зеркало из https://github.com/microsoft/git.git
89 строки
1.9 KiB
C
89 строки
1.9 KiB
C
|
/*
|
||
|
|
* patch-delta.c:
|
||
|
|
* recreate a buffer from a source and the delta produced by diff-delta.c
|
||
|
|
*
|
||
|
|
* (C) 2005 Nicolas Pitre <nico@cam.org>
|
||
|
|
*
|
||
|
|
* This code is free software; you can redistribute it and/or modify
|
||
|
|
* it under the terms of the GNU General Public License version 2 as
|
||
|
|
* published by the Free Software Foundation.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <stdlib.h>
|
||
|
|
#include <string.h>
|
||
|
|
#include "delta.h"
|
||
|
|
|
||
|
|
void *patch_delta(void *src_buf, unsigned long src_size,
|
||
|
|
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)
|
||
|
|
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;
|
||
|
|
}
|
||
|
|
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);
|
||
|
|
if (!dst_buf)
|
||
|
|
return NULL;
|
||
|
|
|
||
|
|
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 (cp_size == 0) cp_size = 0x10000;
|
||
|
|
buf = (cmd & 0x40) ? dst_buf : src_buf;
|
||
|
|
memcpy(out, buf + cp_off, cp_size);
|
||
|
|
out += cp_size;
|
||
|
|
} else {
|
||
|
|
memcpy(out, data, cmd);
|
||
|
|
out += cmd;
|
||
|
|
data += cmd;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/* sanity check */
|
||
|
|
if (data != top || out - dst_buf != size) {
|
||
|
|
free(dst_buf);
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
*dst_size = size;
|
||
|
|
return dst_buf;
|
||
|
|
}
|