.\"	$OpenBSD: mdoc.template,v 1.15 2014/03/31 00:09:54 dlg Exp $
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.\" Copyright (c) 2022 Guilherme Janczak <guilherme.janczak@yandex.com>
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.Dd $Mdocdate: April 20 2022 $
.Dt SETPROCTITLE 3
.Os
.Sh NAME
.Nm setproctitle_init ,
.Nm setproctitle
.Nd set process title
.Sh SYNOPSIS
.In stdlib.h
.Fd #if defined(setproctitle_init)
.Ft void
.Fn setproctitle_init "int argc" "char *argv[]" "char *envp[]"
.Fd #endif
.Ft void
.Fn setproctitle "const char *fmt" "..."
.Sh DESCRIPTION
If
.Dv setproctitle_init
is defined,
call
.Fn setproctitle_init "argc" "argv" "environ"
before using
.Fa argc ,
.Fa argv ,
or the environment.
.Pp
The
.Fn setproctitle
function sets the process' title; the title is set to the program's name as
returned by
.Xr getprogname 3 ,
followed by a colon, a space, and the output of
.Xr printf 3
with
.Fa fmt
and
.Fa ...
as arguments.
The title is limited to 2048 bytes.
.Pp
If
.Fa fmt
is
.Dv NULL ,
the title is set to the program's name.
.Pp
If
.Fn setproctitle
is called before
.Fn setproctitle_init ,
it is no-op.
.Fn setproctitle_init
is compatible with libbsd.
.Sh EXAMPLES
As far as
.Fn setproctitle_init ,
.Fn setproctitle ,
and their users are concerned, there are 3 kinds of systems:
.Bl -bullet
.It
Systems in which libobsd is not used because it's not needed.
.It
Systems in which libobsd is in use, and libobsd's
.Fn setproctitle
does not need initialization.
.It
Systems in which libobsd is in use, and libobsd's
.Fn setproctitle
needs initialization.
.El
.Pp
The following is a complete program listing which works unmodified across all 3
kinds of systems,
and showcases proper usage of
.Fn setproctitle_init
and
.Fn setproctitle :
.Bd -literal -offset indent
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int
main(int argc, char *argv[])
{
	int ch;
	char *tflag;

#if defined(setproctitle_init)
	extern char **environ;
	setproctitle_init(argc, argv, environ);
#endif

	tflag = NULL;
	while ((ch = getopt(argc, argv, "t:")) != -1) {
		switch(ch) {
		case 't':
			tflag = optarg;
			break;
		default:
			exit(1);
		}
	}

	if (tflag == NULL)
		setproctitle("libobsd setproctitle");
	else
		setproctitle("%s", tflag);
	fputs("Press enter to exit: ", stdout);
	fflush(stdout);
	getchar();
}
.Ed
.Sh SEE ALSO
.Xr getprogname 3 ,
.Xr vsnprintf 3
.Sh CAVEATS
.Fn setproctitle_init
is a necessary libbsd extension and does not exist on
.Ox .
.Pp
The process' title may be truncated to less than 2048 bytes in some cases.
.Pp
A
.Fn setproctitle NULL
call doesn't set the title to the original title.
It only sets the title to the program name,
the original might have contained the program's path and arguments.
.Pp
Do not pass an user-supplied string as the value of
.Fa fmt .
Format specifiers in
.Fa fmt
will be interpreted and can be used to manipulate the stack,
this is a security vulnerability.
Always use the secure idiom:
.Bd -literal -offset indent
setproctitle("%s", str);
.Ed