examples/minitar/minitar.c

/*-
 * This file is in the public domain.
 * Do with it as you will.
 */

/*-
 * This is a compact "tar" program whose primary goal is small size.
 * Statically linked, it can be very small indeed.  This serves a number
 * of goals:
 *   o a testbed for libarchive (to check for link pollution),
 *   o a useful tool for space-constrained systems (boot floppies, etc),
 *   o a place to experiment with new implementation ideas for bsdtar,
 *   o a small program to demonstrate libarchive usage.
 *
 * Use the following macros to suppress features:
 *   NO_BZIP2 - Implies NO_BZIP2_CREATE and NO_BZIP2_EXTRACT
 *   NO_BZIP2_CREATE - Suppress bzip2 compression support.
 *   NO_BZIP2_EXTRACT - Suppress bzip2 auto-detection and decompression.
 *   NO_COMPRESS - Implies NO_COMPRESS_CREATE and NO_COMPRESS_EXTRACT
 *   NO_COMPRESS_CREATE - Suppress compress(1) compression support
 *   NO_COMPRESS_EXTRACT - Suppress compress(1) auto-detect and decompression.
 *   NO_CREATE - Suppress all archive creation support.
 *   NO_CPIO_EXTRACT - Suppress auto-detect and dearchiving of cpio archives.
 *   NO_GZIP - Implies NO_GZIP_CREATE and NO_GZIP_EXTRACT
 *   NO_GZIP_CREATE - Suppress gzip compression support.
 *   NO_GZIP_EXTRACT - Suppress gzip auto-detection and decompression.
 *   NO_LOOKUP - Try to avoid getpw/getgr routines, which can be very large
 *   NO_TAR_EXTRACT - Suppress tar extraction
 *
 * With all of the above macros defined (except NO_TAR_EXTRACT), you
 * get a very small program that can recognize and extract essentially
 * any uncompressed tar archive.  On FreeBSD 5.1, this minimal program
 * is under 64k, statically linked, which compares rather favorably to
 *         main(){printf("hello, world");}
 * which is over 60k statically linked on the same operating system.
 * Without any of the above macros, you get a static executable of
 * about 180k with a lot of very sophisticated modern features.
 * Obviously, it's trivial to add support for ISO, Zip, mtree,
 * lzma/xz, etc.  Just fill in the appropriate setup calls.
 */

#include <sys/types.h>
#include <sys/stat.h>

#include <archive.h>
#include <archive_entry.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/*
 * NO_CREATE implies NO_BZIP2_CREATE and NO_GZIP_CREATE and NO_COMPRESS_CREATE.
 */
#ifdef NO_CREATE
#undef NO_BZIP2_CREATE
#define NO_BZIP2_CREATE
#undef NO_COMPRESS_CREATE
#define	NO_COMPRESS_CREATE
#undef NO_GZIP_CREATE
#define NO_GZIP_CREATE
#endif

/*
 * The combination of NO_BZIP2_CREATE and NO_BZIP2_EXTRACT is
 * equivalent to NO_BZIP2.
 */
#ifdef NO_BZIP2_CREATE
#ifdef NO_BZIP2_EXTRACT
#undef NO_BZIP2
#define NO_BZIP2
#endif
#endif

#ifdef NO_BZIP2
#undef NO_BZIP2_EXTRACT
#define NO_BZIP2_EXTRACT
#undef NO_BZIP2_CREATE
#define NO_BZIP2_CREATE
#endif

/*
 * The combination of NO_COMPRESS_CREATE and NO_COMPRESS_EXTRACT is
 * equivalent to NO_COMPRESS.
 */
#ifdef NO_COMPRESS_CREATE
#ifdef NO_COMPRESS_EXTRACT
#undef NO_COMPRESS
#define NO_COMPRESS
#endif
#endif

#ifdef NO_COMPRESS
#undef NO_COMPRESS_EXTRACT
#define NO_COMPRESS_EXTRACT
#undef NO_COMPRESS_CREATE
#define NO_COMPRESS_CREATE
#endif

/*
 * The combination of NO_GZIP_CREATE and NO_GZIP_EXTRACT is
 * equivalent to NO_GZIP.
 */
#ifdef NO_GZIP_CREATE
#ifdef NO_GZIP_EXTRACT
#undef NO_GZIP
#define NO_GZIP
#endif
#endif

#ifdef NO_GZIP
#undef NO_GZIP_EXTRACT
#define NO_GZIP_EXTRACT
#undef NO_GZIP_CREATE
#define NO_GZIP_CREATE
#endif

#ifndef NO_CREATE
static void	create(const char *filename, int compress, const char **argv);
#endif
static void	errmsg(const char *);
static void	extract(const char *filename, int do_extract, int flags);
static int	copy_data(struct archive *, struct archive *);
static void	msg(const char *);
static void	usage(void);

static int verbose = 0;

int
main(int argc, const char **argv)
{
	const char *filename = NULL;
	int compress, flags, mode, opt;

	(void)argc;
	mode = 'x';
	verbose = 0;
	compress = '\0';
	flags = ARCHIVE_EXTRACT_TIME;

	/* Among other sins, getopt(3) pulls in printf(3). */
	while (*++argv != NULL && **argv == '-') {
		const char *p = *argv + 1;

		while ((opt = *p++) != '\0') {
			switch (opt) {
#ifndef NO_CREATE
			case 'c':
				mode = opt;
				break;
#endif
			case 'f':
				if (*p != '\0')
					filename = p;
				else
					filename = *++argv;
				p += strlen(p);
				break;
#ifndef NO_BZIP2_CREATE
			case 'j':
				compress = opt;
				break;
#endif
			case 'p':
				flags |= ARCHIVE_EXTRACT_PERM;
				flags |= ARCHIVE_EXTRACT_ACL;
				flags |= ARCHIVE_EXTRACT_FFLAGS;
				break;
			case 't':
				mode = opt;
				break;
			case 'v':
				verbose++;
				break;
			case 'x':
				mode = opt;
				break;
#ifndef NO_BZIP2_CREATE
			case 'y':
				compress = opt;
				break;
#endif
#ifndef NO_COMPRESS_CREATE
			case 'Z':
				compress = opt;
				break;
#endif
#ifndef NO_GZIP_CREATE
			case 'z':
				compress = opt;
				break;
#endif
			default:
				usage();
			}
		}
	}

	switch (mode) {
#ifndef NO_CREATE
	case 'c':
		create(filename, compress, argv);
		break;
#endif
	case 't':
		extract(filename, 0, flags);
		break;
	case 'x':
		extract(filename, 1, flags);
		break;
	}

	return (0);
}


#ifndef NO_CREATE
static char buff[16384];

static void
create(const char *filename, int compress, const char **argv)
{
	struct archive *a;
	struct archive_entry *entry;
	ssize_t len;
	int fd;

	a = archive_write_new();
	switch (compress) {
#ifndef NO_BZIP2_CREATE
	case 'j': case 'y':
		archive_write_add_filter_bzip2(a);
		break;
#endif
#ifndef NO_COMPRESS_CREATE
	case 'Z':
		archive_write_add_filter_compress(a);
		break;
#endif
#ifndef NO_GZIP_CREATE
	case 'z':
		archive_write_add_filter_gzip(a);
		break;
#endif
	default:
		archive_write_add_filter_none(a);
		break;
	}
	archive_write_set_format_ustar(a);
	if (filename != NULL && strcmp(filename, "-") == 0)
		filename = NULL;
	archive_write_open_filename(a, filename);

	while (*argv != NULL) {
		struct archive *disk = archive_read_disk_new();
#ifndef NO_LOOKUP
		archive_read_disk_set_standard_lookup(disk);
#endif
		int r;

		r = archive_read_disk_open(disk, *argv);
		if (r != ARCHIVE_OK) {
			errmsg(archive_error_string(disk));
			errmsg("\n");
			exit(1);
		}

		for (;;) {
			int needcr = 0;

			entry = archive_entry_new();
			r = archive_read_next_header2(disk, entry);
			if (r == ARCHIVE_EOF)
				break;
			if (r != ARCHIVE_OK) {
				errmsg(archive_error_string(disk));
				errmsg("\n");
				exit(1);
			}
			archive_read_disk_descend(disk);
			if (verbose) {
				msg("a ");
				msg(archive_entry_pathname(entry));
				needcr = 1;
			}
			r = archive_write_header(a, entry);
			if (r < ARCHIVE_OK) {
				errmsg(": ");
				errmsg(archive_error_string(a));
				needcr = 1;
			}
			if (r == ARCHIVE_FATAL)
				exit(1);
			if (r > ARCHIVE_FAILED) {
#if 0
				/* Ideally, we would be able to use
				 * the same code to copy a body from
				 * an archive_read_disk to an
				 * archive_write that we use for
				 * copying data from an archive_read
				 * to an archive_write_disk.
				 * Unfortunately, this doesn't quite
				 * work yet. */
				copy_data(disk, a);
#else
				/* For now, we use a simpler loop to copy data
				 * into the target archive. */
				fd = open(archive_entry_sourcepath(entry), O_RDONLY);
				len = read(fd, buff, sizeof(buff));
				while (len > 0) {
					archive_write_data(a, buff, len);
					len = read(fd, buff, sizeof(buff));
				}
				close(fd);
#endif
			}
			archive_entry_free(entry);
			if (needcr)
				msg("\n");
		}
		archive_read_close(disk);
		archive_read_free(disk);
		argv++;
	}
	archive_write_close(a);
	archive_write_free(a);
}
#endif

static void
extract(const char *filename, int do_extract, int flags)
{
	struct archive *a;
	struct archive *ext;
	struct archive_entry *entry;
	int r;

	a = archive_read_new();
	ext = archive_write_disk_new();
	archive_write_disk_set_options(ext, flags);
#ifndef NO_BZIP2_EXTRACT
	archive_read_support_filter_bzip2(a);
#endif
#ifndef NO_GZIP_EXTRACT
	archive_read_support_filter_gzip(a);
#endif
#ifndef NO_COMPRESS_EXTRACT
	archive_read_support_filter_compress(a);
#endif
#ifndef NO_TAR_EXTRACT
	archive_read_support_format_tar(a);
#endif
#ifndef NO_CPIO_EXTRACT
	archive_read_support_format_cpio(a);
#endif
#ifndef NO_LOOKUP
	archive_write_disk_set_standard_lookup(ext);
#endif
	if (filename != NULL && strcmp(filename, "-") == 0)
		filename = NULL;
	if ((r = archive_read_open_filename(a, filename, 10240))) {
		errmsg(archive_error_string(a));
		errmsg("\n");
		exit(r);
	}
	for (;;) {
		int needcr = 0;
		r = archive_read_next_header(a, &entry);
		if (r == ARCHIVE_EOF)
			break;
		if (r != ARCHIVE_OK) {
			errmsg(archive_error_string(a));
			errmsg("\n");
			exit(1);
		}
		if (verbose && do_extract)
			msg("x ");
		if (verbose || !do_extract) {
			msg(archive_entry_pathname(entry));
			msg(" ");
			needcr = 1;
		}
		if (do_extract) {
			r = archive_write_header(ext, entry);
			if (r != ARCHIVE_OK) {
				errmsg(archive_error_string(a));
				needcr = 1;
			}
			else {
				r = copy_data(a, ext);
				if (r != ARCHIVE_OK)
					needcr = 1;
			}
		}
		if (needcr)
			msg("\n");
	}
	archive_read_close(a);
	archive_read_free(a);
	exit(0);
}

static int
copy_data(struct archive *ar, struct archive *aw)
{
	int r;
	const void *buff;
	size_t size;
	int64_t offset;

	for (;;) {
		r = archive_read_data_block(ar, &buff, &size, &offset);
		if (r == ARCHIVE_EOF)
			return (ARCHIVE_OK);
		if (r != ARCHIVE_OK) {
			errmsg(archive_error_string(ar));
			return (r);
		}
		r = archive_write_data_block(aw, buff, size, offset);
		if (r != ARCHIVE_OK) {
			errmsg(archive_error_string(ar));
			return (r);
		}
	}
}

static void
msg(const char *m)
{
	write(1, m, strlen(m));
}

static void
errmsg(const char *m)
{
	if (m == NULL) {
		m = "Error: No error description provided.\n";
	}
	write(2, m, strlen(m));
}

static void
usage(void)
{
/* Many program options depend on compile options. */
	const char *m = "Usage: minitar [-"
#ifndef NO_CREATE
	    "c"
#endif
#ifndef	NO_BZIP2
	    "j"
#endif
	    "tvx"
#ifndef NO_BZIP2
	    "y"
#endif
#ifndef NO_COMPRESS
	    "Z"
#endif
#ifndef NO_GZIP
	    "z"
#endif
	    "] [-f file] [file]\n";

	errmsg(m);
	exit(1);
}