xref: /freebsd/contrib/libarchive/tar/util.c (revision bd66c1b43e33540205dbc1187c2f2a15c58b57ba)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2003-2007 Tim Kientzle
5  * All rights reserved.
6  */
7 
8 #include "bsdtar_platform.h"
9 
10 #ifdef HAVE_SYS_STAT_H
11 #include <sys/stat.h>
12 #endif
13 #ifdef HAVE_SYS_TYPES_H
14 #include <sys/types.h>  /* Linux doesn't define mode_t, etc. in sys/stat.h. */
15 #endif
16 #include <ctype.h>
17 #ifdef HAVE_ERRNO_H
18 #include <errno.h>
19 #endif
20 #ifdef HAVE_IO_H
21 #include <io.h>
22 #endif
23 #ifdef HAVE_STDARG_H
24 #include <stdarg.h>
25 #endif
26 #ifdef HAVE_STDINT_H
27 #include <stdint.h>
28 #endif
29 #include <stdio.h>
30 #ifdef HAVE_STDLIB_H
31 #include <stdlib.h>
32 #endif
33 #ifdef HAVE_STRING_H
34 #include <string.h>
35 #endif
36 #ifdef HAVE_WCTYPE_H
37 #include <wctype.h>
38 #else
39 /* If we don't have wctype, we need to hack up some version of iswprint(). */
40 #define	iswprint isprint
41 #endif
42 
43 #include "bsdtar.h"
44 #include "err.h"
45 #include "passphrase.h"
46 
47 static size_t	bsdtar_expand_char(char *, size_t, size_t, char);
48 static const char *strip_components(const char *path, int elements);
49 
50 #if defined(_WIN32) && !defined(__CYGWIN__)
51 #define	read _read
52 #endif
53 
54 /* TODO:  Hack up a version of mbtowc for platforms with no wide
55  * character support at all.  I think the following might suffice,
56  * but it needs careful testing.
57  * #if !HAVE_MBTOWC
58  * #define	mbtowc(wcp, p, n) ((*wcp = *p), 1)
59  * #endif
60  */
61 
62 /*
63  * Print a string, taking care with any non-printable characters.
64  *
65  * Note that we use a stack-allocated buffer to receive the formatted
66  * string if we can.  This is partly performance (avoiding a call to
67  * malloc()), partly out of expedience (we have to call vsnprintf()
68  * before malloc() anyway to find out how big a buffer we need; we may
69  * as well point that first call at a small local buffer in case it
70  * works), but mostly for safety (so we can use this to print messages
71  * about out-of-memory conditions).
72  */
73 
74 void
safe_fprintf(FILE * f,const char * fmt,...)75 safe_fprintf(FILE *f, const char *fmt, ...)
76 {
77 	char fmtbuff_stack[256]; /* Place to format the printf() string. */
78 	char outbuff[256]; /* Buffer for outgoing characters. */
79 	char *fmtbuff_heap; /* If fmtbuff_stack is too small, we use malloc */
80 	char *fmtbuff;  /* Pointer to fmtbuff_stack or fmtbuff_heap. */
81 	int fmtbuff_length;
82 	int length, n;
83 	va_list ap;
84 	const char *p;
85 	unsigned i;
86 	wchar_t wc;
87 	char try_wc;
88 
89 	/* Use a stack-allocated buffer if we can, for speed and safety. */
90 	fmtbuff_heap = NULL;
91 	fmtbuff_length = sizeof(fmtbuff_stack);
92 	fmtbuff = fmtbuff_stack;
93 
94 	/* Try formatting into the stack buffer. */
95 	va_start(ap, fmt);
96 	length = vsnprintf(fmtbuff, fmtbuff_length, fmt, ap);
97 	va_end(ap);
98 
99 	/* If the result was too large, allocate a buffer on the heap. */
100 	while (length < 0 || length >= fmtbuff_length) {
101 		if (length >= fmtbuff_length)
102 			fmtbuff_length = length+1;
103 		else if (fmtbuff_length < 8192)
104 			fmtbuff_length *= 2;
105 		else if (fmtbuff_length < 1000000)
106 			fmtbuff_length += fmtbuff_length / 4;
107 		else {
108 			length = fmtbuff_length;
109 			fmtbuff_heap[length-1] = '\0';
110 			break;
111 		}
112 		free(fmtbuff_heap);
113 		fmtbuff_heap = malloc(fmtbuff_length);
114 
115 		/* Reformat the result into the heap buffer if we can. */
116 		if (fmtbuff_heap != NULL) {
117 			fmtbuff = fmtbuff_heap;
118 			va_start(ap, fmt);
119 			length = vsnprintf(fmtbuff, fmtbuff_length, fmt, ap);
120 			va_end(ap);
121 		} else {
122 			/* Leave fmtbuff pointing to the truncated
123 			 * string in fmtbuff_stack. */
124 			fmtbuff = fmtbuff_stack;
125 			length = sizeof(fmtbuff_stack) - 1;
126 			break;
127 		}
128 	}
129 
130 	/* Note: mbrtowc() has a cleaner API, but mbtowc() seems a bit
131 	 * more portable, so we use that here instead. */
132 	if (mbtowc(NULL, NULL, 1) == -1) { /* Reset the shift state. */
133 		/* mbtowc() should never fail in practice, but
134 		 * handle the theoretical error anyway. */
135 		free(fmtbuff_heap);
136 		return;
137 	}
138 
139 	/* Write data, expanding unprintable characters. */
140 	p = fmtbuff;
141 	i = 0;
142 	try_wc = 1;
143 	while (*p != '\0') {
144 
145 		/* Convert to wide char, test if the wide
146 		 * char is printable in the current locale. */
147 		if (try_wc && (n = mbtowc(&wc, p, length)) != -1) {
148 			length -= n;
149 			if (iswprint(wc) && wc != L'\\') {
150 				/* Printable, copy the bytes through. */
151 				while (n-- > 0)
152 					outbuff[i++] = *p++;
153 			} else {
154 				/* Not printable, format the bytes. */
155 				while (n-- > 0)
156 					i += (unsigned)bsdtar_expand_char(
157 					    outbuff, sizeof(outbuff), i, *p++);
158 			}
159 		} else {
160 			/* After any conversion failure, don't bother
161 			 * trying to convert the rest. */
162 			i += (unsigned)bsdtar_expand_char(outbuff, sizeof(outbuff), i, *p++);
163 			try_wc = 0;
164 		}
165 
166 		/* If our output buffer is full, dump it and keep going. */
167 		if (i > (sizeof(outbuff) - 128)) {
168 			outbuff[i] = '\0';
169 			fprintf(f, "%s", outbuff);
170 			i = 0;
171 		}
172 	}
173 	outbuff[i] = '\0';
174 	fprintf(f, "%s", outbuff);
175 
176 	/* If we allocated a heap-based formatting buffer, free it now. */
177 	free(fmtbuff_heap);
178 }
179 
180 /*
181  * Render an arbitrary sequence of bytes into printable ASCII characters.
182  */
183 static size_t
bsdtar_expand_char(char * buff,size_t buffsize,size_t offset,char c)184 bsdtar_expand_char(char *buff, size_t buffsize, size_t offset, char c)
185 {
186 	size_t i = offset;
187 
188 	if (isprint((unsigned char)c) && c != '\\')
189 		buff[i++] = c;
190 	else {
191 		buff[i++] = '\\';
192 		switch (c) {
193 		case '\a': buff[i++] = 'a'; break;
194 		case '\b': buff[i++] = 'b'; break;
195 		case '\f': buff[i++] = 'f'; break;
196 		case '\n': buff[i++] = 'n'; break;
197 #if '\r' != '\n'
198 		/* On some platforms, \n and \r are the same. */
199 		case '\r': buff[i++] = 'r'; break;
200 #endif
201 		case '\t': buff[i++] = 't'; break;
202 		case '\v': buff[i++] = 'v'; break;
203 		case '\\': buff[i++] = '\\'; break;
204 		default:
205 			snprintf(buff + i, buffsize - i, "%03o", 0xFF & (int)c);
206 			i += 3;
207 		}
208 	}
209 
210 	return (i - offset);
211 }
212 
213 int
yes(const char * fmt,...)214 yes(const char *fmt, ...)
215 {
216 	char buff[32];
217 	char *p;
218 	ssize_t l;
219 	int read_fd = 2; /* stderr */
220 
221 	va_list ap;
222 	va_start(ap, fmt);
223 	vfprintf(stderr, fmt, ap);
224 	va_end(ap);
225 	fprintf(stderr, " (y/N)? ");
226 	fflush(stderr);
227 
228 #if defined(_WIN32) && !defined(__CYGWIN__)
229 	/* To be resilient when stdin is a pipe, bsdtar prefers to read from
230 	 * stderr.  On Windows, stderr cannot be read. The nearest "piping
231 	 * resilient" equivalent is reopening the console input handle.
232 	 */
233 	read_fd = _open("CONIN$", O_RDONLY);
234 	if (read_fd < 0) {
235 	  fprintf(stderr, "Keyboard read failed\n");
236 	  exit(1);
237 	}
238 #endif
239 
240 	l = read(read_fd, buff, sizeof(buff) - 1);
241 
242 #if defined(_WIN32) && !defined(__CYGWIN__)
243 	_close(read_fd);
244 #endif
245 
246 	if (l < 0) {
247 	  fprintf(stderr, "Keyboard read failed\n");
248 	  exit(1);
249 	}
250 	if (l == 0)
251 		return (0);
252 	buff[l] = 0;
253 
254 	for (p = buff; *p != '\0'; p++) {
255 		if (isspace((unsigned char)*p))
256 			continue;
257 		switch(*p) {
258 		case 'y': case 'Y':
259 			return (1);
260 		case 'n': case 'N':
261 			return (0);
262 		default:
263 			return (0);
264 		}
265 	}
266 
267 	return (0);
268 }
269 
270 /*-
271  * The logic here for -C <dir> attempts to avoid
272  * chdir() as long as possible.  For example:
273  * "-C /foo -C /bar file"          needs chdir("/bar") but not chdir("/foo")
274  * "-C /foo -C bar file"           needs chdir("/foo/bar")
275  * "-C /foo -C bar /file1"         does not need chdir()
276  * "-C /foo -C bar /file1 file2"   needs chdir("/foo/bar") before file2
277  *
278  * The only correct way to handle this is to record a "pending" chdir
279  * request and combine multiple requests intelligently until we
280  * need to process a non-absolute file.  set_chdir() adds the new dir
281  * to the pending list; do_chdir() actually executes any pending chdir.
282  *
283  * This way, programs that build tar command lines don't have to worry
284  * about -C with non-existent directories; such requests will only
285  * fail if the directory must be accessed.
286  *
287  */
288 void
set_chdir(struct bsdtar * bsdtar,const char * newdir)289 set_chdir(struct bsdtar *bsdtar, const char *newdir)
290 {
291 #if defined(_WIN32) && !defined(__CYGWIN__)
292 	if (newdir[0] == '/' || newdir[0] == '\\' ||
293 	    /* Detect this type, for example, "C:\" or "C:/" */
294 	    (((newdir[0] >= 'a' && newdir[0] <= 'z') ||
295 	      (newdir[0] >= 'A' && newdir[0] <= 'Z')) &&
296 	    newdir[1] == ':' && (newdir[2] == '/' || newdir[2] == '\\'))) {
297 #else
298 	if (newdir[0] == '/') {
299 #endif
300 		/* The -C /foo -C /bar case; dump first one. */
301 		free(bsdtar->pending_chdir);
302 		bsdtar->pending_chdir = NULL;
303 	}
304 	if (bsdtar->pending_chdir == NULL)
305 		/* Easy case: no previously-saved dir. */
306 		bsdtar->pending_chdir = strdup(newdir);
307 	else {
308 		/* The -C /foo -C bar case; concatenate */
309 		char *old_pending = bsdtar->pending_chdir;
310 		size_t old_len = strlen(old_pending);
311         size_t new_len = old_len + strlen(newdir) + 2;
312 		bsdtar->pending_chdir = malloc(new_len);
313 		if (old_pending[old_len - 1] == '/')
314 			old_pending[old_len - 1] = '\0';
315 		if (bsdtar->pending_chdir != NULL)
316 			snprintf(bsdtar->pending_chdir, new_len, "%s/%s",
317 			    old_pending, newdir);
318 		free(old_pending);
319 	}
320 	if (bsdtar->pending_chdir == NULL)
321 		lafe_errc(1, errno, "No memory");
322 }
323 
324 void
325 do_chdir(struct bsdtar *bsdtar)
326 {
327 	if (bsdtar->pending_chdir == NULL)
328 		return;
329 
330 	if (chdir(bsdtar->pending_chdir) != 0) {
331 		lafe_errc(1, 0, "could not chdir to '%s'\n",
332 		    bsdtar->pending_chdir);
333 	}
334 	free(bsdtar->pending_chdir);
335 	bsdtar->pending_chdir = NULL;
336 }
337 
338 static const char *
339 strip_components(const char *p, int elements)
340 {
341 	/* Skip as many elements as necessary. */
342 	while (elements > 0) {
343 		switch (*p++) {
344 		case '/':
345 #if defined(_WIN32) && !defined(__CYGWIN__)
346 		case '\\': /* Support \ path sep on Windows ONLY. */
347 #endif
348 			elements--;
349 			break;
350 		case '\0':
351 			/* Path is too short, skip it. */
352 			return (NULL);
353 		}
354 	}
355 
356 	/* Skip any / characters.  This handles short paths that have
357 	 * additional / termination.  This also handles the case where
358 	 * the logic above stops in the middle of a duplicate //
359 	 * sequence (which would otherwise get converted to an
360 	 * absolute path). */
361 	for (;;) {
362 		switch (*p) {
363 		case '/':
364 #if defined(_WIN32) && !defined(__CYGWIN__)
365 		case '\\': /* Support \ path sep on Windows ONLY. */
366 #endif
367 			++p;
368 			break;
369 		case '\0':
370 			return (NULL);
371 		default:
372 			return (p);
373 		}
374 	}
375 }
376 
377 static void
378 warn_strip_leading_char(struct bsdtar *bsdtar, const char *c)
379 {
380 	if (!bsdtar->warned_lead_slash) {
381 		lafe_warnc(0,
382 			   "Removing leading '%c' from member names",
383 			   c[0]);
384 		bsdtar->warned_lead_slash = 1;
385 	}
386 }
387 
388 static void
389 warn_strip_drive_letter(struct bsdtar *bsdtar)
390 {
391 	if (!bsdtar->warned_lead_slash) {
392 		lafe_warnc(0,
393 			   "Removing leading drive letter from "
394 			   "member names");
395 		bsdtar->warned_lead_slash = 1;
396 	}
397 }
398 
399 /*
400  * Convert absolute path to non-absolute path by skipping leading
401  * absolute path prefixes.
402  */
403 static const char*
404 strip_absolute_path(struct bsdtar *bsdtar, const char *p)
405 {
406 	const char *rp;
407 
408 	/* Remove leading "//./" or "//?/" or "//?/UNC/"
409 	 * (absolute path prefixes used by Windows API) */
410 	if ((p[0] == '/' || p[0] == '\\') &&
411 	    (p[1] == '/' || p[1] == '\\') &&
412 	    (p[2] == '.' || p[2] == '?') &&
413 	    (p[3] == '/' || p[3] == '\\'))
414 	{
415 		if (p[2] == '?' &&
416 		    (p[4] == 'U' || p[4] == 'u') &&
417 		    (p[5] == 'N' || p[5] == 'n') &&
418 		    (p[6] == 'C' || p[6] == 'c') &&
419 		    (p[7] == '/' || p[7] == '\\'))
420 			p += 8;
421 		else
422 			p += 4;
423 		warn_strip_drive_letter(bsdtar);
424 	}
425 
426 	/* Remove multiple leading slashes and Windows drive letters. */
427 	do {
428 		rp = p;
429 		if (((p[0] >= 'a' && p[0] <= 'z') ||
430 		     (p[0] >= 'A' && p[0] <= 'Z')) &&
431 		    p[1] == ':') {
432 			p += 2;
433 			warn_strip_drive_letter(bsdtar);
434 		}
435 
436 		/* Remove leading "/../", "/./", "//", etc. */
437 		while (p[0] == '/' || p[0] == '\\') {
438 			if (p[1] == '.' &&
439 			    p[2] == '.' &&
440 			    (p[3] == '/' || p[3] == '\\')) {
441 				p += 3; /* Remove "/..", leave "/" for next pass. */
442 			} else if (p[1] == '.' &&
443 				   (p[2] == '/' || p[2] == '\\')) {
444 				p += 2; /* Remove "/.", leave "/" for next pass. */
445 			} else
446 				p += 1; /* Remove "/". */
447 			warn_strip_leading_char(bsdtar, rp);
448 		}
449 	} while (rp != p);
450 
451 	return (p);
452 }
453 
454 /*
455  * Handle --strip-components and any future path-rewriting options.
456  * Returns non-zero if the pathname should not be extracted.
457  *
458  * Note: The rewrites are applied uniformly to pathnames and hardlink
459  * names but not to symlink bodies.  This is deliberate: Symlink
460  * bodies are not necessarily filenames.  Even when they are, they
461  * need to be interpreted relative to the directory containing them,
462  * so simple rewrites like this are rarely appropriate.
463  *
464  * TODO: Support pax-style regex path rewrites.
465  */
466 int
467 edit_pathname(struct bsdtar *bsdtar, struct archive_entry *entry)
468 {
469 	const char *name = archive_entry_pathname(entry);
470 	const char *original_name = name;
471 	const char *hardlinkname = archive_entry_hardlink(entry);
472 	const char *original_hardlinkname = hardlinkname;
473 #if defined(HAVE_REGEX_H) || defined(HAVE_PCREPOSIX_H) || defined(HAVE_PCRE2POSIX_H)
474 	char *subst_name;
475 	int r;
476 
477 	/* Apply user-specified substitution to pathname. */
478 	r = apply_substitution(bsdtar, name, &subst_name, 0, 0);
479 	if (r == -1) {
480 		lafe_warnc(0, "Invalid substitution, skipping entry");
481 		return 1;
482 	}
483 	if (r == 1) {
484 		archive_entry_copy_pathname(entry, subst_name);
485 		if (*subst_name == '\0') {
486 			free(subst_name);
487 			return -1;
488 		} else
489 			free(subst_name);
490 		name = archive_entry_pathname(entry);
491 		original_name = name;
492 	}
493 
494 	/* Apply user-specified substitution to hardlink target. */
495 	if (hardlinkname != NULL) {
496 		r = apply_substitution(bsdtar, hardlinkname, &subst_name, 0, 1);
497 		if (r == -1) {
498 			lafe_warnc(0, "Invalid substitution, skipping entry");
499 			return 1;
500 		}
501 		if (r == 1) {
502 			archive_entry_copy_hardlink(entry, subst_name);
503 			free(subst_name);
504 		}
505 		hardlinkname = archive_entry_hardlink(entry);
506 		original_hardlinkname = hardlinkname;
507 	}
508 
509 	/* Apply user-specified substitution to symlink body. */
510 	if (archive_entry_symlink(entry) != NULL) {
511 		r = apply_substitution(bsdtar, archive_entry_symlink(entry), &subst_name, 1, 0);
512 		if (r == -1) {
513 			lafe_warnc(0, "Invalid substitution, skipping entry");
514 			return 1;
515 		}
516 		if (r == 1) {
517 			archive_entry_copy_symlink(entry, subst_name);
518 			free(subst_name);
519 		}
520 	}
521 #endif
522 
523 	/* Strip leading dir names as per --strip-components option. */
524 	if (bsdtar->strip_components > 0) {
525 		name = strip_components(name, bsdtar->strip_components);
526 		if (name == NULL)
527 			return (1);
528 
529 		if (hardlinkname != NULL) {
530 			hardlinkname = strip_components(hardlinkname,
531 			    bsdtar->strip_components);
532 			if (hardlinkname == NULL)
533 				return (1);
534 		}
535 	}
536 
537 	if ((bsdtar->flags & OPTFLAG_ABSOLUTE_PATHS) == 0) {
538 		/* By default, don't write or restore absolute pathnames. */
539 		name = strip_absolute_path(bsdtar, name);
540 		if (*name == '\0')
541 			name = ".";
542 
543 		if (hardlinkname != NULL) {
544 			hardlinkname = strip_absolute_path(bsdtar, hardlinkname);
545 			if (*hardlinkname == '\0')
546 				return (1);
547 		}
548 	} else {
549 		/* Strip redundant leading '/' characters. */
550 		while (name[0] == '/' && name[1] == '/')
551 			name++;
552 	}
553 
554 	/* Replace name in archive_entry. */
555 	if (name != original_name) {
556 		archive_entry_copy_pathname(entry, name);
557 	}
558 	if (hardlinkname != original_hardlinkname) {
559 		archive_entry_copy_hardlink(entry, hardlinkname);
560 	}
561 	return (0);
562 }
563 
564 /*
565  * It would be nice to just use printf() for formatting large numbers,
566  * but the compatibility problems are quite a headache.  Hence the
567  * following simple utility function.
568  */
569 const char *
570 tar_i64toa(int64_t n0)
571 {
572 	static char buff[24];
573 	uint64_t n = n0 < 0 ? -n0 : n0;
574 	char *p = buff + sizeof(buff);
575 
576 	*--p = '\0';
577 	do {
578 		*--p = '0' + (int)(n % 10);
579 	} while (n /= 10);
580 	if (n0 < 0)
581 		*--p = '-';
582 	return p;
583 }
584 
585 /*
586  * Like strcmp(), but try to be a little more aware of the fact that
587  * we're comparing two paths.  Right now, it just handles leading
588  * "./" and trailing '/' specially, so that "a/b/" == "./a/b"
589  *
590  * TODO: Make this better, so that "./a//b/./c/" == "a/b/c"
591  * TODO: After this works, push it down into libarchive.
592  * TODO: Publish the path normalization routines in libarchive so
593  * that bsdtar can normalize paths and use fast strcmp() instead
594  * of this.
595  *
596  * Note: This is currently only used within write.c, so should
597  * not handle \ path separators.
598  */
599 
600 int
601 pathcmp(const char *a, const char *b)
602 {
603 	/* Skip leading './' */
604 	if (a[0] == '.' && a[1] == '/' && a[2] != '\0')
605 		a += 2;
606 	if (b[0] == '.' && b[1] == '/' && b[2] != '\0')
607 		b += 2;
608 	/* Find the first difference, or return (0) if none. */
609 	while (*a == *b) {
610 		if (*a == '\0')
611 			return (0);
612 		a++;
613 		b++;
614 	}
615 	/*
616 	 * If one ends in '/' and the other one doesn't,
617 	 * they're the same.
618 	 */
619 	if (a[0] == '/' && a[1] == '\0' && b[0] == '\0')
620 		return (0);
621 	if (a[0] == '\0' && b[0] == '/' && b[1] == '\0')
622 		return (0);
623 	/* They're really different, return the correct sign. */
624 	return (*(const unsigned char *)a - *(const unsigned char *)b);
625 }
626 
627 #define PPBUFF_SIZE 1024
628 const char *
629 passphrase_callback(struct archive *a, void *_client_data)
630 {
631 	struct bsdtar *bsdtar = (struct bsdtar *)_client_data;
632 	(void)a; /* UNUSED */
633 
634 	if (bsdtar->ppbuff == NULL) {
635 		bsdtar->ppbuff = malloc(PPBUFF_SIZE);
636 		if (bsdtar->ppbuff == NULL)
637 			lafe_errc(1, errno, "Out of memory");
638 	}
639 	return lafe_readpassphrase("Enter passphrase:",
640 		bsdtar->ppbuff, PPBUFF_SIZE);
641 }
642 
643 void
644 passphrase_free(char *ppbuff)
645 {
646 	if (ppbuff != NULL) {
647 		memset(ppbuff, 0, PPBUFF_SIZE);
648 		free(ppbuff);
649 	}
650 }
651 
652 /*
653  * Display information about the current file.
654  *
655  * The format here roughly duplicates the output of 'ls -l'.
656  * This is based on SUSv2, where 'tar tv' is documented as
657  * listing additional information in an "unspecified format,"
658  * and 'pax -l' is documented as using the same format as 'ls -l'.
659  */
660 void
661 list_item_verbose(struct bsdtar *bsdtar, FILE *out, struct archive_entry *entry)
662 {
663 	char			 tmp[100];
664 	size_t			 w;
665 	const char		*p;
666 	const char		*fmt;
667 	time_t			 tim;
668 	static time_t		 now;
669 	struct tm		*ltime;
670 #if defined(HAVE_LOCALTIME_R) || defined(HAVE_LOCALTIME_S)
671 	struct tm		tmbuf;
672 #endif
673 
674 	/*
675 	 * We avoid collecting the entire list in memory at once by
676 	 * listing things as we see them.  However, that also means we can't
677 	 * just pre-compute the field widths.  Instead, we start with guesses
678 	 * and just widen them as necessary.  These numbers are completely
679 	 * arbitrary.
680 	 */
681 	if (!bsdtar->u_width) {
682 		bsdtar->u_width = 6;
683 		bsdtar->gs_width = 13;
684 	}
685 	if (!now)
686 		time(&now);
687 	fprintf(out, "%s %d ",
688 	    archive_entry_strmode(entry),
689 	    archive_entry_nlink(entry));
690 
691 	/* Use uname if it's present, else uid. */
692 	p = archive_entry_uname(entry);
693 	if ((p == NULL) || (*p == '\0')) {
694 		snprintf(tmp, sizeof(tmp), "%lu ",
695 		    (unsigned long)archive_entry_uid(entry));
696 		p = tmp;
697 	}
698 	w = strlen(p);
699 	if (w > bsdtar->u_width)
700 		bsdtar->u_width = w;
701 	fprintf(out, "%-*s ", (int)bsdtar->u_width, p);
702 
703 	/* Use gname if it's present, else gid. */
704 	p = archive_entry_gname(entry);
705 	if (p != NULL && p[0] != '\0') {
706 		fprintf(out, "%s", p);
707 		w = strlen(p);
708 	} else {
709 		snprintf(tmp, sizeof(tmp), "%lu",
710 		    (unsigned long)archive_entry_gid(entry));
711 		w = strlen(tmp);
712 		fprintf(out, "%s", tmp);
713 	}
714 
715 	/*
716 	 * Print device number or file size, right-aligned so as to make
717 	 * total width of group and devnum/filesize fields be gs_width.
718 	 * If gs_width is too small, grow it.
719 	 */
720 	if (archive_entry_filetype(entry) == AE_IFCHR
721 	    || archive_entry_filetype(entry) == AE_IFBLK) {
722 		snprintf(tmp, sizeof(tmp), "%lu,%lu",
723 		    (unsigned long)archive_entry_rdevmajor(entry),
724 		    (unsigned long)archive_entry_rdevminor(entry));
725 	} else {
726 		strcpy(tmp, tar_i64toa(archive_entry_size(entry)));
727 	}
728 	if (w + strlen(tmp) >= bsdtar->gs_width)
729 		bsdtar->gs_width = w+strlen(tmp)+1;
730 	fprintf(out, "%*s", (int)(bsdtar->gs_width - w), tmp);
731 
732 	/* Format the time using 'ls -l' conventions. */
733 	tim = archive_entry_mtime(entry);
734 #define	HALF_YEAR (time_t)365 * 86400 / 2
735 #if defined(_WIN32) && !defined(__CYGWIN__)
736 #define	DAY_FMT  "%d"  /* Windows' strftime function does not support %e format. */
737 #else
738 #define	DAY_FMT  "%e"  /* Day number without leading zeros */
739 #endif
740 	if (tim < now - HALF_YEAR || tim > now + HALF_YEAR)
741 		fmt = bsdtar->day_first ? DAY_FMT " %b  %Y" : "%b " DAY_FMT "  %Y";
742 	else
743 		fmt = bsdtar->day_first ? DAY_FMT " %b %H:%M" : "%b " DAY_FMT " %H:%M";
744 #if defined(HAVE_LOCALTIME_S)
745 	ltime = localtime_s(&tmbuf, &tim) ? NULL : &tmbuf;
746 #elif defined(HAVE_LOCALTIME_R)
747 	ltime = localtime_r(&tim, &tmbuf);
748 #else
749 	ltime = localtime(&tim);
750 #endif
751 	strftime(tmp, sizeof(tmp), fmt, ltime);
752 	fprintf(out, " %s ", tmp);
753 	safe_fprintf(out, "%s", archive_entry_pathname(entry));
754 
755 	/* Extra information for links. */
756 	if (archive_entry_hardlink(entry)) /* Hard link */
757 		safe_fprintf(out, " link to %s",
758 		    archive_entry_hardlink(entry));
759 	else if (archive_entry_symlink(entry)) /* Symbolic link */
760 		safe_fprintf(out, " -> %s", archive_entry_symlink(entry));
761 }
762