[PATCH] Add git-verify-pack command.

Given a list of <pack>.idx files, this command validates the
index file and the corresponding .pack file for consistency.

This patch also uses the same validation mechanism in fsck-cache
when the --full flag is used.

During normal operation, sha1_file.c verifies that a given .idx
file matches the .pack file by comparing the SHA1 checksum
stored in .idx file and .pack file as a minimum sanity check.
We may further want to check the pack signature and version when
we map the pack, but that would be a separate patch.

Earlier, errors to map a pack file was not flagged fatal but led
to a random fatal error later.  This version explicitly die()s
when such an error is detected.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fsck-cache.c b/fsck-cache.c
index eae73cc..4e19352 100644
--- a/fsck-cache.c
+++ b/fsck-cache.c
@@ -6,6 +6,7 @@
 #include "tree.h"
 #include "blob.h"
 #include "tag.h"
+#include "pack.h"
 
 #define REACHABLE 0x0001
 
@@ -437,6 +438,10 @@
 			alt_odb[j].name[-1] = '/';
 		}
 		prepare_packed_git();
+		for (p = packed_git; p; p = p->next)
+			/* verify gives error messages itself */
+			verify_pack(p); 
+
 		for (p = packed_git; p; p = p->next) {
 			int num = num_packed_objects(p);
 			for (i = 0; i < num; i++) {