Implement global/system file search paths

The goal of this work is to expose the search logic for "global",
"system", and "xdg" files through the git_libgit2_opts() interface.

Behind the scenes, I changed the logic for finding files to have a
notion of a git_strarray that represents a search path and to store
a separate search path for each of the three tiers of config file.
For each tier, I implemented a function to initialize it to default
values (generally based on environment variables), and then general
interfaces to get it, set it, reset it, and prepend new directories
to it.

Next, I exposed these interfaces through the git_libgit2_opts
interface, reusing the GIT_CONFIG_LEVEL_SYSTEM, etc., constants
for the user to control which search path they were modifying.
There are alternative designs for the opts interface / argument
ordering, so I'm putting this phase out for discussion.

Additionally, I ended up doing a little bit of clean up regarding
attr.h and attr_file.h, adding a new attrcache.h so the other two
files wouldn't have to be included in so many places.

1 files changed, 3 insertions, 17 deletions

diff --git a/src/attr.h b/src/attr.h
index 0fc33089b..19c979bcd 100644
--- a/src/attr.h
+++ b/src/attr.h
@@ -8,27 +8,13 @@
 #define INCLUDE_attr_h__
 
 #include "attr_file.h"
-#include "strmap.h"
-
-#define GIT_ATTR_CONFIG   "core.attributesfile"
-#define GIT_ATTR_CONFIG_DEFAULT ".config/git/attributes"
-#define GIT_IGNORE_CONFIG "core.excludesfile"
-#define GIT_IGNORE_CONFIG_DEFAULT ".config/git/ignore"
-
-typedef struct {
-	int initialized;
-	git_pool pool;
-	git_strmap *files;	/* hash path to git_attr_file of rules */
-	git_strmap *macros;	/* hash name to vector<git_attr_assignment> */
-	const char *cfg_attr_file; /* cached value of core.attributesfile */
-	const char *cfg_excl_file; /* cached value of core.excludesfile */
-} git_attr_cache;
+
+#define GIT_ATTR_CONFIG       "core.attributesfile"
+#define GIT_IGNORE_CONFIG     "core.excludesfile"
 
 typedef int (*git_attr_file_parser)(
 	git_repository *, void *, const char *, git_attr_file *);
 
-extern int git_attr_cache__init(git_repository *repo);
-
 extern int git_attr_cache__insert_macro(
 	git_repository *repo, git_attr_rule *macro);