xref: /dflybsd-src/usr.bin/undo/undo.c (revision 201c8c4447cad562e0a54ebbe0e7ee4e8a0be647)
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 		free(path);
271 	}
272 	if ((fd = open(filename, O_RDONLY)) > 0) {
273 		collect_history(fd, &error, &tse_tree);
274 		close(fd);
275 	}
276 	if (cmd == CMD_DUMP) {
277 		if ((ts1.tid == 0 ||
278 		     flags & (UNDO_FLAG_SETTID1|UNDO_FLAG_SETTID2)) &&
279 		    RB_EMPTY(&tse_tree)) {
280 			if ((fd = open(filename, O_RDONLY)) > 0) {
281 				collect_history(fd, &error, &tse_tree);
282 				close(fd);
283 			}
284 		}
285 		/*
286 		 * Find entry if tid set to placeholder index
287 		 */
288 		if (flags & UNDO_FLAG_SETTID1){
289 			tse1 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
290 			while (tse1 && ts1.tid--) {
291 				tse1 = RB_PREV(undo_hist_entry_rb_tree,
292 					       &tse_tree, tse1);
293 			}
294 			if (tse1)
295 				ts1 = tse1->tse;
296 			else
297 				ts1.tid = 0;
298 		}
299 		if (flags & UNDO_FLAG_SETTID2){
300 			tse2 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
301 			while (tse2 && ts2.tid--) {
302 				tse2 = RB_PREV(undo_hist_entry_rb_tree,
303 					       &tse_tree, tse2);
304 			}
305 			if (tse2)
306 				ts2 = tse2->tse;
307 			else
308 				ts2.tid = 0;
309 		}
310 
311 		/*
312 		 * Single entry, most recent prior to current
313 		 */
314 		if (ts1.tid == 0) {
315 			tse2 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
316 			if (tse2) {
317 				ts2 = tse2->tse;
318 				tse1 = RB_PREV(undo_hist_entry_rb_tree,
319 					       &tse_tree, tse2);
320 				if (tse1)
321 					ts1 = tse1->tse;
322 			}
323 		}
324 		if (ts1.tid == 0) {
325 			printf("%s: No UNDO history found\n", filename);
326 		} else {
327 			dogenerate(filename,
328 				   outFileName, outFilePostfix,
329 				   0, 0, type,
330 				   ts1, ts2);
331 		}
332 	} else if (RB_ROOT(&tse_tree)) {
333 		/*
334 		 * Iterate entire history
335 		 */
336 		printf("%s: ITERATE ENTIRE HISTORY\n", filename);
337 
338 		tse1 = NULL;
339 		i = 0;
340 		RB_FOREACH(tse2, undo_hist_entry_rb_tree, &tse_tree) {
341 			if (tse1) {
342 				dogenerate(filename,
343 					   outFileName, outFilePostfix,
344 					   flags, i, type,
345 					   tse1->tse, tse2->tse);
346 			}
347 			if (tse1 && tse2->inum != tse1->inum)
348 				flags |= UNDO_FLAG_INOCHG;
349 			else
350 				flags &= ~UNDO_FLAG_INOCHG;
351 			tse1 = tse2;
352 			++i;
353 		}
354 		/*
355 		 * There is no delta to print for the last pair,
356 		 * because they are identical.
357 		 */
358 		if (type != TYPE_DIFF && type != TYPE_RDIFF) {
359 			dogenerate(filename,
360 				   outFileName, outFilePostfix,
361 				   flags, i, type,
362 				   tse1->tse, tid_max);
363 		}
364 	} else {
365 		printf("%s: ITERATE ENTIRE HISTORY: %s\n",
366 		       filename, strerror(error));
367 	}
368 	clean_tree(&dir_tree);
369 	clean_tree(&tse_tree);
370 }
371 
372 /*
373  * Generate output for a file as-of ts1 (ts1 may be 0!), if diffing then
374  * through ts2.
375  */
376 static
377 void
378 dogenerate(const char *filename, const char *outFileName,
379 	   const char *outFilePostfix,
380 	   int flags, int idx, enum undo_type type,
381 	   struct hammer_ioc_hist_entry ts1,
382 	   struct hammer_ioc_hist_entry ts2)
383 {
384 	struct stat st;
385 	const char *elm;
386 	char *ipath1 = NULL;
387 	char *ipath2 = NULL;
388 	FILE *fi;
389 	FILE *fp;
390 	char *buf;
391 	char *path;
392 	time_t t;
393 	struct tm *tp;
394 	char datestr[64];
395 	int n;
396 
397 	buf = malloc(8192);
398 
399 	/*
400 	 * Open the input file.  If ts1 is 0 try to locate the most recent
401 	 * version of the file prior to the current version.
402 	 */
403 	if (ts1.tid == 0)
404 		asprintf(&ipath1, "%s", filename);
405 	else
406 		asprintf(&ipath1, "%s@@0x%016jx", filename, (uintmax_t)ts1.tid);
407 
408 	if (ts2.tid == 0)
409 		asprintf(&ipath2, "%s", filename);
410 	else
411 		asprintf(&ipath2, "%s@@0x%016jx", filename, (uintmax_t)ts2.tid);
412 
413 	if (lstat(ipath1, &st) < 0 && lstat(ipath2, &st) < 0) {
414 		if (idx == 0 || VerboseOpt) {
415 			fprintf(stderr, "Unable to access either %s or %s\n",
416 				ipath1, ipath2);
417 		}
418 		free(ipath1);
419 		free(ipath2);
420 		goto done;
421 	}
422 
423 	/*
424 	 * elm is the last component of the input file name
425 	 */
426 	if ((elm = strrchr(filename, '/')) != NULL)
427 		++elm;
428 	else
429 		elm = filename;
430 
431 	/*
432 	 * Where do we stuff our output?
433 	 */
434 	if (outFileName) {
435 		if (flags & UNDO_FLAG_MULT) {
436 			asprintf(&path, outFileName, elm);
437 			fp = fopen(path, "w");
438 			if (fp == NULL) {
439 				perror(path);
440 				exit(1);
441 			}
442 			free(path);
443 		} else {
444 			fp = fopen(outFileName, "w");
445 			if (fp == NULL) {
446 				perror(outFileName);
447 				exit(1);
448 			}
449 		}
450 	} else if (outFilePostfix) {
451 		if (idx >= 0) {
452 			asprintf(&path, "%s%s.%04d", filename,
453 				 outFilePostfix, idx);
454 		} else {
455 			asprintf(&path, "%s%s", filename, outFilePostfix);
456 		}
457 		fp = fopen(path, "w");
458 		if (fp == NULL) {
459 			perror(path);
460 			exit(1);
461 		}
462 		free(path);
463 	} else {
464 		if ((flags & UNDO_FLAG_MULT) && type == TYPE_FILE) {
465 			if (idx >= 0) {
466 				printf("\n>>> %s %04d 0x%016jx %s\n\n",
467 				       filename, idx, (uintmax_t)ts1.tid,
468 				       timestamp(&ts1));
469 			} else {
470 				printf("\n>>> %s ---- 0x%016jx %s\n\n",
471 				       filename, (uintmax_t)ts1.tid,
472 				       timestamp(&ts1));
473 			}
474 		} else if (idx >= 0 && type == TYPE_FILE) {
475 			printf("\n>>> %s %04d 0x%016jx %s\n\n",
476 			       filename, idx, (uintmax_t)ts1.tid,
477 			       timestamp(&ts1));
478 		}
479 		fp = stdout;
480 	}
481 
482 	switch(type) {
483 	case TYPE_FILE:
484 		if ((fi = fopen(ipath1, "r")) != NULL) {
485 			while ((n = fread(buf, 1, 8192, fi)) > 0)
486 				fwrite(buf, 1, n, fp);
487 			fclose(fi);
488 		}
489 		break;
490 	case TYPE_DIFF:
491 		printf("diff -N -r -u %s %s (to %s)\n",
492 		       ipath1, ipath2, timestamp(&ts2));
493 		fflush(stdout);
494 		runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u", ipath1, ipath2, NULL);
495 		break;
496 	case TYPE_RDIFF:
497 		printf("diff -N -r -u %s %s\n", ipath2, ipath1);
498 		fflush(stdout);
499 		runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u", ipath2, ipath1, NULL);
500 		break;
501 	case TYPE_HISTORY:
502 		t = (time_t)ts1.time32;
503 		tp = localtime(&t);
504 		strftime(datestr, sizeof(datestr), "%d-%b-%Y %H:%M:%S", tp);
505 		printf("\t0x%016jx %s", (uintmax_t)ts1.tid, datestr);
506 		if (flags & UNDO_FLAG_INOCHG)
507 			printf(" inode-change");
508 		if (lstat(ipath1, &st) < 0)
509 			printf(" file-deleted");
510 		printf("\n");
511 		break;
512 	}
513 
514 	if (fp != stdout)
515 		fclose(fp);
516 done:
517 	free(buf);
518 }
519 
520 static
521 void
522 clean_tree(struct undo_hist_entry_rb_tree *tree)
523 {
524 	struct undo_hist_entry *tse;
525 
526 	while ((tse = RB_ROOT(tree)) != NULL) {
527 		RB_REMOVE(undo_hist_entry_rb_tree, tree, tse);
528 		free(tse);
529 	}
530 }
531 
532 static
533 void
534 collect_history(int fd, int *errorp, struct undo_hist_entry_rb_tree *tse_tree)
535 {
536 	struct hammer_ioc_history hist;
537 	struct undo_hist_entry *tse;
538 	struct stat st;
539 	int istmp;
540 	int i;
541 
542 	/*
543 	 * Setup
544 	 */
545 	bzero(&hist, sizeof(hist));
546 	hist.beg_tid = HAMMER_MIN_TID;
547 	hist.end_tid = HAMMER_MAX_TID;
548 	hist.head.flags |= HAMMER_IOC_HISTORY_ATKEY;
549 	hist.key = 0;
550 	hist.nxt_key = HAMMER_MAX_KEY;
551 
552 	*errorp = 0;
553 
554 	if (tse_tree == NULL) {
555 		tse_tree = malloc(sizeof(*tse_tree));
556 		RB_INIT(tse_tree);
557 		istmp = 1;
558 	} else {
559 		istmp = 0;
560 	}
561 
562 	/*
563 	 * Save the inode so inode changes can be reported.
564 	 */
565 	st.st_ino = 0;
566 	fstat(fd, &st);
567 
568 	/*
569 	 * Collect a unique set of transaction ids
570 	 */
571 	if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
572 		*errorp = errno;
573 		goto done;
574 	}
575 	for (;;) {
576 		for (i = 0; i < hist.count; ++i) {
577 			tse = malloc(sizeof(*tse));
578 			tse->tse = hist.hist_ary[i];
579 			tse->inum = st.st_ino;
580 			if (RB_INSERT(undo_hist_entry_rb_tree, tse_tree, tse)) {
581 				free(tse);
582 			}
583 		}
584 		if (hist.head.flags & HAMMER_IOC_HISTORY_EOF)
585 			break;
586 		if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_KEY) {
587 			hist.key = hist.nxt_key;
588 			hist.nxt_key = HAMMER_MAX_KEY;
589 		}
590 		if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_TID)
591 			hist.beg_tid = hist.nxt_tid;
592 		if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
593 			*errorp = errno;
594 			break;
595 		}
596 	}
597 
598 	/*
599 	 * Cleanup
600 	 */
601 done:
602 	if (istmp) {
603 		clean_tree(tse_tree);
604 		free(tse_tree);
605 	}
606 }
607 
608 static
609 void
610 collect_dir_history(const char *filename, int *errorp,
611 		    struct undo_hist_entry_rb_tree *dir_tree)
612 {
613 	char *dirname;
614 	int fd;
615 	int error;
616 
617 	*errorp = 0;
618 	if (strrchr(filename, '/')) {
619 		dirname = strdup(filename);
620 		*strrchr(dirname, '/') = 0;
621 	} else {
622 		dirname = strdup(".");
623 	}
624 	if ((fd = open(dirname, O_RDONLY)) > 0) {
625 		collect_history(fd, &error, dir_tree);
626 		close(fd);
627 	}
628 }
629 
630 static
631 hammer_tid_t
632 parse_delta_time(const char *timeStr, int *flags, int ind_flag)
633 {
634 	hammer_tid_t tid;
635 
636 	tid = strtoull(timeStr, NULL, 0);
637 	if (timeStr[0] == '+')
638 		++timeStr;
639 	if (timeStr[0] >= '0' && timeStr[0] <= '9' && timeStr[1] != 'x')
640 		*flags |= ind_flag;
641 	return(tid);
642 }
643 
644 static void
645 runcmd(int fd, const char *cmd, ...)
646 {
647 	va_list va;
648 	pid_t pid;
649 	char **av;
650 	int ac;
651 	int i;
652 
653 	va_start(va, cmd);
654 	for (ac = 0; va_arg(va, void *) != NULL; ++ac)
655 		;
656 	va_end(va);
657 
658 	av = malloc((ac + 1) * sizeof(char *));
659 	va_start(va, cmd);
660 	for (i = 0; i < ac; ++i)
661 		av[i] = va_arg(va, char *);
662 	va_end(va);
663 	av[i] = NULL;
664 
665 	if ((pid = fork()) < 0) {
666 		perror("fork");
667 		exit(1);
668 	} else if (pid == 0) {
669 		if (fd != 1) {
670 			dup2(fd, 1);
671 			close(fd);
672 		}
673 		execv(cmd, av);
674 		_exit(1);
675 	} else {
676 		while (waitpid(pid, NULL, 0) != pid)
677 			;
678 	}
679 	free(av);
680 }
681 
682 /*
683  * Convert tid to timestamp.
684  */
685 static char *
686 timestamp(hammer_ioc_hist_entry_t hen)
687 {
688 	static char timebuf[64];
689 	time_t t = (time_t)hen->time32;
690 	struct tm *tp;
691 
692 	tp = localtime(&t);
693 	strftime(timebuf, sizeof(timebuf), "%d-%b-%Y %H:%M:%S", tp);
694 	return(timebuf);
695 }
696 
697 static
698 int
699 undo_hist_entry_compare(struct undo_hist_entry *he1,
700 			struct undo_hist_entry *he2)
701 {
702 	if (he1->tse.tid < he2->tse.tid)
703 		return(-1);
704 	if (he1->tse.tid > he2->tse.tid)
705 		return(1);
706 	return(0);
707 }
708 
709 static void
710 usage(void)
711 {
712 	fprintf(stderr, "undo [-adDiuv] [-o outfile] "
713 			"[-t transaction-id] [-t transaction-id] path...\n"
714 			"    -a       Iterate all historical segments\n"
715 			"    -d       Forward diff\n"
716 			"    -D       Reverse diff\n"
717 			"    -i       Dump history transaction ids\n"
718 			"    -u       Generate .undo files\n"
719 			"    -v       Verbose\n"
720 			"    -o file  Output to the specified file\n"
721 			"    -t TID   Retrieve as of transaction-id, TID\n"
722 			"             (a second `-t TID' to diff two)\n"
723 			"    transaction ids must be prefixed with 0x, and\n"
724 			"    otherwise may specify an index starting at 0\n"
725 			"    and iterating backwards through the history.\n"
726 	);
727 	exit(1);
728 }
729 
730