A packfile may have up to 2^32-1 objects in it, so the
"right" data type to use is uint32_t. We currently use a
signed int, which means that we may behave incorrectly for
packfiles with more than 2^31-1 objects on 32-bit systems.

Nobody has noticed because having 2^31 objects is pretty
insane. The linux.git repo has on the order of 2^22 objects,
which is hundreds of times smaller than necessary to trigger
the bug.

Let's bump this up to an "unsigned". On 32-bit systems, this
gives us the correct data-type, and on 64-bit systems, it is
probably more efficient to use the native "unsigned" than a
true uint32_t.

While we're at it, we can fix the binary search not to
overflow in such a case if our unsigned is 32 bits.

Signed-off-by: Jeff King <p...@peff.net>
I didn't look farther in the pack code to see if we have other
problematic instances. So there may be others lurking, but these ones
were close to the area I was working in.

 pack-revindex.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/pack-revindex.c b/pack-revindex.c
index 77a0465..1aa9754 100644
--- a/pack-revindex.c
+++ b/pack-revindex.c
@@ -72,8 +72,8 @@ static void create_pack_revindex(struct pack_revindex *rix)
 static void create_pack_revindex(struct pack_revindex *rix)
        struct packed_git *p = rix->p;
-       int num_ent = p->num_objects;
-       int i;
+       unsigned num_ent = p->num_objects;
+       unsigned i;
        const char *index = p->index_data;
        rix->revindex = xmalloc(sizeof(*rix->revindex) * (num_ent + 1));
@@ -114,7 +114,7 @@ struct revindex_entry *find_pack_revindex(struct packed_git 
*p, off_t ofs)
 struct revindex_entry *find_pack_revindex(struct packed_git *p, off_t ofs)
        int num;
-       int lo, hi;
+       unsigned lo, hi;
        struct pack_revindex *rix;
        struct revindex_entry *revindex;
@@ -132,7 +132,7 @@ struct revindex_entry *find_pack_revindex(struct packed_git 
*p, off_t ofs)
        lo = 0;
        hi = p->num_objects + 1;
        do {
-               int mi = (lo + hi) / 2;
+               unsigned mi = lo + (hi - lo) / 2;
                if (revindex[mi].offset == ofs) {
                        return revindex + mi;
                } else if (ofs < revindex[mi].offset)

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