X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=lib%2Ffdopendir.c;h=9adefd210b515b8cfce76ee0655d0429841205b6;hb=eff6930a7860e84acb666b594c34de5f3b041ef3;hp=f7b29af30c62539f9836c3971bc990911b6701d2;hpb=dc0ab95dbae38577efebe2283fc9b76e92ef4233;p=debian%2Fgzip

diff --git a/lib/fdopendir.c b/lib/fdopendir.c
index f7b29af..9adefd2 100644
--- a/lib/fdopendir.c
+++ b/lib/fdopendir.c
@@ -1,5 +1,5 @@
 /* provide a replacement fdopendir function
-   Copyright (C) 2004-2010 Free Software Foundation, Inc.
+   Copyright (C) 2004-2018 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -12,7 +12,7 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
 
 /* written by Jim Meyering */
 
@@ -33,79 +33,194 @@
 #  include "dirent--.h"
 # endif
 
-/* Replacement for Solaris' function by the same name.
-   <http://www.google.com/search?q=fdopendir+site:docs.sun.com>
-   First, try to simulate it via opendir ("/proc/self/fd/FD").  Failing
+# ifndef REPLACE_FCHDIR
+#  define REPLACE_FCHDIR 0
+# endif
+
+static DIR *fdopendir_with_dup (int, int, struct saved_cwd const *);
+static DIR *fd_clone_opendir (int, struct saved_cwd const *);
+
+/* Replacement for POSIX fdopendir.
+
+   First, try to simulate it via opendir ("/proc/self/fd/...").  Failing
    that, simulate it by using fchdir metadata, or by doing
    save_cwd/fchdir/opendir(".")/restore_cwd.
    If either the save_cwd or the restore_cwd fails (relatively unlikely),
    then give a diagnostic and exit nonzero.
-   Otherwise, this function works just like Solaris' fdopendir.
+
+   If successful, the resulting stream is based on FD in
+   implementations where streams are based on file descriptors and in
+   applications where no other thread or signal handler allocates or
+   frees file descriptors.  In other cases, consult dirfd on the result
+   to find out whether FD is still being used.
+
+   Otherwise, this function works just like POSIX fdopendir.
 
    W A R N I N G:
-   Unlike other fd-related functions, this one effectively consumes
-   its FD parameter.  The caller should not close or otherwise
-   manipulate FD if this function returns successfully.  Also, this
-   implementation does not guarantee that dirfd(fdopendir(n))==n;
-   the open directory stream may use a clone of FD, or have no
-   associated fd at all.  */
+
+   Unlike other fd-related functions, this one places constraints on FD.
+   If this function returns successfully, FD is under control of the
+   dirent.h system, and the caller should not close or modify the state of
+   FD other than by the dirent.h functions.  */
+# ifdef __KLIBC__
+#  include <InnoTekLIBC/backend.h>
+
 DIR *
 fdopendir (int fd)
 {
-  int saved_errno;
-  DIR *dir;
+  char path[_MAX_PATH];
+  DIR *dirp;
 
-  char buf[OPENAT_BUFFER_SIZE];
-  char *proc_file = openat_proc_name (buf, fd, ".");
-  if (proc_file)
+  /* Get a path from fd */
+  if (__libc_Back_ioFHToPath (fd, path, sizeof (path)))
+    return NULL;
+
+  dirp = opendir (path);
+  if (!dirp)
+    return NULL;
+
+  /* Unregister fd registered by opendir() */
+  _gl_unregister_dirp_fd (dirfd (dirp));
+
+  /* Register our fd */
+  if (_gl_register_dirp_fd (fd, dirp))
     {
-      dir = opendir (proc_file);
-      saved_errno = errno;
+      int saved_errno = errno;
+
+      closedir (dirp);
+
+      errno = saved_errno;
+
+      dirp = NULL;
     }
-  else
+
+  return dirp;
+}
+# else
+DIR *
+fdopendir (int fd)
+{
+  DIR *dir = fdopendir_with_dup (fd, -1, NULL);
+
+  if (! REPLACE_FCHDIR && ! dir)
     {
-      dir = NULL;
-      saved_errno = EOPNOTSUPP;
+      int saved_errno = errno;
+      if (EXPECTED_ERRNO (saved_errno))
+        {
+          struct saved_cwd cwd;
+          if (save_cwd (&cwd) != 0)
+            openat_save_fail (errno);
+          dir = fdopendir_with_dup (fd, -1, &cwd);
+          saved_errno = errno;
+          free_cwd (&cwd);
+          errno = saved_errno;
+        }
     }
 
-  /* If the syscall fails with an expected errno value, resort to
-     save_cwd/restore_cwd.  */
-  if (! dir && EXPECTED_ERRNO (saved_errno))
-    {
-# if REPLACE_FCHDIR
-      const char *name = _gl_directory_name (fd);
-      if (name)
-        dir = opendir (name);
-      saved_errno = errno;
-# else /* !REPLACE_FCHDIR */
-      struct saved_cwd saved_cwd;
-      if (save_cwd (&saved_cwd) != 0)
-        openat_save_fail (errno);
+  return dir;
+}
+# endif
 
-      if (fchdir (fd) != 0)
+/* Like fdopendir, except that if OLDER_DUPFD is not -1, it is known
+   to be a dup of FD which is less than FD - 1 and which will be
+   closed by the caller and not otherwise used by the caller.  This
+   function makes sure that FD is closed and all file descriptors less
+   than FD are open, and then calls fd_clone_opendir on a dup of FD.
+   That way, barring race conditions, fd_clone_opendir returns a
+   stream whose file descriptor is FD.
+
+   If REPLACE_FCHDIR or CWD is null, use opendir ("/proc/self/fd/...",
+   falling back on fchdir metadata.  Otherwise, CWD is a saved version
+   of the working directory; use fchdir/opendir(".")/restore_cwd(CWD).  */
+static DIR *
+fdopendir_with_dup (int fd, int older_dupfd, struct saved_cwd const *cwd)
+{
+  int dupfd = dup (fd);
+  if (dupfd < 0 && errno == EMFILE)
+    dupfd = older_dupfd;
+  if (dupfd < 0)
+    return NULL;
+  else
+    {
+      DIR *dir;
+      int saved_errno;
+      if (dupfd < fd - 1 && dupfd != older_dupfd)
         {
-          dir = NULL;
+          dir = fdopendir_with_dup (fd, dupfd, cwd);
           saved_errno = errno;
         }
       else
         {
-          dir = opendir (".");
+          close (fd);
+          dir = fd_clone_opendir (dupfd, cwd);
           saved_errno = errno;
-
-          if (restore_cwd (&saved_cwd) != 0)
-            openat_restore_fail (errno);
+          if (! dir)
+            {
+              int fd1 = dup (dupfd);
+              if (fd1 != fd)
+                openat_save_fail (fd1 < 0 ? errno : EBADF);
+            }
         }
 
-      free_cwd (&saved_cwd);
-# endif /* !REPLACE_FCHDIR */
+      if (dupfd != older_dupfd)
+        close (dupfd);
+      errno = saved_errno;
+      return dir;
     }
+}
 
-  if (dir)
-    close (fd);
-  if (proc_file != buf)
-    free (proc_file);
-  errno = saved_errno;
-  return dir;
+/* Like fdopendir, except the result controls a clone of FD.  It is
+   the caller's responsibility both to close FD and (if the result is
+   not null) to closedir the result.  */
+static DIR *
+fd_clone_opendir (int fd, struct saved_cwd const *cwd)
+{
+  if (REPLACE_FCHDIR || ! cwd)
+    {
+      DIR *dir = NULL;
+      int saved_errno = EOPNOTSUPP;
+      char buf[OPENAT_BUFFER_SIZE];
+      char *proc_file = openat_proc_name (buf, fd, ".");
+      if (proc_file)
+        {
+          dir = opendir (proc_file);
+          saved_errno = errno;
+          if (proc_file != buf)
+            free (proc_file);
+        }
+# if REPLACE_FCHDIR
+      if (! dir && EXPECTED_ERRNO (saved_errno))
+        {
+          char const *name = _gl_directory_name (fd);
+          DIR *dp = name ? opendir (name) : NULL;
+
+          /* The caller has done an elaborate dance to arrange for opendir to
+             consume just the right file descriptor.  If dirfd returns -1,
+             though, we're on a system like mingw where opendir does not
+             consume a file descriptor.  Consume it via 'dup' instead.  */
+          if (dp && dirfd (dp) < 0)
+            dup (fd);
+
+          return dp;
+        }
+# endif
+      errno = saved_errno;
+      return dir;
+    }
+  else
+    {
+      if (fchdir (fd) != 0)
+        return NULL;
+      else
+        {
+          DIR *dir = opendir (".");
+          int saved_errno = errno;
+          if (restore_cwd (cwd) != 0)
+            openat_restore_fail (errno);
+          errno = saved_errno;
+          return dir;
+        }
+    }
 }
 
 #else /* HAVE_FDOPENDIR */