[PATCH] Fix packname hash generation.

From

Junio C Hamano <junkio@cox.net>

Date

Oct 12, 2005, 23:57 UTC

Message-ID

<7vslv6b86l.fsf_-_@assigned-by-dhcp.cox.net>

In-Reply-To

<20051012135405.CDE55E005E3@center4.mivlgu.local>

Signed-off-by: Junio C Hamano <junkio@cox.net>

---

 * Right now, the pack "hash" name only serves the collision
   avoidance purposes, but not true identification.  The same
   set of objects can be fed to pack-objects in different order,
   produce the same pack, and still end up with different
   names.

   This will be used in the next experiment, "git-clone not
   exploding the downloaded pack".

 index-pack.c   |   15 +++++++++++++--
 pack-objects.c |   14 ++++++++++----
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/index-pack.c b/index-pack.c
index badbeab..785fe71 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -349,7 +349,7 @@ static int sha1_compare(const void *_a, 
 	return memcmp(a->sha1, b->sha1, 20);
 }
 
-static void write_index_file(const char *index_name)
+static void write_index_file(const char *index_name, unsigned char *sha1)
 {
 	struct sha1file *f;
 	struct object_entry **sorted_by_sha =
@@ -358,6 +358,7 @@ static void write_index_file(const char 
 	struct object_entry **last = sorted_by_sha + nr_objects;
 	unsigned int array[256];
 	int i;
+	SHA_CTX ctx;
 
 	for (i = 0; i < nr_objects; ++i)
 		sorted_by_sha[i] = &objects[i];
@@ -385,6 +386,11 @@ static void write_index_file(const char 
 	}
 	sha1write(f, array, 256 * sizeof(int));
 
+	/* recompute the SHA1 hash of sorted object names.
+	 * currently pack-objects does not do this, but that
+	 * can be fixed.
+	 */
+	SHA1_Init(&ctx);
 	/*
 	 * Write the actual SHA1 entries..
 	 */
@@ -394,10 +400,12 @@ static void write_index_file(const char 
 		unsigned int offset = htonl(obj->offset);
 		sha1write(f, &offset, 4);
 		sha1write(f, obj->sha1, 20);
+		SHA1_Update(&ctx, obj->sha1, 20);
 	}
 	sha1write(f, pack_base + pack_size - 20, 20);
 	sha1close(f, NULL, 1);
 	free(sorted_by_sha);
+	SHA1_Final(sha1, &ctx);
 }
 
 int main(int argc, char **argv)
@@ -405,6 +413,7 @@ int main(int argc, char **argv)
 	int i;
 	char *index_name = NULL;
 	char *index_name_buf = NULL;
+	unsigned char sha1[20];
 
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
@@ -443,9 +452,11 @@ int main(int argc, char **argv)
 	deltas = xcalloc(nr_objects, sizeof(struct delta_entry));
 	parse_pack_objects();
 	free(deltas);
-	write_index_file(index_name);
+	write_index_file(index_name, sha1);
 	free(objects);
 	free(index_name_buf);
 
+	printf("%s\n", sha1_to_hex(sha1));
+
 	return 0;
 }
diff --git a/pack-objects.c b/pack-objects.c
index 3d62278..ef55cab 100644
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -393,6 +393,7 @@ int main(int argc, char **argv)
 	SHA_CTX ctx;
 	char line[PATH_MAX + 20];
 	int window = 10, depth = 10, pack_to_stdout = 0;
+	struct object_entry **list;
 	int i;
 
 	for (i = 1; i < argc; i++) {
@@ -435,7 +436,6 @@ int main(int argc, char **argv)
 	if (pack_to_stdout != !base_name)
 		usage(pack_usage);
 
-	SHA1_Init(&ctx);
 	while (fgets(line, sizeof(line), stdin) != NULL) {
 		unsigned int hash;
 		char *p;
@@ -451,10 +451,8 @@ int main(int argc, char **argv)
 				continue;
 			hash = hash * 11 + c;
 		}
-		if (add_object_entry(sha1, hash))
-			SHA1_Update(&ctx, sha1, 20);
+		add_object_entry(sha1, hash);
 	}
-	SHA1_Final(object_list_sha1, &ctx);
 	if (non_empty && !nr_objects)
 		return 0;
 	get_object_details();
@@ -462,6 +460,14 @@ int main(int argc, char **argv)
 	fprintf(stderr, "Packing %d objects\n", nr_objects);
 
 	sorted_by_sha = create_sorted_list(sha1_sort);
+	SHA1_Init(&ctx);
+	list = sorted_by_sha;
+	for (i = 0; i < nr_objects; i++) {
+		struct object_entry *entry = *list++;
+		SHA1_Update(&ctx, entry->sha1, 20);
+	}
+	SHA1_Final(object_list_sha1, &ctx);
+
 	sorted_by_type = create_sorted_list(type_size_sort);
 	if (window && depth)
 		find_deltas(sorted_by_type, window+1, depth);
---
0.99.8.GIT