Merge branch 'hv/submodule-config'

The gitmodules API accessed from the C code learned to cache stuff
lazily.

* hv/submodule-config:
  submodule: allow erroneous values for the fetchRecurseSubmodules option
  submodule: use new config API for worktree configurations
  submodule: extract functions for config set and lookup
  submodule: implement a config API for lookup of .gitmodules values

1 files changed, 62 insertions, 0 deletions

diff --git a/Documentation/technical/api-submodule-config.txt b/Documentation/technical/api-submodule-config.txt
new file mode 100644
index 0000000000..941fa178dd
--- /dev/null
+++ b/Documentation/technical/api-submodule-config.txt
@@ -0,0 +1,62 @@
+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 .gitmodule 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()`::
+
+	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 *commit_sha1, const char *path)`::
+
+	Lookup values for one submodule by its commit_sha1 and path.
+
+`const struct submodule *submodule_from_name(const unsigned char *commit_sha1, const char *name)`::
+
+	The same as above but lookup by name.
+
+If given the null_sha1 as commit_sha1 the local configuration of a
+submodule will be returned (e.g. consolidated values from local git
+configuration and the .gitmodules file in the worktree).
+
+For an example usage see test-submodule-config.c.