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pack-objects: do not truncate result in-pack object size on 32-bit systems

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A typical diff will not show what's going on and you need to see full
functions. The core code is like this, at the end of of write_one()

	e->idx.offset = *offset;
	size = write_object(f, e, *offset);
	if (!size) {
		e->idx.offset = recursing;
		return WRITE_ONE_BREAK;
	}
	written_list[nr_written++] = &e->idx;

	/* make sure off_t is sufficiently large not to wrap */
	if (signed_add_overflows(*offset, size))
		die("pack too large for current definition of off_t");
	*offset += size;

Here we can see that the in-pack object size is returned by
write_object (or indirectly by write_reuse_object). And it's used to
calculate object offsets, which end up in the pack index file,
generated at the end.

If "size" overflows (on 32-bit sytems, unsigned long is 32-bit while
off_t can be 64-bit), we got wrong offsets and produce incorrect .idx
file, which may make it look like the .pack file is corrupted.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Nguyễn Thái Ngọc Duy 2016-07-13 17:44:03 +02:00 committed by Junio C Hamano
parent da49a7da3a
commit af92a645d3
1 changed files with 8 additions and 7 deletions
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15
builtin/pack-objects.c
View file

@ -341,8 +341,8 @@ static unsigned long write_no_reuse_object(struct sha1file *f, struct object_ent
}
/* Return 0 if we will bust the pack-size limit */
static unsigned long write_reuse_object(struct sha1file *f, struct object_entry *entry,
unsigned long limit, int usable_delta)
static off_t write_reuse_object(struct sha1file *f, struct object_entry *entry,
unsigned long limit, int usable_delta)
{
struct packed_git *p = entry->in_pack;
struct pack_window *w_curs = NULL;
@ -415,11 +415,12 @@ static unsigned long write_reuse_object(struct sha1file *f, struct object_entry
}
/* Return 0 if we will bust the pack-size limit */
static unsigned long write_object(struct sha1file *f,
struct object_entry *entry,
off_t write_offset)
static off_t write_object(struct sha1file *f,
struct object_entry *entry,
off_t write_offset)
{
unsigned long limit, len;
unsigned long limit;
off_t len;
int usable_delta, to_reuse;
if (!pack_to_stdout)
@ -491,7 +492,7 @@ static enum write_one_status write_one(struct sha1file *f,
struct object_entry *e,
off_t *offset)
{
unsigned long size;
off_t size;
int recursing;
/*