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@xxxxxxx>
---
diff-delta.c | 24 ++++++++++++++----------
1 files changed, 14 insertions(+), 10 deletions(-)
95c1d1f82a8e36ab1e46b8186ecb34f441914961
diff --git a/diff-delta.c b/diff-delta.c
index c2f656a..ac992e2 100644
--- a/diff-delta.c
+++ b/diff-delta.c
@@ -148,16 +148,20 @@ static void delta_cleanup(bdfile_t *bdf)
cha_free(&bdf->cha);
}
+/* provide the size of the copy opcode given the block offset and size */
#define COPYOP_SIZE(o, s) \
(!!(o & 0xff) + !!(o & 0xff00) + !!(o & 0xff0000) + !!(o & 0xff000000) + \
!!(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 *to_buf, unsigned long to_size,
unsigned long *delta_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;
const unsigned char *ref_data, *ref_top, *data, *top, *ptr1, *ptr2;
unsigned char *out, *orig;
@@ -169,6 +173,8 @@ void *diff_delta(void *from_buf, unsigne
outpos = 0;
outsize = 8192;
+ if (max_size && outsize >= max_size)
+ outsize = max_size + MAX_OP_SIZE + 1;
out = malloc(outsize);
if (!out) {
delta_cleanup(&bdf);
@@ -259,17 +265,15 @@ void *diff_delta(void *from_buf, unsigne
*orig = i;
}
- if (max_size && outpos > max_size) {
- free(out);
- delta_cleanup(&bdf);
- return NULL;
- }
-
- /* next time around the largest possible output is 1 + 4 + 3 */
- if (outpos > outsize - 8) {
+ if (outpos >= outsize - MAX_OP_SIZE) {
void *tmp = out;
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) {
free(tmp);
delta_cleanup(&bdf);
--
1.2.2.g6643-dirty
-
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