CLOEXEC: use open(CLOEXEC) if exist; do not check fcntl(FD_CLOEXEC) failure

    text           data     bss     dec     hex filename
-    370              0       0     370     172 libc/misc/dirent/opendir.o
+    366              0       0     366     16e libc/misc/dirent/opendir.o
-    375              4       0     379     17b libc/pwd_grp/lckpwdf.o
+    356              4       0     360     168 libc/pwd_grp/lckpwdf.o
-    248              0       0     248      f8 librt/shm.o
+    209              0       0     209      d1 librt/shm.o

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

2 files changed, 30 insertions, 22 deletions

diff --git a/libc/misc/dirent/opendir.c b/libc/misc/dirent/opendir.c
index fa07d0052..70b30658e 100644
--- a/libc/misc/dirent/opendir.c
+++ b/libc/misc/dirent/opendir.c
@@ -81,28 +81,31 @@ DIR *opendir(const char *name)
 	}
 # define O_DIRECTORY 0
 #endif
-	if ((fd = open(name, O_RDONLY|O_NDELAY|O_DIRECTORY)) < 0)
+#ifndef O_CLOEXEC
+# define O_CLOEXEC 0
+#endif
+	fd = open(name, O_RDONLY|O_NDELAY|O_DIRECTORY|O_CLOEXEC);
+	if (fd < 0)
 		return NULL;
 
 	/* Note: we should check to make sure that between the stat() and open()
 	 * call, 'name' didnt change on us, but that's only if O_DIRECTORY isnt
 	 * defined and since Linux has supported it for like ever, i'm not going
 	 * to worry about it right now (if ever). */
-	if (fstat(fd, &statbuf) < 0)
-		goto close_and_ret;
-
-	/* According to POSIX, directory streams should be closed when
-	 * exec. From "Anna Pluzhnikov" <besp@midway.uchicago.edu>.
-	 */
-	if (fcntl(fd, F_SETFD, FD_CLOEXEC) < 0) {
+	if (fstat(fd, &statbuf) < 0) {
 		int saved_errno;
-close_and_ret:
 		saved_errno = errno;
 		close(fd);
 		__set_errno(saved_errno);
 		return NULL;
 	}
 
+	/* According to POSIX, directory streams should be closed when
+	 * exec. From "Anna Pluzhnikov" <besp@midway.uchicago.edu>.
+	 */
+	if (O_CLOEXEC == 0)
+		fcntl(fd, F_SETFD, FD_CLOEXEC);
+
 	ptr = fd_to_DIR(fd, statbuf.st_blksize);
 	if (!ptr) {
 		close(fd);
diff --git a/libc/misc/utmp/utent.c b/libc/misc/utmp/utent.c
index f0700af21..7d8a2d3c1 100644
--- a/libc/misc/utmp/utent.c
+++ b/libc/misc/utmp/utent.c
@@ -34,24 +34,29 @@ static const char *static_ut_name = default_file_name;
 static void __setutent(void)
 {
     if (static_fd < 0) {
-	static_fd = open(static_ut_name, O_RDWR);
+#ifndef O_CLOEXEC
+# define O_CLOEXEC 0
+#endif
+	static_fd = open(static_ut_name, O_RDWR | O_CLOEXEC);
 	if (static_fd < 0) {
-	    static_fd = open(static_ut_name, O_RDONLY);
+	    static_fd = open(static_ut_name, O_RDONLY | O_CLOEXEC);
 	    if (static_fd < 0) {
 		return; /* static_fd remains < 0 */
 	    }
 	}
-	/* Make sure the file will be closed on exec()  */
-	fcntl(static_fd, F_SETFD, FD_CLOEXEC);
-	// thus far, {G,S}ETFD only has this single flag,
-	// and setting it never fails.
-	//int ret = fcntl(static_fd, F_GETFD, 0);
-	//if (ret >= 0) {
-	//    ret = fcntl(static_fd, F_SETFD, ret | FD_CLOEXEC);
-	//}
-	//if (ret < 0) {
-	//    static_fd = -1;
-	//}
+	if (O_CLOEXEC == 0) {
+	    /* Make sure the file will be closed on exec()  */
+	    fcntl(static_fd, F_SETFD, FD_CLOEXEC);
+	    // thus far, {G,S}ETFD only has this single flag,
+	    // and setting it never fails.
+	    //int ret = fcntl(static_fd, F_GETFD, 0);
+	    //if (ret >= 0) {
+	    //    ret = fcntl(static_fd, F_SETFD, ret | FD_CLOEXEC);
+	    //}
+	    //if (ret < 0) {
+	    //    static_fd = -1;
+	    //}
+	}
 	return;
     }
     lseek(static_fd, 0, SEEK_SET);