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140 lines
5.2 KiB
140 lines
5.2 KiB
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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