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/* input_avail.c -- check whether or not data is available for reading on a
specified file descriptor. */
/* Copyright (C) 2008,2009-2019 Free Software Foundation, Inc.
This file is part of GNU Bash, the Bourne Again SHell.
Bash 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 3 of the License, or
(at your option) any later version.
Bash 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 Bash. If not, see <http://www.gnu.org/licenses/>.
*/
#if defined (__TANDEM)
# include <floss.h>
#endif
#if defined (HAVE_CONFIG_H)
# include <config.h>
#endif
#include <sys/types.h>
#include <fcntl.h>
#if defined (HAVE_SYS_FILE_H)
# include <sys/file.h>
#endif /* HAVE_SYS_FILE_H */
#include <signal.h>
#if defined (HAVE_UNISTD_H)
# include <unistd.h>
#endif /* HAVE_UNISTD_H */
#include "bashansi.h"
#include "posixselect.h"
#if defined (FIONREAD_IN_SYS_IOCTL)
# include <sys/ioctl.h>
#endif
#include <stdio.h>
#include <errno.h>
#if !defined (errno)
extern int errno;
#endif /* !errno */
#if !defined (O_NDELAY) && defined (O_NONBLOCK)
# define O_NDELAY O_NONBLOCK /* Posix style */
#endif
/* Return >= 1 if select/FIONREAD indicates data available for reading on
file descriptor FD; 0 if no data available. Return -1 on error. */
int
input_avail (fd)
int fd;
{
int result, chars_avail;
#if defined(HAVE_SELECT)
fd_set readfds, exceptfds;
struct timeval timeout;
#endif
if (fd < 0)
return -1;
chars_avail = 0;
#if defined (HAVE_SELECT)
FD_ZERO (&readfds);
FD_ZERO (&exceptfds);
FD_SET (fd, &readfds);
FD_SET (fd, &exceptfds);
timeout.tv_sec = 0;
timeout.tv_usec = 0;
result = select (fd + 1, &readfds, (fd_set *)NULL, &exceptfds, &timeout);
return ((result <= 0) ? 0 : 1);
#endif
#if defined (FIONREAD)
errno = 0;
result = ioctl (fd, FIONREAD, &chars_avail);
if (result == -1 && errno == EIO)
return -1;
return (chars_avail);
#endif
return 0;
}
/* Wait until NCHARS are available for reading on file descriptor FD.
This can wait indefinitely. Return -1 on error. */
int
nchars_avail (fd, nchars)
int fd;
int nchars;
{
int result, chars_avail;
#if defined (HAVE_PSELECT) || defined (HAVE_SELECT)
fd_set readfds, exceptfds;
sigset_t set, oset;
#endif
if (fd < 0 || nchars < 0)
return -1;
if (nchars == 0)
return (input_avail (fd));
chars_avail = 0;
#if defined (HAVE_PSELECT) || defined (HAVE_SELECT)
FD_ZERO (&readfds);
FD_ZERO (&exceptfds);
FD_SET (fd, &readfds);
FD_SET (fd, &exceptfds);
sigprocmask (SIG_BLOCK, (sigset_t *)NULL, &set);
# ifdef SIGCHLD
sigaddset (&set, SIGCHLD);
# endif
sigemptyset (&oset);
#endif
while (1)
{
result = 0;
#if defined (HAVE_PSELECT)
/* XXX - use pselect(2) to block SIGCHLD atomically */
result = pselect (fd + 1, &readfds, (fd_set *)NULL, &exceptfds, (struct timespec *)NULL, &set);
#elif defined (HAVE_SELECT)
sigprocmask (SIG_BLOCK, &set, &oset);
result = select (fd + 1, &readfds, (fd_set *)NULL, &exceptfds, (struct timeval *)NULL);
sigprocmask (SIG_BLOCK, &oset, (sigset_t *)NULL);
#endif
if (result < 0)
return -1;
#if defined (FIONREAD)
errno = 0;
result = ioctl (fd, FIONREAD, &chars_avail);
if (result == -1 && errno == EIO)
return -1;
if (chars_avail >= nchars)
break;
#else
break;
#endif
}
return 0;
}
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