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@@ -1,283 +1,283 b'' | |||||
1 | /* |
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1 | /* | |
2 | mpatch.c - efficient binary patching for Mercurial |
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2 | mpatch.c - efficient binary patching for Mercurial | |
3 |
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3 | |||
4 | This implements a patch algorithm that's O(m + nlog n) where m is the |
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4 | This implements a patch algorithm that's O(m + nlog n) where m is the | |
5 | size of the output and n is the number of patches. |
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5 | size of the output and n is the number of patches. | |
6 |
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6 | |||
7 | Given a list of binary patches, it unpacks each into a hunk list, |
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7 | Given a list of binary patches, it unpacks each into a hunk list, | |
8 | then combines the hunk lists with a treewise recursion to form a |
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8 | then combines the hunk lists with a treewise recursion to form a | |
9 | single hunk list. This hunk list is then applied to the original |
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9 | single hunk list. This hunk list is then applied to the original | |
10 | text. |
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10 | text. | |
11 |
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11 | |||
12 | The text (or binary) fragments are copied directly from their source |
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12 | The text (or binary) fragments are copied directly from their source | |
13 | Python objects into a preallocated output string to avoid the |
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13 | Python objects into a preallocated output string to avoid the | |
14 | allocation of intermediate Python objects. Working memory is about 2x |
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14 | allocation of intermediate Python objects. Working memory is about 2x | |
15 | the total number of hunks. |
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15 | the total number of hunks. | |
16 |
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16 | |||
17 | Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> |
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17 | Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> | |
18 |
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18 | |||
19 | This software may be used and distributed according to the terms |
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19 | This software may be used and distributed according to the terms | |
20 | of the GNU General Public License, incorporated herein by reference. |
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20 | of the GNU General Public License, incorporated herein by reference. | |
21 | */ |
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21 | */ | |
22 |
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22 | |||
23 | #include <stdlib.h> |
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23 | #include <stdlib.h> | |
24 | #include <string.h> |
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24 | #include <string.h> | |
25 |
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25 | |||
26 | #include "bitmanipulation.h" |
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26 | #include "bitmanipulation.h" | |
27 | #include "compat.h" |
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27 | #include "compat.h" | |
28 | #include "mpatch.h" |
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28 | #include "mpatch.h" | |
29 |
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29 | |||
30 | char *mpatch_errors[] = {NULL, "invalid patch", "patch cannot be decoded", |
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30 | char *mpatch_errors[] = {NULL, "invalid patch", "patch cannot be decoded", | |
31 | "no memory"}; |
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31 | "no memory"}; | |
32 |
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32 | |||
33 | struct mpatch_flist *lalloc(ssize_t size) |
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33 | static struct mpatch_flist *lalloc(ssize_t size) | |
34 | { |
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34 | { | |
35 | struct mpatch_flist *a = NULL; |
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35 | struct mpatch_flist *a = NULL; | |
36 |
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36 | |||
37 | if (size < 1) |
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37 | if (size < 1) | |
38 | size = 1; |
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38 | size = 1; | |
39 |
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39 | |||
40 | a = (struct mpatch_flist *)malloc(sizeof(struct mpatch_flist)); |
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40 | a = (struct mpatch_flist *)malloc(sizeof(struct mpatch_flist)); | |
41 | if (a) { |
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41 | if (a) { | |
42 | a->base = (struct mpatch_frag *)malloc(sizeof(struct mpatch_frag) * size); |
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42 | a->base = (struct mpatch_frag *)malloc(sizeof(struct mpatch_frag) * size); | |
43 | if (a->base) { |
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43 | if (a->base) { | |
44 | a->head = a->tail = a->base; |
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44 | a->head = a->tail = a->base; | |
45 | return a; |
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45 | return a; | |
46 | } |
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46 | } | |
47 | free(a); |
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47 | free(a); | |
48 | } |
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48 | } | |
49 | return NULL; |
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49 | return NULL; | |
50 | } |
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50 | } | |
51 |
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51 | |||
52 | void mpatch_lfree(struct mpatch_flist *a) |
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52 | void mpatch_lfree(struct mpatch_flist *a) | |
53 | { |
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53 | { | |
54 | if (a) { |
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54 | if (a) { | |
55 | free(a->base); |
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55 | free(a->base); | |
56 | free(a); |
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56 | free(a); | |
57 | } |
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57 | } | |
58 | } |
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58 | } | |
59 |
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59 | |||
60 | static ssize_t lsize(struct mpatch_flist *a) |
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60 | static ssize_t lsize(struct mpatch_flist *a) | |
61 | { |
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61 | { | |
62 | return a->tail - a->head; |
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62 | return a->tail - a->head; | |
63 | } |
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63 | } | |
64 |
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64 | |||
65 | /* move hunks in source that are less cut to dest, compensating |
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65 | /* move hunks in source that are less cut to dest, compensating | |
66 | for changes in offset. the last hunk may be split if necessary. |
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66 | for changes in offset. the last hunk may be split if necessary. | |
67 | */ |
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67 | */ | |
68 | static int gather(struct mpatch_flist *dest, struct mpatch_flist *src, int cut, |
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68 | static int gather(struct mpatch_flist *dest, struct mpatch_flist *src, int cut, | |
69 | int offset) |
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69 | int offset) | |
70 | { |
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70 | { | |
71 | struct mpatch_frag *d = dest->tail, *s = src->head; |
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71 | struct mpatch_frag *d = dest->tail, *s = src->head; | |
72 | int postend, c, l; |
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72 | int postend, c, l; | |
73 |
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73 | |||
74 | while (s != src->tail) { |
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74 | while (s != src->tail) { | |
75 | if (s->start + offset >= cut) |
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75 | if (s->start + offset >= cut) | |
76 | break; /* we've gone far enough */ |
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76 | break; /* we've gone far enough */ | |
77 |
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77 | |||
78 | postend = offset + s->start + s->len; |
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78 | postend = offset + s->start + s->len; | |
79 | if (postend <= cut) { |
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79 | if (postend <= cut) { | |
80 | /* save this hunk */ |
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80 | /* save this hunk */ | |
81 | offset += s->start + s->len - s->end; |
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81 | offset += s->start + s->len - s->end; | |
82 | *d++ = *s++; |
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82 | *d++ = *s++; | |
83 | } |
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83 | } | |
84 | else { |
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84 | else { | |
85 | /* break up this hunk */ |
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85 | /* break up this hunk */ | |
86 | c = cut - offset; |
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86 | c = cut - offset; | |
87 | if (s->end < c) |
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87 | if (s->end < c) | |
88 | c = s->end; |
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88 | c = s->end; | |
89 | l = cut - offset - s->start; |
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89 | l = cut - offset - s->start; | |
90 | if (s->len < l) |
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90 | if (s->len < l) | |
91 | l = s->len; |
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91 | l = s->len; | |
92 |
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92 | |||
93 | offset += s->start + l - c; |
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93 | offset += s->start + l - c; | |
94 |
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94 | |||
95 | d->start = s->start; |
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95 | d->start = s->start; | |
96 | d->end = c; |
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96 | d->end = c; | |
97 | d->len = l; |
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97 | d->len = l; | |
98 | d->data = s->data; |
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98 | d->data = s->data; | |
99 | d++; |
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99 | d++; | |
100 | s->start = c; |
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100 | s->start = c; | |
101 | s->len = s->len - l; |
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101 | s->len = s->len - l; | |
102 | s->data = s->data + l; |
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102 | s->data = s->data + l; | |
103 |
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103 | |||
104 | break; |
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104 | break; | |
105 | } |
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105 | } | |
106 | } |
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106 | } | |
107 |
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107 | |||
108 | dest->tail = d; |
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108 | dest->tail = d; | |
109 | src->head = s; |
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109 | src->head = s; | |
110 | return offset; |
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110 | return offset; | |
111 | } |
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111 | } | |
112 |
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112 | |||
113 | /* like gather, but with no output list */ |
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113 | /* like gather, but with no output list */ | |
114 | static int discard(struct mpatch_flist *src, int cut, int offset) |
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114 | static int discard(struct mpatch_flist *src, int cut, int offset) | |
115 | { |
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115 | { | |
116 | struct mpatch_frag *s = src->head; |
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116 | struct mpatch_frag *s = src->head; | |
117 | int postend, c, l; |
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117 | int postend, c, l; | |
118 |
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118 | |||
119 | while (s != src->tail) { |
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119 | while (s != src->tail) { | |
120 | if (s->start + offset >= cut) |
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120 | if (s->start + offset >= cut) | |
121 | break; |
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121 | break; | |
122 |
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122 | |||
123 | postend = offset + s->start + s->len; |
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123 | postend = offset + s->start + s->len; | |
124 | if (postend <= cut) { |
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124 | if (postend <= cut) { | |
125 | offset += s->start + s->len - s->end; |
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125 | offset += s->start + s->len - s->end; | |
126 | s++; |
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126 | s++; | |
127 | } |
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127 | } | |
128 | else { |
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128 | else { | |
129 | c = cut - offset; |
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129 | c = cut - offset; | |
130 | if (s->end < c) |
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130 | if (s->end < c) | |
131 | c = s->end; |
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131 | c = s->end; | |
132 | l = cut - offset - s->start; |
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132 | l = cut - offset - s->start; | |
133 | if (s->len < l) |
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133 | if (s->len < l) | |
134 | l = s->len; |
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134 | l = s->len; | |
135 |
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135 | |||
136 | offset += s->start + l - c; |
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136 | offset += s->start + l - c; | |
137 | s->start = c; |
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137 | s->start = c; | |
138 | s->len = s->len - l; |
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138 | s->len = s->len - l; | |
139 | s->data = s->data + l; |
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139 | s->data = s->data + l; | |
140 |
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140 | |||
141 | break; |
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141 | break; | |
142 | } |
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142 | } | |
143 | } |
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143 | } | |
144 |
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144 | |||
145 | src->head = s; |
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145 | src->head = s; | |
146 | return offset; |
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146 | return offset; | |
147 | } |
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147 | } | |
148 |
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148 | |||
149 | /* combine hunk lists a and b, while adjusting b for offset changes in a/ |
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149 | /* combine hunk lists a and b, while adjusting b for offset changes in a/ | |
150 | this deletes a and b and returns the resultant list. */ |
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150 | this deletes a and b and returns the resultant list. */ | |
151 | static struct mpatch_flist *combine(struct mpatch_flist *a, |
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151 | static struct mpatch_flist *combine(struct mpatch_flist *a, | |
152 | struct mpatch_flist *b) |
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152 | struct mpatch_flist *b) | |
153 | { |
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153 | { | |
154 | struct mpatch_flist *c = NULL; |
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154 | struct mpatch_flist *c = NULL; | |
155 | struct mpatch_frag *bh, *ct; |
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155 | struct mpatch_frag *bh, *ct; | |
156 | int offset = 0, post; |
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156 | int offset = 0, post; | |
157 |
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157 | |||
158 | if (a && b) |
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158 | if (a && b) | |
159 | c = lalloc((lsize(a) + lsize(b)) * 2); |
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159 | c = lalloc((lsize(a) + lsize(b)) * 2); | |
160 |
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160 | |||
161 | if (c) { |
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161 | if (c) { | |
162 |
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162 | |||
163 | for (bh = b->head; bh != b->tail; bh++) { |
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163 | for (bh = b->head; bh != b->tail; bh++) { | |
164 | /* save old hunks */ |
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164 | /* save old hunks */ | |
165 | offset = gather(c, a, bh->start, offset); |
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165 | offset = gather(c, a, bh->start, offset); | |
166 |
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166 | |||
167 | /* discard replaced hunks */ |
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167 | /* discard replaced hunks */ | |
168 | post = discard(a, bh->end, offset); |
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168 | post = discard(a, bh->end, offset); | |
169 |
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169 | |||
170 | /* insert new hunk */ |
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170 | /* insert new hunk */ | |
171 | ct = c->tail; |
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171 | ct = c->tail; | |
172 | ct->start = bh->start - offset; |
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172 | ct->start = bh->start - offset; | |
173 | ct->end = bh->end - post; |
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173 | ct->end = bh->end - post; | |
174 | ct->len = bh->len; |
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174 | ct->len = bh->len; | |
175 | ct->data = bh->data; |
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175 | ct->data = bh->data; | |
176 | c->tail++; |
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176 | c->tail++; | |
177 | offset = post; |
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177 | offset = post; | |
178 | } |
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178 | } | |
179 |
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179 | |||
180 | /* hold on to tail from a */ |
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180 | /* hold on to tail from a */ | |
181 | memcpy(c->tail, a->head, sizeof(struct mpatch_frag) * lsize(a)); |
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181 | memcpy(c->tail, a->head, sizeof(struct mpatch_frag) * lsize(a)); | |
182 | c->tail += lsize(a); |
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182 | c->tail += lsize(a); | |
183 | } |
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183 | } | |
184 |
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184 | |||
185 | mpatch_lfree(a); |
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185 | mpatch_lfree(a); | |
186 | mpatch_lfree(b); |
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186 | mpatch_lfree(b); | |
187 | return c; |
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187 | return c; | |
188 | } |
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188 | } | |
189 |
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189 | |||
190 | /* decode a binary patch into a hunk list */ |
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190 | /* decode a binary patch into a hunk list */ | |
191 | int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist **res) |
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191 | int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist **res) | |
192 | { |
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192 | { | |
193 | struct mpatch_flist *l; |
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193 | struct mpatch_flist *l; | |
194 | struct mpatch_frag *lt; |
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194 | struct mpatch_frag *lt; | |
195 | int pos = 0; |
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195 | int pos = 0; | |
196 |
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196 | |||
197 | /* assume worst case size, we won't have many of these lists */ |
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197 | /* assume worst case size, we won't have many of these lists */ | |
198 | l = lalloc(len / 12 + 1); |
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198 | l = lalloc(len / 12 + 1); | |
199 | if (!l) |
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199 | if (!l) | |
200 | return MPATCH_ERR_NO_MEM; |
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200 | return MPATCH_ERR_NO_MEM; | |
201 |
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201 | |||
202 | lt = l->tail; |
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202 | lt = l->tail; | |
203 |
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203 | |||
204 | while (pos >= 0 && pos < len) { |
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204 | while (pos >= 0 && pos < len) { | |
205 | lt->start = getbe32(bin + pos); |
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205 | lt->start = getbe32(bin + pos); | |
206 | lt->end = getbe32(bin + pos + 4); |
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206 | lt->end = getbe32(bin + pos + 4); | |
207 | lt->len = getbe32(bin + pos + 8); |
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207 | lt->len = getbe32(bin + pos + 8); | |
208 | lt->data = bin + pos + 12; |
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208 | lt->data = bin + pos + 12; | |
209 | pos += 12 + lt->len; |
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209 | pos += 12 + lt->len; | |
210 | if (lt->start > lt->end || lt->len < 0) |
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210 | if (lt->start > lt->end || lt->len < 0) | |
211 | break; /* sanity check */ |
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211 | break; /* sanity check */ | |
212 | lt++; |
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212 | lt++; | |
213 | } |
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213 | } | |
214 |
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214 | |||
215 | if (pos != len) { |
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215 | if (pos != len) { | |
216 | mpatch_lfree(l); |
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216 | mpatch_lfree(l); | |
217 | return MPATCH_ERR_CANNOT_BE_DECODED; |
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217 | return MPATCH_ERR_CANNOT_BE_DECODED; | |
218 | } |
|
218 | } | |
219 |
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219 | |||
220 | l->tail = lt; |
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220 | l->tail = lt; | |
221 | *res = l; |
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221 | *res = l; | |
222 | return 0; |
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222 | return 0; | |
223 | } |
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223 | } | |
224 |
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224 | |||
225 | /* calculate the size of resultant text */ |
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225 | /* calculate the size of resultant text */ | |
226 | ssize_t mpatch_calcsize(ssize_t len, struct mpatch_flist *l) |
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226 | ssize_t mpatch_calcsize(ssize_t len, struct mpatch_flist *l) | |
227 | { |
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227 | { | |
228 | ssize_t outlen = 0, last = 0; |
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228 | ssize_t outlen = 0, last = 0; | |
229 | struct mpatch_frag *f = l->head; |
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229 | struct mpatch_frag *f = l->head; | |
230 |
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230 | |||
231 | while (f != l->tail) { |
|
231 | while (f != l->tail) { | |
232 | if (f->start < last || f->end > len) { |
|
232 | if (f->start < last || f->end > len) { | |
233 | return MPATCH_ERR_INVALID_PATCH; |
|
233 | return MPATCH_ERR_INVALID_PATCH; | |
234 | } |
|
234 | } | |
235 | outlen += f->start - last; |
|
235 | outlen += f->start - last; | |
236 | last = f->end; |
|
236 | last = f->end; | |
237 | outlen += f->len; |
|
237 | outlen += f->len; | |
238 | f++; |
|
238 | f++; | |
239 | } |
|
239 | } | |
240 |
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240 | |||
241 | outlen += len - last; |
|
241 | outlen += len - last; | |
242 | return outlen; |
|
242 | return outlen; | |
243 | } |
|
243 | } | |
244 |
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244 | |||
245 | int mpatch_apply(char *buf, const char *orig, ssize_t len, |
|
245 | int mpatch_apply(char *buf, const char *orig, ssize_t len, | |
246 | struct mpatch_flist *l) |
|
246 | struct mpatch_flist *l) | |
247 | { |
|
247 | { | |
248 | struct mpatch_frag *f = l->head; |
|
248 | struct mpatch_frag *f = l->head; | |
249 | int last = 0; |
|
249 | int last = 0; | |
250 | char *p = buf; |
|
250 | char *p = buf; | |
251 |
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251 | |||
252 | while (f != l->tail) { |
|
252 | while (f != l->tail) { | |
253 | if (f->start < last || f->end > len) { |
|
253 | if (f->start < last || f->end > len) { | |
254 | return MPATCH_ERR_INVALID_PATCH; |
|
254 | return MPATCH_ERR_INVALID_PATCH; | |
255 | } |
|
255 | } | |
256 | memcpy(p, orig + last, f->start - last); |
|
256 | memcpy(p, orig + last, f->start - last); | |
257 | p += f->start - last; |
|
257 | p += f->start - last; | |
258 | memcpy(p, f->data, f->len); |
|
258 | memcpy(p, f->data, f->len); | |
259 | last = f->end; |
|
259 | last = f->end; | |
260 | p += f->len; |
|
260 | p += f->len; | |
261 | f++; |
|
261 | f++; | |
262 | } |
|
262 | } | |
263 | memcpy(p, orig + last, len - last); |
|
263 | memcpy(p, orig + last, len - last); | |
264 | return 0; |
|
264 | return 0; | |
265 | } |
|
265 | } | |
266 |
|
266 | |||
267 | /* recursively generate a patch of all bins between start and end */ |
|
267 | /* recursively generate a patch of all bins between start and end */ | |
268 | struct mpatch_flist *mpatch_fold(void *bins, |
|
268 | struct mpatch_flist *mpatch_fold(void *bins, | |
269 | struct mpatch_flist* (*get_next_item)(void*, ssize_t), |
|
269 | struct mpatch_flist* (*get_next_item)(void*, ssize_t), | |
270 | ssize_t start, ssize_t end) |
|
270 | ssize_t start, ssize_t end) | |
271 | { |
|
271 | { | |
272 | ssize_t len; |
|
272 | ssize_t len; | |
273 |
|
273 | |||
274 | if (start + 1 == end) { |
|
274 | if (start + 1 == end) { | |
275 | /* trivial case, output a decoded list */ |
|
275 | /* trivial case, output a decoded list */ | |
276 | return get_next_item(bins, start); |
|
276 | return get_next_item(bins, start); | |
277 | } |
|
277 | } | |
278 |
|
278 | |||
279 | /* divide and conquer, memory management is elsewhere */ |
|
279 | /* divide and conquer, memory management is elsewhere */ | |
280 | len = (end - start) / 2; |
|
280 | len = (end - start) / 2; | |
281 | return combine(mpatch_fold(bins, get_next_item, start, start + len), |
|
281 | return combine(mpatch_fold(bins, get_next_item, start, start + len), | |
282 | mpatch_fold(bins, get_next_item, start + len, end)); |
|
282 | mpatch_fold(bins, get_next_item, start + len, end)); | |
283 | } |
|
283 | } |
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