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/* Test of select() substitute, reading from stdin.
Copyright (C) 2008-2021 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 3 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, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2008. */
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/select.h>
#include <sys/time.h>
#include <unistd.h>
#include "macros.h"
int
main (void)
{
printf ("Applying select() from standard input. Press Ctrl-C to abort.\n");
for (;;)
{
struct timeval before;
struct timeval after;
unsigned long spent_usec;
fd_set readfds;
struct timeval timeout;
int ret;
gettimeofday (&before, NULL);
FD_ZERO (&readfds);
FD_SET (0, &readfds);
timeout.tv_sec = 0;
timeout.tv_usec = 500000;
ret = select (1, &readfds, NULL, NULL, &timeout);
gettimeofday (&after, NULL);
spent_usec = (after.tv_sec - before.tv_sec) * 1000000
+ after.tv_usec - before.tv_usec;
if (ret < 0)
{
perror ("select failed");
exit (1);
}
if ((ret == 0) != ! FD_ISSET (0, &readfds))
{
fprintf (stderr, "incorrect return value\n");
exit (1);
}
if (ret == 0)
{
if (spent_usec < 250000)
{
fprintf (stderr, "returned too early\n");
exit (1);
}
/* Timeout */
printf (".");
ASSERT (fflush (stdout) == 0);
}
else
{
char c;
printf ("Input available! Trying to read 1 byte...\n");
ASSERT (read (0, &c, 1) == 1);
}
}
}
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