[PATCH 02/10] make overflow test on delta base offset work regardless of variable size
- From
Nicolas Pitre <nico@cam.org>
- Date
- Apr 9, 2007, 05:06 UTC
- Message-ID
- <11760951993458-git-send-email-nico@cam.org>
- In-Reply-To
- <11760951973319-git-send-email-nico@cam.org>
This patch introduces the MSB() macro to obtain the desired number of most significant bits from a given variable independently of the variable type.
It is then used to better implement the overflow test on the OBJ_OFS_DELTA base offset variable with the property of always working correctly regardless of the type/size of that variable.
Signed-off-by: Nicolas Pitre <nico@cam.org> --- builtin-pack-objects.c | 2 +- builtin-unpack-objects.c | 2 +- git-compat-util.h | 8 ++++++++ index-pack.c | 2 +- sha1_file.c | 2 +- 5 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c index 6bff17b..ee607a0 100644 --- a/builtin-pack-objects.c +++ b/builtin-pack-objects.c @@ -1014,7 +1014,7 @@ static void check_object(struct object_entry *entry) ofs = c & 127; while (c & 128) { ofs += 1; - if (!ofs || ofs & ~(~0UL >> 7)) + if (!ofs || MSB(ofs, 7)) die("delta base offset overflow in pack for %s", sha1_to_hex(entry->sha1)); c = buf[used_0++]; diff --git a/builtin-unpack-objects.c b/builtin-unpack-objects.c index 3956c56..63f7db6 100644 --- a/builtin-unpack-objects.c +++ b/builtin-unpack-objects.c @@ -209,7 +209,7 @@ static void unpack_delta_entry(enum object_type type, unsigned long delta_size, base_offset = c & 127; while (c & 128) { base_offset += 1; - if (!base_offset || base_offset & ~(~0UL >> 7)) + if (!base_offset || MSB(base_offset, 7)) die("offset value overflow for delta base object"); pack = fill(1); c = *pack; diff --git a/git-compat-util.h b/git-compat-util.h index 139fc19..bcfcb35 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -13,6 +13,14 @@ #define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0])) +#ifdef __GNUC__ +#define TYPEOF(x) (__typeof__(x)) +#else +#define TYPEOF(x) +#endif + +#define MSB(x, bits) ((x) & TYPEOF(x)(~0ULL << (sizeof(x) * 8 - (bits)))) + #if !defined(__APPLE__) && !defined(__FreeBSD__) #define _XOPEN_SOURCE 600 /* glibc2 and AIX 5.3L need 500, OpenBSD needs 600 for S_ISLNK() */ #define _XOPEN_SOURCE_EXTENDED 1 /* AIX 5.3L needs this */ diff --git a/index-pack.c b/index-pack.c index 3c768fb..0e54aa6 100644 --- a/index-pack.c +++ b/index-pack.c @@ -249,7 +249,7 @@ static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_ base_offset = c & 127; while (c & 128) { base_offset += 1; - if (!base_offset || base_offset & ~(~0UL >> 7)) + if (!base_offset || MSB(base_offset, 7)) bad_object(obj->offset, "offset value overflow for delta base object"); p = fill(1); c = *p; diff --git a/sha1_file.c b/sha1_file.c index d9ca69a..ebdd497 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -1150,7 +1150,7 @@ static off_t get_delta_base(struct packed_git *p, base_offset = c & 127; while (c & 128) { base_offset += 1; - if (!base_offset || base_offset & ~(~0UL >> 7)) + if (!base_offset || MSB(base_offset, 7)) die("offset value overflow for delta base object"); c = base_info[used++]; base_offset = (base_offset << 7) + (c & 127);
-- 1.5.1.696.g6d352-dirty