tidy up O_NONBLOCK usage. use libbb functions in stty.

Added O_RDONLY where improves readability. Note: O_RDONLY == 0,
so it is there even if not specified.

function                                             old     new   delta
stty_main                                           1289    1235     -54

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

console-tools/openvt.c

@@ -61,9 +61,7 @@ static int get_vt_fd(void)
 	for (fd = 0; fd < 3; fd++)
 		if (!not_vt_fd(fd))
 			return fd;
-	/* _only_ O_NONBLOCK: ask for neither read nor write perms */
+	fd = open(DEV_CONSOLE, O_RDONLY | O_NONBLOCK);
-	/*FIXME: use? device_open(DEV_CONSOLE,0); */
-	fd = open(DEV_CONSOLE, O_NONBLOCK);
 	if (fd >= 0 && !not_vt_fd(fd))
 		return fd;
 	bb_error_msg_and_die("can't find open VT");

coreutils/stty.c

@@ -1293,17 +1293,9 @@ int stty_main(int argc, char **argv)
 
 	/* Now it is safe to start doing things */
 	if (file_name) {
-		int fd, fdflags;
 		G.device_name = file_name;
-		fd = xopen_nonblocking(G.device_name);
+		xmove_fd(xopen_nonblocking(G.device_name), STDIN_FILENO);
-		if (fd != STDIN_FILENO) {
+		ndelay_off(STDIN_FILENO);
-			dup2(fd, STDIN_FILENO);
-			close(fd);
-		}
-		fdflags = fcntl(STDIN_FILENO, F_GETFL);
-		if (fdflags < 0 ||
-			fcntl(STDIN_FILENO, F_SETFL, fdflags & ~O_NONBLOCK) < 0)
-			perror_on_device_and_die("%s: cannot reset non-blocking mode");
 	}
 
 	/* Initialize to all zeroes so there is no risk memcmp will report a

e2fsprogs/e2fs_lib.c

@@ -53,7 +53,7 @@ int fgetsetversion(const char *name, unsigned long *get_version, unsigned long s
 	int fd, r;
 	IF_LONG_IS_WIDER(int ver;)
 
-	fd = open(name, O_NONBLOCK);
+	fd = open(name, O_RDONLY | O_NONBLOCK);
 	if (fd == -1)
 		return -1;
 	if (!get_version) {
@@ -95,7 +95,7 @@ int fgetsetflags(const char *name, unsigned long *get_flags, unsigned long set_f
 	) {
 		goto notsupp;
 	}
-	fd = open(name, O_NONBLOCK); /* neither read nor write asked for */
+	fd = open(name, O_RDONLY | O_NONBLOCK); /* neither read nor write asked for */
 	if (fd == -1)
 		return -1;
 

libbb/read.c

@@ -39,18 +39,18 @@ ssize_t FAST_FUNC safe_read(int fd, void *buf, size_t count)
  * *** BIG SURPRISE! It stays even after child exits! ***
  *
  * This is a design bug in UNIX API.
- *      fcntl(0, F_SETFL, fcntl(0, F_GETFL, 0) | O_NONBLOCK);
+ *      fcntl(0, F_SETFL, fcntl(0, F_GETFL) | O_NONBLOCK);
  * will set nonblocking mode not only on _your_ stdin, but
  * also on stdin of your parent, etc.
  *
  * In general,
  *      fd2 = dup(fd1);
- *      fcntl(fd2, F_SETFL, fcntl(fd2, F_GETFL, 0) | O_NONBLOCK);
+ *      fcntl(fd2, F_SETFL, fcntl(fd2, F_GETFL) | O_NONBLOCK);
  * sets both fd1 and fd2 to O_NONBLOCK. This includes cases
  * where duping is done implicitly by fork() etc.
  *
  * We need
- *      fcntl(fd2, F_SETFD, fcntl(fd2, F_GETFD, 0) | O_NONBLOCK);
+ *      fcntl(fd2, F_SETFD, fcntl(fd2, F_GETFD) | O_NONBLOCK);
  * (note SETFD, not SETFL!) but such thing doesn't exist.
  *
  * Alternatively, we need nonblocking_read(fd, ...) which doesn't

libbb/xfuncs.c

@@ -27,12 +27,12 @@
 /* Turn on nonblocking I/O on a fd */
 int FAST_FUNC ndelay_on(int fd)
 {
-	return fcntl(fd, F_SETFL, fcntl(fd,F_GETFL) | O_NONBLOCK);
+	return fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
 }
 
 int FAST_FUNC ndelay_off(int fd)
 {
-	return fcntl(fd, F_SETFL, fcntl(fd,F_GETFL) & ~O_NONBLOCK);
+	return fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) & ~O_NONBLOCK);
 }
 
 int FAST_FUNC close_on_exec_on(int fd)

miscutils/microcom.c

@@ -92,7 +92,7 @@ int microcom_main(int argc UNUSED_PARAM, char **argv)
 	sfd = open_or_warn(argv[0], O_RDWR | O_NOCTTY | O_NONBLOCK);
 	if (sfd < 0)
 		goto done;
-	fcntl(sfd, F_SETFL, 0);
+	fcntl(sfd, F_SETFL, O_RDWR);
 
 	// put device to "raw mode"
 	xget1(sfd, &tio, &tiosfd);

modutils/modprobe.c

@@ -373,7 +373,7 @@ int modprobe_main(int argc UNUSED_PARAM, char **argv)
 			 * "If name is NULL, all unused modules marked
 			 * autoclean will be removed".
 			 */
-			if (bb_delete_module(NULL, O_NONBLOCK|O_EXCL) != 0)
+			if (bb_delete_module(NULL, O_NONBLOCK | O_EXCL) != 0)
 				bb_perror_msg_and_die("rmmod");
 		}
 		return EXIT_SUCCESS;