1// SPDX-License-Identifier: GPL-2.0
 2#include <sys/select.h>
 3#include <unistd.h>
 4#include <errno.h>
 5
 6int read_with_timeout(int fd, char *buf, size_t count, long usec)
 7{
 8	const long M = 1000 * 1000;
 9	struct timeval tv = { usec / M, usec % M };
10	fd_set fds;
11	int err;
12
13	FD_ZERO(&fds);
14	FD_SET(fd, &fds);
15	err = select(fd + 1, &fds, NULL, NULL, &tv);
16	if (err < 0)
17		return err;
18	if (FD_ISSET(fd, &fds))
19		return read(fd, buf, count);
20	return -EAGAIN;
21}