// SPDX-License-Identifier: GPL-2.0
#include <sys/select.h>
#include <unistd.h>
#include <errno.h>

int read_with_timeout(int fd, char *buf, size_t count, long usec)
{
        const long M = 1000 * 1000;
        struct timeval tv = { usec / M, usec % M };
        fd_set fds;
        int err;

        FD_ZERO(&fds);
        FD_SET(fd, &fds);
        err = select(fd + 1, &fds, NULL, NULL, &tv);
        if (err < 0)
                return err;
        if (FD_ISSET(fd, &fds))
                return read(fd, buf, count);
        return -EAGAIN;
}