Don't return but _exit after failed exec*() and fork()

Quoting POSIX[0]:
"Care should be taken, also, to call _exit() rather than exit() if exec cannot be used, since
exit() flushes and closes standard I/O channels, thereby damaging the parent process' standard
I/O data structures. (Even with fork(), it is wrong to call exit(), since buffered data would
then be flushed twice.)"

[0]: http://pubs.opengroup.org/onlinepubs/009695399/functions/vfork.html

chroot.c

@@ -36,15 +36,14 @@ main(int argc, char *argv[])
 
 	if (argc == 1) {
 		cmd = *shell;
-		execvp(*shell, shell);
+		execvp(cmd, shell);
 	} else {
 		cmd = argv[1];
-		execvp(argv[1], argv + 1);
+		execvp(cmd, argv + 1);
 	}
 
 	savederrno = errno;
 	weprintf("execvp %s:", cmd);
-	_exit(126 + (savederrno == ENOENT));
 
-	return 0; /* not reached */
+	_exit(126 + (savederrno == ENOENT));
 }

env.c

@@ -18,6 +18,8 @@ usage(void)
 int
 main(int argc, char *argv[])
 {
+	int savederrno;
+
 	ARGBEGIN {
 	case 'i':
 		if (environ)
@@ -35,7 +37,9 @@ main(int argc, char *argv[])
 
 	if (*argv) {
 		execvp(*argv, argv);
-		enprintf(126 + (errno == EEXIST), "execvp: %s:", *argv);
+		savederrno = errno;
+		weprintf("execvp %s:", *argv);
+		_exit(126 + (savederrno == EEXIST));
 	}
 
 	for (; environ && *environ; environ++)

nice.c

@@ -44,5 +44,5 @@ main(int argc, char *argv[])
 	savederrno = errno;
 	weprintf("execvp %s:", argv[0]);
 
-	return 126 + (savederrno == ENOENT);
+	_exit(126 + (savederrno == ENOENT));
 }

nohup.c

@@ -42,8 +42,7 @@ main(int argc, char *argv[])
 
 	execvp(argv[0], argv);
 	savederrno = errno;
-	weprintf("exec %s:", argv[0]);
+	weprintf("execvp %s:", argv[0]);
-	_exit(126 + (savederrno == ENOENT));
 
-	return 0; /* not reached */
+	_exit(126 + (savederrno == ENOENT));
 }

setsid.c

@@ -26,7 +26,8 @@ main(int argc, char *argv[])
 	if (getpgrp() == getpid()) {
 		switch (fork()) {
 		case -1:
-			eprintf("fork:");
+			weprintf("fork:");
+			_exit(1);
 		case 0:
 			break;
 		default:
@@ -39,5 +40,5 @@ main(int argc, char *argv[])
 	savederrno = errno;
 	weprintf("execvp %s:", argv[0]);
 
-	return 126 + (savederrno == ENOENT);
+	_exit(126 + (savederrno == ENOENT));
 }

tar.c

@@ -55,7 +55,8 @@ decomp(FILE *fp)
 
 	pid = fork();
 	if (pid < 0) {
-		eprintf("fork:");
+		weprintf("fork:");
+		_exit(1);
 	} else if (!pid) {
 		dup2(fileno(fp), 0);
 		dup2(fds[1], 1);
@@ -64,12 +65,13 @@ decomp(FILE *fp)
 
 		switch (filtermode) {
 		case 'j':
-			execlp("bzip2", "bzip2", "-cd", (char *)0);
+			execlp("bzip2", "bzip2", "-cd", NULL);
-			eprintf("execlp bzip2:");
+			weprintf("execlp bzip2:");
+			_exit(1);
 		case 'z':
-			execlp("gzip", "gzip", "-cd", (char *)0);
+			execlp("gzip", "gzip", "-cd", NULL);
-			eprintf("execlp gzip:");
+			weprintf("execlp gzip:");
-			break;
+			_exit(1);
 		}
 	}
 	close(fds[1]);

time.c

@@ -41,11 +41,12 @@ main(int argc, char *argv[])
 
 	switch ((pid = fork())) {
 	case -1:
-		eprintf("fork:");
+		weprintf("fork:");
+		_exit(1);
 	case 0:
 		execvp(argv[0], argv);
 		savederrno = errno;
-		weprintf("exec %s:", argv[0]);
+		weprintf("execvp %s:", argv[0]);
 		_exit(126 + (savederrno == ENOENT));
 	default:
 		break;

xargs.c

@@ -168,13 +168,15 @@ spawn(void)
 	int savederrno;
 
 	pid = fork();
-	if (pid < 0)
+	if (pid < 0) {
-		eprintf("fork:");
+		weprintf("fork:");
+		_exit(1);
+	}
 	if (pid == 0) {
 		execvp(*cmd, cmd);
 		savederrno = errno;
 		weprintf("execvp %s:", *cmd);
-		_exit(savederrno == ENOENT ? 127 : 126);
+		_exit(126 + (savederrno == ENOENT));
 	}
 	waitchld();
 }