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The klibc implementation of getopt_long() behaves slightly different from the glibc one - in particular, it treats the change of the option string argument between invocations as start of parsing a different command line, and resets its state. However, the udevadm code expected getopt_long() invocations in subcommands to continue parsing the rest of command line after initial options has been parsed at the top level; with klibc this broke, causing all udevadm subcommands to stop recognizing their options. Instead of relying on the glibc behavior, reset the getopt_long() state properly before invoking the subcommand handler: move argv to point to the subcommand name, decrease argc appropriately, and set optind = 0. This also fixes a minor bug visible with glibc - without setting optind = 0 all getopt_long() calls in subcommand handlers were behaving as if "+" was specified as the first character of the option string (which disables option reordering), because that state was set by the first getopt_long() call at the top level, and was not reset when parsing subcommand options. Signed-off-by: Sergey Vlasov <vsu@altlinux.ru>
udev - userspace device management
For more information see the files in the docs/ directory.
Important Note:
Integrating udev in the system has complex dependencies and differs from distro
to distro. All major distros depend on udev these days and the system may not
work without a properly installed version. The upstream udev project does not
recommend to replace a distro's udev installation with the upstream version.
Requirements:
- Version 2.6.19 of the Linux kernel for reliable operation of this release of
udev. The kernel may have a requirement on udev too, see Documentation/Changes
in the kernel source tree for the actual dependency.
- The kernel must have sysfs, unix domain sockets and networking enabled.
(unix domain sockets (CONFIG_UNIX) as a loadable kernel module may work,
but it does not make any sense - don't complain if anything goes wrong.)
- The proc filesystem must be mounted on /proc/, the sysfs filesystem must
be mounted at /sys/. No other locations are supported by udev.
Operation:
Udev creates and removes device nodes in /dev/, based on events the kernel
sends out on device discovery or removal.
- Very early in the boot process, the /dev/ directory should get a 'tmpfs'
filesystem mounted, which is populated from scratch by udev. Created nodes
or changed permissions will not survive a reboot, which is intentional.
- The content of /lib/udev/devices/ directory which contains the nodes,
symlinks and directories, which are always expected to be in /dev, should
be copied over to the tmpfs mounted /dev, to provide the required nodes
to initialize udev and continue booting.
- The old hotplug helper /sbin/hotplug should be disabled on bootup, before
actions like loading kernel modules are taken, which may cause a lot of
events.
- The udevd daemon must be started on bootup to receive netlink uevents
from the kernel driver core.
- All kernel events are matched against a set of specified rules in
/lib/udev/rules.d/ which make it possible to hook into the event
processing to load required kernel modules and setup devices. For all
devices the kernel exports a major/minor number, udev will create a
device node with the default kernel name, or the one specified by a
matching udev rule.
Please direct any comment/question/concern to the linux-hotplug mailing list at:
linux-hotplug@vger.kernel.org