Improved and documented workaround for udev
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@ -92,6 +92,21 @@ Make sure to re-compile all source files after running ./configure
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make install
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Linux only:
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libburn tries to avoid a collision with udev's drive examination by waiting
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0.1 seconds before opening the device file for a longer time, after udev
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might have been alarmed by drive scanning activities.
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The waiting time can be set at ./configure time with microsecond granularity.
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E.g. 2 seconds:
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CFLAGS="$CFLAGS -DLibburn_udev_wait_useC=2000000"
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./configure ...options...
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Closing and re-opening can be disabled by zero waiting time:
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CFLAGS="$CFLAGS -DLibburn_udev_wait_useC=0"
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Alternatively, libburn can try to be nice by opening the device file,
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closing it immediately, waiting, and only then opening it for real:
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CFLAGS="$CFLAGS -DLibburn_udev_extra_open_cyclE"
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------------------------------------------------------------------------------
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An important part of the project, libisofs, is hosted in a bzr repository at
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@ -438,6 +438,22 @@ It will not read startup files, will abort on option dev_translation= ,
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will not have a fifo buffer, and will not be able to put out help texts or
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debugging messages.
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Linux only:
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libburn tries to avoid a collision with udev's drive examination by waiting
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0.1 seconds before opening the device file for a longer time, after udev
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might have been alarmed by drive scanning activities.
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The waiting time can be set at ./configure time with microsecond granularity.
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E.g. 2 seconds:
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CFLAGS="$CFLAGS -DLibburn_udev_wait_useC=2000000"
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./configure ...options...
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Closing and re-opening can be disabled by zero waiting time:
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CFLAGS="$CFLAGS -DLibburn_udev_wait_useC=0"
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Alternatively, libburn can try to be nice by opening the device file,
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closing it immediately, waiting, and only then opening it for real:
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CFLAGS="$CFLAGS -DLibburn_udev_extra_open_cyclE"
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------------------------------------------------------------------------------
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System Dependend Drive Permission Examples
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@ -1 +1 @@
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#define Cdrskin_timestamP "2011.09.20.132438"
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#define Cdrskin_timestamP "2011.09.21.133344"
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@ -1531,6 +1531,33 @@ int sg_grab(struct burn_drive *d)
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relase of drive. Unclear why not the official error return
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value -1 of open(2) war used. */
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if(! burn_drive_is_open(d)) {
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char msg[120];
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#ifndef Libburn_udev_wait_useC
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#define Libburn_udev_wait_useC 100000
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#endif
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#ifndef Libburn_udev_extra_open_cyclE
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if (Libburn_udev_wait_useC > 0) {
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/* ts B10921 : workaround for udev which might get
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a kernel event from open() and might
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remove links if it cannot inspect the
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drive. This waiting period shall allow udev
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to act after it was woken up by the drive scan
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activities.
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*/
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sprintf(msg,
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"To avoid collision with udev: Waiting %lu usec before grabbing",
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(unsigned long) Libburn_udev_wait_useC);
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libdax_msgs_submit(libdax_messenger, -1, 0x00000002,
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LIBDAX_MSGS_SEV_DEBUG, LIBDAX_MSGS_PRIO_HIGH,
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msg, 0, 0);
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usleep(Libburn_udev_wait_useC);
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}
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#endif /* Libburn_udev_extra_open_cyclE */
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try_open:;
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/* ts A60821
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@ -1553,21 +1580,34 @@ try_open:;
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fd = open(d->devname, open_mode);
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os_errno = errno;
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if (fd >= 0) {
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/* ts B10920 : workaround for udev which might get
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a kernel event from open() and might
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remove links if it cannot inspect the
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drive.
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*/
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#ifdef Libburn_udev_extra_open_cyclE
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/* ts B10920 : workaround for udev which might get
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a kernel event from open() and might
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remove links if it cannot inspect the
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drive.
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ts B10921 : this is more obtrusive than above waiting
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before open(). The drive scan already has
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opened and closed the drive several times.
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So it seems to be merely about giving an
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opportunity to udev, before long term grabbing
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happens.
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*/
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if (fd >= 0 && Libburn_udev_wait_useC > 0) {
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close(fd);
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sprintf(msg,
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"To avoid collision with udev: Waiting %lu usec before re-opening",
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(unsigned long) Libburn_udev_wait_useC);
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libdax_msgs_submit(libdax_messenger, -1, 0x00000002,
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LIBDAX_MSGS_SEV_DEBUG, LIBDAX_MSGS_PRIO_HIGH,
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"Waiting 2 seconds to avoid collision with udev",
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0, 0);
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close(fd);
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usleep(2000000);
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msg, 0, 0);
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usleep(Libburn_udev_wait_useC);
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fd = open(d->devname, open_mode);
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os_errno = errno;
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}
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#endif /* Libburn_udev_extra_open_cyclE */
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if (fd >= 0) {
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sg_fcntl_lock(&fd, d->devname, F_WRLCK, 1);
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if (fd < 0)
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@ -1591,6 +1631,10 @@ try_open:;
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drive_is_in_use:;
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tries++;
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if (tries < max_tries) {
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libdax_msgs_submit(libdax_messenger, -1, 0x00000002,
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LIBDAX_MSGS_SEV_DEBUG, LIBDAX_MSGS_PRIO_HIGH,
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"Drive is in use. Waiting 2 seconds before re-try",
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0, 0);
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usleep(2000000);
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goto try_open;
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}
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