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Commit | Line | Data |
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a310d434 NP |
1 | /* |
2 | * patch-delta.c: | |
3 | * recreate a buffer from a source and the delta produced by diff-delta.c | |
4 | * | |
03aa8ff3 | 5 | * (C) 2005 Nicolas Pitre <nico@fluxnic.net> |
a310d434 NP |
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 | ||
57b73150 | 12 | #include "git-compat-util.h" |
a310d434 NP |
13 | #include "delta.h" |
14 | ||
08abe669 NP |
15 | void *patch_delta(const void *src_buf, unsigned long src_size, |
16 | const void *delta_buf, unsigned long delta_size, | |
a310d434 NP |
17 | unsigned long *dst_size) |
18 | { | |
19 | const unsigned char *data, *top; | |
20 | unsigned char *dst_buf, *out, cmd; | |
21 | unsigned long size; | |
a310d434 | 22 | |
dcde55bc | 23 | if (delta_size < DELTA_SIZE_MIN) |
a310d434 NP |
24 | return NULL; |
25 | ||
26 | data = delta_buf; | |
1d7f171c | 27 | top = (const unsigned char *) delta_buf + delta_size; |
a310d434 NP |
28 | |
29 | /* make sure the orig file size matches what we expect */ | |
8960844a | 30 | size = get_delta_hdr_size(&data, top); |
a310d434 NP |
31 | if (size != src_size) |
32 | return NULL; | |
33 | ||
34 | /* now the result size */ | |
8960844a | 35 | size = get_delta_hdr_size(&data, top); |
222083a1 | 36 | dst_buf = xmallocz(size); |
a310d434 NP |
37 | |
38 | out = dst_buf; | |
39 | while (data < top) { | |
40 | cmd = *data++; | |
41 | if (cmd & 0x80) { | |
42 | unsigned long cp_off = 0, cp_size = 0; | |
9514b0b2 JK |
43 | #define PARSE_CP_PARAM(bit, var, shift) do { \ |
44 | if (cmd & (bit)) { \ | |
45 | if (data >= top) \ | |
46 | goto bad_length; \ | |
47 | var |= ((unsigned) *data++ << (shift)); \ | |
48 | } } while (0) | |
49 | PARSE_CP_PARAM(0x01, cp_off, 0); | |
50 | PARSE_CP_PARAM(0x02, cp_off, 8); | |
51 | PARSE_CP_PARAM(0x04, cp_off, 16); | |
52 | PARSE_CP_PARAM(0x08, cp_off, 24); | |
53 | PARSE_CP_PARAM(0x10, cp_size, 0); | |
54 | PARSE_CP_PARAM(0x20, cp_size, 8); | |
55 | PARSE_CP_PARAM(0x40, cp_size, 16); | |
56 | #undef PARSE_CP_PARAM | |
a310d434 | 57 | if (cp_size == 0) cp_size = 0x10000; |
1368f650 | 58 | if (unsigned_add_overflows(cp_off, cp_size) || |
8960844a NP |
59 | cp_off + cp_size > src_size || |
60 | cp_size > size) | |
fa72f90e | 61 | goto bad_length; |
1d7f171c | 62 | memcpy(out, (char *) src_buf + cp_off, cp_size); |
a310d434 | 63 | out += cp_size; |
8960844a NP |
64 | size -= cp_size; |
65 | } else if (cmd) { | |
21870efc | 66 | if (cmd > size || cmd > top - data) |
fa72f90e | 67 | goto bad_length; |
a310d434 NP |
68 | memcpy(out, data, cmd); |
69 | out += cmd; | |
70 | data += cmd; | |
8960844a NP |
71 | size -= cmd; |
72 | } else { | |
73 | /* | |
74 | * cmd == 0 is reserved for future encoding | |
75 | * extensions. In the mean time we must fail when | |
76 | * encountering them (might be data corruption). | |
77 | */ | |
57b73150 | 78 | error("unexpected delta opcode 0"); |
8960844a | 79 | goto bad; |
a310d434 NP |
80 | } |
81 | } | |
82 | ||
83 | /* sanity check */ | |
8960844a | 84 | if (data != top || size != 0) { |
fa72f90e | 85 | bad_length: |
57b73150 | 86 | error("delta replay has gone wild"); |
8960844a | 87 | bad: |
a310d434 NP |
88 | free(dst_buf); |
89 | return NULL; | |
90 | } | |
91 | ||
8960844a | 92 | *dst_size = out - dst_buf; |
a310d434 NP |
93 | return dst_buf; |
94 | } |