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Diffstat (limited to 'Documentation/technical/api-submodule-config.txt')
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diff --git a/Documentation/technical/api-submodule-config.txt b/Documentation/technical/api-submodule-config.txt new file mode 100644 index 000000000000..fb060893931f --- /dev/null +++ b/Documentation/technical/api-submodule-config.txt @@ -0,0 +1,66 @@ +submodule config cache API +========================== + +The submodule config cache API allows to read submodule +configurations/information from specified revisions. Internally +information is lazily read into a cache that is used to avoid +unnecessary parsing of the same .gitmodules files. Lookups can be done by +submodule path or name. + +Usage +----- + +To initialize the cache with configurations from the worktree the caller +typically first calls `gitmodules_config()` to read values from the +worktree .gitmodules and then to overlay the local git config values +`parse_submodule_config_option()` from the config parsing +infrastructure. + +The caller can look up information about submodules by using the +`submodule_from_path()` or `submodule_from_name()` functions. They return +a `struct submodule` which contains the values. The API automatically +initializes and allocates the needed infrastructure on-demand. If the +caller does only want to lookup values from revisions the initialization +can be skipped. + +If the internal cache might grow too big or when the caller is done with +the API, all internally cached values can be freed with submodule_free(). + +Data Structures +--------------- + +`struct submodule`:: + + This structure is used to return the information about one + submodule for a certain revision. It is returned by the lookup + functions. + +Functions +--------- + +`void submodule_free(struct repository *r)`:: + + Use these to free the internally cached values. + +`int parse_submodule_config_option(const char *var, const char *value)`:: + + Can be passed to the config parsing infrastructure to parse + local (worktree) submodule configurations. + +`const struct submodule *submodule_from_path(const unsigned char *treeish_name, const char *path)`:: + + Given a tree-ish in the superproject and a path, return the + submodule that is bound at the path in the named tree. + +`const struct submodule *submodule_from_name(const unsigned char *treeish_name, const char *name)`:: + + The same as above but lookup by name. + +Whenever a submodule configuration is parsed in `parse_submodule_config_option` +via e.g. `gitmodules_config()`, it will overwrite the null_sha1 entry. +So in the normal case, when HEAD:.gitmodules is parsed first and then overlayed +with the repository configuration, the null_sha1 entry contains the local +configuration of a submodule (e.g. consolidated values from local git +configuration and the .gitmodules file in the worktree). + +For an example usage see test-submodule-config.c. |