Just use HOST_NAME_MAX in hostname(1)

Using sysconf() + malloc() is overkill.

hostname.c

@@ -1,7 +1,6 @@
 /* See LICENSE file for copyright and license details. */
 #include <limits.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include "util.h"
@@ -15,16 +14,7 @@ usage(void)
 int
 main(int argc, char *argv[])
 {
-	long sz;
-	char *host;
-
-	sz = sysconf(_SC_HOST_NAME_MAX);
-	if (sz < 0)
-		sz = 255;
-
-	host = malloc(sz + 1);
-	if (!host)
-		eprintf("malloc:");
+	char host[HOST_NAME_MAX + 1];
 
 	ARGBEGIN {
 	default:
@@ -32,15 +22,12 @@ main(int argc, char *argv[])
 	} ARGEND;
 
 	if (argc < 1) {
-		if (gethostname(host, sz + 1) < 0)
+		if (gethostname(host, sizeof(host)) < 0)
 			eprintf("gethostname:");
 		puts(host);
 	} else {
 		if (sethostname(argv[0], strlen(argv[0])) < 0)
 			eprintf("sethostname:");
 	}
-
-	free(host);
-
 	return 0;
 }