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diff-delta: fold two special tests into one plus cleanups

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Testing for realloc and size limit can be done with only one test per
loop. Make it so and fix a theoretical off-by-one comparison error in
the process.

The output buffer memory allocation is also bounded by max_size when
specified.

Finally make some variable unsigned to allow the handling of files up to
4GB in size instead of 2GB.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Nicolas Pitre 2006-02-21 20:41:41 -05:00 committed by Junio C Hamano
parent cac251d0bc
commit fe474b588b
1 changed files with 14 additions and 10 deletions
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24
diff-delta.c
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@ -148,16 +148,20 @@ static void delta_cleanup(bdfile_t *bdf)
cha_free(&bdf->cha); cha_free(&bdf->cha);
} }
/* provide the size of the copy opcode given the block offset and size */
#define COPYOP_SIZE(o, s) \ #define COPYOP_SIZE(o, s) \
(!!(o & 0xff) + !!(o & 0xff00) + !!(o & 0xff0000) + !!(o & 0xff000000) + \ (!!(o & 0xff) + !!(o & 0xff00) + !!(o & 0xff0000) + !!(o & 0xff000000) + \
!!(s & 0xff) + !!(s & 0xff00) + 1) !!(s & 0xff) + !!(s & 0xff00) + 1)
/* the maximum size for any opcode */
#define MAX_OP_SIZE COPYOP_SIZE(0xffffffff, 0xffffffff)
void *diff_delta(void *from_buf, unsigned long from_size, void *diff_delta(void *from_buf, unsigned long from_size,
void *to_buf, unsigned long to_size, void *to_buf, unsigned long to_size,
unsigned long *delta_size, unsigned long *delta_size,
unsigned long max_size) unsigned long max_size)
{ {
int i, outpos, outsize, inscnt, csize, msize, moff; unsigned int i, outpos, outsize, inscnt, csize, msize, moff;
unsigned int fp; unsigned int fp;
const unsigned char *ref_data, *ref_top, *data, *top, *ptr1, *ptr2; const unsigned char *ref_data, *ref_top, *data, *top, *ptr1, *ptr2;
unsigned char *out, *orig; unsigned char *out, *orig;
@ -169,6 +173,8 @@ void *diff_delta(void *from_buf, unsigned long from_size,
outpos = 0; outpos = 0;
outsize = 8192; outsize = 8192;
if (max_size && outsize >= max_size)
outsize = max_size + MAX_OP_SIZE + 1;
out = malloc(outsize); out = malloc(outsize);
if (!out) { if (!out) {
delta_cleanup(&bdf); delta_cleanup(&bdf);
@ -259,17 +265,15 @@ void *diff_delta(void *from_buf, unsigned long from_size,
*orig = i; *orig = i;
} }
if (max_size && outpos > max_size) { if (outpos >= outsize - MAX_OP_SIZE) {
free(out);
delta_cleanup(&bdf);
return NULL;
}
/* next time around the largest possible output is 1 + 4 + 3 */
if (outpos > outsize - 8) {
void *tmp = out; void *tmp = out;
outsize = outsize * 3 / 2; outsize = outsize * 3 / 2;
out = realloc(out, outsize); if (max_size && outsize >= max_size)
outsize = max_size + MAX_OP_SIZE + 1;
if (max_size && outpos > max_size)
out = NULL;
else
out = realloc(out, outsize);
if (!out) { if (!out) {
free(tmp); free(tmp);
delta_cleanup(&bdf); delta_cleanup(&bdf);