1 /*
2  * Copyright (c) 2022 Omar Polo <op@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  *
16  * Apply patches.
17  *
18  * Things that we may want to support:
19  *     + support indented patches?
20  *     + support other kinds of patches?
21  */
22 
23 #include <sys/types.h>
24 #include <sys/queue.h>
25 #include <sys/socket.h>
26 #include <sys/stat.h>
27 #include <sys/uio.h>
28 
29 #include <ctype.h>
30 #include <errno.h>
31 #include <limits.h>
32 #include <stdint.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <unistd.h>
37 
38 #include "got_error.h"
39 #include "got_object.h"
40 #include "got_path.h"
41 #include "got_reference.h"
42 #include "got_cancel.h"
43 #include "got_worktree.h"
44 #include "got_repository.h"
45 #include "got_opentemp.h"
46 #include "got_patch.h"
47 #include "got_diff.h"
48 
49 #include "got_lib_delta.h"
50 #include "got_lib_diff.h"
51 #include "got_lib_object.h"
52 #include "got_lib_privsep.h"
53 #include "got_lib_sha1.h"
54 
55 #define MIN(a, b) ((a) < (b) ? (a) : (b))
56 
57 struct got_patch_hunk {
58 	STAILQ_ENTRY(got_patch_hunk) entries;
59 	const struct got_error *err;
60 	int	ws_mangled;
61 	int	offset;
62 	int	old_nonl;
63 	int	new_nonl;
64 	int	old_from;
65 	int	old_lines;
66 	int	new_from;
67 	int	new_lines;
68 	size_t	len;
69 	size_t	cap;
70 	char	**lines;
71 };
72 
73 STAILQ_HEAD(got_patch_hunk_head, got_patch_hunk);
74 struct got_patch {
75 	int	 xbit;
76 	char	*old;
77 	char	*new;
78 	char	 cid[41];
79 	char	 blob[41];
80 	struct got_patch_hunk_head head;
81 };
82 
83 struct patch_args {
84 	got_patch_progress_cb progress_cb;
85 	void	*progress_arg;
86 	struct got_patch_hunk_head *head;
87 };
88 
89 static const struct got_error *
90 send_patch(struct imsgbuf *ibuf, int fd)
91 {
92 	const struct got_error *err = NULL;
93 
94 	if (imsg_compose(ibuf, GOT_IMSG_PATCH_FILE, 0, 0, fd,
95 	    NULL, 0) == -1) {
96 		err = got_error_from_errno(
97 		    "imsg_compose GOT_IMSG_PATCH_FILE");
98 		close(fd);
99 		return err;
100 	}
101 
102 	return got_privsep_flush_imsg(ibuf);
103 }
104 
105 static void
106 patch_free(struct got_patch *p)
107 {
108 	struct got_patch_hunk *h;
109 	size_t i;
110 
111 	while (!STAILQ_EMPTY(&p->head)) {
112 		h = STAILQ_FIRST(&p->head);
113 		STAILQ_REMOVE_HEAD(&p->head, entries);
114 
115 		for (i = 0; i < h->len; ++i)
116 			free(h->lines[i]);
117 		free(h->lines);
118 		free(h);
119 	}
120 
121 	free(p->new);
122 	free(p->old);
123 
124 	memset(p, 0, sizeof(*p));
125 	STAILQ_INIT(&p->head);
126 }
127 
128 static const struct got_error *
129 pushline(struct got_patch_hunk *h, const char *line)
130 {
131 	void 	*t;
132 	size_t	 newcap;
133 
134 	if (h->len == h->cap) {
135 		if ((newcap = h->cap * 1.5) == 0)
136 			newcap = 16;
137 		t = recallocarray(h->lines, h->cap, newcap,
138 		    sizeof(h->lines[0]));
139 		if (t == NULL)
140 			return got_error_from_errno("recallocarray");
141 		h->lines = t;
142 		h->cap = newcap;
143 	}
144 
145 	if ((t = strdup(line)) == NULL)
146 		return got_error_from_errno("strdup");
147 
148 	h->lines[h->len++] = t;
149 	return NULL;
150 }
151 
152 static const struct got_error *
153 recv_patch(struct imsgbuf *ibuf, int *done, struct got_patch *p, int strip)
154 {
155 	const struct got_error *err = NULL;
156 	struct imsg imsg;
157 	struct got_imsg_patch_hunk hdr;
158 	struct got_imsg_patch patch;
159 	struct got_patch_hunk *h = NULL;
160 	size_t datalen;
161 	int lastmode = -1;
162 
163 	memset(p, 0, sizeof(*p));
164 	STAILQ_INIT(&p->head);
165 
166 	err = got_privsep_recv_imsg(&imsg, ibuf, 0);
167 	if (err)
168 		return err;
169 	if (imsg.hdr.type == GOT_IMSG_PATCH_EOF) {
170 		*done = 1;
171 		goto done;
172 	}
173 	if (imsg.hdr.type != GOT_IMSG_PATCH) {
174 		err = got_error(GOT_ERR_PRIVSEP_MSG);
175 		goto done;
176 	}
177 	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
178 	if (datalen != sizeof(patch)) {
179 		err = got_error(GOT_ERR_PRIVSEP_LEN);
180 		goto done;
181 	}
182 	memcpy(&patch, imsg.data, sizeof(patch));
183 
184 	if (patch.old[sizeof(patch.old)-1] != '\0' ||
185 	    patch.new[sizeof(patch.new)-1] != '\0' ||
186 	    patch.cid[sizeof(patch.cid)-1] != '\0' ||
187 	    patch.blob[sizeof(patch.blob)-1] != '\0') {
188 		err = got_error(GOT_ERR_PRIVSEP_LEN);
189 		goto done;
190 	}
191 
192 	if (*patch.cid != '\0')
193 		strlcpy(p->cid, patch.cid, sizeof(p->cid));
194 
195 	if (*patch.blob != '\0')
196 		strlcpy(p->blob, patch.blob, sizeof(p->blob));
197 
198 	p->xbit = patch.xbit;
199 
200 	/* automatically set strip=1 for git-style diffs */
201 	if (strip == -1 && patch.git &&
202 	    (*patch.old == '\0' || !strncmp(patch.old, "a/", 2)) &&
203 	    (*patch.new == '\0' || !strncmp(patch.new, "b/", 2)))
204 		strip = 1;
205 
206 	/* prefer the new name if not /dev/null for not git-style diffs */
207 	if (!patch.git && *patch.new != '\0' && *patch.old != '\0') {
208 		err = got_path_strip(&p->old, patch.new, strip);
209 		if (err)
210 			goto done;
211 	} else if (*patch.old != '\0') {
212 		err = got_path_strip(&p->old, patch.old, strip);
213 		if (err)
214 			goto done;
215 	}
216 
217 	if (*patch.new != '\0') {
218 		err = got_path_strip(&p->new, patch.new, strip);
219 		if (err)
220 			goto done;
221 	}
222 
223 	if (p->old == NULL && p->new == NULL) {
224 		err = got_error(GOT_ERR_PATCH_MALFORMED);
225 		goto done;
226 	}
227 
228 	imsg_free(&imsg);
229 
230 	for (;;) {
231 		char *t;
232 
233 		err = got_privsep_recv_imsg(&imsg, ibuf, 0);
234 		if (err) {
235 			patch_free(p);
236 			return err;
237 		}
238 
239 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
240 		switch (imsg.hdr.type) {
241 		case GOT_IMSG_PATCH_DONE:
242 			if (h != NULL && h->len == 0)
243 				err = got_error(GOT_ERR_PATCH_MALFORMED);
244 			goto done;
245 		case GOT_IMSG_PATCH_HUNK:
246 			if (h != NULL &&
247 			    (h->len == 0 || h->old_nonl || h->new_nonl)) {
248 				err = got_error(GOT_ERR_PATCH_MALFORMED);
249 				goto done;
250 			}
251 			lastmode = -1;
252 			if (datalen != sizeof(hdr)) {
253 				err = got_error(GOT_ERR_PRIVSEP_LEN);
254 				goto done;
255 			}
256 			memcpy(&hdr, imsg.data, sizeof(hdr));
257 			if (hdr.oldfrom < 0 || hdr.newfrom < 0) {
258 				err = got_error(GOT_ERR_PRIVSEP_LEN);
259 				goto done;
260 			}
261 			if ((h = calloc(1, sizeof(*h))) == NULL) {
262 				err = got_error_from_errno("calloc");
263 				goto done;
264 			}
265 			h->old_from = hdr.oldfrom;
266 			h->old_lines = hdr.oldlines;
267 			h->new_from = hdr.newfrom;
268 			h->new_lines = hdr.newlines;
269 			STAILQ_INSERT_TAIL(&p->head, h, entries);
270 			break;
271 		case GOT_IMSG_PATCH_LINE:
272 			if (h == NULL) {
273 				err = got_error(GOT_ERR_PRIVSEP_MSG);
274 				goto done;
275 			}
276 			t = imsg.data;
277 			/* at least one char */
278 			if (datalen < 2 || t[datalen-1] != '\0') {
279 				err = got_error(GOT_ERR_PRIVSEP_MSG);
280 				goto done;
281 			}
282 			if (*t != ' ' && *t != '-' && *t != '+' &&
283 			    *t != '\\') {
284 				err = got_error(GOT_ERR_PRIVSEP_MSG);
285 				goto done;
286 			}
287 
288 			if (*t != '\\')
289 				err = pushline(h, t);
290 			else if (lastmode == '-')
291 				h->old_nonl = 1;
292 			else if (lastmode == '+')
293 				h->new_nonl = 1;
294 			else
295 				err = got_error(GOT_ERR_PATCH_MALFORMED);
296 
297 			if (err)
298 				goto done;
299 
300 			lastmode = *t;
301 			break;
302 		default:
303 			err = got_error(GOT_ERR_PRIVSEP_MSG);
304 			goto done;
305 		}
306 
307 		imsg_free(&imsg);
308 	}
309 
310 done:
311 	if (err)
312 		patch_free(p);
313 
314 	imsg_free(&imsg);
315 	return err;
316 }
317 
318 static void
319 reverse_patch(struct got_patch *p)
320 {
321 	struct got_patch_hunk *h;
322 	size_t i;
323 	int tmp;
324 
325 	STAILQ_FOREACH(h, &p->head, entries) {
326 		tmp = h->old_from;
327 		h->old_from = h->new_from;
328 		h->new_from = tmp;
329 
330 		tmp = h->old_lines;
331 		h->old_lines = h->new_lines;
332 		h->new_lines = tmp;
333 
334 		tmp = h->old_nonl;
335 		h->old_nonl = h->new_nonl;
336 		h->new_nonl = tmp;
337 
338 		for (i = 0; i < h->len; ++i) {
339 			if (*h->lines[i] == '+')
340 				*h->lines[i] = '-';
341 			else if (*h->lines[i] == '-')
342 				*h->lines[i] = '+';
343 		}
344 	}
345 }
346 
347 /*
348  * Copy data from orig starting at copypos until pos into tmp.
349  * If pos is -1, copy until EOF.
350  */
351 static const struct got_error *
352 copy(FILE *tmp, FILE *orig, off_t copypos, off_t pos)
353 {
354 	char buf[BUFSIZ];
355 	size_t len, r, w;
356 
357 	if (fseeko(orig, copypos, SEEK_SET) == -1)
358 		return got_error_from_errno("fseeko");
359 
360 	while (pos == -1 || copypos < pos) {
361 		len = sizeof(buf);
362 		if (pos > 0)
363 			len = MIN(len, (size_t)pos - copypos);
364 		r = fread(buf, 1, len, orig);
365 		if (r != len && ferror(orig))
366 			return got_error_from_errno("fread");
367 		w = fwrite(buf, 1, r, tmp);
368 		if (w != r)
369 			return got_error_from_errno("fwrite");
370 		copypos += len;
371 		if (r != len && feof(orig)) {
372 			if (pos == -1)
373 				return NULL;
374 			return got_error(GOT_ERR_HUNK_FAILED);
375 		}
376 	}
377 	return NULL;
378 }
379 
380 static int linecmp(const char *, const char *, int *);
381 
382 static const struct got_error *
383 locate_hunk(FILE *orig, struct got_patch_hunk *h, off_t *pos, int *lineno)
384 {
385 	const struct got_error *err = NULL;
386 	char *line = NULL;
387 	char mode = *h->lines[0];
388 	size_t linesize = 0;
389 	ssize_t linelen;
390 	off_t match = -1;
391 	int mangled = 0, match_lineno = -1;
392 
393 	for (;;) {
394 		linelen = getline(&line, &linesize, orig);
395 		if (linelen == -1) {
396 			if (ferror(orig))
397 				err = got_error_from_errno("getline");
398 			else if (match == -1)
399 				err = got_error(GOT_ERR_HUNK_FAILED);
400 			break;
401 		}
402 		if (line[linelen - 1] == '\n')
403 			line[linelen - 1] = '\0';
404 		(*lineno)++;
405 
406 		if ((mode == ' ' && !linecmp(h->lines[0] + 1, line, &mangled)) ||
407 		    (mode == '-' && !linecmp(h->lines[0] + 1, line, &mangled)) ||
408 		    (mode == '+' && *lineno == h->old_from)) {
409 			match = ftello(orig);
410 			if (match == -1) {
411 				err = got_error_from_errno("ftello");
412 				break;
413 			}
414 			match -= linelen;
415 			match_lineno = (*lineno)-1;
416 		}
417 
418 		if (*lineno >= h->old_from && match != -1) {
419 			if (mangled)
420 				h->ws_mangled = 1;
421 			break;
422 		}
423 	}
424 
425 	if (err == NULL) {
426 		*pos = match;
427 		*lineno = match_lineno;
428 		if (fseeko(orig, match, SEEK_SET) == -1)
429 			err = got_error_from_errno("fseeko");
430 	}
431 
432 	free(line);
433 	return err;
434 }
435 
436 static int
437 linecmp(const char *a, const char *b, int *mangled)
438 {
439 	int c;
440 
441 	*mangled = 0;
442 	c = strcmp(a, b);
443 	if (c == 0)
444 		return c;
445 
446 	*mangled = 1;
447 	for (;;) {
448 		while (*a == '\t' || *a == ' ' || *a == '\f')
449 			a++;
450 		while (*b == '\t' || *b == ' ' || *b == '\f')
451 			b++;
452 		if (*a == '\0' || *a != *b)
453 			break;
454 		a++, b++;
455 	}
456 
457 	return *a - *b;
458 }
459 
460 static const struct got_error *
461 test_hunk(FILE *orig, struct got_patch_hunk *h)
462 {
463 	const struct got_error *err = NULL;
464 	char *line = NULL;
465 	size_t linesize = 0, i = 0;
466 	ssize_t linelen;
467 	int mangled;
468 
469 	for (i = 0; i < h->len; ++i) {
470 		switch (*h->lines[i]) {
471 		case '+':
472 			continue;
473 		case ' ':
474 		case '-':
475 			linelen = getline(&line, &linesize, orig);
476 			if (linelen == -1) {
477 				if (ferror(orig))
478 					err = got_error_from_errno("getline");
479 				else
480 					err = got_error(
481 					    GOT_ERR_HUNK_FAILED);
482 				goto done;
483 			}
484 			if (line[linelen - 1] == '\n')
485 				line[linelen - 1] = '\0';
486 			if (linecmp(h->lines[i] + 1, line, &mangled)) {
487 				err = got_error(GOT_ERR_HUNK_FAILED);
488 				goto done;
489 			}
490 			if (mangled)
491 				h->ws_mangled = 1;
492 			break;
493 		}
494 	}
495 
496 done:
497 	free(line);
498 	return err;
499 }
500 
501 static const struct got_error *
502 apply_hunk(FILE *orig, FILE *tmp, struct got_patch_hunk *h, int *lineno,
503     off_t from)
504 {
505 	const struct got_error *err = NULL;
506 	const char *t;
507 	size_t linesize = 0, i, new = 0;
508 	char *line = NULL;
509 	char mode;
510 	ssize_t linelen;
511 
512 	if (orig != NULL && fseeko(orig, from, SEEK_SET) == -1)
513 		return got_error_from_errno("fseeko");
514 
515 	for (i = 0; i < h->len; ++i) {
516 		switch (mode = *h->lines[i]) {
517 		case '-':
518 		case ' ':
519 			(*lineno)++;
520 			if (orig != NULL) {
521 				linelen = getline(&line, &linesize, orig);
522 				if (linelen == -1) {
523 					err = got_error_from_errno("getline");
524 					goto done;
525 				}
526 				if (line[linelen - 1] == '\n')
527 					line[linelen - 1] = '\0';
528 				t = line;
529 			} else
530 				t = h->lines[i] + 1;
531 			if (mode == '-')
532 				continue;
533 			if (fprintf(tmp, "%s\n", t) < 0) {
534 				err = got_error_from_errno("fprintf");
535 				goto done;
536 			}
537 			break;
538 		case '+':
539 			new++;
540 			if (fprintf(tmp, "%s", h->lines[i] + 1) < 0) {
541 				err = got_error_from_errno("fprintf");
542 				goto done;
543 			}
544 			if (new != h->new_lines || !h->new_nonl) {
545 				if (fprintf(tmp, "\n") < 0) {
546 					err = got_error_from_errno("fprintf");
547 					goto done;
548 				}
549 			}
550 			break;
551 		}
552 	}
553 
554 done:
555 	free(line);
556 	return err;
557 }
558 
559 static const struct got_error *
560 patch_file(struct got_patch *p, FILE *orig, FILE *tmp)
561 {
562 	const struct got_error *err = NULL;
563 	struct got_patch_hunk *h;
564 	struct stat sb;
565 	int lineno = 0;
566 	off_t copypos, pos;
567 	char *line = NULL;
568 	size_t linesize = 0;
569 	ssize_t linelen;
570 
571 	if (p->old == NULL) {				/* create */
572 		h = STAILQ_FIRST(&p->head);
573 		if (h == NULL || STAILQ_NEXT(h, entries) != NULL)
574 			return got_error(GOT_ERR_PATCH_MALFORMED);
575 		return apply_hunk(orig, tmp, h, &lineno, 0);
576 	}
577 
578 	if (fstat(fileno(orig), &sb) == -1)
579 		return got_error_from_errno("fstat");
580 
581 	copypos = 0;
582 	STAILQ_FOREACH(h, &p->head, entries) {
583 	tryagain:
584 		err = locate_hunk(orig, h, &pos, &lineno);
585 		if (err != NULL && err->code == GOT_ERR_HUNK_FAILED)
586 			h->err = err;
587 		if (err != NULL)
588 			return err;
589 		err = copy(tmp, orig, copypos, pos);
590 		if (err != NULL)
591 			return err;
592 		copypos = pos;
593 
594 		err = test_hunk(orig, h);
595 		if (err != NULL && err->code == GOT_ERR_HUNK_FAILED) {
596 			/*
597 			 * try to apply the hunk again starting the search
598 			 * after the previous partial match.
599 			 */
600 			if (fseeko(orig, pos, SEEK_SET) == -1)
601 				return got_error_from_errno("fseeko");
602 			linelen = getline(&line, &linesize, orig);
603 			if (linelen == -1)
604 				return got_error_from_errno("getline");
605 			lineno++;
606 			goto tryagain;
607 		}
608 		if (err != NULL)
609 			return err;
610 
611 		if (lineno + 1 != h->old_from)
612 			h->offset = lineno + 1 - h->old_from;
613 
614 		err = apply_hunk(orig, tmp, h, &lineno, pos);
615 		if (err != NULL)
616 			return err;
617 
618 		copypos = ftello(orig);
619 		if (copypos == -1)
620 			return got_error_from_errno("ftello");
621 	}
622 
623 	if (p->new == NULL && sb.st_size != copypos) {
624 		h = STAILQ_FIRST(&p->head);
625 		h->err = got_error(GOT_ERR_HUNK_FAILED);
626 		err = h->err;
627 	} else if (!feof(orig))
628 		err = copy(tmp, orig, copypos, -1);
629 
630 	return err;
631 }
632 
633 static const struct got_error *
634 report_progress(struct patch_args *pa, const char *old, const char *new,
635     unsigned char status, const struct got_error *orig_error)
636 {
637 	const struct got_error *err;
638 	struct got_patch_hunk *h;
639 
640 	err = pa->progress_cb(pa->progress_arg, old, new, status,
641 	    orig_error, 0, 0, 0, 0, 0, 0, NULL);
642 	if (err)
643 		return err;
644 
645 	STAILQ_FOREACH(h, pa->head, entries) {
646 		if (h->offset == 0 && !h->ws_mangled && h->err == NULL)
647 			continue;
648 
649 		err = pa->progress_cb(pa->progress_arg, old, new, 0, NULL,
650 		    h->old_from, h->old_lines, h->new_from, h->new_lines,
651 		    h->offset, h->ws_mangled, h->err);
652 		if (err)
653 			return err;
654 	}
655 
656 	return NULL;
657 }
658 
659 static const struct got_error *
660 patch_delete(void *arg, unsigned char status, unsigned char staged_status,
661     const char *path)
662 {
663 	return report_progress(arg, path, NULL, status, NULL);
664 }
665 
666 static const struct got_error *
667 patch_add(void *arg, unsigned char status, const char *path)
668 {
669 	return report_progress(arg, NULL, path, status, NULL);
670 }
671 
672 static const struct got_error *
673 open_blob(char **path, FILE **fp, const char *blobid,
674     struct got_repository *repo)
675 {
676 	const struct got_error *err = NULL;
677 	struct got_blob_object *blob = NULL;
678 	struct got_object_id id, *idptr, *matched_id = NULL;
679 	int fd = -1;
680 
681 	*fp = NULL;
682 	*path = NULL;
683 
684 	if (strlen(blobid) != SHA1_DIGEST_STRING_LENGTH - 1) {
685 		err = got_repo_match_object_id(&matched_id, NULL, blobid,
686 		    GOT_OBJ_TYPE_BLOB, NULL /* do not resolve tags */,
687 		    repo);
688 		if (err)
689 			return err;
690 		idptr = matched_id;
691 	} else {
692 		if (!got_parse_sha1_digest(id.sha1, blobid))
693 			return got_error(GOT_ERR_BAD_OBJ_ID_STR);
694 		idptr = &id;
695 	}
696 
697 	fd = got_opentempfd();
698 	if (fd == -1) {
699 		err = got_error_from_errno("got_opentempfd");
700 		goto done;
701 	}
702 
703 	err = got_object_open_as_blob(&blob, repo, idptr, 8192, fd);
704 	if (err)
705 		goto done;
706 
707 	err = got_opentemp_named(path, fp, GOT_TMPDIR_STR "/got-patch-blob");
708 	if (err)
709 		goto done;
710 
711 	err = got_object_blob_dump_to_file(NULL, NULL, NULL, *fp, blob);
712 	if (err)
713 		goto done;
714 
715 done:
716 	if (fd != -1 && close(fd) == -1 && err == NULL)
717 		err = got_error_from_errno("close");
718 	if (blob)
719 		got_object_blob_close(blob);
720 	if (matched_id != NULL)
721 		free(matched_id);
722 	if (err) {
723 		if (*fp != NULL)
724 			fclose(*fp);
725 		if (*path != NULL)
726 			unlink(*path);
727 		free(*path);
728 		*fp = NULL;
729 		*path = NULL;
730 	}
731 	return err;
732 }
733 
734 static const struct got_error *
735 prepare_merge(int *do_merge, char **apath, FILE **afile,
736     struct got_worktree *worktree, struct got_repository *repo,
737     struct got_patch *p, struct got_object_id *commit_id,
738     struct got_tree_object *tree, const char *path)
739 {
740 	const struct got_error *err = NULL;
741 
742 	*do_merge = 0;
743 	*apath = NULL;
744 	*afile = NULL;
745 
746 	/* don't run the diff3 merge on creations/deletions */
747 	if (p->old == NULL || p->new == NULL)
748 		return NULL;
749 
750 	if (commit_id) {
751 		struct got_object_id *id;
752 
753 		err = got_object_tree_find_path(&id, NULL, repo, tree, path);
754 		if (err)
755 			return err;
756 		got_sha1_digest_to_str(id->sha1, p->blob, sizeof(p->blob));
757 		got_sha1_digest_to_str(commit_id->sha1, p->cid, sizeof(p->cid));
758 		free(id);
759 		err = open_blob(apath, afile, p->blob, repo);
760 		*do_merge = err == NULL;
761 	} else if (*p->blob != '\0') {
762 		err = open_blob(apath, afile, p->blob, repo);
763 		/*
764 		 * ignore failures to open this blob, we might have
765 		 * parsed gibberish.
766 		 */
767 		if (err && !(err->code == GOT_ERR_ERRNO && errno == ENOENT) &&
768 		    err->code != GOT_ERR_NO_OBJ)
769 			return err;
770 		*do_merge = err == NULL;
771 		err = NULL;
772 	}
773 
774 	return err;
775 }
776 
777 static const struct got_error *
778 apply_patch(int *overlapcnt, struct got_worktree *worktree,
779     struct got_repository *repo, struct got_fileindex *fileindex,
780     const char *old, const char *new, struct got_patch *p, int nop,
781     int reverse, struct got_object_id *commit_id,
782     struct got_tree_object *tree, struct patch_args *pa,
783     got_cancel_cb cancel_cb, void *cancel_arg)
784 {
785 	const struct got_error *err = NULL;
786 	struct stat sb;
787 	int do_merge = 0, file_renamed = 0;
788 	char *oldlabel = NULL, *newlabel = NULL, *anclabel = NULL;
789 	char *oldpath = NULL, *newpath = NULL;
790 	char *tmppath = NULL, *template = NULL, *parent = NULL;
791 	char *apath = NULL, *mergepath = NULL;
792 	FILE *oldfile = NULL, *tmpfile = NULL, *afile = NULL, *mergefile = NULL;
793 	int outfd;
794 	const char *outpath;
795 	mode_t mode = GOT_DEFAULT_FILE_MODE;
796 
797 	*overlapcnt = 0;
798 
799 	err = prepare_merge(&do_merge, &apath, &afile, worktree, repo, p,
800 	    commit_id, tree, old);
801 	if (err)
802 		return err;
803 
804 	if (reverse && !do_merge)
805 		reverse_patch(p);
806 
807 	if (asprintf(&oldpath, "%s/%s", got_worktree_get_root_path(worktree),
808 	    old) == -1) {
809 		err = got_error_from_errno("asprintf");
810 		goto done;
811 	}
812 
813 	if (asprintf(&newpath, "%s/%s", got_worktree_get_root_path(worktree),
814 	    new) == -1) {
815 		err = got_error_from_errno("asprintf");
816 		goto done;
817 	}
818 
819 	file_renamed = strcmp(oldpath, newpath);
820 
821 	if (asprintf(&template, "%s/got-patch",
822 	    got_worktree_get_root_path(worktree)) == -1) {
823 		err = got_error_from_errno(template);
824 		goto done;
825 	}
826 
827 	if (p->old != NULL) {
828 		if ((oldfile = fopen(oldpath, "r")) == NULL) {
829 			err = got_error_from_errno2("open", oldpath);
830 			goto done;
831 		}
832 		if (fstat(fileno(oldfile), &sb) == -1) {
833 			err = got_error_from_errno2("fstat", oldpath);
834 			goto done;
835 		}
836 		mode = sb.st_mode;
837 	} else if (p->xbit)
838 		mode |= (S_IXUSR | S_IXGRP | S_IXOTH);
839 
840 	err = got_opentemp_named(&tmppath, &tmpfile, template);
841 	if (err)
842 		goto done;
843 	outpath = tmppath;
844 	outfd = fileno(tmpfile);
845 	err = patch_file(p, afile != NULL ? afile : oldfile, tmpfile);
846 	if (err)
847 		goto done;
848 
849 	if (do_merge) {
850 		const char *type, *id;
851 
852 		if (fseeko(afile, 0, SEEK_SET) == -1 ||
853 		    fseeko(oldfile, 0, SEEK_SET) == -1 ||
854 		    fseeko(tmpfile, 0, SEEK_SET) == -1) {
855 			err = got_error_from_errno("fseeko");
856 			goto done;
857 		}
858 
859 		if (asprintf(&oldlabel, "--- %s", p->old) == -1) {
860 			err = got_error_from_errno("asprintf");
861 			oldlabel = NULL;
862 			goto done;
863 		}
864 
865 		if (asprintf(&newlabel, "+++ %s", p->new) == -1) {
866 			err = got_error_from_errno("asprintf");
867 			newlabel = NULL;
868 			goto done;
869 		}
870 
871 		if (*p->cid != '\0') {
872 			type = "commit";
873 			id = p->cid;
874 		} else {
875 			type = "blob";
876 			id = p->blob;
877 		}
878 
879 		if (asprintf(&anclabel, "%s %s", type, id) == -1) {
880 			err = got_error_from_errno("asprintf");
881 			anclabel = NULL;
882 			goto done;
883 		}
884 
885 		if (reverse) {
886 			char *s;
887 			FILE *t;
888 
889 			s = anclabel;
890 			anclabel = newlabel;
891 			newlabel = s;
892 
893 			t = afile;
894 			afile = tmpfile;
895 			tmpfile = t;
896 		}
897 
898 		err = got_opentemp_named(&mergepath, &mergefile, template);
899 		if (err)
900 			goto done;
901 		outpath = mergepath;
902 		outfd = fileno(mergefile);
903 
904 		err = got_merge_diff3(overlapcnt, outfd, tmpfile, afile,
905 		    oldfile, oldlabel, anclabel, newlabel,
906 		    GOT_DIFF_ALGORITHM_PATIENCE);
907 		if (err)
908 			goto done;
909 	}
910 
911 	if (nop)
912 		goto done;
913 
914 	if (p->old != NULL && p->new == NULL) {
915 		err = got_worktree_patch_schedule_rm(old, repo, worktree,
916 		    fileindex, patch_delete, pa);
917 		goto done;
918 	}
919 
920 	if (fchmod(outfd, mode) == -1) {
921 		err = got_error_from_errno2("chmod", tmppath);
922 		goto done;
923 	}
924 
925 	if (rename(outpath, newpath) == -1) {
926 		if (errno != ENOENT) {
927 			err = got_error_from_errno3("rename", outpath,
928 			    newpath);
929 			goto done;
930 		}
931 
932 		err = got_path_dirname(&parent, newpath);
933 		if (err != NULL)
934 			goto done;
935 		err = got_path_mkdir(parent);
936 		if (err != NULL)
937 			goto done;
938 		if (rename(outpath, newpath) == -1) {
939 			err = got_error_from_errno3("rename", outpath,
940 			    newpath);
941 			goto done;
942 		}
943 	}
944 
945 	if (file_renamed) {
946 		err = got_worktree_patch_schedule_rm(old, repo, worktree,
947 		    fileindex, patch_delete, pa);
948 		if (err == NULL)
949 			err = got_worktree_patch_schedule_add(new, repo,
950 			    worktree, fileindex, patch_add,
951 			    pa);
952 		if (err)
953 			unlink(newpath);
954 	} else if (p->old == NULL) {
955 		err = got_worktree_patch_schedule_add(new, repo, worktree,
956 		    fileindex, patch_add, pa);
957 		if (err)
958 			unlink(newpath);
959 	} else if (*overlapcnt != 0)
960 		err = report_progress(pa, old, new, GOT_STATUS_CONFLICT, NULL);
961 	else if (do_merge)
962 		err = report_progress(pa, old, new, GOT_STATUS_MERGE, NULL);
963 	else
964 		err = report_progress(pa, old, new, GOT_STATUS_MODIFY, NULL);
965 
966 done:
967 	free(parent);
968 	free(template);
969 
970 	if (tmppath != NULL)
971 		unlink(tmppath);
972 	if (tmpfile != NULL && fclose(tmpfile) == EOF && err == NULL)
973 		err = got_error_from_errno("fclose");
974 	free(tmppath);
975 
976 	free(oldpath);
977 	if (oldfile != NULL && fclose(oldfile) == EOF && err == NULL)
978 		err = got_error_from_errno("fclose");
979 
980 	if (apath != NULL)
981 		unlink(apath);
982 	if (afile != NULL && fclose(afile) == EOF && err == NULL)
983 		err = got_error_from_errno("fclose");
984 	free(apath);
985 
986 	if (mergepath != NULL)
987 		unlink(mergepath);
988 	if (mergefile != NULL && fclose(mergefile) == EOF && err == NULL)
989 		err = got_error_from_errno("fclose");
990 	free(mergepath);
991 
992 	free(newpath);
993 	free(oldlabel);
994 	free(newlabel);
995 	free(anclabel);
996 	return err;
997 }
998 
999 const struct got_error *
1000 got_patch(int fd, struct got_worktree *worktree, struct got_repository *repo,
1001     int nop, int strip, int reverse, struct got_object_id *commit_id,
1002     got_patch_progress_cb progress_cb, void *progress_arg,
1003     got_cancel_cb cancel_cb, void *cancel_arg)
1004 {
1005 	const struct got_error *err = NULL, *complete_err = NULL;
1006 	struct got_fileindex *fileindex = NULL;
1007 	struct got_commit_object *commit = NULL;
1008 	struct got_tree_object *tree = NULL;
1009 	char *fileindex_path = NULL;
1010 	char *oldpath, *newpath;
1011 	struct imsgbuf *ibuf;
1012 	int imsg_fds[2] = {-1, -1};
1013 	int overlapcnt, done = 0, failed = 0;
1014 	pid_t pid;
1015 
1016 	ibuf = calloc(1, sizeof(*ibuf));
1017 	if (ibuf == NULL) {
1018 		err = got_error_from_errno("calloc");
1019 		goto done;
1020 	}
1021 
1022 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, imsg_fds) == -1) {
1023 		err = got_error_from_errno("socketpair");
1024 		goto done;
1025 	}
1026 
1027 	pid = fork();
1028 	if (pid == -1) {
1029 		err = got_error_from_errno("fork");
1030 		goto done;
1031 	} else if (pid == 0) {
1032 		got_privsep_exec_child(imsg_fds, GOT_PATH_PROG_READ_PATCH,
1033 		    NULL);
1034 		/* not reached */
1035 	}
1036 
1037 	if (close(imsg_fds[1]) == -1) {
1038 		err = got_error_from_errno("close");
1039 		goto done;
1040 	}
1041 	imsg_fds[1] = -1;
1042 	imsg_init(ibuf, imsg_fds[0]);
1043 
1044 	err = send_patch(ibuf, fd);
1045 	fd = -1;
1046 	if (err)
1047 		goto done;
1048 
1049 	err = got_worktree_patch_prepare(&fileindex, &fileindex_path,
1050 	    worktree);
1051 	if (err)
1052 		goto done;
1053 
1054 	if (commit_id) {
1055 		err = got_object_open_as_commit(&commit, repo, commit_id);
1056 		if (err)
1057 			goto done;
1058 
1059 		err = got_object_open_as_tree(&tree, repo, commit->tree_id);
1060 		if (err)
1061 			goto done;
1062 	}
1063 
1064 	while (!done && err == NULL) {
1065 		struct got_patch p;
1066 		struct patch_args pa;
1067 
1068 		pa.progress_cb = progress_cb;
1069 		pa.progress_arg = progress_arg;
1070 		pa.head = &p.head;
1071 
1072 		err = recv_patch(ibuf, &done, &p, strip);
1073 		if (err || done)
1074 			break;
1075 
1076 		err = got_worktree_patch_check_path(p.old, p.new, &oldpath,
1077 		    &newpath, worktree, repo, fileindex);
1078 		if (err == NULL)
1079 			err = apply_patch(&overlapcnt, worktree, repo,
1080 			    fileindex, oldpath, newpath, &p, nop, reverse,
1081 			    commit_id, tree, &pa, cancel_cb, cancel_arg);
1082 		if (err != NULL) {
1083 			failed = 1;
1084 			/* recoverable errors */
1085 			if (err->code == GOT_ERR_FILE_STATUS ||
1086 			    (err->code == GOT_ERR_ERRNO && errno == ENOENT))
1087 				err = report_progress(&pa, p.old, p.new,
1088 				    GOT_STATUS_CANNOT_UPDATE, err);
1089 			else if (err->code == GOT_ERR_HUNK_FAILED)
1090 				err = report_progress(&pa, p.old, p.new,
1091 				    GOT_STATUS_CANNOT_UPDATE, NULL);
1092 		}
1093 		if (overlapcnt != 0)
1094 			failed = 1;
1095 
1096 		free(oldpath);
1097 		free(newpath);
1098 		patch_free(&p);
1099 
1100 		if (err)
1101 			break;
1102 	}
1103 
1104 done:
1105 	if (fileindex != NULL)
1106 		complete_err = got_worktree_patch_complete(fileindex,
1107 		    fileindex_path);
1108 	if (complete_err && err == NULL)
1109 		err = complete_err;
1110 	free(fileindex_path);
1111 	if (tree)
1112 		got_object_tree_close(tree);
1113 	if (commit)
1114 		got_object_commit_close(commit);
1115 	if (fd != -1 && close(fd) == -1 && err == NULL)
1116 		err = got_error_from_errno("close");
1117 	if (ibuf != NULL)
1118 		imsg_clear(ibuf);
1119 	if (imsg_fds[0] != -1 && close(imsg_fds[0]) == -1 && err == NULL)
1120 		err = got_error_from_errno("close");
1121 	if (imsg_fds[1] != -1 && close(imsg_fds[1]) == -1 && err == NULL)
1122 		err = got_error_from_errno("close");
1123 	if (err == NULL && failed)
1124 		err = got_error(GOT_ERR_PATCH_FAILED);
1125 	return err;
1126 }