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