Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
branch: trunk
Fetching contributors…

Cannot retrieve contributors at this time

1023 lines (938 sloc) 27.67 kb
/* $NetBSD: buf_subs.c,v 1.28 2007/04/29 20:23:34 msaitoh 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.
*/
#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif
#include <sys/cdefs.h>
#if !defined(lint)
#if 0
static char sccsid[] = "@(#)buf_subs.c 8.2 (Berkeley) 4/18/94";
#else
__RCSID("$NetBSD: buf_subs.c,v 1.28 2007/04/29 20:23:34 msaitoh 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 <ctype.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) {
tty_warn(1, "Write block size of %d too large, maximum is: %d",
wrblksz, MAXBLK);
return -1;
}
if (wrblksz % BLKMULT) {
tty_warn(1, "Write block size of %d is not a %d byte multiple",
wrblksz, BLKMULT);
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) {
tty_warn(1,
"Write block size %d too large, maximum is: %d",
wrblksz, MAXBLK);
return -1;
}
if (wrblksz % BLKMULT) {
tty_warn(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 positions 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 feasable 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) {
tty_warn(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:
tty_warn(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) {
tty_warn(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. otherwise 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))
tty_warn(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);
return;
}
/*
* rd_skip()
* skip forward in the archive during an 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 = 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....
*/
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 = 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
*/
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 = MIN(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 > 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.
*/
int
wr_rdfile(ARCHD *arcn, int ifd, off_t *left)
{
int cnt;
int res = 0;
off_t size = arcn->sb.st_size;
struct stat origsb, sb;
/*
* by default, remember the previously obtained stat information
* (in arcn->sb) for comparing the mtime after reading.
* if Mflag is set, use the actual mtime instead.
*/
origsb = arcn->sb;
if (Mflag && (fstat(ifd, &origsb) < 0))
syswarn(1, errno, "Failed stat on %s", arcn->org_name);
/*
* 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_with_restart(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)
tty_warn(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 (origsb.st_mtime != sb.st_mtime)
tty_warn(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_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 (ofd < 0)
sz = PAXPATHLEN+1;
else 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 forward may not put
* a hole at the end of the file.
*/
if (ofd >= 0 && 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))
tty_warn(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 = 0L;
int res = 0;
char *fnm = arcn->name;
int no_hole = 0;
int isem = 1;
int rem;
int sz = MINFBSZ;
struct stat sb, origsb;
/*
* 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;
/*
* by default, remember the previously obtained stat information
* (in arcn->sb) for comparing the mtime after reading.
* if Mflag is set, use the actual mtime instead.
*/
origsb = arcn->sb;
if (Mflag && (fstat(fd1, &origsb) < 0))
syswarn(1, errno, "Failed stat on %s", arcn->org_name);
/*
* 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_with_restart(fd1, buf, blksz)) <= 0)
break;
if (no_hole)
res = xwrite(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)
tty_warn(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 (origsb.st_mtime != sb.st_mtime)
tty_warn(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 > 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()).
*/
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)) {
tty_warn(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;
}
Jump to Line
Something went wrong with that request. Please try again.