xref: /dflybsd-src/usr.bin/undo/undo.c (revision c1543a890188d397acca9fe7f76bcd982481a763)
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/param.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 <vfs/hammer/hammer_disk.h>
53 #include <vfs/hammer/hammer_ioctl.h>
54 
55 /*
56  * Sorted list of transaction ids
57  */
58 struct undo_hist_entry;
59 RB_HEAD(undo_hist_entry_rb_tree, undo_hist_entry);
60 RB_PROTOTYPE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
61 	undo_hist_entry_compare, hammer_tid_t);
62 
63 struct undo_hist_entry {
64 	RB_ENTRY(undo_hist_entry) rbnode;
65 	struct hammer_ioc_hist_entry tse;
66 	ino_t inum;
67 };
68 
69 enum undo_type { TYPE_FILE, TYPE_DIFF, TYPE_RDIFF, TYPE_HISTORY };
70 enum undo_cmd { CMD_DUMP, CMD_ITERATEALL };
71 
72 #define UNDO_FLAG_MULT		0x0001
73 #define UNDO_FLAG_INOCHG	0x0002
74 #define UNDO_FLAG_SETTID1	0x0004
75 #define UNDO_FLAG_SETTID2	0x0008
76 
77 static int undo_hist_entry_compare(struct undo_hist_entry *he1,
78 		    struct undo_hist_entry *he2);
79 static void doiterate(const char *filename, const char *outFileName,
80 		   const char *outFilePostfix, 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 void dogenerate(const char *filename, const char *outFileName,
85 		   const char *outFilePostfix,
86 		   int flags, int idx, enum undo_type type,
87 		   struct hammer_ioc_hist_entry ts1,
88 		   struct hammer_ioc_hist_entry ts2);
89 static void collect_history(int fd, int *error,
90 		   struct undo_hist_entry_rb_tree *tse_tree);
91 static void collect_dir_history(const char *filename, int *error,
92 		   struct undo_hist_entry_rb_tree *dir_tree);
93 static void clean_tree(struct undo_hist_entry_rb_tree *tree);
94 static hammer_tid_t parse_delta_time(const char *timeStr, int *flags,
95 		   int ind_flag);
96 static void runcmd(int fd, const char *cmd, ...);
97 static char *timestamp(hammer_ioc_hist_entry_t hen);
98 static void usage(void);
99 
100 static int VerboseOpt;
101 
102 RB_GENERATE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
103 	undo_hist_entry_compare, hammer_tid_t, tse.tid);
104 
105 
106 int
107 main(int ac, char **av)
108 {
109 	const char *outFileName = NULL;
110 	const char *outFilePostfix = NULL;
111 	enum undo_cmd cmd;
112 	enum undo_type type;
113 	struct hammer_ioc_hist_entry ts1;
114 	struct hammer_ioc_hist_entry ts2;
115 	int c;
116 	int count_t;
117 	int flags;
118 
119 	bzero(&ts1, sizeof(ts1));
120 	bzero(&ts2, sizeof(ts2));
121 
122 	cmd = CMD_DUMP;
123 	type = TYPE_FILE;
124 	count_t = 0;
125 	flags = 0;
126 
127 	while ((c = getopt(ac, av, "adDiuvo:t:")) != -1) {
128 		switch(c) {
129 		case 'd':
130 			type = TYPE_DIFF;
131 			break;
132 		case 'D':
133 			type = TYPE_RDIFF;
134 			break;
135 		case 'i':
136 			if (type != TYPE_FILE)
137 				usage();
138 			type = TYPE_HISTORY;
139 			cmd = CMD_ITERATEALL;
140 			break;
141 		case 'a':
142 			cmd = CMD_ITERATEALL;
143 			break;
144 		case 'u':
145 			outFilePostfix = ".undo";
146 			break;
147 		case 'v':
148 			++VerboseOpt;
149 			break;
150 		case 'o':
151 			outFileName = optarg;
152 			break;
153 		case 't':
154 			/*
155 			 * Parse one or two -t options.  If two are specified
156 			 * -d is implied (but may be overridden)
157 			 */
158 			++count_t;
159 			if (count_t == 1) {
160 				ts1.tid = parse_delta_time(optarg, &flags,
161 				                           UNDO_FLAG_SETTID1);
162 			} else if (count_t == 2) {
163 				ts2.tid = parse_delta_time(optarg, &flags,
164 				                           UNDO_FLAG_SETTID2);
165 				if (type == TYPE_FILE)
166 					type = TYPE_DIFF;
167 			} else {
168 				usage();
169 			}
170 			break;
171 		default:
172 			usage();
173 			/* NOT REACHED */
174 			break;
175 		}
176 	}
177 
178 	/*
179 	 * Option validation
180 	 */
181 	if (outFileName && outFilePostfix) {
182 		fprintf(stderr, "The -o option may not be combined with -u\n");
183 		usage();
184 	}
185 
186 	ac -= optind;
187 	av += optind;
188 	if (ac > 1)
189 		flags |= UNDO_FLAG_MULT;
190 
191 	if (ac == 0)
192 		usage();
193 
194 	/*
195 	 * Validate the output template, if specified.
196 	 */
197 	if (outFileName && (flags & UNDO_FLAG_MULT)) {
198 		const char *ptr = outFileName;
199 		int didStr = 0;
200 
201 		while ((ptr = strchr(ptr, '%')) != NULL) {
202 			if (ptr[1] == 's') {
203 				if (didStr) {
204 					fprintf(stderr, "Malformed output "
205 							"template\n");
206 					usage();
207 				}
208 				didStr = 1;
209 				++ptr;
210 			} else if (ptr[1] != '%') {
211 				fprintf(stderr, "Malformed output template\n");
212 				usage();
213 			} else {
214 				ptr += 2;
215 			}
216 		}
217 	}
218 
219 	while (ac) {
220 		doiterate(*av, outFileName, outFilePostfix,
221 			  flags, ts1, ts2, cmd, type);
222 		++av;
223 		--ac;
224 	}
225 	return(0);
226 }
227 
228 /*
229  * Iterate through a file's history.  If cmd == CMD_DUMP we take the
230  * next-to-last transaction id, unless another given.  Otherwise if
231  * cmd == CMD_ITERATEALL we scan all transaction ids.
232  *
233  * Also iterate through the directory's history to locate other inodes that
234  * used the particular file name.
235  */
236 static
237 void
238 doiterate(const char *filename, const char *outFileName,
239 	  const char *outFilePostfix, int flags,
240 	  struct hammer_ioc_hist_entry ts1,
241 	  struct hammer_ioc_hist_entry ts2,
242 	  enum undo_cmd cmd, enum undo_type type)
243 {
244 	struct undo_hist_entry_rb_tree dir_tree;
245 	struct undo_hist_entry_rb_tree tse_tree;
246 	struct undo_hist_entry *tse1;
247 	struct undo_hist_entry *tse2;
248 	struct hammer_ioc_hist_entry tid_max;
249 	char *path = NULL;
250 	int i;
251 	int fd;
252 	int error;
253 
254 	RB_INIT(&dir_tree);
255 	RB_INIT(&tse_tree);
256 
257 	tid_max.tid = HAMMER_MAX_TID;
258 	tid_max.time32 = 0;
259 
260 	/*
261 	 * Use the directory history to locate all possible versions of
262 	 * the file.
263 	 */
264 	collect_dir_history(filename, &error, &dir_tree);
265 	RB_FOREACH(tse1, undo_hist_entry_rb_tree, &dir_tree) {
266 		asprintf(&path, "%s@@0x%016jx", filename, (uintmax_t)tse1->tse.tid);
267 		if ((fd = open(path, O_RDONLY)) > 0) {
268 			collect_history(fd, &error, &tse_tree);
269 			close(fd);
270 		}
271 		free(path);
272 	}
273 	if ((fd = open(filename, O_RDONLY)) > 0) {
274 		collect_history(fd, &error, &tse_tree);
275 		close(fd);
276 	}
277 	if (cmd == CMD_DUMP) {
278 		if ((ts1.tid == 0 ||
279 		     flags & (UNDO_FLAG_SETTID1|UNDO_FLAG_SETTID2)) &&
280 		    RB_EMPTY(&tse_tree)) {
281 			if ((fd = open(filename, O_RDONLY)) > 0) {
282 				collect_history(fd, &error, &tse_tree);
283 				close(fd);
284 			}
285 		}
286 		/*
287 		 * Find entry if tid set to placeholder index
288 		 */
289 		if (flags & UNDO_FLAG_SETTID1){
290 			tse1 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
291 			while (tse1 && ts1.tid--) {
292 				tse1 = RB_PREV(undo_hist_entry_rb_tree,
293 					       &tse_tree, tse1);
294 			}
295 			if (tse1)
296 				ts1 = tse1->tse;
297 			else
298 				ts1.tid = 0;
299 		}
300 		if (flags & UNDO_FLAG_SETTID2){
301 			tse2 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
302 			while (tse2 && ts2.tid--) {
303 				tse2 = RB_PREV(undo_hist_entry_rb_tree,
304 					       &tse_tree, tse2);
305 			}
306 			if (tse2)
307 				ts2 = tse2->tse;
308 			else
309 				ts2.tid = 0;
310 		}
311 
312 		/*
313 		 * Single entry, most recent prior to current
314 		 */
315 		if (ts1.tid == 0) {
316 			tse2 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
317 			if (tse2) {
318 				ts2 = tse2->tse;
319 				tse1 = RB_PREV(undo_hist_entry_rb_tree,
320 					       &tse_tree, tse2);
321 				if (tse1)
322 					ts1 = tse1->tse;
323 			}
324 		}
325 		if (ts1.tid == 0) {
326 			printf("%s: No UNDO history found\n", filename);
327 		} else {
328 			dogenerate(filename,
329 				   outFileName, outFilePostfix,
330 				   0, 0, type,
331 				   ts1, ts2);
332 		}
333 	} else if (RB_ROOT(&tse_tree)) {
334 		/*
335 		 * Iterate entire history
336 		 */
337 		printf("%s: ITERATE ENTIRE HISTORY\n", filename);
338 
339 		tse1 = NULL;
340 		i = 0;
341 		RB_FOREACH(tse2, undo_hist_entry_rb_tree, &tse_tree) {
342 			if (tse1) {
343 				dogenerate(filename,
344 					   outFileName, outFilePostfix,
345 					   flags, i, type,
346 					   tse1->tse, tse2->tse);
347 			}
348 			if (tse1 && tse2->inum != tse1->inum)
349 				flags |= UNDO_FLAG_INOCHG;
350 			else
351 				flags &= ~UNDO_FLAG_INOCHG;
352 			tse1 = tse2;
353 			++i;
354 		}
355 		/*
356 		 * There is no delta to print for the last pair,
357 		 * because they are identical.
358 		 */
359 		if (type != TYPE_DIFF && type != TYPE_RDIFF) {
360 			dogenerate(filename,
361 				   outFileName, outFilePostfix,
362 				   flags, i, type,
363 				   tse1->tse, tid_max);
364 		}
365 	} else {
366 		printf("%s: ITERATE ENTIRE HISTORY: %s\n",
367 		       filename, strerror(error));
368 	}
369 	clean_tree(&dir_tree);
370 	clean_tree(&tse_tree);
371 }
372 
373 /*
374  * Generate output for a file as-of ts1 (ts1 may be 0!), if diffing then
375  * through ts2.
376  */
377 static
378 void
379 dogenerate(const char *filename, const char *outFileName,
380 	   const char *outFilePostfix,
381 	   int flags, int idx, enum undo_type type,
382 	   struct hammer_ioc_hist_entry ts1,
383 	   struct hammer_ioc_hist_entry ts2)
384 {
385 	struct stat st;
386 	const char *elm;
387 	char *ipath1 = NULL;
388 	char *ipath2 = NULL;
389 	FILE *fi;
390 	FILE *fp;
391 	char *buf;
392 	char *path;
393 	time_t t;
394 	struct tm *tp;
395 	char datestr[64];
396 	int n;
397 
398 	buf = malloc(8192);
399 
400 	/*
401 	 * Open the input file.  If ts1 is 0 try to locate the most recent
402 	 * version of the file prior to the current version.
403 	 */
404 	if (ts1.tid == 0)
405 		asprintf(&ipath1, "%s", filename);
406 	else
407 		asprintf(&ipath1, "%s@@0x%016jx", filename, (uintmax_t)ts1.tid);
408 
409 	if (ts2.tid == 0)
410 		asprintf(&ipath2, "%s", filename);
411 	else
412 		asprintf(&ipath2, "%s@@0x%016jx", filename, (uintmax_t)ts2.tid);
413 
414 	if (lstat(ipath1, &st) < 0 && lstat(ipath2, &st) < 0) {
415 		if (idx == 0 || VerboseOpt) {
416 			fprintf(stderr, "Unable to access either %s or %s\n",
417 				ipath1, ipath2);
418 		}
419 		free(ipath1);
420 		free(ipath2);
421 		goto done;
422 	}
423 
424 	/*
425 	 * elm is the last component of the input file name
426 	 */
427 	if ((elm = strrchr(filename, '/')) != NULL)
428 		++elm;
429 	else
430 		elm = filename;
431 
432 	/*
433 	 * Where do we stuff our output?
434 	 */
435 	if (outFileName) {
436 		if (flags & UNDO_FLAG_MULT) {
437 			asprintf(&path, outFileName, elm);
438 			fp = fopen(path, "w");
439 			if (fp == NULL) {
440 				perror(path);
441 				exit(1);
442 			}
443 			free(path);
444 		} else {
445 			fp = fopen(outFileName, "w");
446 			if (fp == NULL) {
447 				perror(outFileName);
448 				exit(1);
449 			}
450 		}
451 	} else if (outFilePostfix) {
452 		if (idx >= 0) {
453 			asprintf(&path, "%s%s.%04d", filename,
454 				 outFilePostfix, idx);
455 		} else {
456 			asprintf(&path, "%s%s", filename, outFilePostfix);
457 		}
458 		fp = fopen(path, "w");
459 		if (fp == NULL) {
460 			perror(path);
461 			exit(1);
462 		}
463 		free(path);
464 	} else {
465 		if ((flags & UNDO_FLAG_MULT) && type == TYPE_FILE) {
466 			if (idx >= 0) {
467 				printf("\n>>> %s %04d 0x%016jx %s\n\n",
468 				       filename, idx, (uintmax_t)ts1.tid,
469 				       timestamp(&ts1));
470 			} else {
471 				printf("\n>>> %s ---- 0x%016jx %s\n\n",
472 				       filename, (uintmax_t)ts1.tid,
473 				       timestamp(&ts1));
474 			}
475 		} else if (idx >= 0 && type == TYPE_FILE) {
476 			printf("\n>>> %s %04d 0x%016jx %s\n\n",
477 			       filename, idx, (uintmax_t)ts1.tid,
478 			       timestamp(&ts1));
479 		}
480 		fp = stdout;
481 	}
482 
483 	switch(type) {
484 	case TYPE_FILE:
485 		if ((fi = fopen(ipath1, "r")) != NULL) {
486 			while ((n = fread(buf, 1, 8192, fi)) > 0)
487 				fwrite(buf, 1, n, fp);
488 			fclose(fi);
489 		}
490 		break;
491 	case TYPE_DIFF:
492 		printf("diff -N -r -u %s %s (to %s)\n",
493 		       ipath1, ipath2, timestamp(&ts2));
494 		fflush(stdout);
495 		runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u", ipath1, ipath2, NULL);
496 		break;
497 	case TYPE_RDIFF:
498 		printf("diff -N -r -u %s %s\n", ipath2, ipath1);
499 		fflush(stdout);
500 		runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u", ipath2, ipath1, NULL);
501 		break;
502 	case TYPE_HISTORY:
503 		t = (time_t)ts1.time32;
504 		tp = localtime(&t);
505 		strftime(datestr, sizeof(datestr), "%d-%b-%Y %H:%M:%S", tp);
506 		printf("\t0x%016jx %s", (uintmax_t)ts1.tid, datestr);
507 		if (flags & UNDO_FLAG_INOCHG)
508 			printf(" inode-change");
509 		if (lstat(ipath1, &st) < 0)
510 			printf(" file-deleted");
511 		printf("\n");
512 		break;
513 	}
514 
515 	if (fp != stdout)
516 		fclose(fp);
517 done:
518 	free(buf);
519 }
520 
521 static
522 void
523 clean_tree(struct undo_hist_entry_rb_tree *tree)
524 {
525 	struct undo_hist_entry *tse;
526 
527 	while ((tse = RB_ROOT(tree)) != NULL) {
528 		RB_REMOVE(undo_hist_entry_rb_tree, tree, tse);
529 		free(tse);
530 	}
531 }
532 
533 static
534 void
535 collect_history(int fd, int *errorp, struct undo_hist_entry_rb_tree *tse_tree)
536 {
537 	struct hammer_ioc_history hist;
538 	struct undo_hist_entry *tse;
539 	struct stat st;
540 	int istmp;
541 	int i;
542 
543 	/*
544 	 * Setup
545 	 */
546 	bzero(&hist, sizeof(hist));
547 	hist.beg_tid = HAMMER_MIN_TID;
548 	hist.end_tid = HAMMER_MAX_TID;
549 	hist.head.flags |= HAMMER_IOC_HISTORY_ATKEY;
550 	hist.key = 0;
551 	hist.nxt_key = HAMMER_MAX_KEY;
552 
553 	*errorp = 0;
554 
555 	if (tse_tree == NULL) {
556 		tse_tree = malloc(sizeof(*tse_tree));
557 		RB_INIT(tse_tree);
558 		istmp = 1;
559 	} else {
560 		istmp = 0;
561 	}
562 
563 	/*
564 	 * Save the inode so inode changes can be reported.
565 	 */
566 	st.st_ino = 0;
567 	fstat(fd, &st);
568 
569 	/*
570 	 * Collect a unique set of transaction ids
571 	 */
572 	if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
573 		*errorp = errno;
574 		goto done;
575 	}
576 	for (;;) {
577 		for (i = 0; i < hist.count; ++i) {
578 			tse = malloc(sizeof(*tse));
579 			tse->tse = hist.hist_ary[i];
580 			tse->inum = st.st_ino;
581 			if (RB_INSERT(undo_hist_entry_rb_tree, tse_tree, tse)) {
582 				free(tse);
583 			}
584 		}
585 		if (hist.head.flags & HAMMER_IOC_HISTORY_EOF)
586 			break;
587 		if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_KEY) {
588 			hist.key = hist.nxt_key;
589 			hist.nxt_key = HAMMER_MAX_KEY;
590 		}
591 		if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_TID)
592 			hist.beg_tid = hist.nxt_tid;
593 		if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
594 			*errorp = errno;
595 			break;
596 		}
597 	}
598 
599 	/*
600 	 * Cleanup
601 	 */
602 done:
603 	if (istmp) {
604 		clean_tree(tse_tree);
605 		free(tse_tree);
606 	}
607 }
608 
609 static
610 void
611 collect_dir_history(const char *filename, int *errorp,
612 		    struct undo_hist_entry_rb_tree *dir_tree)
613 {
614 	char *dirname;
615 	int fd;
616 	int error;
617 
618 	*errorp = 0;
619 	if (strrchr(filename, '/')) {
620 		dirname = strdup(filename);
621 		*strrchr(dirname, '/') = 0;
622 	} else {
623 		dirname = strdup(".");
624 	}
625 	if ((fd = open(dirname, O_RDONLY)) > 0) {
626 		collect_history(fd, &error, dir_tree);
627 		close(fd);
628 	}
629 }
630 
631 static
632 hammer_tid_t
633 parse_delta_time(const char *timeStr, int *flags, int ind_flag)
634 {
635 	hammer_tid_t tid;
636 
637 	tid = strtoull(timeStr, NULL, 0);
638 	if (timeStr[0] == '+')
639 		++timeStr;
640 	if (timeStr[0] >= '0' && timeStr[0] <= '9' && timeStr[1] != 'x')
641 		*flags |= ind_flag;
642 	return(tid);
643 }
644 
645 static void
646 runcmd(int fd, const char *cmd, ...)
647 {
648 	va_list va;
649 	pid_t pid;
650 	char **av;
651 	int ac;
652 	int i;
653 
654 	va_start(va, cmd);
655 	for (ac = 0; va_arg(va, void *) != NULL; ++ac)
656 		;
657 	va_end(va);
658 
659 	av = malloc((ac + 1) * sizeof(char *));
660 	va_start(va, cmd);
661 	for (i = 0; i < ac; ++i)
662 		av[i] = va_arg(va, char *);
663 	va_end(va);
664 	av[i] = NULL;
665 
666 	if ((pid = fork()) < 0) {
667 		perror("fork");
668 		exit(1);
669 	} else if (pid == 0) {
670 		if (fd != 1) {
671 			dup2(fd, 1);
672 			close(fd);
673 		}
674 		execv(cmd, av);
675 		_exit(1);
676 	} else {
677 		while (waitpid(pid, NULL, 0) != pid)
678 			;
679 	}
680 	free(av);
681 }
682 
683 /*
684  * Convert tid to timestamp.
685  */
686 static char *
687 timestamp(hammer_ioc_hist_entry_t hen)
688 {
689 	static char timebuf[64];
690 	time_t t = (time_t)hen->time32;
691 	struct tm *tp;
692 
693 	tp = localtime(&t);
694 	strftime(timebuf, sizeof(timebuf), "%d-%b-%Y %H:%M:%S", tp);
695 	return(timebuf);
696 }
697 
698 static
699 int
700 undo_hist_entry_compare(struct undo_hist_entry *he1,
701 			struct undo_hist_entry *he2)
702 {
703 	if (he1->tse.tid < he2->tse.tid)
704 		return(-1);
705 	if (he1->tse.tid > he2->tse.tid)
706 		return(1);
707 	return(0);
708 }
709 
710 static void
711 usage(void)
712 {
713 	fprintf(stderr, "undo [-adDiuv] [-o outfile] "
714 			"[-t transaction-id] [-t transaction-id] path...\n"
715 			"    -a       Iterate all historical segments\n"
716 			"    -d       Forward diff\n"
717 			"    -D       Reverse diff\n"
718 			"    -i       Dump history transaction ids\n"
719 			"    -u       Generate .undo files\n"
720 			"    -v       Verbose\n"
721 			"    -o file  Output to the specified file\n"
722 			"    -t TID   Retrieve as of transaction-id, TID\n"
723 			"             (a second `-t TID' to diff two)\n"
724 			"    transaction ids must be prefixed with 0x, and\n"
725 			"    otherwise may specify an index starting at 0\n"
726 			"    and iterating backwards through the history.\n"
727 	);
728 	exit(1);
729 }
730 
731