`git_config_string`::
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Allocates and copies the value string into the `dest` parameter; if no
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string is given, prints an error message and returns -1.
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`git_config_pathname`::
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Similar to `git_config_string`, but expands `~` or `~user` into the
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user's home directory when found at the beginning of the path.
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Include Directives
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------------------
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By default, the config parser does not respect include directives.
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However, a caller can use the special `git_config_include` wrapper
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callback to support them. To do so, you simply wrap your "real" callback
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function and data pointer in a `struct config_include_data`, and pass
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the wrapper to the regular config-reading functions. For example:
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-------------------------------------------
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int read_file_with_include(const char *file, config_fn_t fn, void *data)
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{
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struct config_include_data inc = CONFIG_INCLUDE_INIT;
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inc.fn = fn;
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inc.data = data;
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return git_config_from_file(git_config_include, file, &inc);
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}
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-------------------------------------------
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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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Writing Config Files
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--------------------
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TODO
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