[PATCH] convert-packs: futureproofing.

From

Junio C Hamano <junkio@cox.net>

Date

Jan 12, 2006, 00:05 UTC

Message-ID

<7voe2ijop0.fsf@assigned-by-dhcp.cox.net>

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

---
 * Currently in "pu".

 .gitignore                          |    1 
 Documentation/git-convert-packs.txt |   41 +++++++++++++++++
 Makefile                            |    2 -
 convert-packs.c                     |   86 +++++++++++++++++++++++++++++++++++
 4 files changed, 129 insertions(+), 1 deletions(-)
 create mode 100644 Documentation/git-convert-packs.txt
 create mode 100644 convert-packs.c

004e17155fe0a739857851cffc5efd3407af389c

diff --git a/.gitignore b/.gitignore
index 1a9090b..0d50843 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,6 +19,7 @@ git-clone-pack
 git-commit
 git-commit-tree
 git-convert-objects
+git-convert-packs
 git-count-objects
 git-cvsexportcommit
 git-cvsimport
diff --git a/Documentation/git-convert-packs.txt b/Documentation/git-convert-packs.txt
new file mode 100644
index 0000000..ba02641
--- /dev/null
+++ b/Documentation/git-convert-packs.txt
@@ -0,0 +1,41 @@
+git-convert-packs(1)
+====================
+
+NAME
+----
+git-convert-packs - Renames packfiles created with pre 0.99.9 GIT
+
+
+SYNOPSIS
+--------
+'git-convert-packs'
+
+DESCRIPTION
+-----------
+Older git-pack-objects named the resulting packfile with an SHA1
+hash of the object names without sorting them first (i.e. random
+unverifiable order), which meant that two packfiles that contain
+the same set of objects can be named differently.  To make
+packfile reliably verifiable, future versions of GIT will
+require that the name of the packfile to match the SHA1 hash of
+the object names contained within, after sorting them, and will
+ignore packfiles whose names do not verify.
+
+This command takes no parameter; it inspects packfiles in the
+local repository, and renames the ones whose names do not match
+their contents.  You need to rename older packfiles using this
+command before GIT starts complaining.
+
+
+Author
+------
+Written by Junio C Hamano <junkio@cox.net>
+
+Documentation
+--------------
+Documentation by the git-list <git@vger.kernel.org>.
+
+GIT
+---
+Part of the gitlink:git[7] suite
+
diff --git a/Makefile b/Makefile
index fa0cd83..6d5f293 100644
--- a/Makefile
+++ b/Makefile
@@ -123,7 +123,7 @@ SIMPLE_PROGRAMS = \
 PROGRAMS = \
 	git-apply$X git-cat-file$X \
 	git-checkout-index$X git-clone-pack$X git-commit-tree$X \
-	git-convert-objects$X git-diff-files$X \
+	git-convert-objects$X git-convert-packs$X git-diff-files$X \
 	git-diff-index$X git-diff-stages$X \
 	git-diff-tree$X git-fetch-pack$X git-fsck-objects$X \
 	git-hash-object$X git-index-pack$X git-init-db$X \
diff --git a/convert-packs.c b/convert-packs.c
new file mode 100644
index 0000000..754599d
--- /dev/null
+++ b/convert-packs.c
@@ -0,0 +1,86 @@
+#include "cache.h"
+
+static int verify_pack_name(struct packed_git *p)
+{
+	SHA_CTX ctx;
+	unsigned char sha1[20];
+	int i, nr, len, bad;
+	const char *hex;
+	char *base_name;
+
+	nr = num_packed_objects(p);
+
+	SHA1_Init(&ctx);
+	for (i = 0; i < nr; i++) {
+		unsigned char *ent = (((unsigned char *)p->index_base) +
+				      4*256 + i * 24 + 4);
+		SHA1_Update(&ctx, ent, 20);
+	}
+	SHA1_Final(sha1, &ctx);
+	hex = sha1_to_hex(sha1);
+	
+	base_name = strrchr(p->pack_name, '/');
+	if (base_name)
+		base_name++;
+	else
+		base_name = p->pack_name;
+
+	bad = 0;
+	/* We require "pack-X{40}.pack" these days before mapping
+	 * the idx file, so the first two conditions of the if()
+	 * statement are always false.
+	 */
+	len = strlen(base_name);
+	if ((len != 50) ||
+	    memcmp(base_name, "pack-", 5) ||
+	    memcmp(base_name + 5, hex, 40)) {
+		char *newname;
+		int newlen;
+
+		fprintf(stderr, "pack '%s' does not match contents '%s'\n",
+			base_name, hex);
+		newname = xmalloc(base_name - p->pack_name + 52);
+		if (base_name != p->pack_name)
+			sprintf(newname, "%.*spack-%s.pack",
+				(base_name - p->pack_name), p->pack_name, hex);
+		else
+			sprintf(newname, "pack-%s.pack", hex);
+		newlen = strlen(newname);
+
+		/* Make sure there is no such pack and idx first. */
+		if (!access(newname, F_OK))
+			return error("But there is a pack with that name!");
+
+		memcpy(newname + newlen - 5, ".idx", 5);
+		if (!access(newname, F_OK))
+			return error("But there is an idx with that name!");
+
+		memcpy(newname + newlen - 5, ".pack", 5);
+		if (rename(p->pack_name, newname))
+			return error("But the pack cannot renamed somehow!");
+
+		/* Now we have renamed the pack, so let's rename the index */
+		memcpy(base_name + len - 5, ".idx", 5);
+		memcpy(newname + newlen - 5, ".idx", 5);
+
+		if (!access(newname, F_OK))
+			return error("But there is an idx with that name!");
+		else if (rename(p->pack_name, newname))
+			return error("But the idx cannot be renamed somehow!");
+
+		fprintf(stderr, "... renamed successfully.\n");
+	}
+	return bad;
+}
+
+int main(int ac, char **av)
+{
+	struct packed_git *p;
+
+	setup_git_directory();
+	prepare_packed_git();
+	for (p = packed_git; p; p = p->next)
+		if (p->pack_local)
+			verify_pack_name(p);
+	return 0;
+}

-- 
1.1.1-g8ecb