Mercurial > hg > mercurial-crew-with-dirclash
annotate mercurial/mpatch.c @ 410:7c678976df3e
Make mpatch.c compilable under the other `OS'
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Make mpatch.c compilable under the other `OS'
From: K Thananchayan <thananck@yahoo.com>
manifest hash: 7b3033b761b147149fb0bcd6ff6120ccb73f16f1
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author | mpm@selenic.com |
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date | Tue, 21 Jun 2005 18:51:46 -0800 |
parents | a29decbf7475 |
children | 9e9f7ab43ce2 |
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> | |
410
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26 #ifdef _WIN32 |
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27 |
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28 typedef unsigned long uint32_t; |
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29 |
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30 uint32_t ntohl(uint32_t x) { |
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31 return ((x & 0x000000ffUL) << 24) | |
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32 ((x & 0x0000ff00UL) << 8) | |
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33 ((x & 0x00ff0000UL) >> 8) | |
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34 ((x & 0xff000000UL) >> 24); |
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35 } |
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36 |
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37 #else |
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38 #include <netinet/in.h> |
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39 #include <sys/types.h> |
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40 #endif |
72 | 41 |
42 static char mpatch_doc[] = "Efficient binary patching."; | |
43 | |
44 struct frag { | |
45 int start, end, len; | |
46 char *data; | |
47 }; | |
48 | |
49 struct flist { | |
50 struct frag *base, *head, *tail; | |
51 }; | |
52 | |
53 static struct flist *lalloc(int size) | |
54 { | |
128 | 55 struct flist *a = NULL; |
72 | 56 |
57 a = malloc(sizeof(struct flist)); | |
128 | 58 if (a) { |
59 a->base = malloc(sizeof(struct frag) * size); | |
282 | 60 if (!a->base) { |
128 | 61 free(a); |
282 | 62 a = NULL; |
63 } else | |
128 | 64 a->head = a->tail = a->base; |
65 } | |
72 | 66 return a; |
67 } | |
68 | |
69 static void lfree(struct flist *a) | |
70 { | |
128 | 71 if (a) { |
72 free(a->base); | |
73 free(a); | |
74 } | |
72 | 75 } |
76 | |
77 static int lsize(struct flist *a) | |
78 { | |
79 return a->tail - a->head; | |
80 } | |
81 | |
82 /* move hunks in source that are less cut to dest, compensating | |
83 for changes in offset. the last hunk may be split if necessary. | |
84 */ | |
85 static int gather(struct flist *dest, struct flist *src, int cut, int offset) | |
86 { | |
87 struct frag *d = dest->tail, *s = src->head; | |
88 int postend, c, l; | |
89 | |
90 while (s != src->tail) { | |
91 if (s->start + offset >= cut) | |
82 | 92 break; /* we've gone far enough */ |
72 | 93 |
94 postend = offset + s->start + s->len; | |
95 if (postend <= cut) { | |
96 /* save this hunk */ | |
97 offset += s->start + s->len - s->end; | |
98 *d++ = *s++; | |
99 } | |
100 else { | |
101 /* break up this hunk */ | |
102 c = cut - offset; | |
103 if (s->end < c) | |
104 c = s->end; | |
105 l = cut - offset - s->start; | |
106 if (s->len < l) | |
107 l = s->len; | |
108 | |
109 offset += s->start + l - c; | |
110 | |
111 d->start = s->start; | |
112 d->end = c; | |
113 d->len = l; | |
114 d->data = s->data; | |
115 d++; | |
116 s->start = c; | |
117 s->len = s->len - l; | |
118 s->data = s->data + l; | |
119 | |
82 | 120 break; |
72 | 121 } |
122 } | |
123 | |
124 dest->tail = d; | |
125 src->head = s; | |
126 return offset; | |
127 } | |
128 | |
129 /* like gather, but with no output list */ | |
130 static int discard(struct flist *src, int cut, int offset) | |
131 { | |
132 struct frag *s = src->head; | |
133 int postend, c, l; | |
134 | |
135 while (s != src->tail) { | |
136 if (s->start + offset >= cut) | |
82 | 137 break; |
72 | 138 |
139 postend = offset + s->start + s->len; | |
140 if (postend <= cut) { | |
141 offset += s->start + s->len - s->end; | |
142 s++; | |
143 } | |
144 else { | |
145 c = cut - offset; | |
146 if (s->end < c) | |
147 c = s->end; | |
148 l = cut - offset - s->start; | |
149 if (s->len < l) | |
150 l = s->len; | |
151 | |
152 offset += s->start + l - c; | |
153 s->start = c; | |
154 s->len = s->len - l; | |
155 s->data = s->data + l; | |
156 | |
82 | 157 break; |
72 | 158 } |
159 } | |
160 | |
161 src->head = s; | |
162 return offset; | |
163 } | |
164 | |
165 /* combine hunk lists a and b, while adjusting b for offset changes in a/ | |
166 this deletes a and b and returns the resultant list. */ | |
167 static struct flist *combine(struct flist *a, struct flist *b) | |
168 { | |
128 | 169 struct flist *c = NULL; |
170 struct frag *bh, *ct; | |
72 | 171 int offset = 0, post; |
172 | |
128 | 173 if (a && b) |
174 c = lalloc((lsize(a) + lsize(b)) * 2); | |
175 | |
176 if (c) { | |
72 | 177 |
128 | 178 for (bh = b->head; bh != b->tail; bh++) { |
179 /* save old hunks */ | |
180 offset = gather(c, a, bh->start, offset); | |
72 | 181 |
128 | 182 /* discard replaced hunks */ |
183 post = discard(a, bh->end, offset); | |
72 | 184 |
128 | 185 /* insert new hunk */ |
186 ct = c->tail; | |
187 ct->start = bh->start - offset; | |
188 ct->end = bh->end - post; | |
189 ct->len = bh->len; | |
190 ct->data = bh->data; | |
191 c->tail++; | |
192 offset = post; | |
193 } | |
194 | |
195 /* hold on to tail from a */ | |
196 memcpy(c->tail, a->head, sizeof(struct frag) * lsize(a)); | |
197 c->tail += lsize(a); | |
72 | 198 } |
199 | |
200 lfree(a); | |
201 lfree(b); | |
202 return c; | |
203 } | |
204 | |
205 /* decode a binary patch into a hunk list */ | |
206 static struct flist *decode(char *bin, int len) | |
207 { | |
208 struct flist *l; | |
209 struct frag *lt; | |
210 char *end = bin + len; | |
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211 char decode[12]; /* for dealing with alignment issues */ |
72 | 212 |
213 /* assume worst case size, we won't have many of these lists */ | |
214 l = lalloc(len / 12); | |
215 lt = l->tail; | |
216 | |
217 while (bin < end) { | |
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218 memcpy(decode, bin, 12); |
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219 lt->start = ntohl(*(uint32_t *)decode); |
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220 lt->end = ntohl(*(uint32_t *)(decode + 4)); |
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221 lt->len = ntohl(*(uint32_t *)(decode + 8)); |
72 | 222 lt->data = bin + 12; |
223 bin += 12 + lt->len; | |
224 lt++; | |
225 } | |
226 | |
227 l->tail = lt; | |
228 return l; | |
229 } | |
230 | |
231 /* calculate the size of resultant text */ | |
232 static int calcsize(int len, struct flist *l) | |
233 { | |
234 int outlen = 0, last = 0; | |
235 struct frag *f = l->head; | |
236 | |
237 while (f != l->tail) { | |
238 outlen += f->start - last; | |
239 last = f->end; | |
240 outlen += f->len; | |
241 f++; | |
242 } | |
243 | |
244 outlen += len - last; | |
245 return outlen; | |
246 } | |
247 | |
248 static void apply(char *buf, char *orig, int len, struct flist *l) | |
249 { | |
250 struct frag *f = l->head; | |
251 int last = 0; | |
252 char *p = buf; | |
253 | |
254 while (f != l->tail) { | |
255 memcpy(p, orig + last, f->start - last); | |
256 p += f->start - last; | |
257 memcpy(p, f->data, f->len); | |
258 last = f->end; | |
259 p += f->len; | |
260 f++; | |
261 } | |
262 memcpy(p, orig + last, len - last); | |
263 } | |
264 | |
265 /* recursively generate a patch of all bins between start and end */ | |
266 static struct flist *fold(PyObject *bins, int start, int end) | |
267 { | |
268 int len; | |
269 | |
270 if (start + 1 == end) { | |
271 /* trivial case, output a decoded list */ | |
272 PyObject *tmp = PyList_GetItem(bins, start); | |
128 | 273 if (!tmp) |
274 return NULL; | |
72 | 275 return decode(PyString_AsString(tmp), PyString_Size(tmp)); |
276 } | |
277 | |
278 /* divide and conquer, memory management is elsewhere */ | |
279 len = (end - start) / 2; | |
280 return combine(fold(bins, start, start + len), | |
281 fold(bins, start + len, end)); | |
282 } | |
283 | |
284 static PyObject * | |
285 patches(PyObject *self, PyObject *args) | |
286 { | |
287 PyObject *text, *bins, *result; | |
288 struct flist *patch; | |
289 char *in, *out; | |
290 int len, outlen; | |
291 | |
128 | 292 if (!PyArg_ParseTuple(args, "SO:mpatch", &text, &bins)) |
72 | 293 return NULL; |
294 | |
295 len = PyList_Size(bins); | |
296 if (!len) { | |
297 /* nothing to do */ | |
298 Py_INCREF(text); | |
299 return text; | |
300 } | |
301 | |
302 patch = fold(bins, 0, len); | |
128 | 303 if (!patch) |
304 return PyErr_NoMemory(); | |
305 | |
72 | 306 outlen = calcsize(PyString_Size(text), patch); |
307 result = PyString_FromStringAndSize(NULL, outlen); | |
128 | 308 if (result) { |
309 in = PyString_AsString(text); | |
310 out = PyString_AsString(result); | |
311 apply(out, in, PyString_Size(text), patch); | |
312 } | |
313 | |
72 | 314 lfree(patch); |
315 return result; | |
316 } | |
317 | |
318 static PyMethodDef methods[] = { | |
319 {"patches", patches, METH_VARARGS, "apply a series of patches\n"}, | |
320 {NULL, NULL} | |
321 }; | |
322 | |
323 PyMODINIT_FUNC | |
324 initmpatch(void) | |
325 { | |
326 Py_InitModule3("mpatch", methods, mpatch_doc); | |
327 } | |
328 |