ash,hush: fix "saved" redirected fds still visible in children

Based on a patch by Mark Marshall <mark.marshall@omicronenergy.com>

function                                             old     new   delta
dup_CLOEXEC                                            -      49     +49
fcntl_F_DUPFD                                         46       -     -46

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

1 files changed, 11 insertions, 5 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 5e281b5ce..85690e555 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -255,6 +255,9 @@ typedef long arith_t;
 # define IF_NOT_FEATURE_SH_STANDALONE(...) __VA_ARGS__
 #endif
 
+#ifndef F_DUPFD_CLOEXEC
+# define F_DUPFD_CLOEXEC F_DUPFD
+#endif
 #ifndef PIPE_BUF
 # define PIPE_BUF 4096           /* amount of buffering in a pipe */
 #endif
@@ -5448,12 +5451,15 @@ dup2_or_raise(int from, int to)
         return newfd;
 }
 static int
-fcntl_F_DUPFD(int fd, int avoid_fd)
+dup_CLOEXEC(int fd, int avoid_fd)
 {
         int newfd;
  repeat:
-        newfd = fcntl(fd, F_DUPFD, avoid_fd + 1);
-        if (newfd < 0) {
+        newfd = fcntl(fd, F_DUPFD_CLOEXEC, avoid_fd + 1);
+        if (newfd >= 0) {
+                if (F_DUPFD_CLOEXEC == F_DUPFD) /* if old libc (w/o F_DUPFD_CLOEXEC) */
+                        fcntl(newfd, F_SETFD, FD_CLOEXEC);
+        } else { /* newfd < 0 */
                 if (errno == EBUSY)
                         goto repeat;
                 if (errno == EINTR)
@@ -5569,7 +5575,7 @@ save_fd_on_redirect(int fd, int avoid_fd, struct redirtab *sq)
         for (i = 0; sq->two_fd[i].orig_fd != EMPTY; i++) {
                 /* If we collide with an already moved fd... */
                 if (fd == sq->two_fd[i].moved_to) {
-                        new_fd = fcntl_F_DUPFD(fd, avoid_fd);
+                        new_fd = dup_CLOEXEC(fd, avoid_fd);
                         sq->two_fd[i].moved_to = new_fd;
                         TRACE(("redirect_fd %d: already busy, moving to %d\n", fd, new_fd));
                         if (new_fd < 0) /* what? */
@@ -5584,7 +5590,7 @@ save_fd_on_redirect(int fd, int avoid_fd, struct redirtab *sq)
         }
 
         /* If this fd is open, we move and remember it; if it's closed, new_fd = CLOSED (-1) */
-        new_fd = fcntl_F_DUPFD(fd, avoid_fd);
+        new_fd = dup_CLOEXEC(fd, avoid_fd);
         TRACE(("redirect_fd %d: previous fd is moved to %d (-1 if it was closed)\n", fd, new_fd));
         if (new_fd < 0) {
                 if (errno != EBADF)