Add logname(1).

utils/.gitignore

@@ -25,6 +25,7 @@ help
 kernelinfo
 kill
 ln
+logname
 ls
 memstat
 mkdir

utils/Makefile

@@ -36,6 +36,7 @@ id \
 kernelinfo \
 kill \
 ln \
+logname \
 ls \
 memstat \
 mkdir \
@@ -74,6 +75,7 @@ xinstall
 MANPAGES1=\
 chkblayout.1 \
 kernelinfo.1 \
+logname.1 \
 memstat.1 \
 pager.1 \
 passwd.1 \

utils/logname.1

@@ -0,0 +1,17 @@
+.Dd October 13, 2016
+.Dt LOGNAME 1
+.Os
+.Sh NAME
+.Nm logname
+.Nd print login name
+.Sh SYNOPSIS
+.Nm
+.Sh DESCRIPTION
+.Nm
+prints the login name of the session.
+.Sh EXIT STATUS
+.Nm
+will exit with 0 on success and non-zero otherwise.
+.Sh SEE ALSO
+.Xr id 1 ,
+.Xr getlogin 3

utils/logname.c

@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2016 Nicholas De Nova.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * logname.c
+ * Print login name.
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+static void compact_arguments(int* argc, char*** argv)
+{
+	for ( int i = 0; i < *argc; i++ )
+	{
+		while ( i < *argc && !(*argv)[i] )
+		{
+			for ( int n = i; n < *argc; n++ )
+				(*argv)[n] = (*argv)[n+1];
+			(*argc)--;
+		}
+	}
+}
+
+int main(int argc, char* argv[])
+{
+	for ( int i = 1; i < argc; i++ )
+	{
+		const char* arg = argv[i];
+		if ( arg[0] != '-' || !arg[1] )
+			continue;
+		argv[i] = NULL;
+		if ( !strcmp(arg, "--") )
+			break;
+		if ( arg[1] != '-' )
+		{
+			char c;
+			while ( (c = *++arg) )
+				switch ( c )
+				{
+				default:
+					errx(1, "unknown option -- '%c'", c);
+				}
+		}
+		else
+			errx(1, "unknown option: %s", arg);
+	}
+
+	compact_arguments(&argc, &argv);
+
+	if ( 1 < argc )
+		errx(1, "unexpected extra operand");
+
+	char* login_name = getlogin();
+	if ( !login_name )
+	{
+		if ( errno )
+			err(1, "could not get login name");
+		else
+			errx(1, "could not get login name");
+	}
+
+	printf("%s\n", login_name);
+	if ( ferror(stdout) || fflush(stdout) == EOF )
+		err(1, "stdout");
+
+	return 0;
+}