@matheusbsbs / matheus-bagliano / commits / f0e7f11d05

index-pack: fix truncation of off_t in comparison

Commit c6458e6 (index-pack: kill union delta_base to save memory, 2015-04-18) refactored the comparison functions used in sorting and binary searching our delta list. The resulting code does something like: int cmp_offsets(off_t a, off_t b) { return a - b; } This works most of the time, but produces nonsensical results when the difference between the two offsets is larger than what can be stored in an "int". This can lead to unresolved deltas if the packsize is larger than 2G (even on 64-bit systems, an int is still typically 32 bits): $ git clone git://github.com/mozilla/gecko-dev Cloning into 'gecko-dev'... remote: Counting objects: 4800161, done. remote: Compressing objects: 100% (178/178), done. remote: Total 4800161 (delta 88), reused 0 (delta 0), pack-reused 4799978 Receiving objects: 100% (4800161/4800161), 2.21 GiB | 3.26 MiB/s, done. Resolving deltas: 99% (3808820/3811944), completed with 0 local objects. fatal: pack has 3124 unresolved deltas fatal: index-pack failed We can fix it by doing direct comparisons between the offsets and returning constants; the callers only care about the sign of the comparison, not the magnitude. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Jun 4, 2015 at 08:35 UTC f0e7f11d054b79de6e1f7bcee6e68c2f17af61bd

1 file changed +6 -2

builtin/index-pack.c

+6 -2

@@ -616,7 +616,9 @@ static int compare_ofs_delta_bases(off_t offset1, off_t offset2,

616 int cmp = type1 - type2;

617 if (cmp)

618 return cmp;

619 - return offset1 - offset2;

619 + return offset1 < offset2 ? -1 :

620 + offset1 > offset2 ? 1 :

621 + 0;

622 }

623

624 static int find_ofs_delta(const off_t offset, enum object_type type)

@@ -1051,7 +1053,9 @@ static int compare_ofs_delta_entry(const void *a, const void *b)

1053 const struct ofs_delta_entry *delta_a = a;

1054 const struct ofs_delta_entry *delta_b = b;

1055

1054 - return delta_a->offset - delta_b->offset;

1056 + return delta_a->offset < delta_b->offset ? -1 :

1057 + delta_a->offset > delta_b->offset ? 1 :

1058 + 0;

1059 }

1060

1061 static int compare_ref_delta_entry(const void *a, const void *b)