Re: [PATCH] procfd_signal.2: document procfd_signal syscall

Christian Brauner
2018-11-28T21:12:17Z

On November 29, 2018 9:59:52 AM GMT+13:00, Florian Weimer <fweimer@redhat.com> wrote:
>* Christian Brauner:
>
>> +.\" Copyright (C) 2018 Christian Brauner <christian@brauner.io>
>
>The text seems to be largely derived from rt_sigqueueinfo, so I'm not
>sure if this appropriate here.
>
>> +the null signal (0) can be used to check if a process with a given
>> +PID exists.
>
>What does this mean if hte process is identified by file descriptor?
>
>> +.PP
>> +The optional
>> +.I info
>> +argument specifies the data to accompany the signal.
>> +This argument is a pointer to a structure of type
>> +.IR siginfo_t ,
>> +described in
>> +.BR sigaction (2)
>> +(and defined by including
>> +.IR <sigaction.h> ).
>> +The caller should set the following fields in this structure:
>> +.TP
>> +.I si_code
>> +This must be one of the
>> +.B SI_*
>> +codes in the Linux kernel source file
>> +.IR include/asm-generic/siginfo.h ,
>> +with the restriction that the code must be negative
>> +(i.e., cannot be
>> +.BR SI_USER ,
>> +which is used by the kernel to indicate a signal sent by
>> +.BR kill (2))
>> +and cannot (since Linux 2.6.39) be
>
>Obsolete reference in this context.
>
>> +.TP
>> +.B ESRCH
>> +The process or process group does not exist.
>> +Note that an existing process might be a zombie,
>> +a process that has terminated execution, but
>> +has not yet been
>> +.BR wait (2)ed
>> +for.
>
>Again: What does this mean if the process identified by a descriptor?
>Does a process in zombie state exist in this sense or not?
>
>Thanks,
>Florian

Updating the document is on my Todo.
Florian, can you take a look at the actual patch too, please?