Commit dcde55bc authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Linus Torvalds

[PATCH] assorted delta code cleanup

This is a wrap-up patch including all the cleanups I've done to the
delta code and its usage.  The most important change is the
factorization of the delta header handling code.
Signed-off-by: default avatarNicolas Pitre <nico@cam.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent e5e3e0f5
......@@ -6,23 +6,9 @@
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include "delta.h"
#include "count-delta.h"
static unsigned long get_hdr_size(const unsigned char **datap)
{
const unsigned char *data = *datap;
unsigned char cmd = *data++;
unsigned long size = cmd & ~0x80;
int i = 7;
while (cmd & 0x80) {
cmd = *data++;
size |= (cmd & ~0x80) << i;
i += 7;
}
*datap = data;
return size;
}
/*
* NOTE. We do not _interpret_ delta fully. As an approximation, we
* just count the number of bytes that are copied from the source, and
......@@ -44,15 +30,14 @@ int count_delta(void *delta_buf, unsigned long delta_size,
unsigned char cmd;
unsigned long src_size, dst_size, out;
/* the smallest delta size possible is 4 bytes */
if (delta_size < 4)
if (delta_size < DELTA_SIZE_MIN)
return -1;
data = delta_buf;
top = delta_buf + delta_size;
src_size = get_hdr_size(&data);
dst_size = get_hdr_size(&data);
src_size = get_delta_hdr_size(&data);
dst_size = get_delta_hdr_size(&data);
added_literal = copied_from_source = out = 0;
while (data < top) {
......
......@@ -9,4 +9,26 @@ extern void *patch_delta(void *src_buf, unsigned long src_size,
void *delta_buf, unsigned long delta_size,
unsigned long *dst_size);
/* the smallest possible delta size is 4 bytes */
#define DELTA_SIZE_MIN 4
/*
* This must be called twice on the delta data buffer, first to get the
* expected reference buffer size, and again to get the result buffer size.
*/
static inline unsigned long get_delta_hdr_size(const unsigned char **datap)
{
const unsigned char *data = *datap;
unsigned char cmd = *data++;
unsigned long size = cmd & ~0x80;
int i = 7;
while (cmd & 0x80) {
cmd = *data++;
size |= (cmd & ~0x80) << i;
i += 7;
}
*datap = data;
return size;
}
#endif
......@@ -306,12 +306,13 @@ void *diff_delta(void *from_buf, unsigned long from_size,
*orig = i;
}
/* next time around the largest possible output is 1 + 4 + 3 */
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) {
void *tmp = out;
outsize = outsize * 3 / 2;
......
......@@ -34,7 +34,7 @@ static void *delta_against(void *buf, unsigned long size, struct object_entry *e
if (!otherbuf)
die("unable to read %s", sha1_to_hex(entry->delta->sha1));
delta_buf = diff_delta(otherbuf, othersize,
buf, size, &delta_size, ~0UL);
buf, size, &delta_size, 0);
if (!delta_buf || delta_size != entry->delta_size)
die("delta size changed");
free(buf);
......
......@@ -20,36 +20,20 @@ void *patch_delta(void *src_buf, unsigned long src_size,
const unsigned char *data, *top;
unsigned char *dst_buf, *out, cmd;
unsigned long size;
int i;
/* the smallest delta size possible is 4 bytes */
if (delta_size < 4)
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 */
cmd = *data++;
size = cmd & ~0x80;
i = 7;
while (cmd & 0x80) {
cmd = *data++;
size |= (cmd & ~0x80) << i;
i += 7;
}
size = get_delta_hdr_size(&data);
if (size != src_size)
return NULL;
/* now the result size */
cmd = *data++;
size = cmd & ~0x80;
i = 7;
while (cmd & 0x80) {
cmd = *data++;
size |= (cmd & ~0x80) << i;
i += 7;
}
size = get_delta_hdr_size(&data);
dst_buf = malloc(size);
if (!dst_buf)
return NULL;
......
......@@ -592,22 +592,6 @@ void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned l
return unpack_sha1_rest(&stream, hdr, *size);
}
static unsigned long parse_delta_size(unsigned char **p)
{
unsigned char c;
unsigned long size = 0;
unsigned shift = 0;
unsigned char *data = *p;
do {
c = *data++;
size += (c & 0x7f) << shift;
shift += 7;
} while (c & 0x80);
*p = data;
return size;
}
static int packed_delta_info(unsigned char *base_sha1,
unsigned long delta_size,
unsigned long left,
......@@ -645,11 +629,12 @@ static int packed_delta_info(unsigned char *base_sha1,
* the result size. Verify the base size while we are at it.
*/
data = delta_head;
verify_base_size = parse_delta_size(&data);
result_size = parse_delta_size(&data);
verify_base_size = get_delta_hdr_size(&data);
if (verify_base_size != base_size)
die("delta base size mismatch");
/* Read the result size */
result_size = get_delta_hdr_size(&data);
*sizep = result_size;
return 0;
}
......
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