threads / discuss / 2922

GIT 1.0.4 and what is in master and proposed updates.

Subject: GIT 1.0.4 and what is in master and proposed updates.

## tl;dr

2 messages between Dec 24, 2005 and Dec 24, 2005.

replies: 1people: 1as markdown or json

Junio C Hamano· Dec 24, 2005, 09:42 UTC · lore
GIT 1.0.4 contains the following updates since GIT 1.0.3:
 * check_packed_git_idx(): check integrity of the idx file itself.
   Earlier we did not use SHA1 checksum at the end of the index
   file that records the checksum of the index file itself.
 * show-branch: usability updates.
   Fixes the bug that made 'git show-branch --heads' show the
   same heads twice, among other things.
 * merge --no-commit: tweak message.
   Instead of saying "failed/prevented", say which one.
 * ls-files --full-name: usage string and documentation.
   The option was not documented.
 * mailinfo: iconv does not like "latin-1" -- should spell it "latin1"
   Noted by Marco; when a message does not identify its own
   charset, we tried to assume latin1 but misspelled it as
   latin-1, and iconv barfed.

The master branch has all of the above, and in addition contains the following:

 * git-clone: do not special case dumb http.
   This is to remove the remnant from the days http-fetch did
   not handle packed repositories natively.
 * rev-parse: --show-cdup
   This is a low-impact shorthand for:
        git rev-parse --show-prefix | sed -e 's|[^/][^/]*|..|g'
   and will be used by "git checkout works from a subdirectory"
   patch.
The proposed updates branch has the following updates.
 * git-daemon --base-path
   Lack of the command line verification bugs me somewhat with
   this patch.  Also we might want to apply the base-path to the
   whitelist as well, which the patch currently does not do.
   Almost there, but not quite ready.
 * help with group permission in a shared repository.
   This series consists of these commits:
      Introduce core.sharedrepository
      git-init-db: initialize shared repositories with --shared
      Tutorial: mention shared repository management.
   I think this one is ready.  I just am taking things slowly.
 * make git-checkout work from a subdirectory.
   This series consists of these commits:
      checkout: sometimes work from a subdirectory.
      ls-tree: chomp leading directories when run from a subdirectory
      Adjust to ls-tree --full-name when run from a subdirectory.
   This seems to work pretty well.  I just am taking things
   slowly.
 * require packfiles to follow the naming convention more strictly.
   This rejects a packfile whose name does not begin with
   "pack-" followed by 40-byte hexadecimal digits.  The core
   never had such limitation (the only thing it required was
   that the pack and the idx are named with the same basename
   with .pack and .idx extention), but the way http-fetch
   handles packs requires this.
   An alternative strategy to handle the current mess would be
   to fix http-fetch so that it does not assume that pack names
   are always in the format "pack-[0-9a-f]{40}.pack", getting
   rid of sha1[] column from struct packed_git.  This is
   probably more work, but would be cleaner.  On the other hand,
   the cleanliness probably would not buy us much.  We do not
   need to insist on "pack-" prefix, but there is no strong
   reason to hate it, and we need to ensure packnames do not
   collide with each other anyway, so having SHA1 hash in the
   name makes sense.  However, we currently allow arbitrary 40
   hexadecimal digits there and the user is free to say 0{40}.
   Continuing to allow this defeats the initial purpose of why
   40 hexadecimal digits are there: collision avoidance.
   This series starts warning if the 40-byte hex that follows
   "pack-" is not the correct hash for contained object names
   that was given by pack-objects when the pack was created, and
   has a provision to later start rejecting such packs.
   This is probably controversial because it would eventually
   require users to rename their packs created using pre v0.99.9
   tools.  There is a small utility program that helps the
   conversion process, so it may not be that painful.
 * Disable USE_SYMLINK_HEAD by default.
   This uses symref for .git/HEAD everywhere.  Some Porcelain
   may not be ready to deal with it, so it is kept in the
   proposed updates branch for now.
   If your Porcelain "cat .git/HEAD", or "readlink .git/HEAD",
   it is already broken in repositories that use symref for
   HEAD, but it will be broken everywhere by this.  Use
   git-symbolic-ref if you want to find out the name of the
   branch HEAD points at, or git-rev-parse if you want to find
   out the commit object name HEAD points at.
   Most notably, git_read_hash(".../HEAD") in gitweb is probably
   affected (meaning, it is already broken).
Junio C Hamano· Dec 24, 2005, 10:03 UTC · re: Junio C Hamano · lore

[PATCH] Require packfiles to follow the naming convention.

Junio C Hamano <junkio@cox.net> writes:
Show 13 quoted lines
> * require packfiles to follow the naming convention more strictly.
>
>   This rejects a packfile whose name does not begin with
>   "pack-" followed by 40-byte hexadecimal digits.  The core
>   never had such limitation (the only thing it required was
>   that the pack and the idx are named with the same basename
>   with .pack and .idx extention), but the way http-fetch
>   handles packs requires this.
> ...
>   This is probably controversial because it would eventually
>   require users to rename their packs created using pre v0.99.9
>   tools.  There is a small utility program that helps the
>   conversion process, so it may not be that painful.

And this is the patch in question. When your packs are the ones produced by pre v0.99.9 tools, you can ask git-convert-packs to suggest you the "right name" to use.

$ git-convert-packs warning: index name '.git/objects/pack/pack-a3b60db8bb6dad970f6dcdc03b0addf3988e8556.idx' does not match contents of the pack '83b60db8bb6dad970f6dcdc03b0addf3988e8556' # Packname does not match contents. mv '.git/objects/pack/pack-a3b60db8bb6dad970f6dcdc03b0addf3988e8556.pack' '.git/objects/pack/pack-83b60db8bb6dad970f6dcdc03b0addf3988e8556.pack' mv '.git/objects/pack/pack-a3b60db8bb6dad970f6dcdc03b0addf3988e8556.idx' '.git/objects/pack/pack-83b60db8bb6dad970f6dcdc03b0addf3988e8556.idx' $ git-convert-packs | sh warning: index name '.git/objects/pack/pack-a3b60db8bb6dad970f6dcdc03b0addf3988e8556.idx' does not match contents of the pack '83b60db8bb6dad970f6dcdc03b0addf3988e8556' $ git-convert-packs $ exit

Comments?

-- >8 -- Pack files names are required to be "pack-[0-9a-f]{40}.pack", with corresponding .idx file. This is not strictly needed at the core level, but the packed file transfer over HTTP relies on this format. With this commit, the core would ignore otherwise a valid packfile in .git/objects/packs that "git-unpack-objects" would expand properly, if it does not follow the naming convention.

The hexadecimal part should be what git-pack-objects computed when the pack was created originally, and it is the SHA1 sum over sorted object names (i.e. 20-byte binary SHA1 checksum each). However, this condition is checked but not enforced currently, because git-pack-objects before v0.99.9 computed a checksum over object names without sorting (i.e. the order git-rev-list fed the object names), just to make pack names unlikely to collide. This made less than ideal use of SHA1 sum to name packs, which we would want to rectify in the future.

Many packfiles in the wild were created with git before v0.99.9, so the check would trigger and will give a warning message like this:

warning: index name '.git/objects/pack/pack-3b60db8....idx' does not match contents of the pack '83b60db...'

You can rename the existing pack that has this old name (3b60db8...) to new name (83b60db...) to squelch this warning message. For that, a new command git-convert-packs is provided to produce suitable "mv" command you can paste into your shell.

Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 .gitignore             |    1 +
 Makefile               |    2 +
 convert-packs.c        |   49 ++++++++++++++++++++++++++++++
 sha1_file.c            |   41 ++++++++++++++++++++++++-
 t/t5300-pack-object.sh |   79 ++++++++++++++++++++++++++----------------------
 5 files changed, 133 insertions(+), 39 deletions(-)
 create mode 100644 convert-packs.c
9c9f23b012e4030f433c7d4260a3fae93c302a0e
diff --git a/.gitignore b/.gitignore
index 6bd508e..d713f62 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,6 +18,7 @@ git-clone-pack
 git-commit
 git-commit-tree
 git-convert-objects
+git-convert-packs
 git-count-objects
 git-cvsexportcommit
 git-cvsimport
diff --git a/Makefile b/Makefile
index 3395a9e..2209f97 100644
--- a/Makefile
+++ b/Makefile
@@ -121,7 +121,7 @@ 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..13f5502
--- /dev/null
+++ b/convert-packs.c
@@ -0,0 +1,49 @@
+#include "cache.h"
+
+void verify_pack_name(struct packed_git *p)
+{
+	SHA_CTX ctx;
+	unsigned char sha1[20];
+	int i, nr, len;
+	const char *hex;
+
+	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);
+	
+	len = strlen(p->pack_name);
+	hex = sha1_to_hex(sha1);
+	/* "pack-X{40}.pack" */
+	if (len < 50 ||
+	    memcmp(p->pack_name + len - 5 - 40, hex, 40)) {
+		char *d = strrchr(p->pack_name, '/');
+		int dlen;
+		
+		if (d)
+			dlen = (d - p->pack_name) + 1;
+		else
+			dlen = 0;
+		printf("# Packname does not match contents.\n");
+		printf("mv '%s' '%.*spack-%s.pack'\n",
+		       p->pack_name, dlen, p->pack_name, hex);
+		printf("mv '%.*sidx' '%.*spack-%s.idx'\n",
+		       len-4, p->pack_name, dlen, p->pack_name, hex);
+	}
+}
+
+int main(int ac, char **av)
+{
+	struct packed_git *p;
+
+	setup_git_directory();
+	prepare_packed_git();
+	for (p = packed_git; p; p = p->next)
+		verify_pack_name(p);
+	return 0;
+}
diff --git a/sha1_file.c b/sha1_file.c
index 6b7577d..fc24d0e 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -323,6 +323,7 @@ static int check_packed_git_idx(const ch
 {
 	SHA_CTX ctx;
 	unsigned char sha1[20];
+	unsigned char packname[20];
 	void *idx_map;
 	unsigned int *index;
 	unsigned long idx_size;
@@ -337,6 +338,16 @@ static int check_packed_git_idx(const ch
 		close(fd);
 		return -1;
 	}
+
+	/* We require "...../pack-XXXX{40}XXXX.idx" now.
+	 * 5-byte "pack-", 40-byte hex and 4-byte .idx.
+	 */
+	i = strlen(path);
+	if (i < 49 || strcmp(path + i - 4, ".idx") ||
+	    strncmp(path + i - 49, "pack-", 5) ||
+	    get_sha1_hex(path + i - 44, packname))
+		return error("non index file %s ignored", path);
+
 	idx_size = st.st_size;
 	idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 	close(fd);
@@ -369,7 +380,7 @@ static int check_packed_git_idx(const ch
 		return error("wrong index file size");
 
 	/*
-	 * File checksum.
+	 * File checksum and index name.
 	 */
 	SHA1_Init(&ctx);
 	SHA1_Update(&ctx, idx_map, idx_size-20);
@@ -378,6 +389,34 @@ static int check_packed_git_idx(const ch
 	if (memcmp(sha1, idx_map + idx_size - 20, 20))
 		return error("index checksum mismatch");
 
+/*
+ * 0: do not check, do not do anything.
+ * 1: check and warn, but do not reject.
+ * 2: check and reject if pack name is obsolete.
+ */
+#define PACK_NAME_ENFORCEMENT_PHASE 1
+
+#if PACK_NAME_ENFORCEMENT_PHASE != 0
+	SHA1_Init(&ctx);
+	for (i = 0; i < nr; i++) {
+		unsigned char *ent = (idx_map + 4*256) + i * 24 + 4;
+		SHA1_Update(&ctx, ent, 20);
+	}
+	SHA1_Final(sha1, &ctx);
+	
+	if (memcmp(sha1, packname, 20)) {
+#if PACK_NAME_ENFORCEMENT_PHASE == 1
+		fprintf(stderr, "warning: index name '%s' does not match "
+			"contents of the pack '%s'\n",
+			path, sha1_to_hex(sha1));
+#else
+		return error("index name '%s' does not match "
+			     "contents of the pack '%s'\n",
+			     path, sha1_to_hex(sha1));
+#endif
+	}
+#endif
+
 	return 0;
 }
 
diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index 7dfb1ab..dba8227 100755
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -10,6 +10,8 @@ test_description='git-pack-object
 
 TRASH=`pwd`
 
+mkdir test-1 test-2
+
 test_expect_success \
     'setup' \
     'rm -f .git/index*
@@ -35,7 +37,7 @@ test_expect_success \
 
 test_expect_success \
     'pack without delta' \
-    'packname_1=$(git-pack-objects --window=0 test-1 <obj-list)'
+    'packname_1=$(git-pack-objects --window=0 test-1/pack <obj-list)'
 
 rm -fr .git2
 mkdir .git2
@@ -45,8 +47,8 @@ test_expect_success \
     "GIT_OBJECT_DIRECTORY=.git2/objects &&
      export GIT_OBJECT_DIRECTORY &&
      git-init-db &&
-     git-unpack-objects -n <test-1-${packname_1}.pack &&
-     git-unpack-objects <test-1-${packname_1}.pack"
+     git-unpack-objects -n <test-1/pack-${packname_1}.pack &&
+     git-unpack-objects <test-1/pack-${packname_1}.pack"
 
 unset GIT_OBJECT_DIRECTORY
 cd "$TRASH/.git2"
@@ -66,7 +68,8 @@ cd "$TRASH"
 test_expect_success \
     'pack with delta' \
     'pwd &&
-     packname_2=$(git-pack-objects test-2 <obj-list)'
+     packname_2=$(git-pack-objects test-2/pack <obj-list) &&
+     test "$packname_2" = "$packname_1"'
 
 rm -fr .git2
 mkdir .git2
@@ -76,8 +79,8 @@ test_expect_success \
     'GIT_OBJECT_DIRECTORY=.git2/objects &&
      export GIT_OBJECT_DIRECTORY &&
      git-init-db &&
-     git-unpack-objects -n <test-2-${packname_2}.pack &&
-     git-unpack-objects <test-2-${packname_2}.pack'
+     git-unpack-objects -n <test-2/pack-${packname_2}.pack &&
+     git-unpack-objects <test-2/pack-${packname_2}.pack'
 
 unset GIT_OBJECT_DIRECTORY
 cd "$TRASH/.git2"
@@ -101,7 +104,8 @@ test_expect_success \
     'GIT_OBJECT_DIRECTORY=.git2/objects &&
      export GIT_OBJECT_DIRECTORY &&
      git-init-db &&
-     cp test-1-${packname_1}.pack test-1-${packname_1}.idx .git2/objects/pack && {
+     cp test-1/pack-${packname_1}.pack test-1/pack-${packname_1}.idx \
+     	.git2/objects/pack && {
 	 git-diff-tree --root -p $commit &&
 	 while read object
 	 do
@@ -116,8 +120,9 @@ test_expect_success \
     'use packed deltified objects' \
     'GIT_OBJECT_DIRECTORY=.git2/objects &&
      export GIT_OBJECT_DIRECTORY &&
-     rm -f .git2/objects/pack/test-?.idx &&
-     cp test-2-${packname_2}.pack test-2-${packname_2}.idx .git2/objects/pack && {
+     rm -f .git2/objects/pack/pack-* &&
+     cp test-2/pack-${packname_2}.pack test-2/pack-${packname_2}.idx \
+     	.git2/objects/pack && {
 	 git-diff-tree --root -p $commit &&
 	 while read object
 	 do
@@ -131,41 +136,41 @@ unset GIT_OBJECT_DIRECTORY
 
 test_expect_success \
     'verify pack' \
-    'git-verify-pack test-1-${packname_1}.idx test-2-${packname_2}.idx'
+    'git-verify-pack test-?/pack-${packname_1}.idx'
 
 test_expect_success \
     'corrupt a pack and see if verify catches' \
-    'cp test-1-${packname_1}.idx test-3.idx &&
-     cp test-2-${packname_2}.pack test-3.pack &&
-     if git-verify-pack test-3.idx
+    'cp test-1/pack-${packname_1}.idx . &&
+     cp test-2/pack-${packname_2}.pack . &&
+     if git-verify-pack pack-${packname_1}.idx
      then false
      else :;
      fi &&
 
-     cp test-1-${packname_1}.pack test-3.pack &&
-     dd if=/dev/zero of=test-3.pack count=1 bs=1 conv=notrunc seek=2 &&
-     if git-verify-pack test-3.idx
+     cp test-1/pack-${packname_1}.pack . &&
+     dd if=/dev/zero of=pack-${packname_1}.pack count=1 bs=1 conv=notrunc seek=2 &&
+     if git-verify-pack pack-${packname_1}.idx
      then false
      else :;
      fi &&
 
-     cp test-1-${packname_1}.pack test-3.pack &&
-     dd if=/dev/zero of=test-3.pack count=1 bs=1 conv=notrunc seek=7 &&
-     if git-verify-pack test-3.idx
+     cp test-1/pack-${packname_1}.pack . &&
+     dd if=/dev/zero of=pack-${packname_1}.pack count=1 bs=1 conv=notrunc seek=7 &&
+     if git-verify-pack pack-${packname_1}.idx
      then false
      else :;
      fi &&
 
-     cp test-1-${packname_1}.pack test-3.pack &&
-     dd if=/dev/zero of=test-3.pack count=1 bs=1 conv=notrunc seek=12 &&
-     if git-verify-pack test-3.idx
+     cp test-1/pack-${packname_1}.pack . &&
+     dd if=/dev/zero of=pack-${packname_1}.pack count=1 bs=1 conv=notrunc seek=12 &&
+     if git-verify-pack pack-${packname_1}.idx
      then false
      else :;
      fi &&
 
-     cp test-1-${packname_1}.pack test-3.pack &&
-     dd if=/dev/zero of=test-3.idx count=1 bs=1 conv=notrunc seek=1200 &&
-     if git-verify-pack test-3.pack
+     cp test-1/pack-${packname_1}.pack . &&
+     dd if=/dev/zero of=pack-${packname_1}.idx count=1 bs=1 conv=notrunc seek=1200 &&
+     if git-verify-pack pack-${packname_1}.idx
      then false
      else :;
      fi &&
@@ -174,19 +179,19 @@ test_expect_success \
 
 test_expect_success \
     'build pack index for an existing pack' \
-    'cp test-1-${packname_1}.pack test-3.pack &&
-     git-index-pack -o tmp.idx test-3.pack &&
-     cmp tmp.idx test-1-${packname_1}.idx &&
-
-     git-index-pack test-3.pack &&
-     cmp test-3.idx test-1-${packname_1}.idx &&
-
-     cp test-2-${packname_2}.pack test-3.pack &&
-     git-index-pack -o tmp.idx test-2-${packname_2}.pack &&
-     cmp tmp.idx test-2-${packname_2}.idx &&
+    'cp test-1/pack-${packname_1}.pack unknown.pack &&
+     git-index-pack -o tmp.idx unknown.pack &&
+     cmp tmp.idx test-1/pack-${packname_1}.idx &&
+
+     git-index-pack unknown.pack &&
+     cmp unknown.idx test-1/pack-${packname_1}.idx &&
+
+     cp test-2/pack-${packname_2}.pack unknown.pack &&
+     git-index-pack -o tmp.idx unknown.pack &&
+     cmp tmp.idx test-2/pack-${packname_2}.idx &&
 
-     git-index-pack test-3.pack &&
-     cmp test-3.idx test-2-${packname_2}.idx &&
+     git-index-pack unknown.pack &&
+     cmp unknown.idx test-2/pack-${packname_2}.idx &&
 
      :'
 
-- 
1.0.GIT

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