#include <string.h>
#include "delta.h"
-void *patch_delta(void *src_buf, unsigned long src_size,
- void *delta_buf, unsigned long delta_size,
+void *patch_delta(const void *src_buf, unsigned long src_size,
+ const void *delta_buf, unsigned long delta_size,
unsigned long *dst_size)
{
const unsigned char *data, *top;
unsigned char *dst_buf, *out, cmd;
unsigned long size;
- int i;
- /* the smallest delta size possible is 6 bytes */
- if (delta_size < 6)
+ if (delta_size < DELTA_SIZE_MIN)
return NULL;
data = delta_buf;
top = delta_buf + delta_size;
/* make sure the orig file size matches what we expect */
- size = i = 0;
- cmd = *data++;
- while (cmd) {
- if (cmd & 1)
- size |= *data++ << i;
- i += 8;
- cmd >>= 1;
- }
+ size = get_delta_hdr_size(&data, top);
if (size != src_size)
return NULL;
/* now the result size */
- size = i = 0;
- cmd = *data++;
- while (cmd) {
- if (cmd & 1)
- size |= *data++ << i;
- i += 8;
- cmd >>= 1;
- }
- dst_buf = malloc(size);
+ size = get_delta_hdr_size(&data, top);
+ dst_buf = malloc(size + 1);
if (!dst_buf)
return NULL;
+ dst_buf[size] = 0;
out = dst_buf;
while (data < top) {
cmd = *data++;
if (cmd & 0x80) {
unsigned long cp_off = 0, cp_size = 0;
- const unsigned char *buf;
if (cmd & 0x01) cp_off = *data++;
if (cmd & 0x02) cp_off |= (*data++ << 8);
if (cmd & 0x04) cp_off |= (*data++ << 16);
if (cmd & 0x08) cp_off |= (*data++ << 24);
if (cmd & 0x10) cp_size = *data++;
if (cmd & 0x20) cp_size |= (*data++ << 8);
+ if (cmd & 0x40) cp_size |= (*data++ << 16);
if (cp_size == 0) cp_size = 0x10000;
- buf = (cmd & 0x40) ? dst_buf : src_buf;
- memcpy(out, buf + cp_off, cp_size);
+ if (cp_off + cp_size < cp_size ||
+ cp_off + cp_size > src_size ||
+ cp_size > size)
+ goto bad;
+ memcpy(out, src_buf + cp_off, cp_size);
out += cp_size;
- } else {
+ size -= cp_size;
+ } else if (cmd) {
+ if (cmd > size)
+ goto bad;
memcpy(out, data, cmd);
out += cmd;
data += cmd;
+ size -= cmd;
+ } else {
+ /*
+ * cmd == 0 is reserved for future encoding
+ * extensions. In the mean time we must fail when
+ * encountering them (might be data corruption).
+ */
+ goto bad;
}
}
/* sanity check */
- if (data != top || out - dst_buf != size) {
+ if (data != top || size != 0) {
+ bad:
free(dst_buf);
return NULL;
}
- *dst_size = size;
+ *dst_size = out - dst_buf;
return dst_buf;
}