bsdtar.c   [plain text]

/*-
 * Copyright (c) 2003-2008 Tim Kientzle
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "bsdtar_platform.h"
__FBSDID("$FreeBSD: src/usr.bin/tar/bsdtar.c,v 1.93 2008/11/08 04:43:24 kientzle Exp $");

#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_LANGINFO_H
#include <langinfo.h>
#endif
#ifdef HAVE_LOCALE_H
#include <locale.h>
#endif
#ifdef HAVE_PATHS_H
#include <paths.h>
#endif
#ifdef HAVE_SIGNAL_H
#include <signal.h>
#endif
#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_ZLIB_H
#include <zlib.h>
#endif

#include <copyfile.h>

#include "bsdtar.h"
#include "err.h"

#ifdef __MINGW32__
int _CRT_glob = 0; /* Disable broken CRT globbing. */
#endif

static struct bsdtar *_bsdtar;

#if defined(HAVE_SIGACTION) && (defined(SIGINFO) || defined(SIGUSR1))
static volatile int siginfo_occurred;

static void
siginfo_handler(int sig)
{
	(void)sig; /* UNUSED */
	siginfo_occurred = 1;
}

int
need_report(void)
{
	int r = siginfo_occurred;
	siginfo_occurred = 0;
	return (r);
}
#else
int
need_report(void)
{
	return (0);
}
#endif

/* External function to parse a date/time string */
time_t get_date(time_t, const char *);

static void		 long_help(void);
static void		 only_mode(struct bsdtar *, const char *opt,
			     const char *valid);
static void		 set_mode(struct bsdtar *, char opt);
static void		 version(void);

/* A basic set of security flags to request from libarchive. */
#define	SECURITY					\
	(ARCHIVE_EXTRACT_SECURE_SYMLINKS		\
	 | ARCHIVE_EXTRACT_SECURE_NODOTDOT)

int
main(int argc, char **argv)
{
	struct bsdtar		*bsdtar, bsdtar_storage;
	int			 opt, t;
	char			 option_o;
	char			 possible_help_request;
	char			 buff[16];
	time_t			 now;

	/*
	 * Use a pointer for consistency, but stack-allocated storage
	 * for ease of cleanup.
	 */
	_bsdtar = bsdtar = &bsdtar_storage;
	memset(bsdtar, 0, sizeof(*bsdtar));
	bsdtar->fd = -1; /* Mark as "unused" */
	option_o = 0;

#if defined(HAVE_SIGACTION) && (defined(SIGINFO) || defined(SIGUSR1))
	{ /* Catch SIGINFO and SIGUSR1, if they exist. */
		struct sigaction sa;
		sa.sa_handler = siginfo_handler;
		sigemptyset(&sa.sa_mask);
		sa.sa_flags = 0;
#ifdef SIGINFO
		if (sigaction(SIGINFO, &sa, NULL))
			lafe_errc(1, errno, "sigaction(SIGINFO) failed");
#endif
#ifdef SIGUSR1
		/* ... and treat SIGUSR1 the same way as SIGINFO. */
		if (sigaction(SIGUSR1, &sa, NULL))
			lafe_errc(1, errno, "sigaction(SIGUSR1) failed");
#endif
	}
#endif


	/* Need lafe_progname before calling lafe_warnc. */
	if (*argv == NULL)
		lafe_progname = "bsdtar";
	else {
#if defined(_WIN32) && !defined(__CYGWIN__)
		lafe_progname = strrchr(*argv, '\\');
#else
		lafe_progname = strrchr(*argv, '/');
#endif
		if (lafe_progname != NULL)
			lafe_progname++;
		else
			lafe_progname = *argv;
	}

	time(&now);

#if HAVE_SETLOCALE
	if (setlocale(LC_ALL, "") == NULL)
		lafe_warnc(0, "Failed to set default locale");
#endif
#if defined(HAVE_NL_LANGINFO) && defined(HAVE_D_MD_ORDER)
	bsdtar->day_first = (*nl_langinfo(D_MD_ORDER) == 'd');
#endif
	possible_help_request = 0;

	/* Look up uid of current user for future reference */
	bsdtar->user_uid = geteuid();

	/* Default: preserve mod time on extract */
	bsdtar->extract_flags = ARCHIVE_EXTRACT_TIME;

	/* Default: Perform basic security checks. */
	bsdtar->extract_flags |= SECURITY;

#ifndef _WIN32
	/* On POSIX systems, assume --same-owner and -p when run by
	 * the root user.  This doesn't make any sense on Windows. */
	if (bsdtar->user_uid == 0) {
		/* --same-owner */
		bsdtar->extract_flags |= ARCHIVE_EXTRACT_OWNER;
		/* -p */
		bsdtar->extract_flags |= ARCHIVE_EXTRACT_PERM;
		bsdtar->extract_flags |= ARCHIVE_EXTRACT_ACL;
		bsdtar->extract_flags |= ARCHIVE_EXTRACT_XATTR;
		bsdtar->extract_flags |= ARCHIVE_EXTRACT_FFLAGS;
	}
#endif

	if (getenv(COPYFILE_DISABLE_VAR))
		bsdtar->disable_copyfile = 1;

	bsdtar->argv = argv;
	bsdtar->argc = argc;

	/*
	 * Comments following each option indicate where that option
	 * originated:  SUSv2, POSIX, GNU tar, star, etc.  If there's
	 * no such comment, then I don't know of anyone else who
	 * implements that option.
	 */
	while ((opt = bsdtar_getopt(bsdtar)) != -1) {
		switch (opt) {
		case 'B': /* GNU tar */
			/* libarchive doesn't need this; just ignore it. */
			break;
		case 'b': /* SUSv2 */
			t = atoi(bsdtar->optarg);
			if (t <= 0 || t > 8192)
				lafe_errc(1, 0,
				    "Argument to -b is out of range (1..8192)");
			bsdtar->bytes_per_block = 512 * t;
			break;
		case 'C': /* GNU tar */
			set_chdir(bsdtar, bsdtar->optarg);
			break;
		case 'c': /* SUSv2 */
			set_mode(bsdtar, opt);
			break;
		case OPTION_CHECK_LINKS: /* GNU tar */
			bsdtar->option_warn_links = 1;
			break;
		case OPTION_CHROOT: /* NetBSD */
			bsdtar->option_chroot = 1;
			break;
		case OPTION_DISABLE_COPYFILE:
			bsdtar->disable_copyfile = 1;
			break;
		case OPTION_EXCLUDE: /* GNU tar */
			if (lafe_exclude(&bsdtar->matching, bsdtar->optarg))
				lafe_errc(1, 0,
				    "Couldn't exclude %s\n", bsdtar->optarg);
			break;
		case OPTION_FORMAT: /* GNU tar, others */
			bsdtar->create_format = bsdtar->optarg;
			break;
		case OPTION_OPTIONS:
			bsdtar->option_options = bsdtar->optarg;
			break;
		case 'f': /* SUSv2 */
			bsdtar->filename = bsdtar->optarg;
			if (strcmp(bsdtar->filename, "-") == 0)
				bsdtar->filename = NULL;
			break;
		case 'H': /* BSD convention */
			bsdtar->symlink_mode = 'H';
			break;
		case 'h': /* Linux Standards Base, gtar; synonym for -L */
			bsdtar->symlink_mode = 'L';
			/* Hack: -h by itself is the "help" command. */
			possible_help_request = 1;
			break;
		case OPTION_HELP: /* GNU tar, others */
			long_help();
			exit(0);
			break;
		case 'I': /* GNU tar */
			/*
			 * TODO: Allow 'names' to come from an archive,
			 * not just a text file.  Design a good UI for
			 * allowing names and mode/owner to be read
			 * from an archive, with contents coming from
			 * disk.  This can be used to "refresh" an
			 * archive or to design archives with special
			 * permissions without having to create those
			 * permissions on disk.
			 */
			bsdtar->names_from_file = bsdtar->optarg;
			break;
		case OPTION_INCLUDE:
			/*
			 * Noone else has the @archive extension, so
			 * noone else needs this to filter entries
			 * when transforming archives.
			 */
			if (lafe_include(&bsdtar->matching, bsdtar->optarg))
				lafe_errc(1, 0,
				    "Failed to add %s to inclusion list",
				    bsdtar->optarg);
			break;
		case 'j': /* GNU tar */
			if (bsdtar->create_compression != '\0')
				lafe_errc(1, 0,
				    "Can't specify both -%c and -%c", opt,
				    bsdtar->create_compression);
			bsdtar->create_compression = opt;
			break;
		case 'J': /* GNU tar 1.21 and later */
			if (bsdtar->create_compression != '\0')
				lafe_errc(1, 0,
				    "Can't specify both -%c and -%c", opt,
				    bsdtar->create_compression);
			bsdtar->create_compression = opt;
			break;
		case 'k': /* GNU tar */
			bsdtar->extract_flags |= ARCHIVE_EXTRACT_NO_OVERWRITE;
			break;
		case OPTION_KEEP_NEWER_FILES: /* GNU tar */
			bsdtar->extract_flags |= ARCHIVE_EXTRACT_NO_OVERWRITE_NEWER;
			break;
		case 'L': /* BSD convention */
			bsdtar->symlink_mode = 'L';
			break;
	        case 'l': /* SUSv2 and GNU tar beginning with 1.16 */
			/* GNU tar 1.13  used -l for --one-file-system */
			bsdtar->option_warn_links = 1;
			break;
		case OPTION_LZMA:
			if (bsdtar->create_compression != '\0')
				lafe_errc(1, 0,
				    "Can't specify both -%c and -%c", opt,
				    bsdtar->create_compression);
			bsdtar->create_compression = opt;
			break;
		case 'm': /* SUSv2 */
			bsdtar->extract_flags &= ~ARCHIVE_EXTRACT_TIME;
			break;
		case 'n': /* GNU tar */
			bsdtar->option_no_subdirs = 1;
			break;
	        /*
		 * Selecting files by time:
		 *    --newer-?time='date' Only files newer than 'date'
		 *    --newer-?time-than='file' Only files newer than time
		 *         on specified file (useful for incremental backups)
		 * TODO: Add corresponding "older" options to reverse these.
		 */
		case OPTION_NEWER_CTIME: /* GNU tar */
			bsdtar->newer_ctime_sec = get_date(now, bsdtar->optarg);
			break;
		case OPTION_NEWER_CTIME_THAN:
			{
				struct stat st;
				if (stat(bsdtar->optarg, &st) != 0)
					lafe_errc(1, 0,
					    "Can't open file %s", bsdtar->optarg);
				bsdtar->newer_ctime_sec = st.st_ctime;
				bsdtar->newer_ctime_nsec =
				    ARCHIVE_STAT_CTIME_NANOS(&st);
			}
			break;
		case OPTION_NEWER_MTIME: /* GNU tar */
			bsdtar->newer_mtime_sec = get_date(now, bsdtar->optarg);
			break;
		case OPTION_NEWER_MTIME_THAN:
			{
				struct stat st;
				if (stat(bsdtar->optarg, &st) != 0)
					lafe_errc(1, 0,
					    "Can't open file %s", bsdtar->optarg);
				bsdtar->newer_mtime_sec = st.st_mtime;
				bsdtar->newer_mtime_nsec =
				    ARCHIVE_STAT_MTIME_NANOS(&st);
			}
			break;
		case OPTION_NODUMP: /* star */
			bsdtar->option_honor_nodump = 1;
			break;
		case OPTION_NO_SAME_OWNER: /* GNU tar */
			bsdtar->extract_flags &= ~ARCHIVE_EXTRACT_OWNER;
			break;
		case OPTION_NO_SAME_PERMISSIONS: /* GNU tar */
			bsdtar->extract_flags &= ~ARCHIVE_EXTRACT_PERM;
			bsdtar->extract_flags &= ~ARCHIVE_EXTRACT_ACL;
			bsdtar->extract_flags &= ~ARCHIVE_EXTRACT_XATTR;
			bsdtar->extract_flags &= ~ARCHIVE_EXTRACT_FFLAGS;
			break;
		case OPTION_NULL: /* GNU tar */
			bsdtar->option_null++;
			break;
		case OPTION_NUMERIC_OWNER: /* GNU tar */
			bsdtar->option_numeric_owner++;
			break;
		case 'O': /* GNU tar */
			bsdtar->option_stdout = 1;
			break;
		case 'o': /* SUSv2 and GNU conflict here, but not fatally */
			option_o = 1; /* Record it and resolve it later. */
			break;
		case OPTION_ONE_FILE_SYSTEM: /* GNU tar */
			bsdtar->option_dont_traverse_mounts = 1;
			break;
#if 0
		/*
		 * The common BSD -P option is not necessary, since
		 * our default is to archive symlinks, not follow
		 * them.  This is convenient, as -P conflicts with GNU
		 * tar anyway.
		 */
		case 'P': /* BSD convention */
			/* Default behavior, no option necessary. */
			break;
#endif
		case 'P': /* GNU tar */
			bsdtar->extract_flags &= ~SECURITY;
			bsdtar->option_absolute_paths = 1;
			break;
		case 'p': /* GNU tar, star */
			bsdtar->extract_flags |= ARCHIVE_EXTRACT_PERM;
			bsdtar->extract_flags |= ARCHIVE_EXTRACT_ACL;
			bsdtar->extract_flags |= ARCHIVE_EXTRACT_XATTR;
			bsdtar->extract_flags |= ARCHIVE_EXTRACT_FFLAGS;
			break;
		case OPTION_POSIX: /* GNU tar */
			bsdtar->create_format = "pax";
			break;
		case 'q': /* FreeBSD GNU tar --fast-read, NetBSD -q */
			bsdtar->option_fast_read = 1;
			break;
		case 'r': /* SUSv2 */
			set_mode(bsdtar, opt);
			break;
		case 'S': /* NetBSD pax-as-tar */
			bsdtar->extract_flags |= ARCHIVE_EXTRACT_SPARSE;
			break;
		case 's': /* NetBSD pax-as-tar */
#if HAVE_REGEX_H
			add_substitution(bsdtar, bsdtar->optarg);
#else
			lafe_warnc(0,
			    "-s is not supported by this version of bsdtar");
			usage();
#endif
			break;
		case OPTION_SAME_OWNER: /* GNU tar */
			bsdtar->extract_flags |= ARCHIVE_EXTRACT_OWNER;
			break;
		case OPTION_STRIP_COMPONENTS: /* GNU tar 1.15 */
			bsdtar->strip_components = atoi(bsdtar->optarg);
			break;
		case 'T': /* GNU tar */
			bsdtar->names_from_file = bsdtar->optarg;
			break;
		case 't': /* SUSv2 */
			set_mode(bsdtar, opt);
			bsdtar->verbose++;
			break;
		case OPTION_TOTALS: /* GNU tar */
			bsdtar->option_totals++;
			break;
		case 'U': /* GNU tar */
			bsdtar->extract_flags |= ARCHIVE_EXTRACT_UNLINK;
			bsdtar->option_unlink_first = 1;
			break;
		case 'u': /* SUSv2 */
			set_mode(bsdtar, opt);
			break;
		case 'v': /* SUSv2 */
			bsdtar->verbose++;
			break;
		case OPTION_VERSION: /* GNU convention */
			version();
			break;
#if 0
		/*
		 * The -W longopt feature is handled inside of
		 * bsdtar_getopt(), so -W is not available here.
		 */
		case 'W': /* Obscure GNU convention. */
			break;
#endif
		case 'w': /* SUSv2 */
			bsdtar->option_interactive = 1;
			break;
		case 'X': /* GNU tar */
			if (lafe_exclude_from_file(&bsdtar->matching, bsdtar->optarg))
				lafe_errc(1, 0,
				    "failed to process exclusions from file %s",
				    bsdtar->optarg);
			break;
		case 'x': /* SUSv2 */
			set_mode(bsdtar, opt);
			break;
		case 'y': /* FreeBSD version of GNU tar */
			if (bsdtar->create_compression != '\0')
				lafe_errc(1, 0,
				    "Can't specify both -%c and -%c", opt,
				    bsdtar->create_compression);
			bsdtar->create_compression = opt;
			break;
		case 'Z': /* GNU tar */
			if (bsdtar->create_compression != '\0')
				lafe_errc(1, 0,
				    "Can't specify both -%c and -%c", opt,
				    bsdtar->create_compression);
			bsdtar->create_compression = opt;
			break;
		case 'z': /* GNU tar, star, many others */
			if (bsdtar->create_compression != '\0')
				lafe_errc(1, 0,
				    "Can't specify both -%c and -%c", opt,
				    bsdtar->create_compression);
			bsdtar->create_compression = opt;
			break;
		case OPTION_USE_COMPRESS_PROGRAM:
			bsdtar->compress_program = bsdtar->optarg;
			break;
		default:
			usage();
		}
	}

	/*
	 * Sanity-check options.
	 */

	/* If no "real" mode was specified, treat -h as --help. */
	if ((bsdtar->mode == '\0') && possible_help_request) {
		long_help();
		exit(0);
	}

	/* Otherwise, a mode is required. */
	if (bsdtar->mode == '\0')
		lafe_errc(1, 0,
		    "Must specify one of -c, -r, -t, -u, -x");

	/* Check boolean options only permitted in certain modes. */
	if (bsdtar->option_dont_traverse_mounts)
		only_mode(bsdtar, "--one-file-system", "cru");
	if (bsdtar->option_fast_read)
		only_mode(bsdtar, "--fast-read", "xt");
	if (bsdtar->option_honor_nodump)
		only_mode(bsdtar, "--nodump", "cru");
	if (option_o > 0) {
		switch (bsdtar->mode) {
		case 'c':
			/*
			 * In GNU tar, -o means "old format."  The
			 * "ustar" format is the closest thing
			 * supported by libarchive.
			 */
			bsdtar->create_format = "ustar";
			/* TODO: bsdtar->create_format = "v7"; */
			break;
		case 'x':
			/* POSIX-compatible behavior. */
			bsdtar->option_no_owner = 1;
			bsdtar->extract_flags &= ~ARCHIVE_EXTRACT_OWNER;
			break;
		default:
			only_mode(bsdtar, "-o", "xc");
			break;
		}
	}
	if (bsdtar->option_no_subdirs)
		only_mode(bsdtar, "-n", "cru");
	if (bsdtar->option_stdout)
		only_mode(bsdtar, "-O", "xt");
	if (bsdtar->option_unlink_first)
		only_mode(bsdtar, "-U", "x");
	if (bsdtar->option_warn_links)
		only_mode(bsdtar, "--check-links", "cr");

	/* Check other parameters only permitted in certain modes. */
	if (bsdtar->create_compression != '\0') {
		strcpy(buff, "-?");
		buff[1] = bsdtar->create_compression;
		only_mode(bsdtar, buff, "cxt");
	}
	if (bsdtar->create_format != NULL)
		only_mode(bsdtar, "--format", "cru");
	if (bsdtar->symlink_mode != '\0') {
		strcpy(buff, "-?");
		buff[1] = bsdtar->symlink_mode;
		only_mode(bsdtar, buff, "cru");
	}
	if (bsdtar->strip_components != 0)
		only_mode(bsdtar, "--strip-components", "xt");

	switch(bsdtar->mode) {
	case 'c':
		tar_mode_c(bsdtar);
		break;
	case 'r':
		tar_mode_r(bsdtar);
		break;
	case 't':
		tar_mode_t(bsdtar);
		break;
	case 'u':
		tar_mode_u(bsdtar);
		break;
	case 'x':
		tar_mode_x(bsdtar);
		break;
	}

	lafe_cleanup_exclusions(&bsdtar->matching);
#if HAVE_REGEX_H
	cleanup_substitution(bsdtar);
#endif

	if (bsdtar->return_value != 0)
		lafe_warnc(0,
		    "Error exit delayed from previous errors.");
	return (bsdtar->return_value);
}

static void
set_mode(struct bsdtar *bsdtar, char opt)
{
	if (bsdtar->mode != '\0' && bsdtar->mode != opt)
		lafe_errc(1, 0,
		    "Can't specify both -%c and -%c", opt, bsdtar->mode);
	bsdtar->mode = opt;
}

/*
 * Verify that the mode is correct.
 */
static void
only_mode(struct bsdtar *bsdtar, const char *opt, const char *valid_modes)
{
	if (strchr(valid_modes, bsdtar->mode) == NULL)
		lafe_errc(1, 0,
		    "Option %s is not permitted in mode -%c",
		    opt, bsdtar->mode);
}


void
usage(void)
{
	const char	*p;

	p = lafe_progname;

	fprintf(stderr, "Usage:\n");
	fprintf(stderr, "  List:    %s -tf <archive-filename>\n", p);
	fprintf(stderr, "  Extract: %s -xf <archive-filename>\n", p);
	fprintf(stderr, "  Create:  %s -cf <archive-filename> [filenames...]\n", p);
	fprintf(stderr, "  Help:    %s --help\n", p);
	exit(1);
}

static void
version(void)
{
	printf("bsdtar %s - %s\n",
	    BSDTAR_VERSION_STRING,
	    archive_version());
	exit(0);
}

static const char *long_help_msg =
	"First option must be a mode specifier:\n"
	"  -c Create  -r Add/Replace  -t List  -u Update  -x Extract\n"
	"Common Options:\n"
	"  -b #  Use # 512-byte records per I/O block\n"
	"  -f <filename>  Location of archive\n"
	"  -v    Verbose\n"
	"  -w    Interactive\n"
	"Create: %p -c [options] [<file> | <dir> | @<archive> | -C <dir> ]\n"
	"  <file>, <dir>  add these items to archive\n"
	"  -z, -j, -J, --lzma  Compress archive with gzip/bzip2/xz/lzma\n"
	"  --format {ustar|pax|cpio|shar}  Select archive format\n"
	"  --exclude <pattern>  Skip files that match pattern\n"
	"  -C <dir>  Change to <dir> before processing remaining files\n"
	"  @<archive>  Add entries from <archive> to output\n"
	"List: %p -t [options] [<patterns>]\n"
	"  <patterns>  If specified, list only entries that match\n"
	"Extract: %p -x [options] [<patterns>]\n"
	"  <patterns>  If specified, extract only entries that match\n"
	"  -k    Keep (don't overwrite) existing files\n"
	"  -m    Don't restore modification times\n"
	"  -O    Write entries to stdout, don't restore to disk\n"
	"  -p    Restore permissions (including ACLs, owner, file flags)\n";


/*
 * Note that the word 'bsdtar' will always appear in the first line
 * of output.
 *
 * In particular, /bin/sh scripts that need to test for the presence
 * of bsdtar can use the following template:
 *
 * if (tar --help 2>&1 | grep bsdtar >/dev/null 2>&1 ) then \
 *          echo bsdtar; else echo not bsdtar; fi
 */
static void
long_help(void)
{
	const char	*prog;
	const char	*p;

	prog = lafe_progname;

	fflush(stderr);

	p = (strcmp(prog,"bsdtar") != 0) ? "(bsdtar)" : "";
	printf("%s%s: manipulate archive files\n", prog, p);

	for (p = long_help_msg; *p != '\0'; p++) {
		if (*p == '%') {
			if (p[1] == 'p') {
				fputs(prog, stdout);
				p++;
			} else
				putchar('%');
		} else
			putchar(*p);
	}
	version();
}