eject
Fri, 03 Jun 2011 23:21 categories: codeA friend of mine recently gave me her Huawei E1550 umts modem and as many
others it first presents itself to the operating system as a usb cdrom drive.
It will only switch to serial modem mode when the cdrom is ejected. For this to
happen you can fire the eject command and you are done. Since I was curious
how linux would eject a cdrom and how eject really works I investigated and
found that I can replicate the eject behavior with this C snippet.
#include <sys/ioctl.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#include <linux/cdrom.h>
int main() {
int ret, fd;
fd = open("/dev/sr0", O_NONBLOCK);
if (fd == -1) {
perror("open");
return EXIT_FAILURE;
}
ret = ioctl(fd, CDROMEJECT, 0);
if (ret == -1) {
perror("ioctl");
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
or alternatively with this python oneliner:
python -c "import fcntl, os; fcntl.ioctl(os.open('/dev/sr0', os.O_NONBLOCK), 0x5309, 0)"