172 lines
3.2 KiB
C
172 lines
3.2 KiB
C
/* zread - read data from file descriptor into buffer with retries */
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/* Copyright (C) 1999-2002 Free Software Foundation, Inc.
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This file is part of GNU Bash, the Bourne Again SHell.
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Bash is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Bash is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Bash. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <config.h>
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#include <sys/types.h>
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#if defined (HAVE_UNISTD_H)
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# include <unistd.h>
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#endif
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#include <errno.h>
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#if !defined (errno)
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extern int errno;
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#endif
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#ifndef SEEK_CUR
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# define SEEK_CUR 1
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#endif
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/* Read LEN bytes from FD into BUF. Retry the read on EINTR. Any other
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error causes the loop to break. */
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ssize_t
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zread (fd, buf, len)
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int fd;
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char *buf;
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size_t len;
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{
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ssize_t r;
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while ((r = read (fd, buf, len)) < 0 && errno == EINTR)
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;
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return r;
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}
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/* Read LEN bytes from FD into BUF. Retry the read on EINTR, up to three
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interrupts. Any other error causes the loop to break. */
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#ifdef NUM_INTR
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# undef NUM_INTR
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#endif
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#define NUM_INTR 3
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ssize_t
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zreadretry (fd, buf, len)
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int fd;
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char *buf;
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size_t len;
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{
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ssize_t r;
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int nintr;
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for (nintr = 0; ; )
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{
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r = read (fd, buf, len);
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if (r >= 0)
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return r;
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if (r == -1 && errno == EINTR)
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{
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if (++nintr >= NUM_INTR)
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return -1;
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continue;
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}
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return r;
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}
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}
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/* Call read(2) and allow it to be interrupted. Just a stub for now. */
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ssize_t
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zreadintr (fd, buf, len)
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int fd;
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char *buf;
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size_t len;
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{
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return (read (fd, buf, len));
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}
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/* Read one character from FD and return it in CP. Return values are as
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in read(2). This does some local buffering to avoid many one-character
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calls to read(2), like those the `read' builtin performs. */
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static char lbuf[128];
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static size_t lind, lused;
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ssize_t
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zreadc (fd, cp)
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int fd;
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char *cp;
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{
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ssize_t nr;
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if (lind == lused || lused == 0)
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{
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nr = zread (fd, lbuf, sizeof (lbuf));
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lind = 0;
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if (nr <= 0)
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{
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lused = 0;
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return nr;
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}
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lused = nr;
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}
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if (cp)
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*cp = lbuf[lind++];
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return 1;
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}
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/* Don't mix calls to zreadc and zreadcintr in the same function, since they
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use the same local buffer. */
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ssize_t
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zreadcintr (fd, cp)
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int fd;
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char *cp;
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{
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ssize_t nr;
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if (lind == lused || lused == 0)
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{
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nr = zreadintr (fd, lbuf, sizeof (lbuf));
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lind = 0;
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if (nr <= 0)
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{
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lused = 0;
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return nr;
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}
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lused = nr;
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}
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if (cp)
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*cp = lbuf[lind++];
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return 1;
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}
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void
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zreset ()
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{
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lind = lused = 0;
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}
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/* Sync the seek pointer for FD so that the kernel's idea of the last char
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read is the last char returned by zreadc. */
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void
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zsyncfd (fd)
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int fd;
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{
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off_t off, r;
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off = lused - lind;
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r = 0;
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if (off > 0)
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r = lseek (fd, -off, SEEK_CUR);
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if (r != -1)
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lused = lind = 0;
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}
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