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

On November 29, 2018 9:59:52 AM GMT+13:00, Florian Weimer [off-list ref] wrote:

* Christian Brauner:

quoted

+.\" Copyright (C) 2018 Christian Brauner [off-list ref]

The text seems to be largely derived from rt_sigqueueinfo, so I'm not
sure if this appropriate here.

quoted

+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?

quoted

+.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.

quoted

+.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?