Mercurial > hg > pyhgsh
annotate mercurial/mpatch.c @ 978:ea67e5b37043
hgweb: Changed file revision page to list format syntax
| author | Josef "Jeff" Sipek <jeffpc@optonline.net> |
|---|---|
| date | Wed, 17 Aug 2005 22:08:15 -0500 |
| parents | e530637ea060 |
| children | 681c5c211b92 |
| rev | line source |
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| 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 | |
| 17 Copyright 2005 Matt Mackall <mpm@selenic.com> | |
| 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 <Python.h> | |
| 24 #include <stdlib.h> | |
| 25 #include <string.h> | |
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26 #ifdef _WIN32 |
| 551 | 27 #ifdef _MSC_VER |
| 28 #define inline __inline | |
| 29 typedef unsigned long uint32_t; | |
| 30 #else | |
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31 #include <stdint.h> |
| 551 | 32 #endif |
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33 static uint32_t ntohl(uint32_t x) |
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34 { |
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35 return ((x & 0x000000ffUL) << 24) | |
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36 ((x & 0x0000ff00UL) << 8) | |
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37 ((x & 0x00ff0000UL) >> 8) | |
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38 ((x & 0xff000000UL) >> 24); |
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39 } |
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40 #else |
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41 #include <sys/types.h> |
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42 #include <arpa/inet.h> |
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43 #endif |
| 72 | 44 |
| 45 static char mpatch_doc[] = "Efficient binary patching."; | |
| 46 | |
| 47 struct frag { | |
| 48 int start, end, len; | |
| 49 char *data; | |
| 50 }; | |
| 51 | |
| 52 struct flist { | |
| 53 struct frag *base, *head, *tail; | |
| 54 }; | |
| 55 | |
| 56 static struct flist *lalloc(int size) | |
| 57 { | |
| 128 | 58 struct flist *a = NULL; |
| 72 | 59 |
| 60 a = malloc(sizeof(struct flist)); | |
| 128 | 61 if (a) { |
| 62 a->base = malloc(sizeof(struct frag) * size); | |
| 282 | 63 if (!a->base) { |
| 128 | 64 free(a); |
| 282 | 65 a = NULL; |
| 66 } else | |
| 128 | 67 a->head = a->tail = a->base; |
| 68 } | |
| 72 | 69 return a; |
| 70 } | |
| 71 | |
| 72 static void lfree(struct flist *a) | |
| 73 { | |
| 128 | 74 if (a) { |
| 75 free(a->base); | |
| 76 free(a); | |
| 77 } | |
| 72 | 78 } |
| 79 | |
| 80 static int lsize(struct flist *a) | |
| 81 { | |
| 82 return a->tail - a->head; | |
| 83 } | |
| 84 | |
| 85 /* move hunks in source that are less cut to dest, compensating | |
| 86 for changes in offset. the last hunk may be split if necessary. | |
| 87 */ | |
| 88 static int gather(struct flist *dest, struct flist *src, int cut, int offset) | |
| 89 { | |
| 90 struct frag *d = dest->tail, *s = src->head; | |
| 91 int postend, c, l; | |
| 92 | |
| 93 while (s != src->tail) { | |
| 94 if (s->start + offset >= cut) | |
| 82 | 95 break; /* we've gone far enough */ |
| 72 | 96 |
| 97 postend = offset + s->start + s->len; | |
| 98 if (postend <= cut) { | |
| 99 /* save this hunk */ | |
| 100 offset += s->start + s->len - s->end; | |
| 101 *d++ = *s++; | |
| 102 } | |
| 103 else { | |
| 104 /* break up this hunk */ | |
| 105 c = cut - offset; | |
| 106 if (s->end < c) | |
| 107 c = s->end; | |
| 108 l = cut - offset - s->start; | |
| 109 if (s->len < l) | |
| 110 l = s->len; | |
| 111 | |
| 112 offset += s->start + l - c; | |
| 113 | |
| 114 d->start = s->start; | |
| 115 d->end = c; | |
| 116 d->len = l; | |
| 117 d->data = s->data; | |
| 118 d++; | |
| 119 s->start = c; | |
| 120 s->len = s->len - l; | |
| 121 s->data = s->data + l; | |
| 122 | |
| 82 | 123 break; |
| 72 | 124 } |
| 125 } | |
| 126 | |
| 127 dest->tail = d; | |
| 128 src->head = s; | |
| 129 return offset; | |
| 130 } | |
| 131 | |
| 132 /* like gather, but with no output list */ | |
| 133 static int discard(struct flist *src, int cut, int offset) | |
| 134 { | |
| 135 struct frag *s = src->head; | |
| 136 int postend, c, l; | |
| 137 | |
| 138 while (s != src->tail) { | |
| 139 if (s->start + offset >= cut) | |
| 82 | 140 break; |
| 72 | 141 |
| 142 postend = offset + s->start + s->len; | |
| 143 if (postend <= cut) { | |
| 144 offset += s->start + s->len - s->end; | |
| 145 s++; | |
| 146 } | |
| 147 else { | |
| 148 c = cut - offset; | |
| 149 if (s->end < c) | |
| 150 c = s->end; | |
| 151 l = cut - offset - s->start; | |
| 152 if (s->len < l) | |
| 153 l = s->len; | |
| 154 | |
| 155 offset += s->start + l - c; | |
| 156 s->start = c; | |
| 157 s->len = s->len - l; | |
| 158 s->data = s->data + l; | |
| 159 | |
| 82 | 160 break; |
| 72 | 161 } |
| 162 } | |
| 163 | |
| 164 src->head = s; | |
| 165 return offset; | |
| 166 } | |
| 167 | |
| 168 /* combine hunk lists a and b, while adjusting b for offset changes in a/ | |
| 169 this deletes a and b and returns the resultant list. */ | |
| 170 static struct flist *combine(struct flist *a, struct flist *b) | |
| 171 { | |
| 128 | 172 struct flist *c = NULL; |
| 173 struct frag *bh, *ct; | |
| 72 | 174 int offset = 0, post; |
| 175 | |
| 128 | 176 if (a && b) |
| 177 c = lalloc((lsize(a) + lsize(b)) * 2); | |
| 178 | |
| 179 if (c) { | |
| 72 | 180 |
| 128 | 181 for (bh = b->head; bh != b->tail; bh++) { |
| 182 /* save old hunks */ | |
| 183 offset = gather(c, a, bh->start, offset); | |
| 72 | 184 |
| 128 | 185 /* discard replaced hunks */ |
| 186 post = discard(a, bh->end, offset); | |
| 72 | 187 |
| 128 | 188 /* insert new hunk */ |
| 189 ct = c->tail; | |
| 190 ct->start = bh->start - offset; | |
| 191 ct->end = bh->end - post; | |
| 192 ct->len = bh->len; | |
| 193 ct->data = bh->data; | |
| 194 c->tail++; | |
| 195 offset = post; | |
| 196 } | |
| 197 | |
| 198 /* hold on to tail from a */ | |
| 199 memcpy(c->tail, a->head, sizeof(struct frag) * lsize(a)); | |
| 200 c->tail += lsize(a); | |
| 72 | 201 } |
| 202 | |
| 203 lfree(a); | |
| 204 lfree(b); | |
| 205 return c; | |
| 206 } | |
| 207 | |
| 208 /* decode a binary patch into a hunk list */ | |
| 209 static struct flist *decode(char *bin, int len) | |
| 210 { | |
| 211 struct flist *l; | |
| 212 struct frag *lt; | |
| 213 char *end = bin + len; | |
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214 char decode[12]; /* for dealing with alignment issues */ |
| 72 | 215 |
| 216 /* assume worst case size, we won't have many of these lists */ | |
| 217 l = lalloc(len / 12); | |
| 218 lt = l->tail; | |
| 219 | |
| 220 while (bin < end) { | |
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221 memcpy(decode, bin, 12); |
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222 lt->start = ntohl(*(uint32_t *)decode); |
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223 lt->end = ntohl(*(uint32_t *)(decode + 4)); |
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224 lt->len = ntohl(*(uint32_t *)(decode + 8)); |
| 72 | 225 lt->data = bin + 12; |
| 226 bin += 12 + lt->len; | |
| 227 lt++; | |
| 228 } | |
| 229 | |
| 230 l->tail = lt; | |
| 231 return l; | |
| 232 } | |
| 233 | |
| 234 /* calculate the size of resultant text */ | |
| 235 static int calcsize(int len, struct flist *l) | |
| 236 { | |
| 237 int outlen = 0, last = 0; | |
| 238 struct frag *f = l->head; | |
| 239 | |
| 240 while (f != l->tail) { | |
| 241 outlen += f->start - last; | |
| 242 last = f->end; | |
| 243 outlen += f->len; | |
| 244 f++; | |
| 245 } | |
| 246 | |
| 247 outlen += len - last; | |
| 248 return outlen; | |
| 249 } | |
| 250 | |
| 251 static void apply(char *buf, char *orig, int len, struct flist *l) | |
| 252 { | |
| 253 struct frag *f = l->head; | |
| 254 int last = 0; | |
| 255 char *p = buf; | |
| 256 | |
| 257 while (f != l->tail) { | |
| 258 memcpy(p, orig + last, f->start - last); | |
| 259 p += f->start - last; | |
| 260 memcpy(p, f->data, f->len); | |
| 261 last = f->end; | |
| 262 p += f->len; | |
| 263 f++; | |
| 264 } | |
| 265 memcpy(p, orig + last, len - last); | |
| 266 } | |
| 267 | |
| 268 /* recursively generate a patch of all bins between start and end */ | |
| 269 static struct flist *fold(PyObject *bins, int start, int end) | |
| 270 { | |
| 271 int len; | |
| 272 | |
| 273 if (start + 1 == end) { | |
| 274 /* trivial case, output a decoded list */ | |
| 275 PyObject *tmp = PyList_GetItem(bins, start); | |
| 128 | 276 if (!tmp) |
| 277 return NULL; | |
| 72 | 278 return decode(PyString_AsString(tmp), PyString_Size(tmp)); |
| 279 } | |
| 280 | |
| 281 /* divide and conquer, memory management is elsewhere */ | |
| 282 len = (end - start) / 2; | |
| 283 return combine(fold(bins, start, start + len), | |
| 284 fold(bins, start + len, end)); | |
| 285 } | |
| 286 | |
| 287 static PyObject * | |
| 288 patches(PyObject *self, PyObject *args) | |
| 289 { | |
| 290 PyObject *text, *bins, *result; | |
| 291 struct flist *patch; | |
| 292 char *in, *out; | |
| 293 int len, outlen; | |
| 294 | |
| 128 | 295 if (!PyArg_ParseTuple(args, "SO:mpatch", &text, &bins)) |
| 72 | 296 return NULL; |
| 297 | |
| 298 len = PyList_Size(bins); | |
| 299 if (!len) { | |
| 300 /* nothing to do */ | |
| 301 Py_INCREF(text); | |
| 302 return text; | |
| 303 } | |
| 304 | |
| 305 patch = fold(bins, 0, len); | |
| 128 | 306 if (!patch) |
| 307 return PyErr_NoMemory(); | |
| 308 | |
| 72 | 309 outlen = calcsize(PyString_Size(text), patch); |
| 310 result = PyString_FromStringAndSize(NULL, outlen); | |
| 128 | 311 if (result) { |
| 312 in = PyString_AsString(text); | |
| 313 out = PyString_AsString(result); | |
| 314 apply(out, in, PyString_Size(text), patch); | |
| 315 } | |
| 316 | |
| 72 | 317 lfree(patch); |
| 318 return result; | |
| 319 } | |
| 320 | |
| 321 static PyMethodDef methods[] = { | |
| 322 {"patches", patches, METH_VARARGS, "apply a series of patches\n"}, | |
| 323 {NULL, NULL} | |
| 324 }; | |
| 325 | |
| 326 PyMODINIT_FUNC | |
| 327 initmpatch(void) | |
| 328 { | |
| 329 Py_InitModule3("mpatch", methods, mpatch_doc); | |
| 330 } | |
| 331 |