Add hostname(1).

Makefile

@@ -15,6 +15,7 @@ disked \
 editor \
 ext \
 games \
+hostname \
 init \
 kblayout \
 kblayout-compiler \

hostname/.gitignore

@@ -0,0 +1 @@
+hostname

hostname/Makefile

@@ -0,0 +1,28 @@
+include ../build-aux/platform.mak
+include ../build-aux/compiler.mak
+include ../build-aux/version.mak
+include ../build-aux/dirs.mak
+
+OPTLEVEL?=$(DEFAULT_OPTLEVEL)
+CFLAGS?=$(OPTLEVEL)
+
+CFLAGS += -Wall -Wextra
+
+BINARIES = hostname
+MANPAGES1 = hostname.1
+
+all: $(BINARIES)
+
+.PHONY: all install clean
+
+install: all
+	mkdir -p $(DESTDIR)$(BINDIR)
+	install $(BINARIES) $(DESTDIR)$(BINDIR)
+	mkdir -p $(DESTDIR)$(MANDIR)/man1
+	install $(MANPAGES1) $(DESTDIR)$(MANDIR)/man1
+
+%: %.c
+	$(CC) -std=gnu11 $(CFLAGS) $(CPPFLAGS) $< -o $@
+
+clean:
+	rm -f $(BINARIES)

hostname/hostname.1

@@ -0,0 +1,28 @@
+.Dd March 19, 2017
+.Dt HOSTNAME 1
+.Os
+.Sh NAME
+.Nm hostname
+.Nd write or set system hostname
+.Sh SYNOPSIS
+.Nm hostname
+.Op Fl s
+.Op Ar hostname
+.Sh DESCRIPTION
+.Nm
+writes the system hostname, or sets the system hostname to
+.Ar hostname
+if specified.
+.Pp
+The options are as follows:
+.Bl -tag -width "12345678"
+.It Fl s , Fl \-short
+Write the hostname up to but not including the first period.
+.El
+.Sh EXIT STATUS
+.Nm
+will exit 0 on success and non-zero otherwise.
+.Sh SEE ALSO
+.Xr gethostname 2 ,
+.Xr sethostname 2 ,
+.Xr hostname 5

hostname/hostname.c

@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2017 Jonas 'Sortie' Termansen.
+ *
+ * Permission to use, copy, modify, and 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.
+ *
+ * hostname.c
+ * Write or set the system hostname.
+ */
+
+#include <err.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+// TODO: The Sortix <limits.h> doesn't expose this at the moment.
+#if !defined(HOST_NAME_MAX) && defined(__sortix__)
+#include <sortix/limits.h>
+#endif
+
+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[])
+{
+	bool short_hostname = false;
+
+	const char* argv0 = argv[0];
+	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 )
+			{
+			case 's': short_hostname = true; break;
+			default:
+				fprintf(stderr, "%s: unknown option -- '%c'\n", argv0, c);
+				exit(1);
+			}
+		}
+		else if ( !strcmp(arg, "--short") )
+			short_hostname = true;
+		else
+		{
+			fprintf(stderr, "%s: unknown option: %s\n", argv0, arg);
+			exit(1);
+		}
+	}
+
+	compact_arguments(&argc, &argv);
+
+	if ( 3 <= argc )
+		errx(1, "unexpected extra operand");
+
+	if ( argc == 2 )
+	{
+		if ( short_hostname )
+			errx(1, "the -s option is incompatible with setting hostname");
+		char* hostname = argv[1];
+		if ( sethostname(hostname, strlen(hostname)) < 0 )
+			err(1, "sethostname: %s", hostname);
+		return 0;
+	}
+
+	char hostname[HOST_NAME_MAX + 1];
+	if ( gethostname(hostname, sizeof(hostname)) < 0 )
+		err(1, "gethostname");
+	if ( short_hostname )
+		hostname[strcspn(hostname, ".")] = '\0';
+	puts(hostname);
+
+	if ( ferror(stdout) || fflush(stdout) == EOF )
+		err(1, "stdout");
+	return 0;
+}

share/man/man5/hostname.5

@@ -26,5 +26,7 @@ System hostname.
 dragon
 .Ed
 .Sh SEE ALSO
+.Xr hostname 1 ,
+.Xr gethostname 2 ,
 .Xr sethostname 2 ,
 .Xr init 8