sleep(1): style(9) and other dusting

- Sort includes alphabetically
- Sort prototypes alphabetically
- Sort stack variables by size
- Add missing braces to the getopt(3) loop
- Be explicit: there is *one* argument, so use argv[0], not *argv
- If nanosleep(2) somehow fails, say that "nanosleep" failed when
  we err(3)
- Remove extra parentheses from the return statement
- De-(void) the obvious fprintf(3) in usage()
- __progname -> getprogname(3)
- POSIX 1003.2 has long since become POSIX.1
- Remove an ARGUSED linter comment
- stdio(3) flushing is not the only potential issue with an exit(3)
  from a signal handler.  Just note that exit(3) isn't safe and leave
  it at that.

bin/sleep/sleep.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: sleep.c,v 1.28 2019/07/01 00:01:34 cheloha Exp $	*/
+/*	$OpenBSD: sleep.c,v 1.29 2020/02/25 15:46:15 cheloha Exp $	*/
 /*	$NetBSD: sleep.c,v 1.8 1995/03/21 09:11:11 cgd Exp $	*/
 
 /*
@@ -33,37 +33,35 @@
 #include <sys/time.h>
 
 #include <ctype.h>
+#include <err.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
 #include <unistd.h>
-#include <err.h>
 
-extern char *__progname;
-
-void usage(void);
 void alarmh(int);
+void usage(void);
 
 int
 main(int argc, char *argv[])
 {
-	int ch;
+	struct timespec rqtp;
 	time_t t;
 	char *cp;
-	struct timespec rqtp;
-	int i;
+	int ch, i;
 
 	if (pledge("stdio", NULL) == -1)
 		err(1, "pledge");
 
 	signal(SIGALRM, alarmh);
 
-	while ((ch = getopt(argc, argv, "")) != -1)
+	while ((ch = getopt(argc, argv, "")) != -1) {
 		switch(ch) {
 		default:
 			usage();
 		}
+	}
 	argc -= optind;
 	argv += optind;
 
@@ -73,12 +71,12 @@ main(int argc, char *argv[])
 	timespecclear(&rqtp);
 
 	/* Handle whole seconds. */
-	for (cp = *argv; *cp != '\0' && *cp != '.'; cp++) {
+	for (cp = argv[0]; *cp != '\0' && *cp != '.'; cp++) {
 		if (!isdigit((unsigned char)*cp))
-			errx(1, "seconds is invalid: %s", *argv);
+			errx(1, "seconds is invalid: %s", argv[0]);
 		t = (rqtp.tv_sec * 10) + (*cp - '0');
 		if (t / 10 != rqtp.tv_sec)	/* overflow */
-			errx(1, "seconds is too large: %s", *argv);
+			errx(1, "seconds is too large: %s", argv[0]);
 		rqtp.tv_sec = t;
 	}
 
@@ -91,7 +89,7 @@ main(int argc, char *argv[])
 		i = 100000000;
 		for (cp++; *cp != '\0'; cp++) {
 			if (!isdigit((unsigned char)*cp))
-				errx(1, "seconds is invalid: %s", *argv);
+				errx(1, "seconds is invalid: %s", argv[0]);
 			rqtp.tv_nsec += (*cp - '0') * i;
 			i /= 10;
 		}
@@ -99,30 +97,29 @@ main(int argc, char *argv[])
 
 	if (timespecisset(&rqtp)) {
 		if (nanosleep(&rqtp, NULL) == -1)
-			err(1, NULL);
+			err(1, "nanosleep");
 	}
 
-	return (0);
+	return 0;
 }
 
 void
 usage(void)
 {
-	(void)fprintf(stderr, "usage: %s seconds\n", __progname);
+	fprintf(stderr, "usage: %s seconds\n", getprogname());
 	exit(1);
 }
 
 /*
- * POSIX 1003.2 says sleep should exit with 0 return code on reception
+ * POSIX.1 says sleep(1) may exit with status zero upon receipt
  * of SIGALRM.
  */
-/* ARGSUSED */
 void
 alarmh(int signo)
 {
 	/*
-	 * exit() flushes stdio buffers, which is not legal in a signal
-	 * handler. Use _exit().
+	 * Always _exit(2) from signal handlers: exit(3) is not
+	 * generally signal-safe.
 	 */
 	_exit(0);
 }