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iop
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1994-01-04
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7KB
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316 lines
/*
* iop.c - do i/o related things.
*/
/*
* Copyright (C) 1986, 1988, 1989, 1991, 1992, 1993 the Free Software Foundation, Inc.
*
* This file is part of GAWK, the GNU implementation of the
* AWK Progamming Language.
*
* GAWK is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GAWK is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GAWK; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "awk.h"
#ifndef atarist
#define INVALID_HANDLE (-1)
#else
#include <stddef.h>
#include <fcntl.h>
#define INVALID_HANDLE (__SMALLEST_VALID_HANDLE - 1)
#endif /* atarist */
#ifdef TEST
int bufsize = 8192;
void
fatal(s)
char *s;
{
printf("%s\n", s);
exit(1);
}
#endif
int
optimal_bufsize(fd)
int fd;
{
struct stat stb;
#ifdef VMS
/*
* These values correspond with the RMS multi-block count used by
* vms_open() in vms/vms_misc.c.
*/
if (isatty(fd) > 0)
return BUFSIZ;
else if (fstat(fd, &stb) < 0)
return 8*512; /* conservative in case of DECnet access */
else
return 32*512;
#else
/*
* System V doesn't have the file system block size in the
* stat structure. So we have to make some sort of reasonable
* guess. We use stdio's BUFSIZ, since that is what it was
* meant for in the first place.
*/
#ifdef BLKSIZE_MISSING
#define DEFBLKSIZE BUFSIZ
#else
#define DEFBLKSIZE (stb.st_blksize ? stb.st_blksize : BUFSIZ)
#endif
#ifdef TEST
return bufsize;
#else
#ifndef atarist
if (isatty(fd))
#else
/*
* On ST redirected stdin does not have a name attached
* (this could be hard to do to) and fstat would fail
*/
if (0 == fd || isatty(fd))
#endif /*atarist */
return BUFSIZ;
#ifndef BLKSIZE_MISSING
/* VMS POSIX 1.0: st_blksize is never assigned a value, so zero it */
stb.st_blksize = 0;
#endif
if (fstat(fd, &stb) == -1)
fatal("can't stat fd %d (%s)", fd, strerror(errno));
if (lseek(fd, (off_t)0, 0) == -1)
return DEFBLKSIZE;
return ((int) (stb.st_size < DEFBLKSIZE ? stb.st_size : DEFBLKSIZE));
#endif /*! TEST */
#endif /*! VMS */
}
IOBUF *
iop_alloc(fd)
int fd;
{
IOBUF *iop;
if (fd == INVALID_HANDLE)
return NULL;
emalloc(iop, IOBUF *, sizeof(IOBUF), "iop_alloc");
iop->flag = 0;
if (isatty(fd))
iop->flag |= IOP_IS_TTY;
iop->size = optimal_bufsize(fd);
iop->secsiz = -2;
errno = 0;
iop->fd = fd;
iop->off = iop->buf = NULL;
iop->cnt = 0;
return iop;
}
/*
* Get the next record. Uses a "split buffer" where the latter part is
* the normal read buffer and the head part is an "overflow" area that is used
* when a record spans the end of the normal buffer, in which case the first
* part of the record is copied into the overflow area just before the
* normal buffer. Thus, the eventual full record can be returned as a
* contiguous area of memory with a minimum of copying. The overflow area
* is expanded as needed, so that records are unlimited in length.
* We also mark both the end of the buffer and the end of the read() with
* a sentinel character (the current record separator) so that the inside
* loop can run as a single test.
*/
int
get_a_record(out, iop, grRS, errcode)
char **out;
IOBUF *iop;
register int grRS;
int *errcode;
{
register char *bp = iop->off;
char *bufend;
char *start = iop->off; /* beginning of record */
char rs;
int saw_newline = 0, eat_whitespace = 0; /* used iff grRS==0 */
if (iop->cnt == EOF) /* previous read hit EOF */
return EOF;
if (grRS == 0) { /* special case: grRS == "" */
rs = '\n';
} else
rs = (char) grRS;
/* set up sentinel */
if (iop->buf) {
bufend = iop->buf + iop->size + iop->secsiz;
*bufend = rs;
} else
bufend = NULL;
for (;;) { /* break on end of record, read error or EOF */
/* Following code is entered on the first call of this routine
* for a new iop, or when we scan to the end of the buffer.
* In the latter case, we copy the current partial record to
* the space preceding the normal read buffer. If necessary,
* we expand this space. This is done so that we can return
* the record as a contiguous area of memory.
*/
if ((iop->flag & IOP_IS_INTERNAL) == 0 && bp >= bufend) {
char *oldbuf = NULL;
char *oldsplit = iop->buf + iop->secsiz;
long len; /* record length so far */
if ((iop->flag & IOP_IS_INTERNAL) != 0)
cant_happen();
len = bp - start;
if (len > iop->secsiz) {
/* expand secondary buffer */
if (iop->secsiz == -2)
iop->secsiz = 256;
while (len > iop->secsiz)
iop->secsiz *= 2;
oldbuf = iop->buf;
emalloc(iop->buf, char *,
iop->size+iop->secsiz+2, "get_a_record");
bufend = iop->buf + iop->size + iop->secsiz;
*bufend = rs;
}
if (len > 0) {
char *newsplit = iop->buf + iop->secsiz;
if (start < oldsplit) {
memcpy(newsplit - len, start,
oldsplit - start);
memcpy(newsplit - (bp - oldsplit),
oldsplit, bp - oldsplit);
} else
memcpy(newsplit - len, start, len);
}
bp = iop->end = iop->off = iop->buf + iop->secsiz;
start = bp - len;
if (oldbuf) {
free(oldbuf);
oldbuf = NULL;
}
}
/* Following code is entered whenever we have no more data to
* scan. In most cases this will read into the beginning of
* the main buffer, but in some cases (terminal, pipe etc.)
* we may be doing smallish reads into more advanced positions.
*/
if (bp >= iop->end) {
if ((iop->flag & IOP_IS_INTERNAL) != 0) {
iop->cnt = EOF;
break;
}
iop->cnt = read(iop->fd, iop->end, bufend - iop->end);
if (iop->cnt == -1) {
if (! do_unix && errcode != NULL) {
*errcode = errno;
iop->cnt = EOF;
break;
} else
fatal("error reading input: %s",
strerror(errno));
} else if (iop->cnt == 0) {
iop->cnt = EOF;
break;
}
iop->end += iop->cnt;
*iop->end = rs;
}
if (grRS == 0) {
extern int default_FS;
if (default_FS && (bp == start || eat_whitespace)) {
while (bp < iop->end && isspace(*bp))
bp++;
if (bp == iop->end) {
eat_whitespace = 1;
continue;
} else
eat_whitespace = 0;
}
if (saw_newline && *bp == rs) {
bp++;
break;
}
saw_newline = 0;
}
while (*bp++ != rs)
;
if (bp <= iop->end) {
if (grRS == 0)
saw_newline = 1;
else
break;
} else
bp--;
if ((iop->flag & IOP_IS_INTERNAL) != 0)
iop->cnt = bp - start;
}
if (iop->cnt == EOF
&& (((iop->flag & IOP_IS_INTERNAL) != 0) || start == bp))
return EOF;
iop->off = bp;
bp--;
if (*bp != rs)
bp++;
*bp = '\0';
if (grRS == 0) {
if (*--bp == rs)
*bp = '\0';
else
bp++;
}
*out = start;
return bp - start;
}
#ifdef TEST
main(argc, argv)
int argc;
char *argv[];
{
IOBUF *iop;
char *out;
int cnt;
char rs[2];
rs[0] = 0;
if (argc > 1)
bufsize = atoi(argv[1]);
if (argc > 2)
rs[0] = *argv[2];
iop = iop_alloc(0);
while ((cnt = get_a_record(&out, iop, rs[0], NULL)) > 0) {
fwrite(out, 1, cnt, stdout);
fwrite(rs, 1, 1, stdout);
}
}
#endif