Add "S_IFDIRLNK" file mode infrastructure for git links

This just adds the basic helper functions to recognize and work with git
tree entries that are links to other git repositories ("subprojects").
They still aren't actually connected up to any of the code-paths, but
now all the infrastructure is in place.

The next commit will start actually adding actual subproject support.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 19 insertions, 1 deletions

diff --git a/cache.h b/cache.h
index eb57507..1b3d00e 100644
--- a/cache.h
+++ b/cache.h
@@ -25,6 +25,22 @@
 #endif
 
 /*
+ * A "directory link" is a link to another git directory.
+ *
+ * The value 0160000 is not normally a valid mode, and
+ * also just happens to be S_IFDIR + S_IFLNK
+ *
+ * NOTE! We *really* shouldn't depend on the S_IFxxx macros
+ * always having the same values everywhere. We should use
+ * our internal git values for these things, and then we can
+ * translate that to the OS-specific value. It just so
+ * happens that everybody shares the same bit representation
+ * in the UNIX world (and apparently wider too..)
+ */
+#define S_IFDIRLNK	0160000
+#define S_ISDIRLNK(m)	(((m) & S_IFMT) == S_IFDIRLNK)
+
+/*
  * Intensive research over the course of many years has shown that
  * port 9418 is totally unused by anything else. Or
  *
@@ -104,6 +120,8 @@ static inline unsigned int create_ce_mode(unsigned int mode)
 {
 	if (S_ISLNK(mode))
 		return htonl(S_IFLNK);
+	if (S_ISDIR(mode) || S_ISDIRLNK(mode))
+		return htonl(S_IFDIRLNK);
 	return htonl(S_IFREG | ce_permissions(mode));
 }
 static inline unsigned int ce_mode_from_stat(struct cache_entry *ce, unsigned int mode)
@@ -121,7 +139,7 @@ static inline unsigned int ce_mode_from_stat(struct cache_entry *ce, unsigned in
 }
 #define canon_mode(mode) \
 	(S_ISREG(mode) ? (S_IFREG | ce_permissions(mode)) : \
-	S_ISLNK(mode) ? S_IFLNK : S_IFDIR)
+	S_ISLNK(mode) ? S_IFLNK : S_ISDIR(mode) ? S_IFDIR : S_IFDIRLNK)
 
 #define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)