ar_subs.c

早期freebsd实现

		    	if (res == 0) {
				if (uflag && Dflag) {
					if ((arcn->sb.st_mtime<=sb.st_mtime) &&
			    		    (arcn->sb.st_ctime<=sb.st_ctime))
						continue;
				} else if (Dflag) {
					if (arcn->sb.st_ctime <= sb.st_ctime)
						continue;
				} else if (arcn->sb.st_mtime <= sb.st_mtime)
					continue;
			}
		}

		/*
		 * this file is considered selected. See if this is a hard link
		 * to a previous file; modify the name as requested by the
		 * user; set the final destination.
		 */
		ftree_sel(arcn);
		if ((chk_lnk(arcn) < 0) || ((res = mod_name(arcn)) < 0))
			break;
		if ((res > 0) || (set_dest(arcn, dirbuf, dlen) < 0)) {
			/*
			 * skip file, purge from link table
			 */
			purg_lnk(arcn);
			continue;
		}

		/*
		 * Non standard -Y and -Z flag. When the exisiting file is
		 * same age or newer skip
		 */
		if ((Yflag || Zflag) && ((lstat(arcn->name, &sb) == 0))) {
			if (Yflag && Zflag) {
				if ((arcn->sb.st_mtime <= sb.st_mtime) &&
				    (arcn->sb.st_ctime <= sb.st_ctime))
					continue;
			} else if (Yflag) {
				if (arcn->sb.st_ctime <= sb.st_ctime)
					continue;
			} else if (arcn->sb.st_mtime <= sb.st_mtime)
				continue;
		}

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

		/*
		 * try to create a hard link to the src file if requested
		 * but make sure we are not trying to overwrite ourselves.
		 */
		if (lflag) 
			res = cross_lnk(arcn);
		else
			res = chk_same(arcn);
		if (res <= 0) {
			if (vflag && vfpart) {
				(void)putc('\n', stderr);
				vfpart = 0;
			}
			continue;
		}

		/*
		 * have to create a new file
		 */
		if ((arcn->type != PAX_REG) && (arcn->type != PAX_CTG)) {
			/*
			 * create a link or special file
			 */
			if ((arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
				res = lnk_creat(arcn);
			else
				res = node_creat(arcn);
			if (res < 0)
				purg_lnk(arcn);
			if (vflag && vfpart) {
				(void)putc('\n', stderr);
				vfpart = 0;
			}
			continue;
		}

		/*
		 * have to copy a regular file to the destination directory.
		 * first open source file and then create the destination file
		 */
		if ((fdsrc = open(arcn->org_name, O_RDONLY, 0)) < 0) {
			syswarn(1, errno, "Unable to open %s to read",
			    arcn->org_name);
			purg_lnk(arcn);
			continue;
		}
		if ((fddest = file_creat(arcn)) < 0) {
			rdfile_close(arcn, &fdsrc);
			purg_lnk(arcn);
			continue;
		}

		/*
		 * copy source file data to the destination file
		 */
		cp_file(arcn, fdsrc, fddest);
		file_close(arcn, fddest);
		rdfile_close(arcn, &fdsrc);

		if (vflag && vfpart) {
			(void)putc('\n', stderr);
			vfpart = 0;
		}
	}

	/*
	 * restore directory modes and times as required; make sure all
	 * patterns were selected block off signals to avoid chance for
	 * multiple entry into the cleanup code.
	 */
	(void)sigprocmask(SIG_BLOCK, &s_mask, (sigset_t *)NULL);
	ar_close();
	proc_dir();
	ftree_chk();
}

/*
 * next_head()
 *	try to find a valid header in the archive. Uses format specific
 *	routines to extract the header and id the trailer. Trailers may be
 *	located within a valid header or in an invalid header (the location
 *	is format specific. The inhead field from the option table tells us
 *	where to look for the trailer).
 *	We keep reading (and resyncing) until we get enough contiguous data
 *	to check for a header. If we cannot find one, we shift by a byte
 *	add a new byte from the archive to the end of the buffer and try again.
 *	If we get a read error, we throw out what we have (as we must have
 *	contiguous data) and start over again.
 *	ASSUMED: headers fit within a BLKMULT header.
 * Return:
 *	0 if we got a header, -1 if we are unable to ever find another one
 *	(we reached the end of input, or we reached the limit on retries. see
 *	the specs for rd_wrbuf() for more details)
 */

#if __STDC__
static int
next_head(register ARCHD *arcn)
#else
static int
next_head(arcn)
	register ARCHD *arcn;
#endif
{
	register int ret;
	register char *hdend;
	register int res;
	register int shftsz;
	register int hsz;
	register int in_resync = 0; 	/* set when we are in resync mode */
	int cnt = 0;			/* counter for trailer function */
	
	/*
	 * set up initial conditions, we want a whole frmt->hsz block as we
	 * have no data yet.
	 */
	res = hsz = frmt->hsz;
	hdend = hdbuf;
	shftsz = hsz - 1;
	for(;;) {
		/*
		 * keep looping until we get a contiguous FULL buffer
		 * (frmt->hsz is the proper size)
		 */
		for (;;) {
			if ((ret = rd_wrbuf(hdend, res)) == res)
				break;

			/*
			 * some kind of archive read problem, try to resync the
			 * storage device, better give the user the bad news.
			 */
			if ((ret == 0) || (rd_sync() < 0)) {
				warn(1,"Premature end of file on archive read");
				return(-1);
			}
			if (!in_resync) {
				if (act == APPND) {
					warn(1,
				          "Archive I/O error, cannot continue");
					return(-1);
				}
				warn(1,"Archive I/O error. Trying to recover.");
				++in_resync;
			}

			/*
			 * oh well, throw it all out and start over
			 */
			res = hsz;
			hdend = hdbuf;
		}

		/*
		 * ok we have a contiguous buffer of the right size. Call the
		 * format read routine. If this was not a valid header and this
		 * format stores trailers outside of the header, call the
		 * format specific trailer routine to check for a trailer. We
		 * have to watch out that we do not mis-identify file data or
		 * block padding as a header or trailer. Format specific
		 * trailer functions must NOT check for the trailer while we
		 * are running in resync mode. Some trailer functions may tell
		 * us that this block cannot contain a valid header either, so
		 * we then throw out the entire block and start over.
		 */
		if ((*frmt->rd)(arcn, hdbuf) == 0)
			break;

		if (!frmt->inhead) {
			/*
			 * this format has trailers outside of valid headers
			 */
			if ((ret = (*frmt->trail)(hdbuf,in_resync,&cnt)) == 0){
				/*
				 * valid trailer found, drain input as required
				 */
				ar_drain();
				return(-1);
			}

			if (ret == 1) {
				/*
				 * we are in resync and we were told to throw
				 * the whole block out because none of the
				 * bytes in this block can be used to form a
				 * valid header
				 */
				res = hsz;
				hdend = hdbuf;
				continue;
			}
		}

		/*
		 * Brute force section.
		 * not a valid header. We may be able to find a header yet. So
		 * we shift over by one byte, and set up to read one byte at a
		 * time from the archive and place it at the end of the buffer.
		 * We will keep moving byte at a time until we find a header or
		 * get a read error and have to start over.
		 */
		if (!in_resync) {
			if (act == APPND) {
				warn(1,"Unable to append, archive header flaw");
				return(-1);
			}
			warn(1,"Invalid header, starting valid header search.");
			++in_resync;
		}
		bcopy(hdbuf+1, hdbuf, shftsz);
		res = 1;
		hdend = hdbuf + shftsz;
	}

	/*
	 * ok got a valid header, check for trailer if format encodes it in the
	 * the header. NOTE: the parameters are different than trailer routines
	 * which encode trailers outside of the header!
	 */
	if (frmt->inhead && ((*frmt->trail)(arcn) == 0)) {
		/*
		 * valid trailer found, drain input as required
		 */
		ar_drain();
		return(-1);
	}

	++flcnt;
	return(0);
}

/*
 * get_arc()
 *	Figure out what format an archive is. Handles archive with flaws by
 *	brute force searches for a legal header in any supported format. The
 *	format id routines have to be careful to NOT mis-identify a format.
 *	ASSUMED: headers fit within a BLKMULT header.
 * Return:
 *	0 if archive found -1 otherwise
 */

#if __STDC__
static int
get_arc(void)
#else
static int
get_arc()
#endif
{
	register int i;
	register int hdsz = 0;
	register int res;
	register int minhd = BLKMULT;
	char *hdend;
	int notice = 0;
	
	/*
	 * find the smallest header size in all archive formats and then set up
	 * to read the archive.
	 */
	for (i = 0; ford[i] >= 0; ++i) {
		if (fsub[ford[i]].hsz < minhd)
			minhd = fsub[ford[i]].hsz;
	}
	if (rd_start() < 0)
		return(-1);
	res = BLKMULT;
	hdsz = 0;
	hdend = hdbuf;
	for(;;) {
		for (;;) {
			/*
			 * fill the buffer with at least the smallest header
			 */
			i = rd_wrbuf(hdend, res);
			if (i > 0)
				hdsz += i;
			if (hdsz >= minhd)
				break;

			/*
			 * if we cannot recover from a read error quit
			 */
			if ((i == 0) || (rd_sync() < 0))
				goto out;

			/*
			 * when we get an error none of the data we already
			 * have can be used to create a legal header (we just
			 * got an error in the middle), so we throw it all out
			 * and refill the buffer with fresh data.
			 */
			res = BLKMULT;
			hdsz = 0;
			hdend = hdbuf;
			if (!notice) {
				if (act == APPND)
					return(-1);
				warn(1,"Cannot identify format. Searching...");
				++notice;
			}
		}

		/*
		 * we have at least the size of the smallest header in any
		 * archive format. Look to see if we have a match. The array
		 * ford[] is used to specify the header id order to reduce the
		 * chance of incorrectly id'ing a valid header (some formats
		 * may be subsets of each other and the order would then be
		 * important).
		 */
		for (i = 0; ford[i] >= 0; ++i) {
			if ((*fsub[ford[i]].id)(hdbuf, hdsz) < 0)
				continue;
			frmt = &(fsub[ford[i]]);
			/* 
			 * yuck, to avoid slow special case code in the extract
			 * routines, just push this header back as if it was
			 * not seen. We have left extra space at start of the
			 * buffer for this purpose. This is a bit ugly, but
			 * adding all the special case code is far worse.
			 */
			pback(hdbuf, hdsz);
			return(0);
		}

		/*
		 * We have a flawed archive, no match. we start searching, but
		 * we never allow additions to flawed archives
		 */
		if (!notice) {
			if (act == APPND)
				return(-1);
			warn(1, "Cannot identify format. Searching...");
			++notice;
		}

		/*
		 * brute force search for a header that we can id.
		 * we shift through byte at a time. this is slow, but we cannot
		 * determine the nature of the flaw in the archive in a
		 * portable manner
		 */
		if (--hdsz > 0) {
			bcopy(hdbuf+1, hdbuf, hdsz);
			res = BLKMULT - hdsz;
			hdend = hdbuf + hdsz;
		} else {
			res = BLKMULT;
			hdend = hdbuf;
			hdsz = 0;
		}
	}

    out:
	/*
	 * we cannot find a header, bow, apologize and quit
	 */
	warn(1, "Sorry, unable to determine archive format.");
	return(-1);
}