.Dd 10 March 2024
.Dt PROGNAME 3
.Os
.Sh NAME
.Nm mlib_progname ,
.Nm mlib_setprogname
.Nd get and set the program name
.Sh LIBRARY
.Lb mlib
.Sh SYNOPSIS
.In errors.h
.Ft "const char *"
.Fn mlib_progname void
.Ft void
.Fn mlib_setprogname "const char *s"
.Sh DESCRIPTION
The
.Fn mlib_progname
and
.Fn mlib_setprogname
functions can be used to get- and set the program name respectively.
The program name is a global c-string used by various diagnostic
functions such as
.Fn err
and
.Fn warn
in their generated diagnostic messages.
.Pp
The
.Fn mlib_progname
function returns a pointer to the global program name.
.Pp
The
.Fn mlib_setprogname
function sets the global program name to the null-terminated string
.Fa s .
This function is not thread-safe.
.Sh RETURN VALUES
The
.Fn mlib_progname
function returns a pointer to the global program name or
.Dv nullptr
if it hasn’t been set yet.
.Sh EXAMPLES
The following calls to
.Fn mlib_progname
and
.Fn mlib_setprogname
set the program name at the beginning of execution as is customary,
and then prints a usage error if no command-line arguments are specified.
.Bd -literal -offset indent
#include <stdio.h>
#include <stdlib.h>

#include <errors.h>

int
main(int argc, char **argv)
{
	mlib_setprogname(argv[0]);

	if (argc < 2) {
		fprintf(stderr, \(dqUsage: %s file ...\en\(dq, mlib_progname());
		exit(EXIT_FAILURE);
	}

	/* … */

	return EXIT_SUCCESS;
}
.Ed
.Sh SEE ALSO
.Xr err 3mlib
.Sh AUTHORS
.An Thomas Voss Aq Mt mail@thomasvoss.com