+/* Mark NEWFD as a duplicate of OLDFD; useful from dup, dup2, dup3,
+ and fcntl. Both arguments must be valid and distinct file
+ descriptors. Close NEWFD and return -1 if OLDFD is tracking a
+ directory, but there is insufficient memory to track the same
+ directory in NEWFD; otherwise return NEWFD. */
+int
+_gl_register_dup (int oldfd, int newfd)
+{
+ assert (0 <= oldfd && 0 <= newfd && oldfd != newfd);
+ if (oldfd < dirs_allocated && dirs[oldfd].name)
+ {
+ /* Duplicated a directory; must ensure newfd is allocated. */
+ if (!ensure_dirs_slot (newfd)
+ || (dirs[newfd].name = strdup (dirs[oldfd].name)) == NULL)
+ {
+ int saved_errno = errno;
+ close (newfd);
+ errno = saved_errno;
+ newfd = -1;
+ }
+ }
+ else if (newfd < dirs_allocated)
+ {
+ /* Duplicated a non-directory; ensure newfd is cleared. */
+ free (dirs[newfd].name);
+ dirs[newfd].name = NULL;
+ }
+ return newfd;
+}
+
+/* If FD is currently visiting a directory, then return the name of
+ that directory. Otherwise, return NULL and set errno. */
+const char *
+_gl_directory_name (int fd)
+{
+ if (0 <= fd && fd < dirs_allocated && dirs[fd].name != NULL)
+ return dirs[fd].name;
+ /* At this point, fd is either invalid, or open but not a directory.
+ If dup2 fails, errno is correctly EBADF. */
+ if (0 <= fd)
+ {
+ if (dup2 (fd, fd) == fd)
+ errno = ENOTDIR;
+ }
+ else
+ errno = EBADF;
+ return NULL;
+}
+
+#if REPLACE_OPEN_DIRECTORY
+/* Return stat information about FD in STATBUF. Needed when
+ rpl_open() used a dummy file to work around an open() that can't
+ normally visit directories. */
+# undef fstat
+int
+rpl_fstat (int fd, struct stat *statbuf)
+{
+ if (0 <= fd && fd < dirs_allocated && dirs[fd].name != NULL)
+ return stat (dirs[fd].name, statbuf);
+ return fstat (fd, statbuf);
+}
+#endif
+