ar_subs.c

早期freebsd实现

		ftree_sel(arcn);
		if (hlk && (chk_lnk(arcn) < 0))
			break;

		if ((arcn->type == PAX_REG) || (arcn->type == PAX_HRG) ||
		    (arcn->type == PAX_CTG)) {
			/*
			 * we will have to read this file. by opening it now we
			 * can avoid writing a header to the archive for a file
			 * we were later unable to read (we also purge it from
			 * the link table).
			 */
			if ((fd = open(arcn->org_name, O_RDONLY, 0)) < 0) {
				syswarn(1,errno, "Unable to open %s to read",
					arcn->org_name);
				purg_lnk(arcn);
				continue;
			}
		}

		/*
		 * Now modify the name as requested by the user
		 */
		if ((res = mod_name(arcn)) < 0) {
			/*
			 * name modification says to skip this file, close the
			 * file and purge link table entry
			 */
			rdfile_close(arcn, &fd);
			purg_lnk(arcn);
			break;
		}

		if ((res > 0) || (docrc && (set_crc(arcn, fd) < 0))) {
			/*
			 * unable to obtain the crc we need, close the file,
			 * purge link table entry 
			 */
			rdfile_close(arcn, &fd);
			purg_lnk(arcn);
			continue;
		}

		if (vflag) {
			(void)fputs(arcn->name, stderr);
			vfpart = 1;
		}
		++flcnt;

		/*
		 * looks safe to store the file, have the format specific
		 * routine write routine store the file header on the archive
		 */
		if ((res = (*wrf)(arcn)) < 0) {
			rdfile_close(arcn, &fd);
			break;
		}
		wr_one = 1;
		if (res > 0) {
			/* 
			 * format write says no file data needs to be stored
			 * so we are done messing with this file
			 */
			if (vflag && vfpart) {
				(void)putc('\n', stderr);
				vfpart = 0;
			}
			rdfile_close(arcn, &fd);
			continue;
		}

		/*
		 * Add file data to the archive, quit on write error. if we
		 * cannot write the entire file contents to the archive we
		 * must pad the archive to replace the missing file data
		 * (otherwise during an extract the file header for the file
		 * which FOLLOWS this one will not be where we expect it to
		 * be).
		 */
		res = (*frmt->wr_data)(arcn, fd, &cnt);
		rdfile_close(arcn, &fd);
		if (vflag && vfpart) {
			(void)putc('\n', stderr);
			vfpart = 0;
		}
		if (res < 0)
			break;

		/*
		 * pad as required, cnt is number of bytes not written
		 */
		if (((cnt > 0) && (wr_skip(cnt) < 0)) ||
		    ((arcn->pad > 0) && (wr_skip(arcn->pad) < 0)))
			break;
	}

	/*
	 * tell format to write trailer; pad to block boundry; reset directory
	 * mode/access times, and check if all patterns supplied by the user
	 * were matched. block off signals to avoid chance for multiple entry
	 * into the cleanup code
	 */
	if (wr_one) {
		(*frmt->end_wr)();
		wr_fin();
	}
	(void)sigprocmask(SIG_BLOCK, &s_mask, (sigset_t *)NULL);
	ar_close();
	if (tflag)
		proc_dir();
	ftree_chk();
}

/*
 * append()
 *	Add file to previously written archive. Archive format specified by the
 *	user must agree with archive. The archive is read first to collect
 *	modification times (if -u) and locate the archive trailer. The archive
 *	is positioned in front of the record with the trailer and wr_archive()
 *	is called to add the new members.
 *	PAX IMPLEMENTATION DETAIL NOTE:
 *	-u is implemented by adding the new members to the end of the archive.
 *	Care is taken so that these do not end up as links to the older 
 *	version of the same file already stored in the archive. It is expected
 *	when extraction occurs these newer versions will over-write the older
 *	ones stored "earlier" in the archive (this may be a bad assumption as
 *	it depends on the implementation of the program doing the extraction).
 *	It is really difficult to splice in members without either re-writing
 *	the entire archive (from the point were the old version was), or having
 *	assistance of the format specification in terms of a special update
 *	header that invalidates a previous archive record. The posix spec left
 *	the method used to implement -u unspecified. This pax is able to
 *	over write existing files that it creates.
 */

#if __STDC__
void
append(void)
#else
void
append()
#endif
{
	register ARCHD *arcn;
	register int res;
	ARCHD archd;
	FSUB *orgfrmt;
	int udev;
	off_t tlen;

	arcn = &archd;
	orgfrmt = frmt;

	/*
	 * Do not allow an append operation if the actual archive is of a
	 * different format than the user specified foramt.
	 */
	if (get_arc() < 0)
		return;
	if ((orgfrmt != NULL) && (orgfrmt != frmt)) {
		warn(1, "Cannot mix current archive format %s with %s",
		    frmt->name, orgfrmt->name);
		return;
	}

	/*
	 * pass the format any options and start up format
	 */
	if (((*frmt->options)() < 0) || ((*frmt->st_rd)() < 0))
		return;

	/*
	 * if we only are adding members that are newer, we need to save the
	 * mod times for all files we see.
	 */
	if (uflag && (ftime_start() < 0))
		return;

	/*
	 * some archive formats encode hard links by recording the device and
	 * file serial number (inode) but copy the file anyway (multiple times)
	 * to the archive. When we append, we run the risk that newly added
	 * files may have the same device and inode numbers as those recorded
	 * on the archive but during a previous run. If this happens, when the
	 * archive is extracted we get INCORRECT hard links. We avoid this by
	 * remapping the device numbers so that newly added files will never
	 * use the same device number as one found on the archive. remapping
	 * allows new members to safely have links among themselves. remapping
	 * also avoids problems with file inode (serial number) truncations
	 * when the inode number is larger than storage space in the archive
	 * header. See the remap routines for more details.
	 */
	if ((udev = frmt->udev) && (dev_start() < 0))
		return;

	/*
	 * reading the archive may take a long time. If verbose tell the user
	 */
	if (vflag) {
		(void)fprintf(stderr,
			"%s: Reading archive to position at the end...", argv0);
		vfpart = 1;
	}

	/*
	 * step through the archive until the format says it is done
	 */
	while (next_head(arcn) == 0) {
		/*
		 * check if this file meets user specified options.
		 */
		if (sel_chk(arcn) != 0) {
			if (rd_skip(arcn->skip + arcn->pad) == 1)
				break;
			continue;
		}

		if (uflag) {
			/*
			 * see if this is the newest version of this file has
			 * already been seen, if so skip.
			 */
			if ((res = chk_ftime(arcn)) < 0)
				break;
			if (res > 0) {
				if (rd_skip(arcn->skip + arcn->pad) == 1)
					break;
				continue;
			}
		}

		/*
		 * Store this device number. Device numbers seen during the
		 * read phase of append will cause newly appended files with a
		 * device number seen in the old part of the archive to be
		 * remapped to an unused device number.
		 */
		if ((udev && (add_dev(arcn) < 0)) ||
		    (rd_skip(arcn->skip + arcn->pad) == 1))
			break;
	}

	/*
	 * done, finish up read and get the number of bytes to back up so we
	 * can add new members. The format might have used the hard link table,
	 * purge it.
	 */
	tlen = (*frmt->end_rd)();
	lnk_end();

	/*
	 * try to postion for write, if this fails quit. if any error occurs,
	 * we will refuse to write
	 */
	if (appnd_start(tlen) < 0)
		return;

	/*
	 * tell the user we are done reading.
	 */
	if (vflag && vfpart) {
		(void)fputs("done.\n", stderr);
		vfpart = 0;
	}
       
	/*
	 * go to the writing phase to add the new members
	 */
	wr_archive(arcn, 1);
}

/*
 * archive()
 *	write a new archive
 */

#if __STDC__
void
archive(void)
#else
void
archive()
#endif
{
	ARCHD archd;

	/*
	 * if we only are adding members that are newer, we need to save the
	 * mod times for all files; set up for writing; pass the format any
	 * options write the archive
	 */
	if ((uflag && (ftime_start() < 0)) || (wr_start() < 0))
		return;
	if ((*frmt->options)() < 0)
		return;

	wr_archive(&archd, 0);
}

/*
 * copy()
 *	copy files from one part of the file system to another. this does not
 *	use any archive storage. The EFFECT OF THE COPY IS THE SAME as if an
 *	archive was written and then extracted in the destination directory
 *	(except the files are forced to be under the destination directory).
 */

#if __STDC__
void
copy(void)
#else
void
copy()
#endif
{
	register ARCHD *arcn;
	register int res;
	register int fddest;
	register char *dest_pt;
	register int dlen;
	register int drem;
	int fdsrc = -1;
	struct stat sb;
	ARCHD archd;
	char dirbuf[PAXPATHLEN+1];

	arcn = &archd;
	/*
	 * set up the destination dir path and make sure it is a directory. We
	 * make sure we have a trailing / on the destination
	 */
	dlen = l_strncpy(dirbuf, dirptr, PAXPATHLEN);
	dest_pt = dirbuf + dlen;
	if (*(dest_pt-1) != '/') {
		*dest_pt++ = '/';
		++dlen;
	}
	*dest_pt = '\0';
	drem = PAXPATHLEN - dlen;

	if (stat(dirptr, &sb) < 0) {
		syswarn(1, errno, "Cannot access destination directory %s",
			dirptr);
		return;
	}
	if (!S_ISDIR(sb.st_mode)) {
		warn(1, "Destination is not a directory %s", dirptr);
		return;
	}

	/*
	 * start up the hard link table; file traversal routines and the
	 * modification time and access mode database 
	 */
	if ((lnk_start() < 0) || (ftree_start() < 0) || (dir_start() < 0))
		return;

	/*
	 * When we are doing interactive rename, we store the mapping of names
	 * so we can fix up hard links files later in the archive.
	 */
	if (iflag && (name_start() < 0))
		return;

	/*
	 * set up to cp file trees
	 */
	cp_start();

	/*
	 * while there are files to archive, process them
	 */
	while (next_file(arcn) == 0) {
		fdsrc = -1;

		/*
		 * check if this file meets user specified options
		 */
		if (sel_chk(arcn) != 0)
			continue;

		/*
		 * if there is already a file in the destination directory with
		 * the same name and it is newer, skip the one stored on the
		 * archive.
		 * NOTE: this test is done BEFORE name modifications as
		 * specified by pax. this can be confusing to the user who
		 * might expect the test to be done on an existing file AFTER
		 * the name mod. In honesty the pax spec is probably flawed in
		 * this respect
		 */
		if (uflag || Dflag) {
			/*
			 * create the destination name
			 */
			if (*(arcn->name) == '/')
				res = 1;
			else
				res = 0;
			if ((arcn->nlen - res) > drem) {
				warn(1, "Destination pathname too long %s",
					arcn->name);
				continue;
			}
			(void)strncpy(dest_pt, arcn->name + res, drem);
			dirbuf[PAXPATHLEN] = '\0';

			/*
			 * if existing file is same age or newer skip
			 */
			res = lstat(dirbuf, &sb);
			*dest_pt = '\0';