/* $OpenBSD: buf_subs.c,v 1.7 1997/09/01 18:29:46 deraadt Exp $ */ /* $NetBSD: buf_subs.c,v 1.5 1995/03/21 09:07:08 cgd Exp $ */ /*- * 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 #if 0 static char sccsid[] = "@(#)buf_subs.c 8.2 (Berkeley) 4/18/94"; #else static char rcsid[] __attribute__((__unused__)) = "$OpenBSD: buf_subs.c,v 1.7 1997/09/01 18:29:46 deraadt Exp $"; #endif #endif /* not lint */ #include <sys/types.h> #include <sys/time.h> #include <sys/stat.h> #include <sys/param.h> #include <stdio.h> #include <errno.h> #include <unistd.h> #include <stdlib.h> #include <string.h> #include "pax.h" #include "extern.h" /* * routines which implement archive and file buffering */ #define MINFBSZ 512 /* default block size for hole detect */ #define MAXFLT 10 /* default media read error limit */ /* * Need to change bufmem to dynamic allocation when the upper * limit on blocking size is removed (though that will violate pax spec) * MAXBLK define and tests will also need to be updated. */ static char bufmem[MAXBLK+BLKMULT]; /* i/o buffer + pushback id space */ static char *buf; /* normal start of i/o buffer */ static char *bufend; /* end or last char in i/o buffer */ static char *bufpt; /* read/write point in i/o buffer */ int blksz = MAXBLK; /* block input/output size in bytes */ int wrblksz; /* user spec output size in bytes */ int maxflt = MAXFLT; /* MAX consecutive media errors */ int rdblksz; /* first read blksize (tapes only) */ off_t wrlimit; /* # of bytes written per archive vol */ off_t wrcnt; /* # of bytes written on current vol */ off_t rdcnt; /* # of bytes read on current vol */ /* * wr_start() * set up the buffering system to operate in a write mode * Return: * 0 if ok, -1 if the user specified write block size violates pax spec */ #ifdef __STDC__ int wr_start(void) #else int wr_start() #endif { buf = &(bufmem[BLKMULT]); /* * Check to make sure the write block size meets pax specs. If the user * does not specify a blocksize, we use the format default blocksize. * We must be picky on writes, so we do not allow the user to create an * archive that might be hard to read elsewhere. If all ok, we then * open the first archive volume */ if (!wrblksz) wrblksz = frmt->bsz; if (wrblksz > MAXBLK) { paxwarn(1, "Write block size of %d too large, maximium is: %d", wrblksz, MAXBLK); return(-1); } if (wrblksz % BLKMULT) { paxwarn(1, "Write block size of %d is not a %d byte multiple", wrblksz, BLKMULT); return(-1); } if (wrblksz > MAXBLK_POSIX) { paxwarn(0, "Write block size of %d larger than POSIX max %d, archive may not be portable", wrblksz, MAXBLK_POSIX); return(-1); } /* * we only allow wrblksz to be used with all archive operations */ blksz = rdblksz = wrblksz; if ((ar_open(arcname) < 0) && (ar_next() < 0)) return(-1); wrcnt = 0; bufend = buf + wrblksz; bufpt = buf; return(0); } /* * rd_start() * set up buffering system to read an archive * Return: * 0 if ok, -1 otherwise */ #ifdef __STDC__ int rd_start(void) #else int rd_start() #endif { /* * leave space for the header pushback (see get_arc()). If we are * going to append and user specified a write block size, check it * right away */ buf = &(bufmem[BLKMULT]); if ((act == APPND) && wrblksz) { if (wrblksz > MAXBLK) { paxwarn(1,"Write block size %d too large, maximium is: %d", wrblksz, MAXBLK); return(-1); } if (wrblksz % BLKMULT) { paxwarn(1, "Write block size %d is not a %d byte multiple", wrblksz, BLKMULT); return(-1); } } /* * open the archive */ if ((ar_open(arcname) < 0) && (ar_next() < 0)) return(-1); bufend = buf + rdblksz; bufpt = bufend; rdcnt = 0; return(0); } /* * cp_start() * set up buffer system for copying within the file system */ #ifdef __STDC__ void cp_start(void) #else void cp_start() #endif { buf = &(bufmem[BLKMULT]); rdblksz = blksz = MAXBLK; } /* * appnd_start() * Set up the buffering system to append new members to an archive that * was just read. The last block(s) of an archive may contain a format * specific trailer. To append a new member, this trailer has to be * removed from the archive. The first byte of the trailer is replaced by * the start of the header of the first file added to the archive. The * format specific end read function tells us how many bytes to move * backwards in the archive to be positioned BEFORE the trailer. Two * different postions have to be adjusted, the O.S. file offset (e.g. the * position of the tape head) and the write point within the data we have * stored in the read (soon to become write) buffer. We may have to move * back several records (the number depends on the size of the archive * record and the size of the format trailer) to read up the record where * the first byte of the trailer is recorded. Trailers may span (and * overlap) record boundries. * We first calculate which record has the first byte of the trailer. We * move the OS file offset back to the start of this record and read it * up. We set the buffer write pointer to be at this byte (the byte where * the trailer starts). We then move the OS file pointer back to the * start of this record so a flush of this buffer will replace the record * in the archive. * A major problem is rewriting this last record. For archives stored * on disk files, this is trival. However, many devices are really picky * about the conditions under which they will allow a write to occur. * Often devices restrict the conditions where writes can be made writes, * so it may not be feasable to append archives stored on all types of * devices. * Return: * 0 for success, -1 for failure */ #ifdef __STDC__ int appnd_start(off_t skcnt) #else int appnd_start(skcnt) off_t skcnt; #endif { register int res; off_t cnt; if (exit_val != 0) { paxwarn(0, "Cannot append to an archive that may have flaws."); return(-1); } /* * if the user did not specify a write blocksize, inherit the size used * in the last archive volume read. (If a is set we still use rdblksz * until next volume, cannot shift sizes within a single volume). */ if (!wrblksz) wrblksz = blksz = rdblksz; else blksz = rdblksz; /* * make sure that this volume allows appends */ if (ar_app_ok() < 0) return(-1); /* * Calculate bytes to move back and move in front of record where we * need to start writing from. Remember we have to add in any padding * that might be in the buffer after the trailer in the last block. We * travel skcnt + padding ROUNDED UP to blksize. */ skcnt += bufend - bufpt; if ((cnt = (skcnt/blksz) * blksz) < skcnt) cnt += blksz; if (ar_rev((off_t)cnt) < 0) goto out; /* * We may have gone too far if there is valid data in the block we are * now in front of, read up the block and position the pointer after * the valid data. */ if ((cnt -= skcnt) > 0) { /* * watch out for stupid tape drives. ar_rev() will set rdblksz * to be real physical blocksize so we must loop until we get * the old rdblksz (now in blksz). If ar_rev() fouls up the * determination of the physical block size, we will fail. */ bufpt = buf; bufend = buf + blksz; while (bufpt < bufend) { if ((res = ar_read(bufpt, rdblksz)) <= 0) goto out; bufpt += res; } if (ar_rev((off_t)(bufpt - buf)) < 0) goto out; bufpt = buf + cnt; bufend = buf + blksz; } else { /* * buffer is empty */ bufend = buf + blksz; bufpt = buf; } rdblksz = blksz; rdcnt -= skcnt; wrcnt = 0; /* * At this point we are ready to write. If the device requires special * handling to write at a point were previously recorded data resides, * that is handled in ar_set_wr(). From now on we operate under normal * ARCHIVE mode (write) conditions */ if (ar_set_wr() < 0) return(-1); act = ARCHIVE; return(0); out: paxwarn(1, "Unable to rewrite archive trailer, cannot append."); return(-1); } /* * rd_sync() * A read error occurred on this archive volume. Resync the buffer and * try to reset the device (if possible) so we can continue to read. Keep * trying to do this until we get a valid read, or we reach the limit on * consecutive read faults (at which point we give up). The user can * adjust the read error limit through a command line option. * Returns: * 0 on success, and -1 on failure */ #ifdef __STDC__ int rd_sync(void) #else int rd_sync() #endif { register int errcnt = 0; register int res; /* * if the user says bail out on first fault, we are out of here... */ if (maxflt == 0) return(-1); if (act == APPND) { paxwarn(1, "Unable to append when there are archive read errors."); return(-1); } /* * poke at device and try to get past media error */ if (ar_rdsync() < 0) { if (ar_next() < 0) return(-1); else rdcnt = 0; } for (;;) { if ((res = ar_read(buf, blksz)) > 0) { /* * All right! got some data, fill that buffer */ bufpt = buf; bufend = buf + res; rdcnt += res; return(0); } /* * Oh well, yet another failed read... * if error limit reached, ditch. o.w. poke device to move past * bad media and try again. if media is badly damaged, we ask * the poor (and upset user at this point) for the next archive * volume. remember the goal on reads is to get the most we * can extract out of the archive. */ if ((maxflt > 0) && (++errcnt > maxflt)) paxwarn(0,"Archive read error limit (%d) reached",maxflt); else if (ar_rdsync() == 0) continue; if (ar_next() < 0) break; rdcnt = 0; errcnt = 0; } return(-1); } /* * pback() * push the data used during the archive id phase back into the I/O * buffer. This is required as we cannot be sure that the header does NOT * overlap a block boundry (as in the case we are trying to recover a * flawed archived). This was not designed to be used for any other * purpose. (What software engineering, HA!) * WARNING: do not even THINK of pback greater than BLKMULT, unless the * pback space is increased. */ #ifdef __STDC__ void pback(char *pt, int cnt) #else void pback(pt, cnt) char *pt; int cnt; #endif { bufpt -= cnt; memcpy(bufpt, pt, cnt); return; } /* * rd_skip() * skip foward in the archive during a archive read. Used to get quickly * past file data and padding for files the user did NOT select. * Return: * 0 if ok, -1 failure, and 1 when EOF on the archive volume was detected. */ #ifdef __STDC__ int rd_skip(off_t skcnt) #else int rd_skip(skcnt) off_t skcnt; #endif { off_t res; off_t cnt; off_t skipped = 0; /* * consume what data we have in the buffer. If we have to move foward * whole records, we call the low level skip function to see if we can * move within the archive without doing the expensive reads on data we * do not want. */ if (skcnt == 0) return(0); res = MIN((bufend - bufpt), skcnt); bufpt += res; skcnt -= res; /* * if skcnt is now 0, then no additional i/o is needed */ if (skcnt == 0) return(0); /* * We have to read more, calculate complete and partial record reads * based on rdblksz. we skip over "cnt" complete records */ res = skcnt%rdblksz; cnt = (skcnt/rdblksz) * rdblksz; /* * if the skip fails, we will have to resync. ar_fow will tell us * how much it can skip over. We will have to read the rest. */ if (ar_fow(cnt, &skipped) < 0) return(-1); res += cnt - skipped; rdcnt += skipped; /* * what is left we have to read (which may be the whole thing if * ar_fow() told us the device can only read to skip records); */ while (res > 0L) { cnt = bufend - bufpt; /* * if the read fails, we will have to resync */ if ((cnt <= 0) && ((cnt = buf_fill()) < 0)) return(-1); if (cnt == 0) return(1); cnt = MIN(cnt, res); bufpt += cnt; res -= cnt; } return(0); } /* * wr_fin() * flush out any data (and pad if required) the last block. We always pad * with zero (even though we do not have to). Padding with 0 makes it a * lot easier to recover if the archive is damaged. zero paddding SHOULD * BE a requirement.... */ #ifdef __STDC__ void wr_fin(void) #else void wr_fin() #endif { if (bufpt > buf) { memset(bufpt, 0, bufend - bufpt); bufpt = bufend; (void)buf_flush(blksz); } } /* * wr_rdbuf() * fill the write buffer from data passed to it in a buffer (usually used * by format specific write routines to pass a file header). On failure we * punt. We do not allow the user to continue to write flawed archives. * We assume these headers are not very large (the memory copy we use is * a bit expensive). * Return: * 0 if buffer was filled ok, -1 o.w. (buffer flush failure) */ #ifdef __STDC__ int wr_rdbuf(register char *out, register int outcnt) #else int wr_rdbuf(out, outcnt) register char *out; register int outcnt; #endif { register int cnt; /* * while there is data to copy copy into the write buffer. when the * write buffer fills, flush it to the archive and continue */ while (outcnt > 0) { cnt = bufend - bufpt; if ((cnt <= 0) && ((cnt = buf_flush(blksz)) < 0)) return(-1); /* * only move what we have space for */ cnt = MIN(cnt, outcnt); memcpy(bufpt, out, cnt); bufpt += cnt; out += cnt; outcnt -= cnt; } return(0); } /* * rd_wrbuf() * copy from the read buffer into a supplied buffer a specified number of * bytes. If the read buffer is empty fill it and continue to copy. * usually used to obtain a file header for processing by a format * specific read routine. * Return * number of bytes copied to the buffer, 0 indicates EOF on archive volume, * -1 is a read error */ #ifdef __STDC__ int rd_wrbuf(register char *in, register int cpcnt) #else int rd_wrbuf(in, cpcnt) register char *in; register int cpcnt; #endif { register int res; register int cnt; register int incnt = cpcnt; /* * loop until we fill the buffer with the requested number of bytes */ while (incnt > 0) { cnt = bufend - bufpt; if ((cnt <= 0) && ((cnt = buf_fill()) <= 0)) { /* * read error, return what we got (or the error if * no data was copied). The caller must know that an * error occured and has the best knowledge what to * do with it */ if ((res = cpcnt - incnt) > 0) return(res); return(cnt); } /* * calculate how much data to copy based on whats left and * state of buffer */ cnt = MIN(cnt, incnt); memcpy(in, bufpt, cnt); bufpt += cnt; incnt -= cnt; in += cnt; } return(cpcnt); } /* * wr_skip() * skip foward during a write. In other words add padding to the file. * we add zero filled padding as it makes flawed archives much easier to * recover from. the caller tells us how many bytes of padding to add * This routine was not designed to add HUGE amount of padding, just small * amounts (a few 512 byte blocks at most) * Return: * 0 if ok, -1 if there was a buf_flush failure */ #ifdef __STDC__ int wr_skip(off_t skcnt) #else int wr_skip(skcnt) off_t skcnt; #endif { register int cnt; /* * loop while there is more padding to add */ while (skcnt > 0L) { cnt = bufend - bufpt; if ((cnt <= 0) && ((cnt = buf_flush(blksz)) < 0)) return(-1); cnt = MIN(cnt, skcnt); memset(bufpt, 0, cnt); bufpt += cnt; skcnt -= cnt; } return(0); } /* * wr_rdfile() * fill write buffer with the contents of a file. We are passed an open * file descriptor to the file an the archive structure that describes the * file we are storing. The variable "left" is modified to contain the * number of bytes of the file we were NOT able to write to the archive. * it is important that we always write EXACTLY the number of bytes that * the format specific write routine told us to. The file can also get * bigger, so reading to the end of file would create an improper archive, * we just detect this case and warn the user. We never create a bad * archive if we can avoid it. Of course trying to archive files that are * active is asking for trouble. It we fail, we pass back how much we * could NOT copy and let the caller deal with it. * Return: * 0 ok, -1 if archive write failure. a short read of the file returns a * 0, but "left" is set to be greater than zero. */ #ifdef __STDC__ int wr_rdfile(ARCHD *arcn, int ifd, off_t *left) #else int wr_rdfile(arcn, ifd, left) ARCHD *arcn; int ifd; off_t *left; #endif { register int cnt; register int res = 0; register off_t size = arcn->sb.st_size; struct stat sb; /* * while there are more bytes to write */ while (size > 0L) { cnt = bufend - bufpt; if ((cnt <= 0) && ((cnt = buf_flush(blksz)) < 0)) { *left = size; return(-1); } cnt = MIN(cnt, size); if ((res = read(ifd, bufpt, cnt)) <= 0) break; size -= res; bufpt += res; } /* * better check the file did not change during this operation * or the file read failed. */ if (res < 0) syswarn(1, errno, "Read fault on %s", arcn->org_name); else if (size != 0L) paxwarn(1, "File changed size during read %s", arcn->org_name); else if (fstat(ifd, &sb) < 0) syswarn(1, errno, "Failed stat on %s", arcn->org_name); else if (arcn->sb.st_mtime != sb.st_mtime) paxwarn(1, "File %s was modified during copy to archive", arcn->org_name); *left = size; return(0); } /* * rd_wrfile() * extract the contents of a file from the archive. If we are unable to * extract the entire file (due to failure to write the file) we return * the numbers of bytes we did NOT process. This way the caller knows how * many bytes to skip past to find the next archive header. If the failure * was due to an archive read, we will catch that when we try to skip. If * the format supplies a file data crc value, we calculate the actual crc * so that it can be compared to the value stored in the header * NOTE: * We call a special function to write the file. This function attempts to * restore file holes (blocks of zeros) into the file. When files are * sparse this saves space, and is a LOT faster. For non sparse files * the performance hit is small. As of this writing, no archive supports * information on where the file holes are. * Return: * 0 ok, -1 if archive read failure. if we cannot write the entire file, * we return a 0 but "left" is set to be the amount unwritten */ #ifdef __STDC__ int rd_wrfile(ARCHD *arcn, int ofd, off_t *left) #else int rd_wrfile(arcn, ofd, left) ARCHD *arcn; int ofd; off_t *left; #endif { register int cnt = 0; register off_t size = arcn->sb.st_size; register int res = 0; register char *fnm = arcn->name; int isem = 1; int rem; int sz = MINFBSZ; struct stat sb; u_long crc = 0L; /* * pass the blocksize of the file being written to the write routine, * if the size is zero, use the default MINFBSZ */ if (fstat(ofd, &sb) == 0) { if (sb.st_blksize > 0) sz = (int)sb.st_blksize; } else syswarn(0,errno,"Unable to obtain block size for file %s",fnm); rem = sz; *left = 0L; /* * Copy the archive to the file the number of bytes specified. We have * to assume that we want to recover file holes as none of the archive * formats can record the location of file holes. */ while (size > 0L) { cnt = bufend - bufpt; /* * if we get a read error, we do not want to skip, as we may * miss a header, so we do not set left, but if we get a write * error, we do want to skip over the unprocessed data. */ if ((cnt <= 0) && ((cnt = buf_fill()) <= 0)) break; cnt = MIN(cnt, size); if ((res = file_write(ofd,bufpt,cnt,&rem,&isem,sz,fnm)) <= 0) { *left = size; break; } if (docrc) { /* * update the actual crc value */ cnt = res; while (--cnt >= 0) crc += *bufpt++ & 0xff; } else bufpt += res; size -= res; } /* * if the last block has a file hole (all zero), we must make sure this * gets updated in the file. We force the last block of zeros to be * written. just closing with the file offset moved foward may not put * a hole at the end of the file. */ if (isem && (arcn->sb.st_size > 0L)) file_flush(ofd, fnm, isem); /* * if we failed from archive read, we do not want to skip */ if ((size > 0L) && (*left == 0L)) return(-1); /* * some formats record a crc on file data. If so, then we compare the * calculated crc to the crc stored in the archive */ if (docrc && (size == 0L) && (arcn->crc != crc)) paxwarn(1,"Actual crc does not match expected crc %s",arcn->name); return(0); } /* * cp_file() * copy the contents of one file to another. used during -rw phase of pax * just as in rd_wrfile() we use a special write function to write the * destination file so we can properly copy files with holes. */ #ifdef __STDC__ void cp_file(ARCHD *arcn, int fd1, int fd2) #else void cp_file(arcn, fd1, fd2) ARCHD *arcn; int fd1; int fd2; #endif { register int cnt; register off_t cpcnt = 0L; register int res = 0; register char *fnm = arcn->name; register int no_hole = 0; int isem = 1; int rem; int sz = MINFBSZ; struct stat sb; /* * check for holes in the source file. If none, we will use regular * write instead of file write. */ if (((off_t)(arcn->sb.st_blocks * BLKMULT)) >= arcn->sb.st_size) ++no_hole; /* * pass the blocksize of the file being written to the write routine, * if the size is zero, use the default MINFBSZ */ if (fstat(fd2, &sb) == 0) { if (sb.st_blksize > 0) sz = sb.st_blksize; } else syswarn(0,errno,"Unable to obtain block size for file %s",fnm); rem = sz; /* * read the source file and copy to destination file until EOF */ for(;;) { if ((cnt = read(fd1, buf, blksz)) <= 0) break; if (no_hole) res = write(fd2, buf, cnt); else res = file_write(fd2, buf, cnt, &rem, &isem, sz, fnm); if (res != cnt) break; cpcnt += cnt; } /* * check to make sure the copy is valid. */ if (res < 0) syswarn(1, errno, "Failed write during copy of %s to %s", arcn->org_name, arcn->name); else if (cpcnt != arcn->sb.st_size) paxwarn(1, "File %s changed size during copy to %s", arcn->org_name, arcn->name); else if (fstat(fd1, &sb) < 0) syswarn(1, errno, "Failed stat of %s", arcn->org_name); else if (arcn->sb.st_mtime != sb.st_mtime) paxwarn(1, "File %s was modified during copy to %s", arcn->org_name, arcn->name); /* * if the last block has a file hole (all zero), we must make sure this * gets updated in the file. We force the last block of zeros to be * written. just closing with the file offset moved foward may not put * a hole at the end of the file. */ if (!no_hole && isem && (arcn->sb.st_size > 0L)) file_flush(fd2, fnm, isem); return; } /* * buf_fill() * fill the read buffer with the next record (or what we can get) from * the archive volume. * Return: * Number of bytes of data in the read buffer, -1 for read error, and * 0 when finished (user specified termination in ar_next()). */ #ifdef __STDC__ int buf_fill(void) #else int buf_fill() #endif { register int cnt; static int fini = 0; if (fini) return(0); for(;;) { /* * try to fill the buffer. on error the next archive volume is * opened and we try again. */ if ((cnt = ar_read(buf, blksz)) > 0) { bufpt = buf; bufend = buf + cnt; rdcnt += cnt; return(cnt); } /* * errors require resync, EOF goes to next archive */ if (cnt < 0) break; if (ar_next() < 0) { fini = 1; return(0); } rdcnt = 0; } exit_val = 1; return(-1); } /* * buf_flush() * force the write buffer to the archive. We are passed the number of * bytes in the buffer at the point of the flush. When we change archives * the record size might change. (either larger or smaller). * Return: * 0 if all is ok, -1 when a write error occurs. */ #ifdef __STDC__ int buf_flush(register int bufcnt) #else int buf_flush(bufcnt) register int bufcnt; #endif { register int cnt; register int push = 0; register int totcnt = 0; /* * if we have reached the user specified byte count for each archive * volume, prompt for the next volume. (The non-standrad -R flag). * NOTE: If the wrlimit is smaller than wrcnt, we will always write * at least one record. We always round limit UP to next blocksize. */ if ((wrlimit > 0) && (wrcnt > wrlimit)) { paxwarn(0, "User specified archive volume byte limit reached."); if (ar_next() < 0) { wrcnt = 0; exit_val = 1; return(-1); } wrcnt = 0; /* * The new archive volume might have changed the size of the * write blocksize. if so we figure out if we need to write * (one or more times), or if there is now free space left in * the buffer (it is no longer full). bufcnt has the number of * bytes in the buffer, (the blocksize, at the point we were * CALLED). Push has the amount of "extra" data in the buffer * if the block size has shrunk from a volume change. */ bufend = buf + blksz; if (blksz > bufcnt) return(0); if (blksz < bufcnt) push = bufcnt - blksz; } /* * We have enough data to write at least one archive block */ for (;;) { /* * write a block and check if it all went out ok */ cnt = ar_write(buf, blksz); if (cnt == blksz) { /* * the write went ok */ wrcnt += cnt; totcnt += cnt; if (push > 0) { /* we have extra data to push to the front. * check for more than 1 block of push, and if * so we loop back to write again */ memcpy(buf, bufend, push); bufpt = buf + push; if (push >= blksz) { push -= blksz; continue; } } else bufpt = buf; return(totcnt); } else if (cnt > 0) { /* * Oh drat we got a partial write! * if format doesnt care about alignment let it go, * we warned the user in ar_write().... but this means * the last record on this volume violates pax spec.... */ totcnt += cnt; wrcnt += cnt; bufpt = buf + cnt; cnt = bufcnt - cnt; memcpy(buf, bufpt, cnt); bufpt = buf + cnt; if (!frmt->blkalgn || ((cnt % frmt->blkalgn) == 0)) return(totcnt); break; } /* * All done, go to next archive */ wrcnt = 0; if (ar_next() < 0) break; /* * The new archive volume might also have changed the block * size. if so, figure out if we have too much or too little * data for using the new block size */ bufend = buf + blksz; if (blksz > bufcnt) return(0); if (blksz < bufcnt) push = bufcnt - blksz; } /* * write failed, stop pax. we must not create a bad archive! */ exit_val = 1; return(-1); }