title: input/output error in ejecting Cd rom from C code
body: <p>I Have problems with my CD-Rom on Ubuntu 14.10. I`m trying to run this piece of code, and it writes <strong>ioctl: Input/output error</strong> and open() returns number 3. Where should be an mistake? is my CDROM PATH right? When I wrote eject "dev/cdrom" in terminal, it is ejected.</p>
  
  <pre><code>/* eject.c
  ** Copyright Paul Dwerryhouse, 1997-2004
  */
  #include &lt;sys/types.h&gt;
  #include &lt;sys/ioctl.h&gt;
  #include &lt;fcntl.h&gt;
  #include &lt;linux/cdrom.h&gt;
  
  #define CDDEVICE "/dev/cdrom"           /* CDROM device */
  
  int main(int argc,char **argv)
  {
     int cdrom;                           /* CDROM device file descriptor */
  
     /* Open the CDROM device. The linux/cdrom.h header file specifies that
     ** it must be given the O_NONBLOCK flag when opening. My tests showed
     ** that if this isn't done, this program will not work. 
     */
     if ((cdrom = open(CDDEVICE,O_RDONLY | O_NONBLOCK)) &lt; 0) {
          perror("open");
          exit(1);
     }
  
     /* Use ioctl to send the CDROMEJECT command to the device
     */
     if (ioctl(cdrom,CDROMEJECT,0)&lt;0) {
          perror("ioctl");
          exit(1);
     }
  
     close(cdrom);
  }
  </code></pre>
  
  <p>Here is strace output.</p>
  
  <pre><code>execve("./frca", ["./frca"], [/* 76 vars */]) = 0
  brk(0)                                  = 0x2015000
  access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
  mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f4240016000
  access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
  open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
  fstat(3, {st_mode=S_IFREG|0644, st_size=136133, ...}) = 0
  mmap(NULL, 136133, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f423fff4000
  close(3)                                = 0
  access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
  open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
  read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0&gt;\0\1\0\0\0\320\37\2\0\0\0\0\0"..., 832) = 832
  fstat(3, {st_mode=S_IFREG|0755, st_size=1845024, ...}) = 0
  mmap(NULL, 3953344, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f423fa30000
  mprotect(0x7f423fbeb000, 2097152, PROT_NONE) = 0
  mmap(0x7f423fdeb000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1bb000) = 0x7f423fdeb000
  mmap(0x7f423fdf1000, 17088, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f423fdf1000
  close(3)                                = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f423fff3000
  mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f423fff1000
  arch_prctl(ARCH_SET_FS, 0x7f423fff1740) = 0
  mprotect(0x7f423fdeb000, 16384, PROT_READ) = 0
  mprotect(0x600000, 4096, PROT_READ)     = 0
  mprotect(0x7f4240018000, 4096, PROT_READ) = 0
  munmap(0x7f423fff4000, 136133)          = 0
  open("/dev/cdrom", O_RDONLY|O_NONBLOCK) = 3
  fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 1), ...}) = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f4240015000
  write(1, "3\n", 23
  )                      = 2
  ioctl(3, CDROMEJECT, 0)                 = -1 EIO (Input/output error)
  dup(2)                                  = 4
  fcntl(4, F_GETFL)                       = 0x8002 (flags O_RDWR|O_LARGEFILE)
  brk(0)                                  = 0x2015000
  brk(0x2036000)                          = 0x2036000
  fstat(4, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 1), ...}) = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f4240014000
  lseek(4, 0, SEEK_CUR)                   = -1 ESPIPE (Illegal seek)
  write(4, "ioctl: Input/output error\n", 26ioctl: Input/output error
  ) = 26
  close(4)                                = 0
  munmap(0x7f4240014000, 4096)            = 0
  exit_group(1)                           = ?
  +++ exited with 1 +++
  </code></pre>
  
  <p>Straced system eject:</p>
  
  <pre><code>bo@bo-ThinkPad-Edge-E530:~$ strace eject 
  execve("/usr/bin/eject", ["eject"], [/* 75 vars */]) = 0
  brk(0)                                  = 0x7f3dbd946000
  access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
  mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3dbd094000
  access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
  open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
  fstat(3, {st_mode=S_IFREG|0644, st_size=136133, ...}) = 0
  mmap(NULL, 136133, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3dbd072000
  close(3)                                = 0
  access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
  open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
  read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0&gt;\0\1\0\0\0\320\37\2\0\0\0\0\0"..., 832) = 832
  fstat(3, {st_mode=S_IFREG|0755, st_size=1845024, ...}) = 0
  mmap(NULL, 3953344, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f3dbcaae000
  mprotect(0x7f3dbcc69000, 2097152, PROT_NONE) = 0
  mmap(0x7f3dbce69000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1bb000) = 0x7f3dbce69000
  mmap(0x7f3dbce6f000, 17088, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f3dbce6f000
  close(3)                                = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3dbd071000
  mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3dbd06f000
  arch_prctl(ARCH_SET_FS, 0x7f3dbd06f740) = 0
  mprotect(0x7f3dbce69000, 16384, PROT_READ) = 0
  mprotect(0x7f3dbd29f000, 4096, PROT_READ) = 0
  mprotect(0x7f3dbd096000, 4096, PROT_READ) = 0
  munmap(0x7f3dbd072000, 136133)          = 0
  brk(0)                                  = 0x7f3dbd946000
  brk(0x7f3dbd967000)                     = 0x7f3dbd967000
  open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
  fstat(3, {st_mode=S_IFREG|0644, st_size=4427728, ...}) = 0
  mmap(NULL, 4427728, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3dbc675000
  close(3)                                = 0
  access("/dev/cdrom", F_OK)              = 0
  readlink("/dev/cdrom", "sr0", 4095)     = 3
  lstat("/dev", {st_mode=S_IFDIR|0755, st_size=4300, ...}) = 0
  lstat("/dev/sr0", {st_mode=S_IFBLK|0660, st_rdev=makedev(11, 0), ...}) = 0
  readlink("/dev/sr0", 0x7fff014d9428, 4095) = -1 EINVAL (Invalid argument)
  stat("/dev/sr0", {st_mode=S_IFBLK|0660, st_rdev=makedev(11, 0), ...}) = 0
  open("/etc/mtab", O_RDONLY)             = 3
  fstat(3, {st_mode=S_IFREG|0644, st_size=911, ...}) = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3dbd093000
  read(3, "/dev/sda5 / ext4 rw,errors=remou"..., 4096) = 911
  stat("/dev/sda5", {st_mode=S_IFBLK|0660, st_rdev=makedev(8, 5), ...}) = 0
  stat("proc", 0x7fff014dc740)            = -1 ENOENT (No such file or directory)
  stat("sysfs", 0x7fff014dc740)           = -1 ENOENT (No such file or directory)
  stat("none", 0x7fff014dc740)            = -1 ENOENT (No such file or directory)
  stat("none", 0x7fff014dc740)            = -1 ENOENT (No such file or directory)
  stat("none", 0x7fff014dc740)            = -1 ENOENT (No such file or directory)
  stat("none", 0x7fff014dc740)            = -1 ENOENT (No such file or directory)
  stat("udev", 0x7fff014dc740)            = -1 ENOENT (No such file or directory)
  stat("devpts", 0x7fff014dc740)          = -1 ENOENT (No such file or directory)
  stat("tmpfs", 0x7fff014dc740)           = -1 ENOENT (No such file or directory)
  stat("none", 0x7fff014dc740)            = -1 ENOENT (No such file or directory)
  stat("none", 0x7fff014dc740)            = -1 ENOENT (No such file or directory)
  stat("none", 0x7fff014dc740)            = -1 ENOENT (No such file or directory)
  stat("none", 0x7fff014dc740)            = -1 ENOENT (No such file or directory)
  stat("/dev/sda6", {st_mode=S_IFBLK|0660, st_rdev=makedev(8, 6), ...}) = 0
  stat("binfmt_misc", 0x7fff014dc740)     = -1 ENOENT (No such file or directory)
  stat("systemd", 0x7fff014dc740)         = -1 ENOENT (No such file or directory)
  stat("gvfsd-fuse", 0x7fff014dc740)      = -1 ENOENT (No such file or directory)
  read(3, "", 4096)                       = 0
  close(3)                                = 0
  munmap(0x7f3dbd093000, 4096)            = 0
  open("/etc/fstab", O_RDONLY)            = 3
  fstat(3, {st_mode=S_IFREG|0664, st_size=595, ...}) = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3dbd093000
  read(3, "# /etc/fstab: static file system"..., 4096) = 595
  read(3, "", 4096)                       = 0
  close(3)                                = 0
  munmap(0x7f3dbd093000, 4096)            = 0
  stat("/dev/sr0", {st_mode=S_IFBLK|0660, st_rdev=makedev(11, 0), ...}) = 0
  open("/usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache", O_RDONLY) = 3
  fstat(3, {st_mode=S_IFREG|0644, st_size=26258, ...}) = 0
  mmap(NULL, 26258, PROT_READ, MAP_SHARED, 3, 0) = 0x7f3dbd08d000
  close(3)                                = 0
  geteuid()                               = 1000
  open("/dev/sr0", O_RDWR|O_NONBLOCK)     = 3
  ioctl(3, CDROMEJECT, 0x7f3dbd9490e0)    = -1 EIO (Input/output error)
  ioctl(3, SG_GET_VERSION_NUM, 0x7fff014dd4b8) = 0
  ioctl(3, SG_IO, {'S', SG_DXFER_NONE, cmd[6]=[1e, 00, 00, 00, 00, 00], mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=10000, flags=0, status=00, masked_status=00, sb[0]=[], host_status=0, driver_status=0, resid=0, duration=16, info=0}) = 0
  ioctl(3, SG_IO, {'S', SG_DXFER_NONE, cmd[6]=[1b, 00, 00, 00, 01, 00], mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=10000, flags=0, status=00, masked_status=00, sb[0]=[], host_status=0, driver_status=0, resid=0, duration=856, info=0}) = 0
  ioctl(3, SG_IO, {'S', SG_DXFER_NONE, cmd[6]=[1b, 00, 00, 00, 02, 00], mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=10000, flags=0, status=02, masked_status=01, sb[18]=[70, 00, 05, 00, 00, 00, 00, 0a, 00, 00, 00, 00, 53, 02, 00, 00, 00, 00], host_status=0, driver_status=0x8, resid=0, duration=4, info=0x1}) = 0
  ioctl(3, FDEJECT, 0x7fff014dd4c8)       = -1 ENOTTY (Inappropriate ioctl for device)
  ioctl(3, MGSL_IOCGPARAMS or MMTIMER_GETRES or MTIOCTOP or SNDCTL_MIDI_MPUMODE, 0x7fff014dd4c8) = -1 ENOTTY (Inappropriate ioctl for device)
  open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 4
  fstat(4, {st_mode=S_IFREG|0644, st_size=2570, ...}) = 0
  mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3dbd08c000
  read(4, "# Locale name alias data base.\n#"..., 4096) = 2570
  read(4, "", 4096)                       = 0
  close(4)                                = 0
  munmap(0x7f3dbd08c000, 4096)            = 0
  open("/usr/share/locale/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
  open("/usr/share/locale/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
  open("/usr/share/locale-langpack/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
  open("/usr/share/locale-langpack/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
  open("/usr/share/locale/en_US/LC_MESSAGES/eject.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
  open("/usr/share/locale/en/LC_MESSAGES/eject.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
  open("/usr/share/locale-langpack/en_US/LC_MESSAGES/eject.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
  open("/usr/share/locale-langpack/en/LC_MESSAGES/eject.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
  write(2, "eject: unable to eject, last err"..., 67eject: unable to eject, last error: Inappropriate ioctl for device
  ) = 67
  exit_group(1)                           = ?
  +++ exited with 1 +++
  </code></pre>