Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

89 lines (79 sloc) 2.172 kb
/*
* 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(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;
if (delta_size < DELTA_SIZE_MIN)
return NULL;
data = delta_buf;
top = (const unsigned char *) delta_buf + delta_size;
/* make sure the orig file size matches what we expect */
size = get_delta_hdr_size(&data, top);
if (size != src_size)
return NULL;
/* now the result 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;
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;
if (cp_off + cp_size < cp_size ||
cp_off + cp_size > src_size ||
cp_size > size)
goto bad;
memcpy(out, (char *) src_buf + cp_off, cp_size);
out += cp_size;
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 || size != 0) {
bad:
free(dst_buf);
return NULL;
}
*dst_size = out - dst_buf;
return dst_buf;
}
Jump to Line
Something went wrong with that request. Please try again.