tload: new usage & fix coding style

Coding style fixed and more readable help output.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

tload.c

@@ -11,15 +11,18 @@
  */
 #include "proc/version.h"
 #include "proc/sysinfo.h"
-#include <stdio.h>
+#include <err.h>
-#include <stdlib.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
 #include <setjmp.h>
 #include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
-#include <termios.h>
-#include <fcntl.h>
 #include <sys/ioctl.h>
+#include <termios.h>
+#include <unistd.h>
 
 static char *screen;
 
@@ -30,9 +33,8 @@ static int fd=1;
 static int dly = 5;
 static jmp_buf jb;
 
-static void alrm(int signo)
+static void alrm(int signo __attribute__ ((__unused__)))
 {
-    (void)signo;
 	signal(SIGALRM, alrm);
 	alarm(dly);
 }
@@ -54,16 +56,31 @@ static void setsize(int i)
 	else
 		screen = (char *)realloc(screen, scr_size);
 
-    if (screen == NULL) {
+	if (screen == NULL)
-	perror("");
+		err(EXIT_FAILURE, "cannot allocate %zu bytes", scr_size);
-	exit(1);
+
-    }
 	memset(screen, ' ', scr_size - 1);
 	*(screen + scr_size - 2) = '\0';
 	if (i)
 		longjmp(jb, 0);
 }
 
+static void __attribute__ ((__noreturn__))
+    usage(FILE * out)
+{
+	fprintf(out,
+		"\nUsage: %s [options] [tty]\n"
+		"\nOptions:\n", program_invocation_short_name);
+	fprintf(out,
+		"  -d, --delay <secs>  update delay in seconds\n"
+		"  -s, --scale <num>   vertical scale\n"
+		"  -h, --help          display this help text\n"
+		"  -V, --version       display version information and exit\n");
+	fprintf(out, "\nFor more information see tload(1).\n");
+
+	exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
+}
+
 int main(int argc, char **argv)
 {
 	int lines, row, col = 0;
@@ -72,22 +89,35 @@ int main(int argc, char **argv)
 	static double max_scale, scale_fact;
 	char *scale_arg = NULL;
 
-    while ((opt = getopt(argc, argv, "s:d:V")) != -1)
+	static const struct option longopts[] = {
+		{"scale", required_argument, NULL, 's'},
+		{"delay", required_argument, NULL, 'd'},
+		{"help", no_argument, NULL, 'h'},
+		{"version", no_argument, NULL, 'V'},
+		{NULL, 0, NULL, 0}
+	};
+
+	while ((opt = getopt_long(argc, argv, "s:d:Vh", longopts, NULL)) != -1)
 		switch (opt) {
-	    case 's': scale_arg = optarg; break;
+		case 's':
-	    case 'd': dly = atoi(optarg); break;
+			scale_arg = optarg;
-	    case 'V': display_version(); exit(0); break;
+			break;
+		case 'd':
+			dly = atoi(optarg);
+			break;
+		case 'V':
+			display_version();
+			exit(0);
+			break;
+		case 'h':
+			usage(stdout);
 		default:
-		printf("usage: tload [-V] [-d delay] [-s scale] [tty]\n");
+			usage(stderr);
-		exit(1);
 		}
 
-    if (argc > optind) {
+	if (argc > optind)
-	if ((fd = open(argv[optind], 1)) == -1) {
+		if ((fd = open(argv[optind], 1)) == -1)
-	    perror("tty");
+			err(EXIT_FAILURE, "can not open tty");
-	    exit(1);
-	}
-    }
 
 	setsize(0);
 
@@ -141,8 +171,7 @@ int main(int argc, char **argv)
 			for (row = nrows - 2; row >= 0; --row)
 				*(screen + row * ncols + col) = ' ';
 		}
-	i = sprintf(screen, " %.2f, %.2f, %.2f",
+		i = sprintf(screen, " %.2f, %.2f, %.2f", av[0], av[1], av[2]);
-		av[0], av[1], av[2]);
 		if (i > 0)
 			screen[i] = ' ';