git-apply: if no input files specified, apply stdin
[git/git.git] / apply.c
CommitLineData
c1bb9350
LT
1/*
2 * apply.c
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 *
6 * This applies patches on top of some (arbitrary) version of the SCM.
7 *
8 * NOTE! It does all its work in the index file, and only cares about
9 * the files in the working directory if you tell it to "merge" the
10 * patch apply.
11 *
12 * Even when merging it always takes the source from the index, and
13 * uses the working tree as a "branch" for a 3-way merge.
14 */
15#include <ctype.h>
16
17#include "cache.h"
18
19// We default to the merge behaviour, since that's what most people would
20// expect
21static int merge_patch = 1;
22static const char apply_usage[] = "git-apply <patch>";
23
a4acb0eb
LT
24/*
25 * Various "current state", notably line numbers and what
26 * file (and how) we're patching right now.. The "is_xxxx"
27 * things are flags, where -1 means "don't know yet".
28 */
46979f56 29static int linenr = 1;
a4acb0eb
LT
30static int old_mode, new_mode;
31static char *old_name, *new_name, *def_name;
32static int is_rename, is_copy, is_new, is_delete;
46979f56 33
c1bb9350 34#define CHUNKSIZE (8192)
a4acb0eb 35#define SLOP (16)
c1bb9350
LT
36
37static void *read_patch_file(int fd, unsigned long *sizep)
38{
39 unsigned long size = 0, alloc = CHUNKSIZE;
40 void *buffer = xmalloc(alloc);
41
42 for (;;) {
43 int nr = alloc - size;
44 if (nr < 1024) {
45 alloc += CHUNKSIZE;
46 buffer = xrealloc(buffer, alloc);
47 nr = alloc - size;
48 }
49 nr = read(fd, buffer + size, nr);
50 if (!nr)
51 break;
52 if (nr < 0) {
53 if (errno == EAGAIN)
54 continue;
55 die("git-apply: read returned %s", strerror(errno));
56 }
57 size += nr;
58 }
59 *sizep = size;
a4acb0eb
LT
60
61 /*
62 * Make sure that we have some slop in the buffer
63 * so that we can do speculative "memcmp" etc, and
64 * see to it that it is NUL-filled.
65 */
66 if (alloc < size + SLOP)
67 buffer = xrealloc(buffer, size + SLOP);
68 memset(buffer + size, 0, SLOP);
c1bb9350
LT
69 return buffer;
70}
71
72static unsigned long linelen(char *buffer, unsigned long size)
73{
74 unsigned long len = 0;
75 while (size--) {
76 len++;
77 if (*buffer++ == '\n')
78 break;
79 }
80 return len;
81}
82
a4acb0eb
LT
83static int is_dev_null(const char *str)
84{
85 return !memcmp("/dev/null", str, 9) && isspace(str[9]);
86}
87
88static char * find_name(const char *line, char *def, int p_value)
c1bb9350 89{
a4acb0eb
LT
90 int len;
91 const char *start = line;
92 char *name;
93
c1bb9350 94 for (;;) {
a4acb0eb
LT
95 char c = *line;
96 if (isspace(c))
c1bb9350 97 break;
a4acb0eb
LT
98 line++;
99 if (c == '/' && !--p_value)
100 start = line;
101 }
102 if (!start)
103 return def;
104 len = line - start;
105 if (!len)
106 return def;
107
108 /*
109 * Generally we prefer the shorter name, especially
110 * if the other one is just a variation of that with
111 * something else tacked on to the end (ie "file.orig"
112 * or "file~").
113 */
114 if (def) {
115 int deflen = strlen(def);
116 if (deflen < len && !strncmp(start, def, deflen))
117 return def;
c1bb9350 118 }
a4acb0eb
LT
119
120 name = xmalloc(len + 1);
121 memcpy(name, start, len);
122 name[len] = 0;
123 free(def);
124 return name;
125}
126
127/*
128 * Get the name etc info from the --/+++ lines of a traditional patch header
129 *
130 * NOTE! This hardcodes "-p1" behaviour in filename detection.
131 */
132static int parse_traditional_patch(const char *first, const char *second)
133{
134 int p_value = 1;
135 char *name;
136
137 first += 4; // skip "--- "
138 second += 4; // skip "+++ "
139 if (is_dev_null(first)) {
140 is_new = 1;
141 name = find_name(second, def_name, p_value);
142 } else if (is_dev_null(second)) {
143 is_delete = 1;
144 name = find_name(first, def_name, p_value);
145 } else {
146 name = find_name(first, def_name, p_value);
147 name = find_name(second, name, p_value);
148 }
149 if (!name)
150 die("unable to find filename in patch at line %d", linenr);
151 old_name = name;
152 new_name = name;
153}
154
155static int gitdiff_hdrend(const char *line)
156{
157 return -1;
158}
159
160static int gitdiff_oldname(const char *line)
161{
162 if (!old_name)
163 old_name = find_name(line, NULL, 1);
164 return 0;
165}
166
167static int gitdiff_newname(const char *line)
168{
169 if (!new_name)
170 new_name = find_name(line, NULL, 1);
171 return 0;
172}
173
174static int gitdiff_oldmode(const char *line)
175{
176 old_mode = strtoul(line, NULL, 8);
177 return 0;
178}
179
180static int gitdiff_newmode(const char *line)
181{
182 new_mode = strtoul(line, NULL, 8);
183 return 0;
184}
185
186static int gitdiff_delete(const char *line)
187{
188 is_delete = 1;
189 return gitdiff_oldmode(line);
190}
191
192static int gitdiff_newfile(const char *line)
193{
194 is_new = 1;
195 return gitdiff_newmode(line);
196}
197
198static int gitdiff_copysrc(const char *line)
199{
200 is_copy = 1;
201 old_name = find_name(line, NULL, 0);
202 return 0;
203}
204
205static int gitdiff_copydst(const char *line)
206{
207 is_copy = 1;
208 new_name = find_name(line, NULL, 0);
209 return 0;
210}
211
212static int gitdiff_renamesrc(const char *line)
213{
214 is_rename = 1;
215 old_name = find_name(line, NULL, 0);
216 return 0;
217}
218
219static int gitdiff_renamedst(const char *line)
220{
221 is_rename = 1;
222 new_name = find_name(line, NULL, 0);
223 return 0;
224}
225
226static int gitdiff_similarity(const char *line)
227{
228 return 0;
c1bb9350
LT
229}
230
231/* Verify that we recognize the lines following a git header */
a4acb0eb 232static int parse_git_header(char *line, int len, unsigned int size)
c1bb9350 233{
a4acb0eb
LT
234 unsigned long offset;
235
236 /* A git diff has explicit new/delete information, so we don't guess */
237 is_new = 0;
238 is_delete = 0;
239
240 line += len;
241 size -= len;
242 linenr++;
243 for (offset = len ; size > 0 ; offset += len, size -= len, line += len, linenr++) {
244 static const struct opentry {
245 const char *str;
246 int (*fn)(const char *);
247 } optable[] = {
248 { "@@ -", gitdiff_hdrend },
249 { "--- ", gitdiff_oldname },
250 { "+++ ", gitdiff_newname },
251 { "old mode ", gitdiff_oldmode },
252 { "new mode ", gitdiff_newmode },
253 { "deleted file mode ", gitdiff_delete },
254 { "new file mode ", gitdiff_newfile },
255 { "copy from ", gitdiff_copysrc },
256 { "copy to ", gitdiff_copydst },
257 { "rename from ", gitdiff_renamesrc },
258 { "rename to ", gitdiff_renamedst },
259 { "similarity index ", gitdiff_similarity },
260 };
261 int i;
c1bb9350 262
c1bb9350 263 len = linelen(line, size);
a4acb0eb 264 if (!len || line[len-1] != '\n')
c1bb9350 265 break;
a4acb0eb
LT
266 for (i = 0; i < sizeof(optable) / sizeof(optable[0]); i++) {
267 const struct opentry *p = optable + i;
268 int oplen = strlen(p->str);
269 if (len < oplen || memcmp(p->str, line, oplen))
270 continue;
271 if (p->fn(line + oplen) < 0)
272 return offset;
273 }
c1bb9350
LT
274 }
275
a4acb0eb 276 return offset;
c1bb9350
LT
277}
278
46979f56
LT
279static int parse_num(const char *line, int len, int offset, const char *expect, unsigned long *p)
280{
281 char *ptr;
282 int digits, ex;
283
284 if (offset < 0 || offset >= len)
285 return -1;
286 line += offset;
287 len -= offset;
288
289 if (!isdigit(*line))
290 return -1;
291 *p = strtoul(line, &ptr, 10);
292
293 digits = ptr - line;
294
295 offset += digits;
296 line += digits;
297 len -= digits;
298
299 ex = strlen(expect);
300 if (ex > len)
301 return -1;
302 if (memcmp(line, expect, ex))
303 return -1;
304
305 return offset + ex;
306}
307
308/*
309 * Parse a unified diff fragment header of the
310 * form "@@ -a,b +c,d @@"
311 */
312static int parse_fragment_header(char *line, int len, unsigned long *pos)
313{
314 int offset;
315
316 if (!len || line[len-1] != '\n')
317 return -1;
318
319 /* Figure out the number of lines in a fragment */
320 offset = parse_num(line, len, 4, ",", pos);
321 offset = parse_num(line, len, offset, " +", pos+1);
322 offset = parse_num(line, len, offset, ",", pos+2);
323 offset = parse_num(line, len, offset, " @@", pos+3);
324
325 return offset;
326}
327
c1bb9350
LT
328static int find_header(char *line, unsigned long size, int *hdrsize)
329{
330 unsigned long offset, len;
331
a4acb0eb
LT
332 is_rename = is_copy = 0;
333 is_new = is_delete = -1;
881b0765 334 old_mode = new_mode = 0;
a4acb0eb 335 def_name = old_name = new_name = NULL;
46979f56 336 for (offset = 0; size > 0; offset += len, size -= len, line += len, linenr++) {
c1bb9350
LT
337 unsigned long nextlen;
338
339 len = linelen(line, size);
340 if (!len)
341 break;
342
343 /* Testing this early allows us to take a few shortcuts.. */
344 if (len < 6)
345 continue;
46979f56
LT
346
347 /*
348 * Make sure we don't find any unconnected patch fragmants.
349 * That's a sign that we didn't find a header, and that a
350 * patch has become corrupted/broken up.
351 */
352 if (!memcmp("@@ -", line, 4)) {
353 unsigned long pos[4];
354 if (parse_fragment_header(line, len, pos) < 0)
355 continue;
356 error("patch fragment without header at line %d: %.*s", linenr, len-1, line);
357 }
358
c1bb9350
LT
359 if (size < len + 6)
360 break;
361
362 /*
363 * Git patch? It might not have a real patch, just a rename
364 * or mode change, so we handle that specially
365 */
366 if (!memcmp("diff --git ", line, 11)) {
a4acb0eb 367 int git_hdr_len = parse_git_header(line, len, size);
c1bb9350
LT
368 if (git_hdr_len < 0)
369 continue;
370
a4acb0eb 371 *hdrsize = git_hdr_len;
c1bb9350
LT
372 return offset;
373 }
374
375 /** --- followed by +++ ? */
376 if (memcmp("--- ", line, 4) || memcmp("+++ ", line + len, 4))
377 continue;
378
379 /*
380 * We only accept unified patches, so we want it to
381 * at least have "@@ -a,b +c,d @@\n", which is 14 chars
382 * minimum
383 */
384 nextlen = linelen(line + len, size - len);
385 if (size < nextlen + 14 || memcmp("@@ -", line + len + nextlen, 4))
386 continue;
387
388 /* Ok, we'll consider it a patch */
a4acb0eb 389 parse_traditional_patch(line, line+len);
c1bb9350 390 *hdrsize = len + nextlen;
46979f56 391 linenr += 2;
c1bb9350
LT
392 return offset;
393 }
394 return -1;
395}
396
c1bb9350
LT
397/*
398 * Parse a unified diff. Note that this really needs
399 * to parse each fragment separately, since the only
400 * way to know the difference between a "---" that is
401 * part of a patch, and a "---" that starts the next
402 * patch is to look at the line counts..
403 */
404static int apply_fragment(char *line, unsigned long size)
405{
406 int len = linelen(line, size), offset;
46979f56 407 unsigned long pos[4], oldlines, newlines;
c1bb9350 408
46979f56 409 offset = parse_fragment_header(line, len, pos);
c1bb9350
LT
410 if (offset < 0)
411 return -1;
46979f56
LT
412 oldlines = pos[1];
413 newlines = pos[3];
c1bb9350 414
a4acb0eb
LT
415 if (is_new < 0 && (pos[0] || oldlines))
416 is_new = 0;
417 if (is_delete < 0 && (pos[1] || newlines))
418 is_delete = 0;
419
c1bb9350
LT
420 /* Parse the thing.. */
421 line += len;
422 size -= len;
46979f56
LT
423 linenr++;
424 for (offset = len; size > 0; offset += len, size -= len, line += len, linenr++) {
c1bb9350
LT
425 if (!oldlines && !newlines)
426 break;
427 len = linelen(line, size);
428 if (!len || line[len-1] != '\n')
429 return -1;
430 switch (*line) {
431 default:
432 return -1;
433 case ' ':
434 oldlines--;
435 newlines--;
436 break;
437 case '-':
438 oldlines--;
439 break;
440 case '+':
441 newlines--;
442 break;
443 }
444 }
445 return offset;
446}
447
448static int apply_single_patch(char *line, unsigned long size)
449{
450 unsigned long offset = 0;
451
452 while (size > 4 && !memcmp(line, "@@ -", 4)) {
453 int len = apply_fragment(line, size);
454 if (len <= 0)
46979f56 455 die("corrupt patch at line %d", linenr);
c1bb9350
LT
456
457printf("applying fragment:\n%.*s\n\n", len, line);
458
459 offset += len;
460 line += len;
461 size -= len;
462 }
463 return offset;
464}
465
466static int apply_chunk(char *buffer, unsigned long size)
467{
468 int hdrsize, patchsize;
469 int offset = find_header(buffer, size, &hdrsize);
470 char *header, *patch;
471
472 if (offset < 0)
473 return offset;
474 header = buffer + offset;
475
476printf("Found header:\n%.*s\n\n", hdrsize, header);
a4acb0eb
LT
477printf("Rename: %d\n", is_rename);
478printf("Copy: %d\n", is_copy);
479printf("New: %d\n", is_new);
480printf("Delete: %d\n", is_delete);
481printf("Mode: %o->%o\n", old_mode, new_mode);
482printf("Name: '%s'->'%s'\n", old_name, new_name);
c1bb9350
LT
483
484 patch = header + hdrsize;
485 patchsize = apply_single_patch(patch, size - offset - hdrsize);
486
487 return offset + hdrsize + patchsize;
488}
489
490static int apply_patch(int fd)
491{
492 unsigned long offset, size;
493 char *buffer = read_patch_file(fd, &size);
494
495 if (!buffer)
496 return -1;
497 offset = 0;
498 while (size > 0) {
499 int nr = apply_chunk(buffer + offset, size);
500 if (nr < 0)
501 break;
502 offset += nr;
503 size -= nr;
504 }
505 free(buffer);
506 return 0;
507}
508
509int main(int argc, char **argv)
510{
511 int i;
4dfdbe10 512 int read_stdin = 1;
c1bb9350
LT
513
514 if (read_cache() < 0)
515 die("unable to read index file");
516
517 for (i = 1; i < argc; i++) {
518 const char *arg = argv[i];
519 int fd;
520
521 if (!strcmp(arg, "-")) {
522 apply_patch(0);
4dfdbe10 523 read_stdin = 0;
c1bb9350
LT
524 continue;
525 }
526 if (!strcmp(arg, "--no-merge")) {
527 merge_patch = 0;
528 continue;
529 }
530 fd = open(arg, O_RDONLY);
531 if (fd < 0)
532 usage(apply_usage);
4dfdbe10 533 read_stdin = 0;
c1bb9350
LT
534 apply_patch(fd);
535 close(fd);
536 }
4dfdbe10
LT
537 if (read_stdin)
538 apply_patch(0);
c1bb9350
LT
539 return 0;
540}