gitweb: use new Git::Repo API, and add optional caching
[git/gitweb-caching.git] / patch-delta.c
blobed9db81fa82c812c9ffa07f5a40540dbb15da0d3
1 /*
2 * patch-delta.c:
3 * recreate a buffer from a source and the delta produced by diff-delta.c
5 * (C) 2005 Nicolas Pitre <nico@cam.org>
7 * This code is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
12 #include "git-compat-util.h"
13 #include "delta.h"
15 void *patch_delta(const void *src_buf, unsigned long src_size,
16 const void *delta_buf, unsigned long delta_size,
17 unsigned long *dst_size)
19 const unsigned char *data, *top;
20 unsigned char *dst_buf, *out, cmd;
21 unsigned long size;
23 if (delta_size < DELTA_SIZE_MIN)
24 return NULL;
26 data = delta_buf;
27 top = (const unsigned char *) delta_buf + delta_size;
29 /* make sure the orig file size matches what we expect */
30 size = get_delta_hdr_size(&data, top);
31 if (size != src_size)
32 return NULL;
34 /* now the result size */
35 size = get_delta_hdr_size(&data, top);
36 dst_buf = xmalloc(size + 1);
37 dst_buf[size] = 0;
39 out = dst_buf;
40 while (data < top) {
41 cmd = *data++;
42 if (cmd & 0x80) {
43 unsigned long cp_off = 0, cp_size = 0;
44 if (cmd & 0x01) cp_off = *data++;
45 if (cmd & 0x02) cp_off |= (*data++ << 8);
46 if (cmd & 0x04) cp_off |= (*data++ << 16);
47 if (cmd & 0x08) cp_off |= (*data++ << 24);
48 if (cmd & 0x10) cp_size = *data++;
49 if (cmd & 0x20) cp_size |= (*data++ << 8);
50 if (cmd & 0x40) cp_size |= (*data++ << 16);
51 if (cp_size == 0) cp_size = 0x10000;
52 if (cp_off + cp_size < cp_size ||
53 cp_off + cp_size > src_size ||
54 cp_size > size)
55 break;
56 memcpy(out, (char *) src_buf + cp_off, cp_size);
57 out += cp_size;
58 size -= cp_size;
59 } else if (cmd) {
60 if (cmd > size)
61 break;
62 memcpy(out, data, cmd);
63 out += cmd;
64 data += cmd;
65 size -= cmd;
66 } else {
68 * cmd == 0 is reserved for future encoding
69 * extensions. In the mean time we must fail when
70 * encountering them (might be data corruption).
72 error("unexpected delta opcode 0");
73 goto bad;
77 /* sanity check */
78 if (data != top || size != 0) {
79 error("delta replay has gone wild");
80 bad:
81 free(dst_buf);
82 return NULL;
85 *dst_size = out - dst_buf;
86 return dst_buf;