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Diffstat (limited to 'bin/pax/buf_subs.c')
| -rw-r--r-- | bin/pax/buf_subs.c | 983 |
1 files changed, 983 insertions, 0 deletions
diff --git a/bin/pax/buf_subs.c b/bin/pax/buf_subs.c new file mode 100644 index 0000000..e84f9e0 --- /dev/null +++ b/bin/pax/buf_subs.c @@ -0,0 +1,983 @@ +/* $OpenBSD: buf_subs.c,v 1.31 2019/06/28 13:34:59 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. 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. + */ + +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/time.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 + */ + +int +wr_start(void) +{ + 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 + */ + +int +rd_start(void) +{ + /* + * 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 + */ + +void +cp_start(void) +{ + 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 position 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 boundaries. + * 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 trivial. 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, + * so it may not be feasible to append archives stored on all types of + * devices. + * Return: + * 0 for success, -1 for failure + */ + +int +appnd_start(off_t skcnt) +{ + 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(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(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 + */ + +int +rd_sync(void) +{ + int errcnt = 0; + 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 boundary (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. + */ + +void +pback(char *pt, int cnt) +{ + bufpt -= cnt; + memcpy(bufpt, pt, cnt); +} + +/* + * rd_skip() + * skip forward 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. + */ + +int +rd_skip(off_t skcnt) +{ + off_t res; + off_t cnt; + off_t skipped = 0; + + /* + * consume what data we have in the buffer. If we have to move forward + * 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 = MINIMUM((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 > 0) { + 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 = MINIMUM(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 padding SHOULD + * BE a requirement.... + */ + +void +wr_fin(void) +{ + 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) + */ + +int +wr_rdbuf(char *out, int outcnt) +{ + 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 = MINIMUM(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 + */ + +int +rd_wrbuf(char *in, int cpcnt) +{ + int res; + int cnt; + 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 occurred 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 = MINIMUM(cnt, incnt); + memcpy(in, bufpt, cnt); + bufpt += cnt; + incnt -= cnt; + in += cnt; + } + return(cpcnt); +} + +/* + * wr_skip() + * skip forward 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 + */ + +int +wr_skip(off_t skcnt) +{ + int cnt; + + /* + * loop while there is more padding to add + */ + while (skcnt > 0) { + cnt = bufend - bufpt; + if ((cnt <= 0) && ((cnt = buf_flush(blksz)) < 0)) + return(-1); + cnt = MINIMUM(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. + */ + +int +wr_rdfile(ARCHD *arcn, int ifd, off_t *left) +{ + int cnt; + int res = 0; + off_t size = arcn->sb.st_size; + struct stat sb; + + /* + * while there are more bytes to write + */ + while (size > 0) { + cnt = bufend - bufpt; + if ((cnt <= 0) && ((cnt = buf_flush(blksz)) < 0)) { + *left = size; + return(-1); + } + cnt = MINIMUM(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 != 0) + paxwarn(1, "File changed size during read %s", arcn->org_name); + else if (fstat(ifd, &sb) == -1) + syswarn(1, errno, "Failed stat on %s", arcn->org_name); + else if (timespeccmp(&arcn->sb.st_mtim, &sb.st_mtim, !=)) + 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 + */ + +int +rd_wrfile(ARCHD *arcn, int ofd, off_t *left) +{ + int cnt = 0; + off_t size = arcn->sb.st_size; + int res = 0; + char *fnm = arcn->name; + int isem = 1; + int rem; + int sz = MINFBSZ; + struct stat sb; + u_int32_t crc = 0; + + /* + * 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 = 0; + + /* + * 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 > 0) { + 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 = MINIMUM(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 forward may not put + * a hole at the end of the file. + */ + if (isem && (arcn->sb.st_size > 0)) + file_flush(ofd, fnm, isem); + + /* + * if we failed from archive read, we do not want to skip + */ + if ((size > 0) && (*left == 0)) + 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 == 0) && (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. + */ + +void +cp_file(ARCHD *arcn, int fd1, int fd2) +{ + int cnt; + off_t cpcnt = 0; + int res = 0; + char *fnm = arcn->name; + 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) == -1) + syswarn(1, errno, "Failed stat of %s", arcn->org_name); + else if (timespeccmp(&arcn->sb.st_mtim, &sb.st_mtim, !=)) + 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 forward may not put + * a hole at the end of the file. + */ + if (!no_hole && isem && (arcn->sb.st_size > 0)) + file_flush(fd2, fnm, isem); +} + +/* + * 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()). + */ + +int +buf_fill(void) +{ + 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 + * but in case we have not determined yet the format, + * this means that we have a very short file, so we + * are done again. + */ + if (cnt < 0) + break; + if (frmt == NULL || 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. + */ + +int +buf_flush(int bufcnt) +{ + int cnt; + int push = 0; + int totcnt = 0; + + /* + * if we have reached the user specified byte count for each archive + * volume, prompt for the next volume. (The non-standard -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 does not 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); +} |