Udev::FFI - Perl bindings for libudev using ffi.
use Udev::FFI; use Udev::FFI::Devnum qw(:all); # <- import major, minor and makedev # get udev library version my $udev_version = Udev::FFI::udev_version() or die("Can't get udev library version: $@"); # create Udev::FFI object my $udev = Udev::FFI->new() or die("Can't create Udev::FFI object: $@"); # create udev monitor my $monitor = $udev->new_monitor() or die("Can't create udev monitor: $@"); # add filter to monitor unless ($monitor->filter_by_subsystem_devtype('block')) { warn("Ouch!"); } # start monitor if ($monitor->start()) { for (;;) { # poll devices, now insert or remove your block device my $device = $monitor->poll(); # blocking read my $action = $device->get_action(); print("ACTION: $action\n"); print('SYSNAME: '.$device->get_sysname()."\n"); print('DEVNODE: '.$device->get_devnode()."\n"); last; # for example } for (;;) { # poll devices, now insert or remove your block device if (defined(my $device = $monitor->poll(0))) { # non-blocking read like can_read in IO::Select my $action = $device->get_action(); print("ACTION: $action\n"); print('SYSNAME: '.$device->get_sysname()."\n"); print('DEVNODE: '.$device->get_devnode()."\n"); } sleep(1); last; # for example } } # enumerate devices my $enumerate = $udev->new_enumerate() or die("Can't create enumerate context: $@"); $enumerate->add_match_subsystem('block'); $enumerate->scan_devices(); use Data::Dumper; # for dump values in $href and @a # scalar context my $href = $enumerate->get_list_entries(); print(Dumper($href)."\n"); # list context my @a = $enumerate->get_list_entries(); print(Dumper(@a)."\n"); if (@a) { # we got devices my $device = $udev->new_device_from_syspath($a[0]); if (defined($device)) { print('Device: '.$device->get_sysname()."\n"); my $devnum = $device->get_devnum(); # major, minor and makedev from Udev::FFI::Devnum my ($ma, $mi) = (major($devnum), minor($devnum)); print("Major: $ma\n"); print("Minor: $mi\n"); $devnum = makedev($ma, $mi); print("Devnum: $devnum\n"); # scalar context $href = $device->get_properties_list_entries(); print(Dumper($href)."\n"); # list context @a = $device->get_properties_list_entries(); print(Dumper(@a)."\n"); } }
Udev::FFI exposes OO interface to libudev.
This is the constructor for a new Udev::FFI object.
If the constructor fails undef will be returned and an error message will be in $@.
my $udev = Udev::FFI->new() or die("Can't create Udev::FFI object: $@");
Create new udev monitor and connect to a specified event source. Valid sources identifiers are 'udev' and 'kernel'. This argument is optional and defaults to 'udev'.
'udev'
'kernel'
Return new Udev::FFI::Monitor object on success, undef with the error in $@ on failure.
my $monitor = $udev->new_monitor() or die("Can't create udev monitor: $@");
Create an enumeration context to scan /sys.
Return new Udev::FFI::Enumerate object on success, undef with the error in $@ on failure.
my $enumerate = $udev->new_enumerate() or die("Can't create enumerate context: $@");
Create new udev device, and fill in information from the sys device and the udev database entry. The syspath is the absolute path to the device, including the sys mount point.
Return new Udev::FFI::Device object or undef, if device does not exist.
my $device0 = $udev->new_device_from_syspath('/sys/class/block/sda1'); my $device1 = $udev->new_device_from_syspath('/sys/class/net/eth0'); # ... some code my @devices = $enumerate->get_list_entries(); for (@devices) { my $device = $udev->new_device_from_syspath($_); # ... some code
Create new udev device, and fill in information from the sys device and the udev database entry. The device is looked-up by its type and major/minor number.
use Udev::FFI::Devnum qw(makedev); my $device0 = $udev->new_device_from_devnum('b', makedev(8, 1)); my $device1 = $udev->new_device_from_devnum('c', makedev(189, 515));
Create new udev device, and fill in information from the sys device and the udev database entry. The device is looked up by the subsystem and name string of the device.
my $device0 = $udev->new_device_from_subsystem_sysname('block', 'sda1'); my $device1 = $udev->new_device_from_subsystem_sysname('net', 'lo'); my $device2 = $udev->new_device_from_subsystem_sysname('mem', 'urandom');
Create new udev device, and fill in information from the sys device and the udev database entry. The device is looked-up by a special string:
'b8:1' - block device major:minor
'b8:1'
'c128:2' - char device major:minor
'c128:2'
'n2' - network device ifindex
'n2'
'+sound:card29' - kernel driver core subsystem:device name
'+sound:card29'
my $device = $udev->new_device_from_device_id('b8:1');
Create new udev device, and fill in information from the current process environment. This only works reliable if the process is called from a udev rule.
# in udev.rules (for example) # SUBSYSTEM=="backlight", ACTION=="change", IMPORT{program}="/path/script.pl" # in script my $udev = Udev::FFI->new() or die("Can't create Udev::FFI object: $@"); my $device = $udev->new_device_from_environment(); if (defined($device)) { # $device is the device from the udev rule (backlight in this example) # work with $device
Return the version of the udev library. Because the udev library does not provide a function to get the version number, this function runs the `udevadm` utility.
Return undef with the error in $@ on failure. Also you can check $! value: ENOENT (`udevadm` not found) or EACCES (permission denied).
# simple my $udev_version = Udev::FFI::udev_version() or die("Can't get udev library version: $@"); # or catch the error use Errno qw( :POSIX ); my $udev_version = Udev::FFI::udev_version(); unless (defined($udev_version)) { if ($!{ENOENT}) { # udevadm not found } elsif ($!{EACCES}) { # permission denied } die("Can't get udev library version: $@"); }
Examples are provided with the Udev::FFI distribution in the "examples" directory.
libudev
eudev
FFI::Platypus (Write Perl bindings to non-Perl libraries without C or XS)
FFI::CheckLib (Check that a library is available for FFI)
Udev::FFI supports libudev 171 or newer. Older versions may work too, but it was not tested.
Please report any bugs through the web interface at https://github.com/Ilya33/udev-ffi/issues. Patches are always welcome.
Ilya Pavlov, <ilux@cpan.org>
Contributors:
Mohammad S Anwar
Copyright (C) 2017-2022 by Ilya Pavlov
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
To install Udev::FFI, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Udev::FFI
CPAN shell
perl -MCPAN -e shell install Udev::FFI
For more information on module installation, please visit the detailed CPAN module installation guide.