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// SPDX-License-Identifier: GPL-2.0
/*
* Simple poll on a file.
*
* Copyright (c) 2024 Google LLC.
*/
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define BUFSIZE 4096
/*
* Usage:
* poll [-I|-P] [-t timeout] FILE
*/
int main(int argc, char *argv[])
{
struct pollfd pfd = {.events = POLLIN};
char buf[BUFSIZE];
int timeout = -1;
int ret, opt;
while ((opt = getopt(argc, argv, "IPt:")) != -1) {
switch (opt) {
case 'I':
pfd.events = POLLIN;
break;
case 'P':
pfd.events = POLLPRI;
break;
case 't':
timeout = atoi(optarg);
break;
default:
fprintf(stderr, "Usage: %s [-I|-P] [-t timeout] FILE\n",
argv[0]);
return -1;
}
}
if (optind >= argc) {
fprintf(stderr, "Error: Polling file is not specified\n");
return -1;
}
pfd.fd = open(argv[optind], O_RDONLY);
if (pfd.fd < 0) {
fprintf(stderr, "failed to open %s", argv[optind]);
perror("open");
return -1;
}
/* Reset poll by read if POLLIN is specified. */
if (pfd.events & POLLIN)
do {} while (read(pfd.fd, buf, BUFSIZE) == BUFSIZE);
ret = poll(&pfd, 1, timeout);
if (ret < 0 && errno != EINTR) {
perror("poll");
return -1;
}
close(pfd.fd);
/* If timeout happned (ret == 0), exit code is 1 */
if (ret == 0)
return 1;
return 0;
}
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