Mercurial > public > mercurial-scm > hg
annotate mercurial/mpatch.c @ 34633:347c0f4232e1
mpatch: re-wrap wide line with clang-format
Differential Revision: https://phab.mercurial-scm.org/D1027
| author | Augie Fackler <augie@google.com> |
|---|---|
| date | Wed, 04 Oct 2017 10:55:51 -0400 |
| parents | 155f0cc3f813 |
| children | 2e08b69bcd29 |
| rev | line source |
|---|---|
| 72 | 1 /* |
| 2 mpatch.c - efficient binary patching for Mercurial | |
| 3 | |
| 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. | |
| 6 | |
| 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 | |
| 9 single hunk list. This hunk list is then applied to the original | |
| 10 text. | |
| 11 | |
| 12 The text (or binary) fragments are copied directly from their source | |
| 13 Python objects into a preallocated output string to avoid the | |
| 14 allocation of intermediate Python objects. Working memory is about 2x | |
| 15 the total number of hunks. | |
| 16 | |
| 2859 | 17 Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> |
| 72 | 18 |
| 19 This software may be used and distributed according to the terms | |
| 20 of the GNU General Public License, incorporated herein by reference. | |
| 21 */ | |
| 22 | |
| 23 #include <stdlib.h> | |
| 24 #include <string.h> | |
|
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25 |
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26 #include "bitmanipulation.h" |
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27 #include "compat.h" |
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28 #include "mpatch.h" |
| 72 | 29 |
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30 static struct mpatch_flist *lalloc(ssize_t size) |
| 72 | 31 { |
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32 struct mpatch_flist *a = NULL; |
| 72 | 33 |
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34 if (size < 1) |
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35 size = 1; |
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36 |
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37 a = (struct mpatch_flist *)malloc(sizeof(struct mpatch_flist)); |
| 128 | 38 if (a) { |
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39 a->base = (struct mpatch_frag *)malloc( |
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40 sizeof(struct mpatch_frag) * size); |
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41 if (a->base) { |
| 128 | 42 a->head = a->tail = a->base; |
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43 return a; |
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44 } |
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45 free(a); |
| 128 | 46 } |
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47 return NULL; |
| 72 | 48 } |
| 49 | |
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50 void mpatch_lfree(struct mpatch_flist *a) |
| 72 | 51 { |
| 128 | 52 if (a) { |
| 53 free(a->base); | |
| 54 free(a); | |
| 55 } | |
| 72 | 56 } |
| 57 | |
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58 static ssize_t lsize(struct mpatch_flist *a) |
| 72 | 59 { |
| 60 return a->tail - a->head; | |
| 61 } | |
| 62 | |
| 63 /* move hunks in source that are less cut to dest, compensating | |
| 64 for changes in offset. the last hunk may be split if necessary. | |
| 65 */ | |
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66 static int gather(struct mpatch_flist *dest, struct mpatch_flist *src, int cut, |
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67 int offset) |
| 72 | 68 { |
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69 struct mpatch_frag *d = dest->tail, *s = src->head; |
| 72 | 70 int postend, c, l; |
| 71 | |
| 72 while (s != src->tail) { | |
| 73 if (s->start + offset >= cut) | |
| 82 | 74 break; /* we've gone far enough */ |
| 72 | 75 |
| 76 postend = offset + s->start + s->len; | |
| 77 if (postend <= cut) { | |
| 78 /* save this hunk */ | |
| 79 offset += s->start + s->len - s->end; | |
| 80 *d++ = *s++; | |
| 81 } | |
| 82 else { | |
| 83 /* break up this hunk */ | |
| 84 c = cut - offset; | |
| 85 if (s->end < c) | |
| 86 c = s->end; | |
| 87 l = cut - offset - s->start; | |
| 88 if (s->len < l) | |
| 89 l = s->len; | |
| 90 | |
| 91 offset += s->start + l - c; | |
| 92 | |
| 93 d->start = s->start; | |
| 94 d->end = c; | |
| 95 d->len = l; | |
| 96 d->data = s->data; | |
| 97 d++; | |
| 98 s->start = c; | |
| 99 s->len = s->len - l; | |
| 100 s->data = s->data + l; | |
| 101 | |
| 82 | 102 break; |
| 72 | 103 } |
| 104 } | |
| 105 | |
| 106 dest->tail = d; | |
| 107 src->head = s; | |
| 108 return offset; | |
| 109 } | |
| 110 | |
| 111 /* like gather, but with no output list */ | |
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112 static int discard(struct mpatch_flist *src, int cut, int offset) |
| 72 | 113 { |
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114 struct mpatch_frag *s = src->head; |
| 72 | 115 int postend, c, l; |
| 116 | |
| 117 while (s != src->tail) { | |
| 118 if (s->start + offset >= cut) | |
| 82 | 119 break; |
| 72 | 120 |
| 121 postend = offset + s->start + s->len; | |
| 122 if (postend <= cut) { | |
| 123 offset += s->start + s->len - s->end; | |
| 124 s++; | |
| 125 } | |
| 126 else { | |
| 127 c = cut - offset; | |
| 128 if (s->end < c) | |
| 129 c = s->end; | |
| 130 l = cut - offset - s->start; | |
| 131 if (s->len < l) | |
| 132 l = s->len; | |
| 133 | |
| 134 offset += s->start + l - c; | |
| 135 s->start = c; | |
| 136 s->len = s->len - l; | |
| 137 s->data = s->data + l; | |
| 138 | |
| 82 | 139 break; |
| 72 | 140 } |
| 141 } | |
| 142 | |
| 143 src->head = s; | |
| 144 return offset; | |
| 145 } | |
| 146 | |
| 147 /* combine hunk lists a and b, while adjusting b for offset changes in a/ | |
| 148 this deletes a and b and returns the resultant list. */ | |
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149 static struct mpatch_flist *combine(struct mpatch_flist *a, |
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150 struct mpatch_flist *b) |
| 72 | 151 { |
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152 struct mpatch_flist *c = NULL; |
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153 struct mpatch_frag *bh, *ct; |
| 72 | 154 int offset = 0, post; |
| 155 | |
| 128 | 156 if (a && b) |
| 157 c = lalloc((lsize(a) + lsize(b)) * 2); | |
| 158 | |
| 159 if (c) { | |
| 72 | 160 |
| 128 | 161 for (bh = b->head; bh != b->tail; bh++) { |
| 162 /* save old hunks */ | |
| 163 offset = gather(c, a, bh->start, offset); | |
| 72 | 164 |
| 128 | 165 /* discard replaced hunks */ |
| 166 post = discard(a, bh->end, offset); | |
| 72 | 167 |
| 128 | 168 /* insert new hunk */ |
| 169 ct = c->tail; | |
| 170 ct->start = bh->start - offset; | |
| 171 ct->end = bh->end - post; | |
| 172 ct->len = bh->len; | |
| 173 ct->data = bh->data; | |
| 174 c->tail++; | |
| 175 offset = post; | |
| 176 } | |
| 177 | |
| 178 /* hold on to tail from a */ | |
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179 memcpy(c->tail, a->head, sizeof(struct mpatch_frag) * lsize(a)); |
| 128 | 180 c->tail += lsize(a); |
| 72 | 181 } |
| 182 | |
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183 mpatch_lfree(a); |
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184 mpatch_lfree(b); |
| 72 | 185 return c; |
| 186 } | |
| 187 | |
| 188 /* decode a binary patch into a hunk list */ | |
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189 int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist **res) |
| 72 | 190 { |
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191 struct mpatch_flist *l; |
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192 struct mpatch_frag *lt; |
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193 int pos = 0; |
| 72 | 194 |
| 195 /* assume worst case size, we won't have many of these lists */ | |
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196 l = lalloc(len / 12 + 1); |
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197 if (!l) |
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198 return MPATCH_ERR_NO_MEM; |
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199 |
| 72 | 200 lt = l->tail; |
| 201 | |
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202 while (pos >= 0 && pos < len) { |
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203 lt->start = getbe32(bin + pos); |
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204 lt->end = getbe32(bin + pos + 4); |
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205 lt->len = getbe32(bin + pos + 8); |
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206 lt->data = bin + pos + 12; |
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207 pos += 12 + lt->len; |
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208 if (lt->start > lt->end || lt->len < 0) |
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209 break; /* sanity check */ |
| 72 | 210 lt++; |
| 211 } | |
| 212 | |
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213 if (pos != len) { |
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214 mpatch_lfree(l); |
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215 return MPATCH_ERR_CANNOT_BE_DECODED; |
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216 } |
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217 |
| 72 | 218 l->tail = lt; |
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219 *res = l; |
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220 return 0; |
| 72 | 221 } |
| 222 | |
| 223 /* calculate the size of resultant text */ | |
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224 ssize_t mpatch_calcsize(ssize_t len, struct mpatch_flist *l) |
| 72 | 225 { |
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226 ssize_t outlen = 0, last = 0; |
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227 struct mpatch_frag *f = l->head; |
| 72 | 228 |
| 229 while (f != l->tail) { | |
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230 if (f->start < last || f->end > len) { |
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231 return MPATCH_ERR_INVALID_PATCH; |
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232 } |
| 72 | 233 outlen += f->start - last; |
| 234 last = f->end; | |
| 235 outlen += f->len; | |
| 236 f++; | |
| 237 } | |
| 238 | |
| 239 outlen += len - last; | |
| 240 return outlen; | |
| 241 } | |
| 242 | |
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243 int mpatch_apply(char *buf, const char *orig, ssize_t len, |
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244 struct mpatch_flist *l) |
| 72 | 245 { |
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246 struct mpatch_frag *f = l->head; |
| 72 | 247 int last = 0; |
| 248 char *p = buf; | |
| 249 | |
| 250 while (f != l->tail) { | |
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251 if (f->start < last || f->end > len) { |
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252 return MPATCH_ERR_INVALID_PATCH; |
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253 } |
| 72 | 254 memcpy(p, orig + last, f->start - last); |
| 255 p += f->start - last; | |
| 256 memcpy(p, f->data, f->len); | |
| 257 last = f->end; | |
| 258 p += f->len; | |
| 259 f++; | |
| 260 } | |
| 261 memcpy(p, orig + last, len - last); | |
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262 return 0; |
| 72 | 263 } |
| 264 | |
| 265 /* recursively generate a patch of all bins between start and end */ | |
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266 struct mpatch_flist *mpatch_fold(void *bins, |
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267 struct mpatch_flist* (*get_next_item)(void*, ssize_t), |
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268 ssize_t start, ssize_t end) |
| 72 | 269 { |
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270 ssize_t len; |
| 72 | 271 |
| 272 if (start + 1 == end) { | |
| 273 /* trivial case, output a decoded list */ | |
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29694
55dd12204b8e
mpatch: remove dependency on Python.h in mpatch.c
Maciej Fijalkowski <fijall@gmail.com>
parents:
29693
diff
changeset
|
274 return get_next_item(bins, start); |
| 72 | 275 } |
| 276 | |
| 277 /* divide and conquer, memory management is elsewhere */ | |
| 278 len = (end - start) / 2; | |
|
29694
55dd12204b8e
mpatch: remove dependency on Python.h in mpatch.c
Maciej Fijalkowski <fijall@gmail.com>
parents:
29693
diff
changeset
|
279 return combine(mpatch_fold(bins, get_next_item, start, start + len), |
|
55dd12204b8e
mpatch: remove dependency on Python.h in mpatch.c
Maciej Fijalkowski <fijall@gmail.com>
parents:
29693
diff
changeset
|
280 mpatch_fold(bins, get_next_item, start + len, end)); |
| 72 | 281 } |