xref: /dragonfly/usr.bin/undo/undo.c (revision 335b9e93) 
1 /*
2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
3  *
4  * This code is derived from software contributed to The DragonFly Project
5  * by Matthew Dillon <dillon@backplane.com>
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in
15  *    the documentation and/or other materials provided with the
16  *    distribution.
17  * 3. Neither the name of The DragonFly Project nor the names of its
18  *    contributors may be used to endorse or promote products derived
19  *    from this software without specific, prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  * $DragonFly: src/usr.bin/undo/undo.c,v 1.6 2008/07/17 21:34:47 thomas Exp $
35  */
36 /*
37  * UNDO - retrieve an older version of a file.
38  */
39 
40 #include <sys/types.h>
41 #include <sys/stat.h>
42 #include <sys/wait.h>
43 #include <sys/tree.h>
44 #include <sys/ioctl.h>
45 #include <stdio.h>
46 #include <stdlib.h>
47 #include <stdarg.h>
48 #include <string.h>
49 #include <unistd.h>
50 #include <fcntl.h>
51 #include <errno.h>
52 #include <err.h>
53 #include <vfs/hammer/hammer_disk.h>
54 #include <vfs/hammer/hammer_ioctl.h>
55 
56 /*
57  * Sorted list of transaction ids
58  */
59 struct undo_hist_entry;
60 RB_HEAD(undo_hist_entry_rb_tree, undo_hist_entry);
61 RB_PROTOTYPE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
62 	undo_hist_entry_compare, hammer_tid_t);
63 
64 struct undo_hist_entry {
65 	RB_ENTRY(undo_hist_entry) rbnode;
66 	struct hammer_ioc_hist_entry tse;
67 	ino_t inum;
68 };
69 
70 enum undo_type { TYPE_FILE, TYPE_DIFF, TYPE_RDIFF, TYPE_HISTORY };
71 enum undo_cmd { CMD_DUMP, CMD_ITERATEALL };
72 
73 #define UNDO_FLAG_MULT		0x0001
74 #define UNDO_FLAG_INOCHG	0x0002
75 #define UNDO_FLAG_TID_INDEX1	0x0004
76 #define UNDO_FLAG_TID_INDEX2	0x0008
77 
78 static int undo_hist_entry_compare(struct undo_hist_entry *he1,
79 		    struct undo_hist_entry *he2);
80 static void doiterate(const char *filename, int flags,
81 		   struct hammer_ioc_hist_entry ts1,
82 		   struct hammer_ioc_hist_entry ts2,
83 		   enum undo_cmd cmd, enum undo_type type);
84 static int doiterate_dump(const char *filename, int flags,
85 		   struct undo_hist_entry_rb_tree *ptse_tree,
86 		   struct hammer_ioc_hist_entry ts1,
87 		   struct hammer_ioc_hist_entry ts2,
88 		   enum undo_type type);
89 static int doiterate_iterall(const char *filename, int flags,
90 		   struct undo_hist_entry_rb_tree *ptse_tree,
91 		   enum undo_type type);
92 static void dogenerate(const char *filename, int flags,
93 		   struct hammer_ioc_hist_entry ts1,
94 		   struct hammer_ioc_hist_entry ts2,
95 		   int idx, enum undo_type type);
96 static void __collect_history(int fd, int *error,
97 		   struct undo_hist_entry_rb_tree *tse_tree);
98 static void collect_history(const char *filename, int *errorp,
99 		   struct undo_hist_entry_rb_tree *dir_tree);
100 static void collect_dir_history(const char *filename, int *error,
101 		   struct undo_hist_entry_rb_tree *dir_tree);
102 static void clean_tree(struct undo_hist_entry_rb_tree *tree);
103 static hammer_tid_t parse_delta_time(const char *timeStr, int *flags,
104 		   int ind_flag);
105 static FILE *_fopen(const char *filename, const char *mode);
106 static void runcmd(int fd, const char *cmd, ...);
107 static char *timestamp(struct hammer_ioc_hist_entry *hen);
108 static void usage(void);
109 
110 static int VerboseOpt;
111 static const char *OutFileName = NULL;
112 static const char *OutFilePostfix = NULL;
113 
114 RB_GENERATE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
115 	undo_hist_entry_compare, hammer_tid_t, tse.tid);
116 
117 
118 int
119 main(int ac, char **av)
120 {
121 	enum undo_cmd cmd;
122 	enum undo_type type;
123 	struct hammer_ioc_hist_entry ts1;
124 	struct hammer_ioc_hist_entry ts2;
125 	int c;
126 	int count_t;
127 	int flags;
128 
129 	bzero(&ts1, sizeof(ts1));
130 	bzero(&ts2, sizeof(ts2));
131 
132 	cmd = CMD_DUMP;
133 	type = TYPE_FILE;
134 	count_t = 0;
135 	flags = 0;
136 
137 	while ((c = getopt(ac, av, "adDiuvo:t:")) != -1) {
138 		switch(c) {
139 		case 'd':
140 			type = TYPE_DIFF;
141 			break;
142 		case 'D':
143 			type = TYPE_RDIFF;
144 			break;
145 		case 'i':
146 			if (type != TYPE_FILE)
147 				usage();
148 			type = TYPE_HISTORY;
149 			cmd = CMD_ITERATEALL;
150 			break;
151 		case 'a':
152 			cmd = CMD_ITERATEALL;
153 			break;
154 		case 'u':
155 			OutFilePostfix = ".undo";
156 			break;
157 		case 'v':
158 			++VerboseOpt;
159 			break;
160 		case 'o':
161 			OutFileName = optarg;
162 			break;
163 		case 't':
164 			/*
165 			 * Parse one or two -t options.  If two are specified
166 			 * -d is implied (but may be overridden)
167 			 */
168 			++count_t;
169 			if (count_t == 1) {
170 				ts1.tid = parse_delta_time(optarg, &flags,
171 							UNDO_FLAG_TID_INDEX1);
172 			} else if (count_t == 2) {
173 				ts2.tid = parse_delta_time(optarg, &flags,
174 							UNDO_FLAG_TID_INDEX2);
175 				if (type == TYPE_FILE)
176 					type = TYPE_DIFF;
177 			} else {
178 				usage();
179 			}
180 			break;
181 		default:
182 			usage();
183 			/* NOT REACHED */
184 			break;
185 		}
186 	}
187 
188 	/*
189 	 * Option validation
190 	 */
191 	if (OutFileName && OutFilePostfix) {
192 		fprintf(stderr, "The -o option may not be combined with -u\n");
193 		usage();
194 	}
195 
196 	ac -= optind;
197 	av += optind;
198 	if (ac > 1)
199 		flags |= UNDO_FLAG_MULT;
200 
201 	if (ac == 0)
202 		usage();
203 
204 	/*
205 	 * Validate the output template, if specified.
206 	 */
207 	if (OutFileName && (flags & UNDO_FLAG_MULT)) {
208 		const char *ptr = OutFileName;
209 		int didStr = 0;
210 
211 		while ((ptr = strchr(ptr, '%')) != NULL) {
212 			if (ptr[1] == 's') {
213 				if (didStr) {
214 					fprintf(stderr, "Malformed output "
215 							"template\n");
216 					usage();
217 				}
218 				didStr = 1;
219 				++ptr;
220 			} else if (ptr[1] != '%') {
221 				fprintf(stderr, "Malformed output template\n");
222 				usage();
223 			} else {
224 				ptr += 2;
225 			}
226 		}
227 	}
228 
229 	while (ac) {
230 		doiterate(*av, flags, ts1, ts2, cmd, type);
231 		++av;
232 		--ac;
233 	}
234 	return(0);
235 }
236 
237 /*
238  * Iterate through a file's history.  If cmd == CMD_DUMP we take the
239  * next-to-last transaction id, unless another given.  Otherwise if
240  * cmd == CMD_ITERATEALL we scan all transaction ids.
241  *
242  * Also iterate through the directory's history to locate other inodes that
243  * used the particular file name.
244  */
245 static
246 void
247 doiterate(const char *filename, int flags,
248 	  struct hammer_ioc_hist_entry ts1,
249 	  struct hammer_ioc_hist_entry ts2,
250 	  enum undo_cmd cmd, enum undo_type type)
251 {
252 	struct undo_hist_entry_rb_tree dir_tree;
253 	struct undo_hist_entry_rb_tree tse_tree;
254 	struct undo_hist_entry *tse;
255 	struct stat sb;
256 	char *path = NULL;
257 	int error;
258 
259 	RB_INIT(&dir_tree);
260 	RB_INIT(&tse_tree);
261 
262 	/*
263 	 * Use the directory history to locate all possible versions of
264 	 * the file.
265 	 */
266 	collect_dir_history(filename, &error, &dir_tree);
267 	RB_FOREACH(tse, undo_hist_entry_rb_tree, &dir_tree) {
268 		asprintf(&path, "%s@@0x%016jx", filename, (uintmax_t)tse->tse.tid);
269 		if (stat(path, &sb) == 0 && (sb.st_mode & S_IFIFO)) {
270 			fprintf(stderr, "Warning: fake transaction id %s@@0x%016jx\n",
271 				filename,
272 				(uintmax_t)tse->tse.tid);
273 			free(path);
274 			continue;
275 		}
276 		collect_history(path, &error, &tse_tree);
277 		free(path);
278 	}
279 	collect_history(filename, &error, &tse_tree);
280 
281 	switch (cmd) {
282 	case CMD_DUMP:
283 		if (doiterate_dump(filename, flags, &tse_tree, ts1, ts2, type) == -1)
284 			printf("%s: No UNDO history found\n", filename);
285 		break;
286 	case CMD_ITERATEALL:
287 		if (doiterate_iterall(filename, flags, &tse_tree, type) == -1)
288 			printf("%s: No UNDO history found\n", filename);
289 		break;
290 	default:
291 		fprintf(stderr, "Invalid command %d\n", cmd);
292 		break;
293 	}
294 
295 	clean_tree(&dir_tree);
296 	clean_tree(&tse_tree);
297 }
298 
299 static
300 int
301 doiterate_dump(const char *filename, int flags,
302 		struct undo_hist_entry_rb_tree *ptse_tree,
303 		struct hammer_ioc_hist_entry ts1,
304 		struct hammer_ioc_hist_entry ts2,
305 		enum undo_type type)
306 {
307 	struct undo_hist_entry *tse1;
308 	struct undo_hist_entry *tse2;
309 
310 	/*
311 	 * Find entry if tid set to placeholder index
312 	 */
313 	if (flags & UNDO_FLAG_TID_INDEX1) {
314 		tse1 = RB_MAX(undo_hist_entry_rb_tree, ptse_tree);
315 		while (tse1 && ts1.tid--) {
316 			tse1 = RB_PREV(undo_hist_entry_rb_tree,
317 				       ptse_tree, tse1);
318 		}
319 		if (tse1)
320 			ts1 = tse1->tse;
321 		else
322 			ts1.tid = 0;
323 	}
324 	if (flags & UNDO_FLAG_TID_INDEX2) {
325 		tse2 = RB_MAX(undo_hist_entry_rb_tree, ptse_tree);
326 		while (tse2 && ts2.tid--) {
327 			tse2 = RB_PREV(undo_hist_entry_rb_tree,
328 				       ptse_tree, tse2);
329 		}
330 		if (tse2)
331 			ts2 = tse2->tse;
332 		else
333 			ts2.tid = 0;
334 	}
335 
336 	/*
337 	 * Single entry, most recent prior to current
338 	 */
339 	if (ts1.tid == 0) {
340 		tse2 = RB_MAX(undo_hist_entry_rb_tree, ptse_tree);
341 		if (tse2) {
342 			ts2 = tse2->tse;
343 			tse1 = RB_PREV(undo_hist_entry_rb_tree,
344 				       ptse_tree, tse2);
345 			if (tse1)
346 				ts1 = tse1->tse;
347 		}
348 	}
349 
350 	if (ts1.tid) {
351 		dogenerate(filename, 0, ts1, ts2, 0, type);
352 		return(0);
353 	}
354 	return(-1);
355 }
356 
357 static
358 int
359 doiterate_iterall(const char *filename, int flags,
360 		struct undo_hist_entry_rb_tree *ptse_tree,
361 		enum undo_type type)
362 {
363 	struct undo_hist_entry *tse1;
364 	struct undo_hist_entry *tse2;
365 	struct hammer_ioc_hist_entry tid_max;
366 	int i;
367 
368 	if (RB_ROOT(ptse_tree) == NULL)
369 		return(-1);
370 
371 	/*
372 	 * Iterate entire history
373 	 */
374 	printf("%s: ITERATE ENTIRE HISTORY\n", filename);
375 
376 	tse1 = NULL;
377 	i = 0;
378 	RB_FOREACH(tse2, undo_hist_entry_rb_tree, ptse_tree) {
379 		if (tse1) {
380 			dogenerate(filename, flags, tse1->tse, tse2->tse, i, type);
381 		}
382 		if (tse1 && tse2->inum != tse1->inum)
383 			flags |= UNDO_FLAG_INOCHG;
384 		else
385 			flags &= ~UNDO_FLAG_INOCHG;
386 		tse1 = tse2;
387 		++i;
388 	}
389 
390 	/*
391 	 * There is no delta to print for the last pair,
392 	 * because they are identical.
393 	 */
394 	if (type != TYPE_DIFF && type != TYPE_RDIFF) {
395 		tid_max.tid = HAMMER_MAX_TID;
396 		tid_max.time32 = 0;
397 		dogenerate(filename, flags, tse1->tse, tid_max, i, type);
398 	}
399 	return(0);
400 }
401 
402 /*
403  * Generate output for a file as-of ts1 (ts1 may be 0!), if diffing then
404  * through ts2.
405  */
406 static
407 void
408 dogenerate(const char *filename, int flags,
409 	   struct hammer_ioc_hist_entry ts1,
410 	   struct hammer_ioc_hist_entry ts2,
411 	   int idx, enum undo_type type)
412 {
413 	struct stat st;
414 	const char *elm;
415 	char *ipath1 = NULL;
416 	char *ipath2 = NULL;
417 	FILE *fi;
418 	FILE *fp;
419 	char *buf;
420 	char *path;
421 	time_t t;
422 	struct tm *tp;
423 	char datestr[64];
424 	int n;
425 
426 	/*
427 	 * Open the input file.  If ts1 is 0 try to locate the most recent
428 	 * version of the file prior to the current version.
429 	 */
430 	if (ts1.tid == 0)
431 		asprintf(&ipath1, "%s", filename);
432 	else
433 		asprintf(&ipath1, "%s@@0x%016jx", filename, (uintmax_t)ts1.tid);
434 
435 	if (ts2.tid == 0)
436 		asprintf(&ipath2, "%s", filename);
437 	else
438 		asprintf(&ipath2, "%s@@0x%016jx", filename, (uintmax_t)ts2.tid);
439 
440 	if (lstat(ipath1, &st) < 0 && lstat(ipath2, &st) < 0) {
441 		if (idx == 0 || VerboseOpt) {
442 			fprintf(stderr, "Unable to access either %s or %s\n",
443 				ipath1, ipath2);
444 		}
445 		free(ipath1);
446 		free(ipath2);
447 		return;
448 	}
449 
450 	/*
451 	 * elm is the last component of the input file name
452 	 */
453 	if ((elm = strrchr(filename, '/')) != NULL)
454 		++elm;
455 	else
456 		elm = filename;
457 
458 	/*
459 	 * Where do we stuff our output?
460 	 */
461 	if (OutFileName) {
462 		if (flags & UNDO_FLAG_MULT) {
463 			asprintf(&path, OutFileName, elm);
464 			fp = _fopen(path, "w");
465 			free(path);
466 		} else {
467 			fp = _fopen(OutFileName, "w");
468 		}
469 	} else if (OutFilePostfix) {
470 		if (idx >= 0) {
471 			asprintf(&path, "%s%s.%04d", filename,
472 				 OutFilePostfix, idx);
473 		} else {
474 			asprintf(&path, "%s%s", filename, OutFilePostfix);
475 		}
476 		fp = _fopen(path, "w");
477 		free(path);
478 	} else {
479 		if ((flags & UNDO_FLAG_MULT) && type == TYPE_FILE) {
480 			if (idx >= 0) {
481 				printf("\n>>> %s %04d 0x%016jx %s\n\n",
482 				       filename, idx, (uintmax_t)ts1.tid,
483 				       timestamp(&ts1));
484 			} else {
485 				printf("\n>>> %s ---- 0x%016jx %s\n\n",
486 				       filename, (uintmax_t)ts1.tid,
487 				       timestamp(&ts1));
488 			}
489 		} else if (idx >= 0 && type == TYPE_FILE) {
490 			printf("\n>>> %s %04d 0x%016jx %s\n\n",
491 			       filename, idx, (uintmax_t)ts1.tid,
492 			       timestamp(&ts1));
493 		}
494 		fp = stdout;
495 	}
496 
497 	switch(type) {
498 	case TYPE_FILE:
499 		buf = malloc(8192);
500 		if (buf == NULL)
501 			err(1, "malloc");
502 		if ((fi = fopen(ipath1, "r")) != NULL) {
503 			while ((n = fread(buf, 1, 8192, fi)) > 0)
504 				fwrite(buf, 1, n, fp);
505 			fclose(fi);
506 		}
507 		free(buf);
508 		break;
509 	case TYPE_DIFF:
510 		printf("diff -N -r -u %s %s (to %s)\n",
511 		       ipath1, ipath2, timestamp(&ts2));
512 		fflush(stdout);
513 		runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u",
514 			ipath1, ipath2, NULL);
515 		break;
516 	case TYPE_RDIFF:
517 		printf("diff -N -r -u %s %s\n", ipath2, ipath1);
518 		fflush(stdout);
519 		runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u",
520 			ipath2, ipath1, NULL);
521 		break;
522 	case TYPE_HISTORY:
523 		t = (time_t)ts1.time32;
524 		tp = localtime(&t);
525 		strftime(datestr, sizeof(datestr), "%d-%b-%Y %H:%M:%S", tp);
526 		printf("\t0x%016jx %s", (uintmax_t)ts1.tid, datestr);
527 		if (flags & UNDO_FLAG_INOCHG)
528 			printf(" inode-change");
529 		if (lstat(ipath1, &st) < 0)
530 			printf(" file-deleted");
531 		printf("\n");
532 		break;
533 	}
534 
535 	if (fp != stdout)
536 		fclose(fp);
537 }
538 
539 static
540 void
541 clean_tree(struct undo_hist_entry_rb_tree *tree)
542 {
543 	struct undo_hist_entry *tse;
544 
545 	while ((tse = RB_ROOT(tree)) != NULL) {
546 		RB_REMOVE(undo_hist_entry_rb_tree, tree, tse);
547 		free(tse);
548 	}
549 }
550 
551 static
552 void
553 __collect_history(int fd, int *errorp, struct undo_hist_entry_rb_tree *tse_tree)
554 {
555 	struct hammer_ioc_history hist;
556 	struct undo_hist_entry *tse;
557 	struct stat st;
558 	int i;
559 
560 	/*
561 	 * Setup
562 	 */
563 	bzero(&hist, sizeof(hist));
564 	hist.beg_tid = HAMMER_MIN_TID;
565 	hist.end_tid = HAMMER_MAX_TID;
566 	hist.head.flags |= HAMMER_IOC_HISTORY_ATKEY;
567 	hist.key = 0;
568 	hist.nxt_key = HAMMER_MAX_KEY;
569 
570 	*errorp = 0;
571 
572 	/*
573 	 * Save the inode so inode changes can be reported.
574 	 */
575 	st.st_ino = 0;
576 	fstat(fd, &st);
577 
578 	/*
579 	 * Collect a unique set of transaction ids
580 	 */
581 	if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
582 		*errorp = errno;
583 		return;
584 	}
585 	for (;;) {
586 		for (i = 0; i < hist.count; ++i) {
587 			tse = malloc(sizeof(*tse));
588 			tse->tse = hist.hist_ary[i];
589 			tse->inum = st.st_ino;
590 			if (RB_INSERT(undo_hist_entry_rb_tree, tse_tree, tse)) {
591 				free(tse);
592 			}
593 		}
594 		if (hist.head.flags & HAMMER_IOC_HISTORY_EOF)
595 			break;
596 		if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_KEY) {
597 			hist.key = hist.nxt_key;
598 			hist.nxt_key = HAMMER_MAX_KEY;
599 		}
600 		if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_TID)
601 			hist.beg_tid = hist.nxt_tid;
602 		if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
603 			*errorp = errno;
604 			break;
605 		}
606 	}
607 }
608 
609 static
610 void
611 collect_history(const char *filename, int *errorp,
612 		struct undo_hist_entry_rb_tree *dir_tree)
613 {
614 	int fd;
615 
616 	fd = open(filename, O_RDONLY);
617 	if (fd == -1) {
618 		*errorp = errno;
619 		return;
620 	}
621 	__collect_history(fd, errorp, dir_tree);
622 	close(fd);
623 }
624 
625 static
626 void
627 collect_dir_history(const char *filename, int *errorp,
628 		    struct undo_hist_entry_rb_tree *dir_tree)
629 {
630 	char *dirname;
631 
632 	if (strrchr(filename, '/')) {
633 		dirname = strdup(filename);
634 		*strrchr(dirname, '/') = 0;
635 	} else {
636 		dirname = strdup(".");
637 	}
638 
639 	collect_history(dirname, errorp, dir_tree);
640 	free(dirname);
641 }
642 
643 static
644 hammer_tid_t
645 parse_delta_time(const char *timeStr, int *flags, int ind_flag)
646 {
647 	hammer_tid_t tid;
648 
649 	tid = strtoull(timeStr, NULL, 0);
650 	if (timeStr[0] == '+')
651 		++timeStr;
652 	if (timeStr[0] >= '0' && timeStr[0] <= '9' && timeStr[1] != 'x')
653 		*flags |= ind_flag;
654 	return(tid);
655 }
656 
657 static
658 FILE*
659 _fopen(const char *filename, const char *mode)
660 {
661 	FILE *fp;
662 
663 	fp = fopen(filename, mode);
664 	if (fp == NULL)
665 		err(1, "%s", filename);
666 	return(fp);
667 }
668 
669 static void
670 runcmd(int fd, const char *cmd, ...)
671 {
672 	va_list va;
673 	pid_t pid;
674 	char **av;
675 	int ac;
676 	int i;
677 
678 	va_start(va, cmd);
679 	for (ac = 0; va_arg(va, void *) != NULL; ++ac)
680 		;
681 	va_end(va);
682 
683 	av = malloc((ac + 1) * sizeof(char *));
684 	va_start(va, cmd);
685 	for (i = 0; i < ac; ++i)
686 		av[i] = va_arg(va, char *);
687 	va_end(va);
688 	av[i] = NULL;
689 
690 	if ((pid = fork()) < 0) {
691 		err(1, "fork");
692 	} else if (pid == 0) {
693 		if (fd != 1) {
694 			dup2(fd, 1);
695 			close(fd);
696 		}
697 		execv(cmd, av);
698 		_exit(1);
699 	} else {
700 		while (waitpid(pid, NULL, 0) != pid)
701 			;
702 	}
703 	free(av);
704 }
705 
706 /*
707  * Convert tid to timestamp.
708  */
709 static char *
710 timestamp(struct hammer_ioc_hist_entry *hen)
711 {
712 	static char timebuf[64];
713 	time_t t = (time_t)hen->time32;
714 	struct tm *tp;
715 
716 	tp = localtime(&t);
717 	strftime(timebuf, sizeof(timebuf), "%d-%b-%Y %H:%M:%S", tp);
718 	return(timebuf);
719 }
720 
721 static
722 int
723 undo_hist_entry_compare(struct undo_hist_entry *he1,
724 			struct undo_hist_entry *he2)
725 {
726 	if (he1->tse.tid < he2->tse.tid)
727 		return(-1);
728 	if (he1->tse.tid > he2->tse.tid)
729 		return(1);
730 	return(0);
731 }
732 
733 static void
734 usage(void)
735 {
736 	fprintf(stderr, "undo [-adDiuv] [-o outfile] "
737 			"[-t transaction-id] [-t transaction-id] path...\n"
738 			"    -a       Iterate all historical segments\n"
739 			"    -d       Forward diff\n"
740 			"    -D       Reverse diff\n"
741 			"    -i       Dump history transaction ids\n"
742 			"    -u       Generate .undo files\n"
743 			"    -v       Verbose\n"
744 			"    -o file  Output to the specified file\n"
745 			"    -t TID   Retrieve as of transaction-id, TID\n"
746 			"             (a second `-t TID' to diff two)\n"
747 			"    transaction ids must be prefixed with 0x, and\n"
748 			"    otherwise may specify an index starting at 0\n"
749 			"    and iterating backwards through the history.\n"
750 	);
751 	exit(1);
752 }
753 
754