projects / thirdparty / git.git / blame
| Commit | Line | Data |
|---|---|---|
| a310d434 NP |
1 | /* |
| 2 | * patch-delta.c: | |
| 3 | * recreate a buffer from a source and the delta produced by diff-delta.c | |
| 4 | * | |
| 5 | * (C) 2005 Nicolas Pitre <nico@cam.org> | |
| 6 | * | |
| 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. | |
| 10 | */ | |
| 11 | ||
| 12 | #include <stdlib.h> | |
| 13 | #include <string.h> | |
| 14 | #include "delta.h" | |
| 15 | ||
| 16 | void *patch_delta(void *src_buf, unsigned long src_size, | |
| 17 | void *delta_buf, unsigned long delta_size, | |
| 18 | unsigned long *dst_size) | |
| 19 | { | |
| 20 | const unsigned char *data, *top; | |
| 21 | unsigned char *dst_buf, *out, cmd; | |
| 22 | unsigned long size; | |
| 23 | int i; | |
| 24 | ||
| 69a2d426 NP |
25 | /* the smallest delta size possible is 4 bytes */ |
| 26 | if (delta_size < 4) | |
| a310d434 NP |
27 | return NULL; |
| 28 | ||
| 29 | data = delta_buf; | |
| 30 | top = delta_buf + delta_size; | |
| 31 | ||
| 32 | /* make sure the orig file size matches what we expect */ | |
| a310d434 | 33 | cmd = *data++; |
| 69a2d426 NP |
34 | size = cmd & ~0x80; |
| 35 | i = 7; | |
| 36 | while (cmd & 0x80) { | |
| 37 | cmd = *data++; | |
| 38 | size |= (cmd & ~0x80) << i; | |
| 39 | i += 7; | |
| a310d434 NP |
40 | } |
| 41 | if (size != src_size) | |
| 42 | return NULL; | |
| 43 | ||
| 44 | /* now the result size */ | |
| a310d434 | 45 | cmd = *data++; |
| 69a2d426 NP |
46 | size = cmd & ~0x80; |
| 47 | i = 7; | |
| 48 | while (cmd & 0x80) { | |
| 49 | cmd = *data++; | |
| 50 | size |= (cmd & ~0x80) << i; | |
| 51 | i += 7; | |
| a310d434 NP |
52 | } |
| 53 | dst_buf = malloc(size); | |
| 54 | if (!dst_buf) | |
| 55 | return NULL; | |
| 56 | ||
| 57 | out = dst_buf; | |
| 58 | while (data < top) { | |
| 59 | cmd = *data++; | |
| 60 | if (cmd & 0x80) { | |
| 61 | unsigned long cp_off = 0, cp_size = 0; | |
| 62 | const unsigned char *buf; | |
| 63 | if (cmd & 0x01) cp_off = *data++; | |
| 64 | if (cmd & 0x02) cp_off |= (*data++ << 8); | |
| 65 | if (cmd & 0x04) cp_off |= (*data++ << 16); | |
| 66 | if (cmd & 0x08) cp_off |= (*data++ << 24); | |
| 67 | if (cmd & 0x10) cp_size = *data++; | |
| 68 | if (cmd & 0x20) cp_size |= (*data++ << 8); | |
| 69 | if (cp_size == 0) cp_size = 0x10000; | |
| 70 | buf = (cmd & 0x40) ? dst_buf : src_buf; | |
| 71 | memcpy(out, buf + cp_off, cp_size); | |
| 72 | out += cp_size; | |
| 73 | } else { | |
| 74 | memcpy(out, data, cmd); | |
| 75 | out += cmd; | |
| 76 | data += cmd; | |
| 77 | } | |
| 78 | } | |
| 79 | ||
| 80 | /* sanity check */ | |
| 81 | if (data != top || out - dst_buf != size) { | |
| 82 | free(dst_buf); | |
| 83 | return NULL; | |
| 84 | } | |
| 85 | ||
| 86 | *dst_size = size; | |
| 87 | return dst_buf; | |
| 88 | } |