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
24/*
25 * For "diff-stat" like behaviour, we keep track of the biggest change
26 * we've seen, and the longest filename. That allows us to do simple
27 * scaling.
28 */
29static int max_change, max_len;
30
31/*
32 * Various "current state", notably line numbers and what
33 * file (and how) we're patching right now.. The "is_xxxx"
34 * things are flags, where -1 means "don't know yet".
35 */
36static int linenr = 1;
37static char *def_name = NULL;
38
39struct fragment {
40 unsigned long oldpos, oldlines;
41 unsigned long newpos, newlines;
42 const char *patch;
43 int size;
44 struct fragment *next;
45};
46
47struct patch {
48 char *new_name, *old_name;
49 unsigned int old_mode, new_mode;
50 int is_rename, is_copy, is_new, is_delete;
51 int lines_added, lines_deleted;
52 struct fragment *fragments;
53 struct patch *next;
54};
55
56#define CHUNKSIZE (8192)
57#define SLOP (16)
58
59static void *read_patch_file(int fd, unsigned long *sizep)
60{
61 unsigned long size = 0, alloc = CHUNKSIZE;
62 void *buffer = xmalloc(alloc);
63
64 for (;;) {
65 int nr = alloc - size;
66 if (nr < 1024) {
67 alloc += CHUNKSIZE;
68 buffer = xrealloc(buffer, alloc);
69 nr = alloc - size;
70 }
71 nr = read(fd, buffer + size, nr);
72 if (!nr)
73 break;
74 if (nr < 0) {
75 if (errno == EAGAIN)
76 continue;
77 die("git-apply: read returned %s", strerror(errno));
78 }
79 size += nr;
80 }
81 *sizep = size;
82
83 /*
84 * Make sure that we have some slop in the buffer
85 * so that we can do speculative "memcmp" etc, and
86 * see to it that it is NUL-filled.
87 */
88 if (alloc < size + SLOP)
89 buffer = xrealloc(buffer, size + SLOP);
90 memset(buffer + size, 0, SLOP);
91 return buffer;
92}
93
94static unsigned long linelen(char *buffer, unsigned long size)
95{
96 unsigned long len = 0;
97 while (size--) {
98 len++;
99 if (*buffer++ == '\n')
100 break;
101 }
102 return len;
103}
104
105static int is_dev_null(const char *str)
106{
107 return !memcmp("/dev/null", str, 9) && isspace(str[9]);
108}
109
110#define TERM_EXIST 1
111#define TERM_SPACE 2
112#define TERM_TAB 4
113
114static int name_terminate(const char *name, int namelen, int c, int terminate)
115{
116 if (c == ' ' && !(terminate & TERM_SPACE))
117 return 0;
118 if (c == '\t' && !(terminate & TERM_TAB))
119 return 0;
120
121 /*
122 * Do we want an existing name? Return false and
123 * continue if it's not there.
124 */
125 if (terminate & TERM_EXIST)
126 return cache_name_pos(name, namelen) >= 0;
127
128 return 1;
129}
130
131static char * find_name(const char *line, char *def, int p_value, int terminate)
132{
133 int len;
134 const char *start = line;
135 char *name;
136
137 for (;;) {
138 char c = *line;
139
140 if (isspace(c)) {
141 if (c == '\n')
142 break;
143 if (name_terminate(start, line-start, c, terminate))
144 break;
145 }
146 line++;
147 if (c == '/' && !--p_value)
148 start = line;
149 }
150 if (!start)
151 return def;
152 len = line - start;
153 if (!len)
154 return def;
155
156 /*
157 * Generally we prefer the shorter name, especially
158 * if the other one is just a variation of that with
159 * something else tacked on to the end (ie "file.orig"
160 * or "file~").
161 */
162 if (def) {
163 int deflen = strlen(def);
164 if (deflen < len && !strncmp(start, def, deflen))
165 return def;
166 }
167
168 name = xmalloc(len + 1);
169 memcpy(name, start, len);
170 name[len] = 0;
171 free(def);
172 return name;
173}
174
175/*
176 * Get the name etc info from the --/+++ lines of a traditional patch header
177 *
178 * NOTE! This hardcodes "-p1" behaviour in filename detection.
179 *
180 * FIXME! The end-of-filename heuristics are kind of screwy. For existing
181 * files, we can happily check the index for a match, but for creating a
182 * new file we should try to match whatever "patch" does. I have no idea.
183 */
184static void parse_traditional_patch(const char *first, const char *second, struct patch *patch)
185{
186 int p_value = 1;
187 char *name;
188
189 first += 4; // skip "--- "
190 second += 4; // skip "+++ "
191 if (is_dev_null(first)) {
192 patch->is_new = 1;
193 patch->is_delete = 0;
194 name = find_name(second, def_name, p_value, TERM_SPACE | TERM_TAB);
195 patch->new_name = name;
196 } else if (is_dev_null(second)) {
197 patch->is_new = 0;
198 patch->is_delete = 1;
199 name = find_name(first, def_name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
200 patch->old_name = name;
201 } else {
202 name = find_name(first, def_name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
203 name = find_name(second, name, p_value, TERM_EXIST | TERM_SPACE | TERM_TAB);
204 patch->old_name = patch->new_name = name;
205 }
206 if (!name)
207 die("unable to find filename in patch at line %d", linenr);
208}
209
210static int gitdiff_hdrend(const char *line, struct patch *patch)
211{
212 return -1;
213}
214
215/*
216 * We're anal about diff header consistency, to make
217 * sure that we don't end up having strange ambiguous
218 * patches floating around.
219 *
220 * As a result, gitdiff_{old|new}name() will check
221 * their names against any previous information, just
222 * to make sure..
223 */
224static char *gitdiff_verify_name(const char *line, int isnull, char *orig_name, const char *oldnew)
225{
226 int len;
227 const char *name;
228
229 if (!orig_name && !isnull)
230 return find_name(line, NULL, 1, 0);
231
232 name = "/dev/null";
233 len = 9;
234 if (orig_name) {
235 name = orig_name;
236 len = strlen(name);
237 if (isnull)
238 die("git-apply: bad git-diff - expected /dev/null, got %s on line %d", name, linenr);
239 }
240
241 if (*name == '/')
242 goto absolute_path;
243
244 for (;;) {
245 char c = *line++;
246 if (c == '\n')
247 break;
248 if (c != '/')
249 continue;
250absolute_path:
251 if (memcmp(line, name, len) || line[len] != '\n')
252 break;
253 return orig_name;
254 }
255 die("git-apply: bad git-diff - inconsistent %s filename on line %d", oldnew, linenr);
256 return NULL;
257}
258
259static int gitdiff_oldname(const char *line, struct patch *patch)
260{
261 patch->old_name = gitdiff_verify_name(line, patch->is_new, patch->old_name, "old");
262 return 0;
263}
264
265static int gitdiff_newname(const char *line, struct patch *patch)
266{
267 patch->new_name = gitdiff_verify_name(line, patch->is_delete, patch->new_name, "new");
268 return 0;
269}
270
271static int gitdiff_oldmode(const char *line, struct patch *patch)
272{
273 patch->old_mode = strtoul(line, NULL, 8);
274 return 0;
275}
276
277static int gitdiff_newmode(const char *line, struct patch *patch)
278{
279 patch->new_mode = strtoul(line, NULL, 8);
280 return 0;
281}
282
283static int gitdiff_delete(const char *line, struct patch *patch)
284{
285 patch->is_delete = 1;
286 return gitdiff_oldmode(line, patch);
287}
288
289static int gitdiff_newfile(const char *line, struct patch *patch)
290{
291 patch->is_new = 1;
292 return gitdiff_newmode(line, patch);
293}
294
295static int gitdiff_copysrc(const char *line, struct patch *patch)
296{
297 patch->is_copy = 1;
298 patch->old_name = find_name(line, NULL, 0, 0);
299 return 0;
300}
301
302static int gitdiff_copydst(const char *line, struct patch *patch)
303{
304 patch->is_copy = 1;
305 patch->new_name = find_name(line, NULL, 0, 0);
306 return 0;
307}
308
309static int gitdiff_renamesrc(const char *line, struct patch *patch)
310{
311 patch->is_rename = 1;
312 patch->old_name = find_name(line, NULL, 0, 0);
313 return 0;
314}
315
316static int gitdiff_renamedst(const char *line, struct patch *patch)
317{
318 patch->is_rename = 1;
319 patch->new_name = find_name(line, NULL, 0, 0);
320 return 0;
321}
322
323static int gitdiff_similarity(const char *line, struct patch *patch)
324{
325 return 0;
326}
327
328/*
329 * This is normal for a diff that doesn't change anything: we'll fall through
330 * into the next diff. Tell the parser to break out.
331 */
332static int gitdiff_unrecognized(const char *line, struct patch *patch)
333{
334 return -1;
335}
336
337/* Verify that we recognize the lines following a git header */
338static int parse_git_header(char *line, int len, unsigned int size, struct patch *patch)
339{
340 unsigned long offset;
341
342 /* A git diff has explicit new/delete information, so we don't guess */
343 patch->is_new = 0;
344 patch->is_delete = 0;
345
346 line += len;
347 size -= len;
348 linenr++;
349 for (offset = len ; size > 0 ; offset += len, size -= len, line += len, linenr++) {
350 static const struct opentry {
351 const char *str;
352 int (*fn)(const char *, struct patch *);
353 } optable[] = {
354 { "@@ -", gitdiff_hdrend },
355 { "--- ", gitdiff_oldname },
356 { "+++ ", gitdiff_newname },
357 { "old mode ", gitdiff_oldmode },
358 { "new mode ", gitdiff_newmode },
359 { "deleted file mode ", gitdiff_delete },
360 { "new file mode ", gitdiff_newfile },
361 { "copy from ", gitdiff_copysrc },
362 { "copy to ", gitdiff_copydst },
363 { "rename from ", gitdiff_renamesrc },
364 { "rename to ", gitdiff_renamedst },
365 { "similarity index ", gitdiff_similarity },
366 { "", gitdiff_unrecognized },
367 };
368 int i;
369
370 len = linelen(line, size);
371 if (!len || line[len-1] != '\n')
372 break;
373 for (i = 0; i < sizeof(optable) / sizeof(optable[0]); i++) {
374 const struct opentry *p = optable + i;
375 int oplen = strlen(p->str);
376 if (len < oplen || memcmp(p->str, line, oplen))
377 continue;
378 if (p->fn(line + oplen, patch) < 0)
379 return offset;
380 break;
381 }
382 }
383
384 return offset;
385}
386
387static int parse_num(const char *line, int len, int offset, const char *expect, unsigned long *p)
388{
389 char *ptr;
390 int digits, ex;
391
392 if (offset < 0 || offset >= len)
393 return -1;
394 line += offset;
395 len -= offset;
396
397 if (!isdigit(*line))
398 return -1;
399 *p = strtoul(line, &ptr, 10);
400
401 digits = ptr - line;
402
403 offset += digits;
404 line += digits;
405 len -= digits;
406
407 ex = strlen(expect);
408 if (ex > len)
409 return -1;
410 if (memcmp(line, expect, ex))
411 return -1;
412
413 return offset + ex;
414}
415
416/*
417 * Parse a unified diff fragment header of the
418 * form "@@ -a,b +c,d @@"
419 */
420static int parse_fragment_header(char *line, int len, struct fragment *fragment)
421{
422 int offset;
423
424 if (!len || line[len-1] != '\n')
425 return -1;
426
427 /* Figure out the number of lines in a fragment */
428 offset = parse_num(line, len, 4, ",", &fragment->oldpos);
429 offset = parse_num(line, len, offset, " +", &fragment->oldlines);
430 offset = parse_num(line, len, offset, ",", &fragment->newpos);
431 offset = parse_num(line, len, offset, " @@", &fragment->newlines);
432
433 return offset;
434}
435
436static int find_header(char *line, unsigned long size, int *hdrsize, struct patch *patch)
437{
438 unsigned long offset, len;
439
440 patch->is_rename = patch->is_copy = 0;
441 patch->is_new = patch->is_delete = -1;
442 patch->old_mode = patch->new_mode = 0;
443 patch->old_name = patch->new_name = NULL;
444 for (offset = 0; size > 0; offset += len, size -= len, line += len, linenr++) {
445 unsigned long nextlen;
446
447 len = linelen(line, size);
448 if (!len)
449 break;
450
451 /* Testing this early allows us to take a few shortcuts.. */
452 if (len < 6)
453 continue;
454
455 /*
456 * Make sure we don't find any unconnected patch fragmants.
457 * That's a sign that we didn't find a header, and that a
458 * patch has become corrupted/broken up.
459 */
460 if (!memcmp("@@ -", line, 4)) {
461 struct fragment dummy;
462 if (parse_fragment_header(line, len, &dummy) < 0)
463 continue;
464 error("patch fragment without header at line %d: %.*s", linenr, len-1, line);
465 }
466
467 if (size < len + 6)
468 break;
469
470 /*
471 * Git patch? It might not have a real patch, just a rename
472 * or mode change, so we handle that specially
473 */
474 if (!memcmp("diff --git ", line, 11)) {
475 int git_hdr_len = parse_git_header(line, len, size, patch);
476 if (git_hdr_len < 0)
477 continue;
478
479 *hdrsize = git_hdr_len;
480 return offset;
481 }
482
483 /** --- followed by +++ ? */
484 if (memcmp("--- ", line, 4) || memcmp("+++ ", line + len, 4))
485 continue;
486
487 /*
488 * We only accept unified patches, so we want it to
489 * at least have "@@ -a,b +c,d @@\n", which is 14 chars
490 * minimum
491 */
492 nextlen = linelen(line + len, size - len);
493 if (size < nextlen + 14 || memcmp("@@ -", line + len + nextlen, 4))
494 continue;
495
496 /* Ok, we'll consider it a patch */
497 parse_traditional_patch(line, line+len, patch);
498 *hdrsize = len + nextlen;
499 linenr += 2;
500 return offset;
501 }
502 return -1;
503}
504
505/*
506 * Parse a unified diff. Note that this really needs
507 * to parse each fragment separately, since the only
508 * way to know the difference between a "---" that is
509 * part of a patch, and a "---" that starts the next
510 * patch is to look at the line counts..
511 */
512static int parse_fragment(char *line, unsigned long size, struct patch *patch, struct fragment *fragment)
513{
514 int added, deleted;
515 int len = linelen(line, size), offset;
516 unsigned long pos[4], oldlines, newlines;
517
518 offset = parse_fragment_header(line, len, fragment);
519 if (offset < 0)
520 return -1;
521 oldlines = fragment->oldlines;
522 newlines = fragment->newlines;
523
524 if (patch->is_new < 0 && (pos[0] || oldlines))
525 patch->is_new = 0;
526 if (patch->is_delete < 0 && (pos[1] || newlines))
527 patch->is_delete = 0;
528
529 /* Parse the thing.. */
530 line += len;
531 size -= len;
532 linenr++;
533 added = deleted = 0;
534 for (offset = len; size > 0; offset += len, size -= len, line += len, linenr++) {
535 if (!oldlines && !newlines)
536 break;
537 len = linelen(line, size);
538 if (!len || line[len-1] != '\n')
539 return -1;
540 switch (*line) {
541 default:
542 return -1;
543 case ' ':
544 oldlines--;
545 newlines--;
546 break;
547 case '-':
548 deleted++;
549 oldlines--;
550 break;
551 case '+':
552 added++;
553 newlines--;
554 break;
555 }
556 }
557 patch->lines_added += added;
558 patch->lines_deleted += deleted;
559 return offset;
560}
561
562static int parse_single_patch(char *line, unsigned long size, struct patch *patch)
563{
564 unsigned long offset = 0;
565 struct fragment **fragp = &patch->fragments;
566
567 while (size > 4 && !memcmp(line, "@@ -", 4)) {
568 struct fragment *fragment;
569 int len;
570
571 fragment = xmalloc(sizeof(*fragment));
572 memset(fragment, 0, sizeof(*fragment));
573 len = parse_fragment(line, size, patch, fragment);
574 if (len <= 0)
575 die("corrupt patch at line %d", linenr);
576
577 fragment->patch = line;
578 fragment->size = len;
579
580 *fragp = fragment;
581 fragp = &fragment->next;
582
583 offset += len;
584 line += len;
585 size -= len;
586 }
587 return offset;
588}
589
590static int parse_chunk(char *buffer, unsigned long size, struct patch *patch)
591{
592 int hdrsize, patchsize;
593 int offset = find_header(buffer, size, &hdrsize, patch);
594
595 if (offset < 0)
596 return offset;
597
598 patchsize = parse_single_patch(buffer + offset + hdrsize, size - offset - hdrsize, patch);
599
600 return offset + hdrsize + patchsize;
601}
602
603const char pluses[] = "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++";
604const char minuses[]= "----------------------------------------------------------------------";
605
606static void show_stats(struct patch *patch)
607{
608 char *name = patch->old_name;
609 int len, max, add, del;
610
611 if (!name)
612 name = patch->new_name;
613
614 /*
615 * "scale" the filename
616 */
617 len = strlen(name);
618 max = max_len;
619 if (max > 50)
620 max = 50;
621 if (len > max)
622 name += len - max;
623 len = max;
624
625 /*
626 * scale the add/delete
627 */
628 max = max_change;
629 if (max + len > 70)
630 max = 70 - len;
631
632 add = (patch->lines_added * max + max_change/2) / max_change;
633 del = (patch->lines_deleted * max + max_change/2) / max_change;
634 printf(" %-*s |%5d %.*s%.*s\n",
635 len, name, patch->lines_added + patch->lines_deleted,
636 add, pluses, del, minuses);
637}
638
639static void apply_patch_list(struct patch *patch)
640{
641 int files, adds, dels;
642
643 files = adds = dels = 0;
644 if (!patch)
645 die("no patch found");
646 do {
647 const char *old_name = patch->old_name;
648 const char *new_name = patch->new_name;
649
650 if (old_name) {
651 if (cache_name_pos(old_name, strlen(old_name)) < 0)
652 die("file %s does not exist", old_name);
653 if (patch->is_new < 0)
654 patch->is_new = 0;
655 }
656 if (new_name && (patch->is_new | patch->is_rename | patch->is_copy)) {
657 if (cache_name_pos(new_name, strlen(new_name)) >= 0)
658 die("file %s already exists", new_name);
659 }
660
661 files++;
662 adds += patch->lines_added;
663 dels += patch->lines_deleted;
664 show_stats(patch);
665 } while ((patch = patch->next) != NULL);
666 printf(" %d files changed, %d insertions(+), %d deletions(-)\n", files, adds, dels);
667}
668
669static void patch_stats(struct patch *patch)
670{
671 int lines = patch->lines_added + patch->lines_deleted;
672
673 if (lines > max_change)
674 max_change = lines;
675 if (patch->old_name) {
676 int len = strlen(patch->old_name);
677 if (len > max_len)
678 max_len = len;
679 }
680 if (patch->new_name) {
681 int len = strlen(patch->new_name);
682 if (len > max_len)
683 max_len = len;
684 }
685}
686
687static int apply_patch(int fd)
688{
689 unsigned long offset, size;
690 char *buffer = read_patch_file(fd, &size);
691 struct patch *list = NULL, **listp = &list;
692
693 if (!buffer)
694 return -1;
695 offset = 0;
696 while (size > 0) {
697 struct patch *patch;
698 int nr;
699
700 patch = xmalloc(sizeof(*patch));
701 memset(patch, 0, sizeof(*patch));
702 nr = parse_chunk(buffer + offset, size, patch);
703 if (nr < 0)
704 break;
705 patch_stats(patch);
706 *listp = patch;
707 listp = &patch->next;
708 offset += nr;
709 size -= nr;
710 }
711
712 apply_patch_list(list);
713
714 free(buffer);
715 return 0;
716}
717
718int main(int argc, char **argv)
719{
720 int i;
721 int read_stdin = 1;
722
723 if (read_cache() < 0)
724 die("unable to read index file");
725
726 for (i = 1; i < argc; i++) {
727 const char *arg = argv[i];
728 int fd;
729
730 if (!strcmp(arg, "-")) {
731 apply_patch(0);
732 read_stdin = 0;
733 continue;
734 }
735 if (!strcmp(arg, "--no-merge")) {
736 merge_patch = 0;
737 continue;
738 }
739 fd = open(arg, O_RDONLY);
740 if (fd < 0)
741 usage(apply_usage);
742 read_stdin = 0;
743 apply_patch(fd);
744 close(fd);
745 }
746 if (read_stdin)
747 apply_patch(0);
748 return 0;
749}