tar.c

早期freebsd实现

/*-
 * Copyright (c) 1992 Keith Muller.
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Keith Muller of the University of California, San Diego.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 */

#ifndef lint
static char sccsid[] = "@(#)tar.c	8.2 (Berkeley) 4/18/94";
#endif /* not lint */

#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <unistd.h>
#include <stdlib.h>
#include "pax.h"
#include "extern.h"
#include "tar.h"

/*
 * Routines for reading, writing and header identify of various versions of tar
 */

static u_long tar_chksm __P((register char *, register int));
static char *name_split __P((register char *, register int));
static int ul_oct __P((u_long, register char *, register int, int));
#ifndef NET2_STAT
static int uqd_oct __P((u_quad_t, register char *, register int, int));
#endif

/*
 * Routines common to all versions of tar
 */

static int tar_nodir;			/* do not write dirs under old tar */

/*
 * tar_endwr()
 *	add the tar trailer of two null blocks
 * Return:
 *	0 if ok, -1 otherwise (what wr_skip returns)
 */

#if __STDC__
int
tar_endwr(void)
#else
int
tar_endwr()
#endif
{
	return(wr_skip((off_t)(NULLCNT*BLKMULT)));
}

/*
 * tar_endrd()
 *	no cleanup needed here, just return size of trailer (for append)
 * Return:
 *	size of trailer (2 * BLKMULT)
 */

#if __STDC__
off_t
tar_endrd(void)
#else
off_t
tar_endrd()
#endif
{
	return((off_t)(NULLCNT*BLKMULT));
}

/*
 * tar_trail()
 *	Called to determine if a header block is a valid trailer. We are passed
 *	the block, the in_sync flag (which tells us we are in resync mode;
 *	looking for a valid header), and cnt (which starts at zero) which is
 *	used to count the number of empty blocks we have seen so far.
 * Return:
 *	0 if a valid trailer, -1 if not a valid trailer, or 1 if the block
 *	could never contain a header.
 */

#if __STDC__
int
tar_trail(register char *buf, register int in_resync, register int *cnt)
#else
int
tar_trail(buf, in_resync, cnt)
	register char *buf;
	register int in_resync;
	register int *cnt;
#endif
{
	register int i;

	/*
	 * look for all zero, trailer is two consecutive blocks of zero
	 */
	for (i = 0; i < BLKMULT; ++i) {
		if (buf[i] != '\0')
			break;
	}

	/*
	 * if not all zero it is not a trailer, but MIGHT be a header.
	 */
	if (i != BLKMULT)
		return(-1);

	/*
	 * When given a zero block, we must be careful!
	 * If we are not in resync mode, check for the trailer. Have to watch
	 * out that we do not mis-identify file data as the trailer, so we do
	 * NOT try to id a trailer during resync mode. During resync mode we
	 * might as well throw this block out since a valid header can NEVER be
	 * a block of all 0 (we must have a valid file name).
	 */
	if (!in_resync && (++*cnt >= NULLCNT))
		return(0);
	return(1);
}

/*
 * ul_oct()
 *	convert an unsigned long to an octal string. many oddball field
 *	termination characters are used by the various versions of tar in the
 *	different fields. term selects which kind to use. str is BLANK padded
 *	at the front to len. we are unable to use only one format as many old
 *	tar readers are very cranky about this.
 * Return:
 *	0 if the number fit into the string, -1 otherwise
 */

#if __STDC__
static int
ul_oct(u_long val, register char *str, register int len, int term)
#else
static int
ul_oct(val, str, len, term)
	u_long val;
	register char *str;
	register int len;
	int term;
#endif
{
	register char *pt;
	
	/*
	 * term selects the appropriate character(s) for the end of the string
	 */
	pt = str + len - 1;
	switch(term) {
	case 3:
		*pt-- = '\0';
		break;
	case 2:
		*pt-- = ' ';
		*pt-- = '\0';
		break;
	case 1:
		*pt-- = ' ';
		break;
	case 0:
	default:
		*pt-- = '\0';
		*pt-- = ' ';
		break;
	}

	/*
	 * convert and blank pad if there is space
	 */
	while (pt >= str) {
		*pt-- = '0' + (char)(val & 0x7);
		if ((val = val >> 3) == (u_long)0)
			break;
	}

	while (pt >= str)
		*pt-- = ' ';
	if (val != (u_long)0)
		return(-1);
	return(0);
}

#ifndef NET2_STAT
/*
 * uqd_oct()
 *	convert an u_quad_t to an octal string. one of many oddball field
 *	termination characters are used by the various versions of tar in the
 *	different fields. term selects which kind to use. str is BLANK padded
 *	at the front to len. we are unable to use only one format as many old
 *	tar readers are very cranky about this.
 * Return:
 *	0 if the number fit into the string, -1 otherwise
 */

#if __STDC__
static int
uqd_oct(u_quad_t val, register char *str, register int len, int term)
#else
static int
uqd_oct(val, str, len, term)
	u_quad_t val;
	register char *str;
	register int len;
	int term;
#endif
{
	register char *pt;
	
	/*
	 * term selects the appropriate character(s) for the end of the string
	 */
	pt = str + len - 1;
	switch(term) {
	case 3:
		*pt-- = '\0';
		break;
	case 2:
		*pt-- = ' ';
		*pt-- = '\0';
		break;
	case 1:
		*pt-- = ' ';
		break;
	case 0:
	default:
		*pt-- = '\0';
		*pt-- = ' ';
		break;
	}

	/*
	 * convert and blank pad if there is space
	 */
	while (pt >= str) {
		*pt-- = '0' + (char)(val & 0x7);
		if ((val = val >> 3) == 0)
			break;
	}

	while (pt >= str)
		*pt-- = ' ';
	if (val != (u_quad_t)0)
		return(-1);
	return(0);
}
#endif

/*
 * tar_chksm()
 *	calculate the checksum for a tar block counting the checksum field as
 *	all blanks (BLNKSUM is that value pre-calculated, the sume of 8 blanks).
 *	NOTE: we use len to short circuit summing 0's on write since we ALWAYS
 *	pad headers with 0.
 * Return:
 *	unsigned long checksum
 */

#if __STDC__
static u_long
tar_chksm(register char *blk, register int len)
#else
static u_long
tar_chksm(blk, len)
	register char *blk;
	register int len;
#endif
{
	register char *stop;
	register char *pt;
	u_long chksm = BLNKSUM;	/* inital value is checksum field sum */

	/*
	 * add the part of the block before the checksum field
	 */
	pt = blk;
	stop = blk + CHK_OFFSET;
	while (pt < stop)	
		chksm += (u_long)(*pt++ & 0xff);	
	/*
	 * move past the checksum field and keep going, spec counts the
	 * checksum field as the sum of 8 blanks (which is pre-computed as
	 * BLNKSUM).
	 * ASSUMED: len is greater than CHK_OFFSET. (len is where our 0 padding
	 * starts, no point in summing zero's)
	 */
	pt += CHK_LEN;
	stop = blk + len;
	while (pt < stop)
		chksm += (u_long)(*pt++ & 0xff);	
	return(chksm);
}

/*
 * Routines for old BSD style tar (also made portable to sysV tar)
 */

/*
 * tar_id()
 *	determine if a block given to us is a valid tar header (and not a USTAR
 *	header). We have to be on the lookout for those pesky blocks of	all
 *	zero's.
 * Return:
 *	0 if a tar header, -1 otherwise
 */

#if __STDC__
int
tar_id(register char *blk, int size)
#else
int
tar_id(blk, size)
	register char *blk;
	int size;
#endif
{
	register HD_TAR *hd;
	register HD_USTAR *uhd;

	if (size < BLKMULT)
		return(-1);
	hd = (HD_TAR *)blk;
	uhd = (HD_USTAR *)blk;

	/*
	 * check for block of zero's first, a simple and fast test, then make
	 * sure this is not a ustar header by looking for the ustar magic
	 * cookie. We should use TMAGLEN, but some USTAR archive programs are
	 * wrong and create archives missing the \0. Last we check the
	 * checksum. If this is ok we have to assume it is a valid header.
	 */
	if (hd->name[0] == '\0')
		return(-1);
	if (strncmp(uhd->magic, TMAGIC, TMAGLEN - 1) == 0)
		return(-1);
	if (asc_ul(hd->chksum,sizeof(hd->chksum),OCT) != tar_chksm(blk,BLKMULT))
		return(-1);
	return(0);
}

/*
 * tar_opt()
 *	handle tar format specific -o options
 * Return:
 *	0 if ok -1 otherwise
 */

#if __STDC__
int
tar_opt(void)
#else
int
tar_opt()
#endif
{
	OPLIST *opt;

	while ((opt = opt_next()) != NULL) {
		if (strcmp(opt->name, TAR_OPTION) ||
		    strcmp(opt->value, TAR_NODIR)) {
			warn(1, "Unknown tar format -o option/value pair %s=%s",
			    opt->name, opt->value);
			warn(1,"%s=%s is the only supported tar format option",
			    TAR_OPTION, TAR_NODIR);
			return(-1);
		}

		/*
		 * we only support one option, and only when writing
		 */
		if ((act != APPND) && (act != ARCHIVE)) {
			warn(1, "%s=%s is only supported when writing.",
			    opt->name, opt->value);
			return(-1);
		}
		tar_nodir = 1;
	}
	return(0);
}


/*
 * tar_rd()
 *	extract the values out of block already determined to be a tar header.
 *	store the values in the ARCHD parameter.
 * Return:
 *	0
 */

#if __STDC__
int
tar_rd(register ARCHD *arcn, register char *buf)
#else
int
tar_rd(arcn, buf)
	register ARCHD *arcn;
	register char *buf;
#endif
{
	register HD_TAR *hd;
	register char *pt;

	/*
	 * we only get proper sized buffers passed to us
	 */
	if (tar_id(buf, BLKMULT) < 0)
		return(-1);
	arcn->org_name = arcn->name;
	arcn->sb.st_nlink = 1;
	arcn->pat = NULL;

	/*
	 * copy out the name and values in the stat buffer
	 */
	hd = (HD_TAR *)buf;
	arcn->nlen = l_strncpy(arcn->name, hd->name, sizeof(hd->name));
	arcn->name[arcn->nlen] = '\0';
	arcn->sb.st_mode = (mode_t)(asc_ul(hd->mode,sizeof(hd->mode),OCT) &
	    0xfff);
	arcn->sb.st_uid = (uid_t)asc_ul(hd->uid, sizeof(hd->uid), OCT);
	arcn->sb.st_gid = (gid_t)asc_ul(hd->gid, sizeof(hd->gid), OCT);
	arcn->sb.st_size = (size_t)asc_ul(hd->size, sizeof(hd->size), OCT);
	arcn->sb.st_mtime = (time_t)asc_ul(hd->mtime, sizeof(hd->mtime), OCT);
	arcn->sb.st_ctime = arcn->sb.st_atime = arcn->sb.st_mtime;

	/*
	 * have to look at the last character, it may be a '/' and that is used
	 * to encode this as a directory
	 */
	pt = &(arcn->name[arcn->nlen - 1]);
	arcn->pad = 0;
	arcn->skip = 0;
	switch(hd->linkflag) {
	case SYMTYPE:
		/*
		 * symbolic link, need to get the link name and set the type in
		 * the st_mode so -v printing will look correct.
		 */
		arcn->type = PAX_SLK;
		arcn->ln_nlen = l_strncpy(arcn->ln_name, hd->linkname,
			sizeof(hd->linkname));
		arcn->ln_name[arcn->ln_nlen] = '\0';
		arcn->sb.st_mode |= S_IFLNK;
		break;
	case LNKTYPE:
		/*
		 * hard link, need to get the link name, set the type in the
		 * st_mode and st_nlink so -v printing will look better.
		 */
		arcn->type = PAX_HLK;
		arcn->sb.st_nlink = 2;
		arcn->ln_nlen = l_strncpy(arcn->ln_name, hd->linkname,
			sizeof(hd->linkname));
		arcn->ln_name[arcn->ln_nlen] = '\0';

		/*
		 * no idea of what type this thing really points at, but
		 * we set something for printing only.
		 */
		arcn->sb.st_mode |= S_IFREG;
		break;
	case AREGTYPE:
	case REGTYPE:
	default:
		/*
		 * If we have a trailing / this is a directory and NOT a file.
		 */
		arcn->ln_name[0] = '\0';
		arcn->ln_nlen = 0;
		if (*pt == '/') {
			/*
			 * it is a directory, set the mode for -v printing
			 */
			arcn->type = PAX_DIR;
			arcn->sb.st_mode |= S_IFDIR;
			arcn->sb.st_nlink = 2;
		} else {
			/*
			 * have a file that will be followed by data. Set the
			 * skip value to the size field and caluculate the size
			 * of the padding.
			 */
			arcn->type = PAX_REG;
			arcn->sb.st_mode |= S_IFREG;
			arcn->pad = TAR_PAD(arcn->sb.st_size);
			arcn->skip = arcn->sb.st_size;
		}
		break;
	}

	/*
	 * strip off any trailing slash.
	 */
	if (*pt == '/') {
		*pt = '\0'; 
		--arcn->nlen;
	}
	return(0);
}

/*
 * tar_wr()
 *	write a tar header for the file specified in the ARCHD to the archive.
 *	Have to check for file types that cannot be stored and file names that
 *	are too long. Be careful of the term (last arg) to ul_oct, each field
 *	of tar has it own spec for the termination character(s).
 *	ASSUMED: space after header in header block is zero filled
 * Return:
 *	0 if file has data to be written after the header, 1 if file has NO
 *	data to write after the header, -1 if archive write failed
 */

#if __STDC__
int
tar_wr(register ARCHD *arcn)
#else
int
tar_wr(arcn)
	register ARCHD *arcn;
#endif
{
	register HD_TAR *hd;
	int len;
	char hdblk[sizeof(HD_TAR)];

	/*
	 * check for those file system types which tar cannot store
	 */
	switch(arcn->type) {
	case PAX_DIR:
		/*
		 * user asked that dirs not be written to the archive
		 */
		if (tar_nodir)
			return(1);
		break;
	case PAX_CHR:
		warn(1, "Tar cannot archive a character device %s",
		    arcn->org_name);
		return(1);
	case PAX_BLK:
		warn(1, "Tar cannot archive a block device %s", arcn->org_name);
		return(1);
	case PAX_SCK:
		warn(1, "Tar cannot archive a socket %s", arcn->org_name);
		return(1);
	case PAX_FIF:
		warn(1, "Tar cannot archive a fifo %s", arcn->org_name);
		return(1);
	case PAX_SLK:
	case PAX_HLK:
	case PAX_HRG:
		if (arcn->ln_nlen > sizeof(hd->linkname)) {
			warn(1,"Link name too long for tar %s", arcn->ln_name);
			return(1);
		}
		break;
	case PAX_REG:
	case PAX_CTG: