[PATCH] fix pack.packSizeLimit and --max-pack-size handling

First, pack.packSizeLimit and --max-pack-size didn't use the same base
unit which was confusing.  They both use MiB now.

Also, if the limit was sufficiently low, having a single object written
could bust the limit (by design), but caused the remaining allowed size 
to go negative for subsequent objects, which for an unsigned variable is 
a rather huge limit.

Signed-off-by: Nicolas Pitre <redacted>
---

On Wed, 12 Nov 2008, Jon Nelson wrote:

I'm using 1.6.0.4 and I've found some weird behavior with
pack.packSizeLimit and/or --max-pack-size.

Initially, I thought I could just use pack.packSizeLimit and set it to
(say) 1 to try to limit the size of individual packfiles to 1MiB or
less. That does not appear to be working.

In one case I performed the following set of commands:

# set pack.packSizeLimit to 20
git config --global pack.packSizeLimit 20

# verify that it's 20
git config --get pack.packSizeLimit # verify it's 20

# run gc --prune
git gc --prune

# show the packfiles
# I find a *single* 65MB packfile, not a series
# of 20MB (or less) packfiles.
ls -la .git/objects/pack/*.pack

# try repack -ad
git repack -ad

# I find a *single* 65MB packfile, not a series
# of 20MB (or less) packfiles.
ls -la .git/objects/pack/*.pack


So it would appear that the pack.packSizeLimit param
is just being ignored??

Then I tested using --max-pack-size explicitly. This works, to a degree.

git repack -ad --max-pack-size 20

# the following shows *4* pack files none larger
# than (about) 20MB
ls -la .git/objects/pack/*.pack

# try again with 3MB. This also works.
git repack -ad --max-pack-size 3
find .git/objects/pack -name '*.pack' -size +3M -ls # nothing

# try again with 1MB. This does NOT work.
git repack -ad --max-pack-size 1

# here, I find a *single* 65MB pack file again:
find .git/objects/pack -name '*.pack' -size +1M -ls

Am I doing something completely wrong with pack.packSizeLimit?
What is going on with --max-pack-size in the 1MB case?

Does this fix it for you?

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 32dcd64..e7808b8 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt

@@ -1036,9 +1036,9 @@ you can use linkgit:git-index-pack[1] on the *.pack file to regenerate
 the `{asterisk}.idx` file.
 
 pack.packSizeLimit::
-	The default maximum size of a pack.  This setting only affects
-	packing to a file, i.e. the git:// protocol is unaffected.  It
-	can be overridden by the `\--max-pack-size` option of
+	The default maximum size of a pack, expressed in MiB.  This
+	setting only affects packing to a file, i.e. the git:// protocol is
+	unaffected. It can be overridden by the `\--max-pack-size` option of
 	linkgit:git-repack[1].
 
 pager.<cmd>::

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index 0c4649c..fdee9c6 100644
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c

@@ -245,8 +245,12 @@ static unsigned long write_object(struct sha1file *f,
 	type = entry->type;
 
 	/* write limit if limited packsize and not first object */
-	limit = pack_size_limit && nr_written ?
-			pack_size_limit - write_offset : 0;
+	if (!pack_size_limit || !nr_written)
+		limit = 0;
+	else if (pack_size_limit <= write_offset)
+		limit = 1;
+	else
+		limit = pack_size_limit - write_offset;
 
 	if (!entry->delta)
 		usable_delta = 0;	/* no delta */

@@ -1844,7 +1848,7 @@ static int git_pack_config(const char *k, const char *v, void *cb)
 		return 0;
 	}
 	if (!strcmp(k, "pack.packsizelimit")) {
-		pack_size_limit_cfg = git_config_ulong(k, v);
+		pack_size_limit_cfg = git_config_ulong(k, v) * 1024 * 1024;
 		return 0;
 	}
 	return git_default_config(k, v, cb);