Weird problem with MDEV as a daemon

[David Henderson]

Good morning Leonid.  Sorry to hear about your issues with BB mdev.
While I can't provide any help regarding this situation, I do know of
another mdev software that might help you resolve some of your
problems:

https://skarnet.org/software/mdevd/

Dave



On 9/8/20, Leonid Zhigunov <lzhigunov at qulsar.com> wrote:
> Hi,
>
> I am using Busybox 1.31.0.
> I tried to use MDEV for SD card automounting, but couldn't make it to work.
>
> If mdev.conf entry has a simple command, say, *echo automount, everything
> works fine.
> As soon as the card is inserted or removed, the command is invoked and
> prints "automount".
>
> But if I specify a script file name intead, i.e. */etc/mdev.d/automount,
> things get strange.
> The sript file has proper permissions. It can be successfully executed from
> the command line by
> # /etc/mdev.d/automount
> # sh /etc/mdev.d/automount
> # sh -c /etc/mdev.d/automount
> and, provided with proper ACTION and MDEV env variables, it does all things
> it suppose to do.
>
> But regardless of script's name, location or contents, whether it has
> #!/bin/sh prefix or not,
> it doesn't work with MDEV.
>
> What I get is the strange output on the terminal (when #mdev -df) every
> time
> the command is invoked:
> : not foundev.d/automount
>
> In the mdev.log is the same:
> running: /etc/mdev.d/automount
> : not foundev.d/automount
>
> Ok, I added some printfs in the busybox's entry point, to print actual
> command line string
> busybox is invoked with. The interesting thing is: on every command
> strating
> from the very first init
> prints are ok, but from mdev it showed:
>  h -c /etc/mdev.d/automount, i.e. the first character was missing (or
> replaced with space).
> So I added argv[0][0] as hex in the beginning, and again everything was ok
> for everything
> # umount
> 75 umount
>
> but MDEV:
> # mdev -df
>  3 sh -c /etc/mdev.d/automount (first character is missing, 7)
> : not foundev.d/automount
>
> Then I thried to replace system() call in MDEV with how it's done in
> ifupdown doit().
> I got even funnier result:
>
> # mdev -df
> 6d mdev -df
>  f /bin/sh /etc/mdev/automount (first character is missing, 2)
> ': No such file or directoryev.d/automount
> ': File existsn '/etc/mdev.d/automount
> The last line is actually a somehow overidden string from MDEV's
> bb_perror_msg("can't run '%s'", command);
>
> This all makes me think that system() call MDEV is using or nested shell
> invocations are not
> working as they suppose to and somehow mess up the output.
>
> Has anyone seen something similar?
> Is it my-only problem? Did I miss some required settings in the build
> configuration?
>
> Any help is much appreciated.
>
> Kind regards,
> Leonid
>
>