98 lines
2.3 KiB
C
98 lines
2.3 KiB
C
/* input_avail.c -- check whether or not data is available for reading on a
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specified file descriptor. */
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/* Copyright (C) 2008,2009 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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#if defined (__TANDEM)
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# include <floss.h>
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#endif
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#if defined (HAVE_CONFIG_H)
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# include <config.h>
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#endif
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#include <sys/types.h>
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#include <fcntl.h>
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#if defined (HAVE_SYS_FILE_H)
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# include <sys/file.h>
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#endif /* HAVE_SYS_FILE_H */
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#if defined (HAVE_UNISTD_H)
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# include <unistd.h>
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#endif /* HAVE_UNISTD_H */
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#include "bashansi.h"
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#include "posixselect.h"
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#if defined (FIONREAD_IN_SYS_IOCTL)
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# include <sys/ioctl.h>
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#endif
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#include <stdio.h>
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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 /* !errno */
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#if !defined (O_NDELAY) && defined (O_NONBLOCK)
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# define O_NDELAY O_NONBLOCK /* Posix style */
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#endif
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/* Return >= 1 if select/FIONREAD indicates data available for reading on
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file descriptor FD; 0 if no data available. Return -1 on error. */
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int
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input_avail (fd)
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int fd;
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{
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int result, chars_avail;
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#if defined(HAVE_SELECT)
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fd_set readfds, exceptfds;
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struct timeval timeout;
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#endif
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if (fd < 0)
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return -1;
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chars_avail = 0;
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#if defined (HAVE_SELECT)
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FD_ZERO (&readfds);
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FD_ZERO (&exceptfds);
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FD_SET (fd, &readfds);
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FD_SET (fd, &exceptfds);
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timeout.tv_sec = 0;
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timeout.tv_usec = 0;
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result = select (fd + 1, &readfds, (fd_set *)NULL, &exceptfds, &timeout);
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return ((result <= 0) ? 0 : 1);
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#endif
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result = -1;
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#if defined (FIONREAD)
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errno = 0;
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result = ioctl (fd, FIONREAD, &chars_avail);
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if (result == -1 && errno == EIO)
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return -1;
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return (chars_avail);
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#endif
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return 0;
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}
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