xref: /dragonfly/usr.bin/undo/undo.c (revision d257a695)
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 <stdio.h>
45 #include <stdlib.h>
46 #include <stdarg.h>
47 #include <string.h>
48 #include <unistd.h>
49 #include <fcntl.h>
50 #include <errno.h>
51 #include <vfs/hammer/hammer_disk.h>
52 #include <vfs/hammer/hammer_ioctl.h>
53 
54 /*
55  * Sorted list of transaction ids
56  */
57 struct undo_hist_entry;
58 RB_HEAD(undo_hist_entry_rb_tree, undo_hist_entry);
59 RB_PROTOTYPE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
60 	undo_hist_entry_compare, hammer_tid_t);
61 
62 struct undo_hist_entry {
63 	RB_ENTRY(undo_hist_entry) rbnode;
64 	struct hammer_ioc_hist_entry tse;
65 	ino_t inum;
66 };
67 
68 enum undo_type { TYPE_FILE, TYPE_DIFF, TYPE_RDIFF, TYPE_HISTORY };
69 enum undo_cmd { CMD_DUMP, CMD_ITERATEALL };
70 
71 #define UNDO_FLAG_MULT		0x0001
72 #define UNDO_FLAG_INOCHG	0x0002
73 #define UNDO_FLAG_SETTID1	0x0004
74 #define UNDO_FLAG_SETTID2	0x0008
75 
76 static int undo_hist_entry_compare(struct undo_hist_entry *he1,
77 		    struct undo_hist_entry *he2);
78 static void doiterate(const char *filename, const char *outFileName,
79 		   const char *outFilePostfix, int flags,
80 		   struct hammer_ioc_hist_entry ts1,
81 		   struct hammer_ioc_hist_entry ts2,
82 		   enum undo_cmd cmd, enum undo_type type);
83 static void dogenerate(const char *filename, const char *outFileName,
84 		   const char *outFilePostfix,
85 		   int flags, int idx, enum undo_type type,
86 		   struct hammer_ioc_hist_entry ts1,
87 		   struct hammer_ioc_hist_entry ts2);
88 static void collect_history(int fd, int *error,
89 		   struct undo_hist_entry_rb_tree *tse_tree);
90 static void collect_dir_history(const char *filename, int *error,
91 		   struct undo_hist_entry_rb_tree *dir_tree);
92 static void clean_tree(struct undo_hist_entry_rb_tree *tree);
93 static hammer_tid_t parse_delta_time(const char *timeStr, int *flags,
94 		   int ind_flag);
95 static void runcmd(int fd, const char *cmd, ...);
96 static char *timestamp(hammer_ioc_hist_entry_t hen);
97 static void usage(void);
98 
99 static int VerboseOpt;
100 
101 RB_GENERATE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
102 	undo_hist_entry_compare, hammer_tid_t, tse.tid);
103 
104 
105 int
106 main(int ac, char **av)
107 {
108 	const char *outFileName = NULL;
109 	const char *outFilePostfix = NULL;
110 	enum undo_cmd cmd;
111 	enum undo_type type;
112 	struct hammer_ioc_hist_entry ts1;
113 	struct hammer_ioc_hist_entry ts2;
114 	int c;
115 	int count_t;
116 	int flags;
117 
118 	bzero(&ts1, sizeof(ts1));
119 	bzero(&ts2, sizeof(ts2));
120 
121 	cmd = CMD_DUMP;
122 	type = TYPE_FILE;
123 	count_t = 0;
124 	flags = 0;
125 
126 	while ((c = getopt(ac, av, "adDiuvo:t:")) != -1) {
127 		switch(c) {
128 		case 'd':
129 			type = TYPE_DIFF;
130 			break;
131 		case 'D':
132 			type = TYPE_RDIFF;
133 			break;
134 		case 'i':
135 			if (type != TYPE_FILE)
136 				usage();
137 			type = TYPE_HISTORY;
138 			cmd = CMD_ITERATEALL;
139 			break;
140 		case 'a':
141 			cmd = CMD_ITERATEALL;
142 			break;
143 		case 'u':
144 			outFilePostfix = ".undo";
145 			break;
146 		case 'v':
147 			++VerboseOpt;
148 			break;
149 		case 'o':
150 			outFileName = optarg;
151 			break;
152 		case 't':
153 			/*
154 			 * Parse one or two -t options.  If two are specified
155 			 * -d is implied (but may be overridden)
156 			 */
157 			++count_t;
158 			if (count_t == 1) {
159 				ts1.tid = parse_delta_time(optarg, &flags,
160 				                           UNDO_FLAG_SETTID1);
161 			} else if (count_t == 2) {
162 				ts2.tid = parse_delta_time(optarg, &flags,
163 				                           UNDO_FLAG_SETTID2);
164 				if (type == TYPE_FILE)
165 					type = TYPE_DIFF;
166 			} else {
167 				usage();
168 			}
169 			break;
170 		default:
171 			usage();
172 			/* NOT REACHED */
173 			break;
174 		}
175 	}
176 
177 	/*
178 	 * Option validation
179 	 */
180 	if (outFileName && outFilePostfix) {
181 		fprintf(stderr, "The -o option may not be combined with -u\n");
182 		usage();
183 	}
184 
185 	ac -= optind;
186 	av += optind;
187 	if (ac > 1)
188 		flags |= UNDO_FLAG_MULT;
189 
190 	if (ac == 0)
191 		usage();
192 
193 	/*
194 	 * Validate the output template, if specified.
195 	 */
196 	if (outFileName && (flags & UNDO_FLAG_MULT)) {
197 		const char *ptr = outFileName;
198 		int didStr = 0;
199 
200 		while ((ptr = strchr(ptr, '%')) != NULL) {
201 			if (ptr[1] == 's') {
202 				if (didStr) {
203 					fprintf(stderr, "Malformed output "
204 							"template\n");
205 					usage();
206 				}
207 				didStr = 1;
208 				++ptr;
209 			} else if (ptr[1] != '%') {
210 				fprintf(stderr, "Malformed output template\n");
211 				usage();
212 			} else {
213 				ptr += 2;
214 			}
215 		}
216 	}
217 
218 	while (ac) {
219 		doiterate(*av, outFileName, outFilePostfix,
220 			  flags, ts1, ts2, cmd, type);
221 		++av;
222 		--ac;
223 	}
224 	return(0);
225 }
226 
227 /*
228  * Iterate through a file's history.  If cmd == CMD_DUMP we take the
229  * next-to-last transaction id, unless another given.  Otherwise if
230  * cmd == CMD_ITERATEALL we scan all transaction ids.
231  *
232  * Also iterate through the directory's history to locate other inodes that
233  * used the particular file name.
234  */
235 static
236 void
237 doiterate(const char *filename, const char *outFileName,
238 	  const char *outFilePostfix, int flags,
239 	  struct hammer_ioc_hist_entry ts1,
240 	  struct hammer_ioc_hist_entry ts2,
241 	  enum undo_cmd cmd, enum undo_type type)
242 {
243 	struct undo_hist_entry_rb_tree dir_tree;
244 	struct undo_hist_entry_rb_tree tse_tree;
245 	struct undo_hist_entry *tse1;
246 	struct undo_hist_entry *tse2;
247 	struct hammer_ioc_hist_entry tid_max;
248 	char *path = NULL;
249 	int i;
250 	int fd;
251 	int error;
252 
253 	RB_INIT(&dir_tree);
254 	RB_INIT(&tse_tree);
255 
256 	tid_max.tid = HAMMER_MAX_TID;
257 	tid_max.time32 = 0;
258 
259 	/*
260 	 * Use the directory history to locate all possible versions of
261 	 * the file.
262 	 */
263 	collect_dir_history(filename, &error, &dir_tree);
264 	RB_FOREACH(tse1, undo_hist_entry_rb_tree, &dir_tree) {
265 		asprintf(&path, "%s@@0x%016jx", filename, (uintmax_t)tse1->tse.tid);
266 		if ((fd = open(path, O_RDONLY)) > 0) {
267 			collect_history(fd, &error, &tse_tree);
268 			close(fd);
269 		}
270 	}
271 	if (cmd == CMD_DUMP) {
272 		if ((ts1.tid == 0 ||
273 		     flags & (UNDO_FLAG_SETTID1|UNDO_FLAG_SETTID2)) &&
274 		    RB_EMPTY(&tse_tree)) {
275 			if ((fd = open(filename, O_RDONLY)) > 0) {
276 				collect_history(fd, &error, &tse_tree);
277 				close(fd);
278 			}
279 		}
280 		/*
281 		 * Find entry if tid set to placeholder index
282 		 */
283 		if (flags & UNDO_FLAG_SETTID1){
284 			tse1 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
285 			while (tse1 && ts1.tid--) {
286 				tse1 = RB_PREV(undo_hist_entry_rb_tree,
287 					       &tse_tree, tse1);
288 			}
289 			if (tse1)
290 				ts1 = tse1->tse;
291 			else
292 				ts1.tid = 0;
293 		}
294 		if (flags & UNDO_FLAG_SETTID2){
295 			tse2 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
296 			while (tse2 && ts2.tid--) {
297 				tse2 = RB_PREV(undo_hist_entry_rb_tree,
298 					       &tse_tree, tse2);
299 			}
300 			if (tse2)
301 				ts2 = tse2->tse;
302 			else
303 				ts2.tid = 0;
304 		}
305 
306 		/*
307 		 * Single entry, most recent prior to current
308 		 */
309 		if (ts1.tid == 0) {
310 			tse2 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
311 			if (tse2) {
312 				ts2 = tse2->tse;
313 				tse1 = RB_PREV(undo_hist_entry_rb_tree,
314 					       &tse_tree, tse2);
315 				if (tse1)
316 					ts1 = tse1->tse;
317 			}
318 		}
319 		if (ts1.tid == 0) {
320 			printf("%s: No UNDO history found\n", filename);
321 		} else {
322 			dogenerate(filename,
323 				   outFileName, outFilePostfix,
324 				   0, 0, type,
325 				   ts1, ts2);
326 		}
327 	} else if (RB_ROOT(&tse_tree)) {
328 		/*
329 		 * Iterate entire history
330 		 */
331 		printf("%s: ITERATE ENTIRE HISTORY\n", filename);
332 
333 		tse1 = NULL;
334 		i = 0;
335 		RB_FOREACH(tse2, undo_hist_entry_rb_tree, &tse_tree) {
336 			if (tse1) {
337 				dogenerate(filename,
338 					   outFileName, outFilePostfix,
339 					   flags, i, type,
340 					   tse1->tse, tse2->tse);
341 			}
342 			if (tse1 && tse2->inum != tse1->inum)
343 				flags |= UNDO_FLAG_INOCHG;
344 			else
345 				flags &= ~UNDO_FLAG_INOCHG;
346 			tse1 = tse2;
347 			++i;
348 		}
349 		/*
350 		 * There is no delta to print for the last pair,
351 		 * because they are identical.
352 		 */
353 		if (type != TYPE_DIFF && type != TYPE_RDIFF) {
354 			dogenerate(filename,
355 				   outFileName, outFilePostfix,
356 				   flags, i, type,
357 				   tse1->tse, tid_max);
358 		}
359 	} else {
360 		printf("%s: ITERATE ENTIRE HISTORY: %s\n",
361 		       filename, strerror(error));
362 	}
363 	if (path)
364 		free(path);
365 	clean_tree(&dir_tree);
366 	clean_tree(&tse_tree);
367 }
368 
369 /*
370  * Generate output for a file as-of ts1 (ts1 may be 0!), if diffing then
371  * through ts2.
372  */
373 static
374 void
375 dogenerate(const char *filename, const char *outFileName,
376 	   const char *outFilePostfix,
377 	   int flags, int idx, enum undo_type type,
378 	   struct hammer_ioc_hist_entry ts1,
379 	   struct hammer_ioc_hist_entry ts2)
380 {
381 	struct stat st;
382 	const char *elm;
383 	char *ipath1 = NULL;
384 	char *ipath2 = NULL;
385 	FILE *fi;
386 	FILE *fp;
387 	char *buf;
388 	char *path;
389 	time_t t;
390 	struct tm *tp;
391 	char datestr[64];
392 	int n;
393 
394 	buf = malloc(8192);
395 
396 	/*
397 	 * Open the input file.  If ts1 is 0 try to locate the most recent
398 	 * version of the file prior to the current version.
399 	 */
400 	if (ts1.tid == 0)
401 		asprintf(&ipath1, "%s", filename);
402 	else
403 		asprintf(&ipath1, "%s@@0x%016jx", filename, (uintmax_t)ts1.tid);
404 
405 	if (ts2.tid == 0)
406 		asprintf(&ipath2, "%s", filename);
407 	else
408 		asprintf(&ipath2, "%s@@0x%016jx", filename, (uintmax_t)ts2.tid);
409 
410 	if (lstat(ipath1, &st) < 0 && lstat(ipath2, &st) < 0) {
411 		if (idx == 0 || VerboseOpt) {
412 			fprintf(stderr, "Unable to access either %s or %s\n",
413 				ipath1, ipath2);
414 		}
415 		free(ipath1);
416 		free(ipath2);
417 		goto done;
418 	}
419 
420 	/*
421 	 * elm is the last component of the input file name
422 	 */
423 	if ((elm = strrchr(filename, '/')) != NULL)
424 		++elm;
425 	else
426 		elm = filename;
427 
428 	/*
429 	 * Where do we stuff our output?
430 	 */
431 	if (outFileName) {
432 		if (flags & UNDO_FLAG_MULT) {
433 			asprintf(&path, outFileName, elm);
434 			fp = fopen(path, "w");
435 			if (fp == NULL) {
436 				perror(path);
437 				exit(1);
438 			}
439 			free(path);
440 		} else {
441 			fp = fopen(outFileName, "w");
442 			if (fp == NULL) {
443 				perror(outFileName);
444 				exit(1);
445 			}
446 		}
447 	} else if (outFilePostfix) {
448 		if (idx >= 0) {
449 			asprintf(&path, "%s%s.%04d", filename,
450 				 outFilePostfix, idx);
451 		} else {
452 			asprintf(&path, "%s%s", filename, outFilePostfix);
453 		}
454 		fp = fopen(path, "w");
455 		if (fp == NULL) {
456 			perror(path);
457 			exit(1);
458 		}
459 		free(path);
460 	} else {
461 		if ((flags & UNDO_FLAG_MULT) && type == TYPE_FILE) {
462 			if (idx >= 0) {
463 				printf("\n>>> %s %04d 0x%016jx %s\n\n",
464 				       filename, idx, (uintmax_t)ts1.tid,
465 				       timestamp(&ts1));
466 			} else {
467 				printf("\n>>> %s ---- 0x%016jx %s\n\n",
468 				       filename, (uintmax_t)ts1.tid,
469 				       timestamp(&ts1));
470 			}
471 		} else if (idx >= 0 && type == TYPE_FILE) {
472 			printf("\n>>> %s %04d 0x%016jx %s\n\n",
473 			       filename, idx, (uintmax_t)ts1.tid,
474 			       timestamp(&ts1));
475 		}
476 		fp = stdout;
477 	}
478 
479 	switch(type) {
480 	case TYPE_FILE:
481 		if ((fi = fopen(ipath1, "r")) != NULL) {
482 			while ((n = fread(buf, 1, 8192, fi)) > 0)
483 				fwrite(buf, 1, n, fp);
484 			fclose(fi);
485 		}
486 		break;
487 	case TYPE_DIFF:
488 		printf("diff -N -r -u %s %s (to %s)\n",
489 		       ipath1, ipath2, timestamp(&ts2));
490 		fflush(stdout);
491 		runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u", ipath1, ipath2, NULL);
492 		break;
493 	case TYPE_RDIFF:
494 		printf("diff -N -r -u %s %s\n", ipath2, ipath1);
495 		fflush(stdout);
496 		runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u", ipath2, ipath1, NULL);
497 		break;
498 	case TYPE_HISTORY:
499 		t = (time_t)ts1.time32;
500 		tp = localtime(&t);
501 		strftime(datestr, sizeof(datestr), "%d-%b-%Y %H:%M:%S", tp);
502 		printf("\t0x%016jx %s", (uintmax_t)ts1.tid, datestr);
503 		if (flags & UNDO_FLAG_INOCHG)
504 			printf(" inode-change");
505 		if (lstat(ipath1, &st) < 0)
506 			printf(" file-deleted");
507 		printf("\n");
508 		break;
509 	}
510 
511 	if (fp != stdout)
512 		fclose(fp);
513 done:
514 	free(buf);
515 }
516 
517 static
518 void
519 clean_tree(struct undo_hist_entry_rb_tree *tree)
520 {
521 	struct undo_hist_entry *tse;
522 
523 	while ((tse = RB_ROOT(tree)) != NULL) {
524 		RB_REMOVE(undo_hist_entry_rb_tree, tree, tse);
525 		free(tse);
526 	}
527 }
528 
529 static
530 void
531 collect_history(int fd, int *errorp, struct undo_hist_entry_rb_tree *tse_tree)
532 {
533 	struct hammer_ioc_history hist;
534 	struct undo_hist_entry *tse;
535 	struct stat st;
536 	int istmp;
537 	int i;
538 
539 	/*
540 	 * Setup
541 	 */
542 	bzero(&hist, sizeof(hist));
543 	hist.beg_tid = HAMMER_MIN_TID;
544 	hist.end_tid = HAMMER_MAX_TID;
545 	hist.head.flags |= HAMMER_IOC_HISTORY_ATKEY;
546 	hist.key = 0;
547 	hist.nxt_key = HAMMER_MAX_KEY;
548 
549 	*errorp = 0;
550 
551 	if (tse_tree == NULL) {
552 		tse_tree = malloc(sizeof(*tse_tree));
553 		RB_INIT(tse_tree);
554 		istmp = 1;
555 	} else {
556 		istmp = 0;
557 	}
558 
559 	/*
560 	 * Save the inode so inode changes can be reported.
561 	 */
562 	st.st_ino = 0;
563 	fstat(fd, &st);
564 
565 	/*
566 	 * Collect a unique set of transaction ids
567 	 */
568 	if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
569 		*errorp = errno;
570 		goto done;
571 	}
572 	for (;;) {
573 		for (i = 0; i < hist.count; ++i) {
574 			tse = malloc(sizeof(*tse));
575 			tse->tse = hist.hist_ary[i];
576 			tse->inum = st.st_ino;
577 			if (RB_INSERT(undo_hist_entry_rb_tree, tse_tree, tse)) {
578 				free(tse);
579 			}
580 		}
581 		if (hist.head.flags & HAMMER_IOC_HISTORY_EOF)
582 			break;
583 		if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_KEY) {
584 			hist.key = hist.nxt_key;
585 			hist.nxt_key = HAMMER_MAX_KEY;
586 		}
587 		if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_TID)
588 			hist.beg_tid = hist.nxt_tid;
589 		if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
590 			*errorp = errno;
591 			break;
592 		}
593 	}
594 
595 	/*
596 	 * Cleanup
597 	 */
598 done:
599 	if (istmp) {
600 		clean_tree(tse_tree);
601 		free(tse_tree);
602 	}
603 }
604 
605 static
606 void
607 collect_dir_history(const char *filename, int *errorp,
608 		    struct undo_hist_entry_rb_tree *dir_tree)
609 {
610 	char *dirname;
611 	int fd;
612 	int error;
613 
614 	*errorp = 0;
615 	if (strrchr(filename, '/')) {
616 		dirname = strdup(filename);
617 		*strrchr(dirname, '/') = 0;
618 	} else {
619 		dirname = strdup(".");
620 	}
621 	if ((fd = open(dirname, O_RDONLY)) > 0) {
622 		collect_history(fd, &error, dir_tree);
623 		close(fd);
624 	}
625 }
626 
627 static
628 hammer_tid_t
629 parse_delta_time(const char *timeStr, int *flags, int ind_flag)
630 {
631 	hammer_tid_t tid;
632 
633 	tid = strtoull(timeStr, NULL, 0);
634 	if (timeStr[0] == '+')
635 		++timeStr;
636 	if (timeStr[0] >= '0' && timeStr[0] <= '9' && timeStr[1] != 'x')
637 		*flags |= ind_flag;
638 	return(tid);
639 }
640 
641 static void
642 runcmd(int fd, const char *cmd, ...)
643 {
644 	va_list va;
645 	pid_t pid;
646 	char **av;
647 	int ac;
648 	int i;
649 
650 	va_start(va, cmd);
651 	for (ac = 0; va_arg(va, void *) != NULL; ++ac)
652 		;
653 	va_end(va);
654 
655 	av = malloc((ac + 1) * sizeof(char *));
656 	va_start(va, cmd);
657 	for (i = 0; i < ac; ++i)
658 		av[i] = va_arg(va, char *);
659 	va_end(va);
660 	av[i] = NULL;
661 
662 	if ((pid = fork()) < 0) {
663 		perror("fork");
664 		exit(1);
665 	} else if (pid == 0) {
666 		if (fd != 1) {
667 			dup2(fd, 1);
668 			close(fd);
669 		}
670 		execv(cmd, av);
671 		_exit(1);
672 	} else {
673 		while (waitpid(pid, NULL, 0) != pid)
674 			;
675 	}
676 	free(av);
677 }
678 
679 /*
680  * Convert tid to timestamp.
681  */
682 static char *
683 timestamp(hammer_ioc_hist_entry_t hen)
684 {
685 	static char timebuf[64];
686 	time_t t = (time_t)hen->time32;
687 	struct tm *tp;
688 
689 	tp = localtime(&t);
690 	strftime(timebuf, sizeof(timebuf), "%d-%b-%Y %H:%M:%S", tp);
691 	return(timebuf);
692 }
693 
694 static
695 int
696 undo_hist_entry_compare(struct undo_hist_entry *he1,
697 			struct undo_hist_entry *he2)
698 {
699 	if (he1->tse.tid < he2->tse.tid)
700 		return(-1);
701 	if (he1->tse.tid > he2->tse.tid)
702 		return(1);
703 	return(0);
704 }
705 
706 static void
707 usage(void)
708 {
709 	fprintf(stderr, "undo [-adDiuv] [-o outfile] "
710 			"[-t transaction-id] [-t transaction-id] path...\n"
711 			"    -a       Iterate all historical segments\n"
712 			"    -d       Forward diff\n"
713 			"    -D       Reverse diff\n"
714 			"    -i       Dump history transaction ids\n"
715 			"    -u       Generate .undo files\n"
716 			"    -v       Verbose\n"
717 			"    -o file  Output to the specified file\n"
718 			"    -t TID   Retrieve as of transaction-id, TID\n"
719 			"             (a second `-t TID' to diff two)\n"
720 			"    transaction ids must be prefixed with 0x, and\n"
721 			"    otherwise may specify an index starting at 0\n"
722 			"    and iterating backwards through the history.\n"
723 	);
724 	exit(1);
725 }
726 
727