glibc/manual/examples/select.c

59 lines
1.5 KiB
C

/* Waiting for Input or Output
Copyright (C) 1991-2015 Free Software Foundation, Inc.
This program 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.
This program 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 this program; if not, if not, see <http://www.gnu.org/licenses/>.
*/
/*@group*/
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>
/*@end group*/
/*@group*/
int
input_timeout (int filedes, unsigned int seconds)
{
fd_set set;
struct timeval timeout;
/*@end group*/
/* Initialize the file descriptor set. */
FD_ZERO (&set);
FD_SET (filedes, &set);
/* Initialize the timeout data structure. */
timeout.tv_sec = seconds;
timeout.tv_usec = 0;
/*@group*/
/* @code{select} returns 0 if timeout, 1 if input available, -1 if error. */
return TEMP_FAILURE_RETRY (select (FD_SETSIZE,
&set, NULL, NULL,
&timeout));
}
/*@end group*/
/*@group*/
int
main (void)
{
fprintf (stderr, "select returned %d.\n",
input_timeout (STDIN_FILENO, 5));
return 0;
}
/*@end group*/