X-Git-Url: https://git.cworth.org/git?p=tar;a=blobdiff_plain;f=gnu%2Ffchdir.c;fp=gnu%2Ffchdir.c;h=83d3c33967e9cb7d15130e83eaed8fbef8a49a02;hp=0000000000000000000000000000000000000000;hb=22f1eb8bc17e5be72dd23d42d6aaa60196ac22e6;hpb=00fa13ff3f2d5b6e2a94c5e948c38616ff7ad37a

diff --git a/gnu/fchdir.c b/gnu/fchdir.c
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+++ b/gnu/fchdir.c
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+/* -*- buffer-read-only: t -*- vi: set ro: */
+/* DO NOT EDIT! GENERATED AUTOMATICALLY! */
+/* fchdir replacement.
+   Copyright (C) 2006-2010 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
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   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/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <unistd.h>
+
+#include <assert.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#ifndef REPLACE_OPEN_DIRECTORY
+# define REPLACE_OPEN_DIRECTORY 0
+#endif
+
+#ifndef HAVE_CANONICALIZE_FILE_NAME
+# if GNULIB_CANONICALIZE || GNULIB_CANONICALIZE_LGPL
+#  define HAVE_CANONICALIZE_FILE_NAME 1
+# else
+#  define HAVE_CANONICALIZE_FILE_NAME 0
+#  define canonicalize_file_name(name) NULL
+# endif
+#endif
+
+/* This replacement assumes that a directory is not renamed while opened
+   through a file descriptor.
+
+   FIXME: On mingw, this would be possible to enforce if we were to
+   also open a HANDLE to each directory currently visited by a file
+   descriptor, since mingw refuses to rename any in-use file system
+   object.  */
+
+/* Array of file descriptors opened.  If REPLACE_OPEN_DIRECTORY or if it points
+   to a directory, it stores info about this directory.  */
+typedef struct
+{
+  char *name;       /* Absolute name of the directory, or NULL.  */
+  /* FIXME - add a DIR* member to make dirfd possible on mingw?  */
+} dir_info_t;
+static dir_info_t *dirs;
+static size_t dirs_allocated;
+
+/* Try to ensure dirs has enough room for a slot at index fd; free any
+   contents already in that slot.  Return false and set errno to
+   ENOMEM on allocation failure.  */
+static bool
+ensure_dirs_slot (size_t fd)
+{
+  if (fd < dirs_allocated)
+    free (dirs[fd].name);
+  else
+    {
+      size_t new_allocated;
+      dir_info_t *new_dirs;
+
+      new_allocated = 2 * dirs_allocated + 1;
+      if (new_allocated <= fd)
+        new_allocated = fd + 1;
+      new_dirs =
+        (dirs != NULL
+         ? (dir_info_t *) realloc (dirs, new_allocated * sizeof *dirs)
+         : (dir_info_t *) malloc (new_allocated * sizeof *dirs));
+      if (new_dirs == NULL)
+        return false;
+      memset (new_dirs + dirs_allocated, 0,
+              (new_allocated - dirs_allocated) * sizeof *dirs);
+      dirs = new_dirs;
+      dirs_allocated = new_allocated;
+    }
+  return true;
+}
+
+/* Return the canonical name of DIR in malloc'd storage.  */
+static char *
+get_name (char const *dir)
+{
+  char *result;
+  if (REPLACE_OPEN_DIRECTORY || !HAVE_CANONICALIZE_FILE_NAME)
+    {
+      /* The function canonicalize_file_name has not yet been ported
+         to mingw, with all its drive letter and backslash quirks.
+         Fortunately, getcwd is reliable in this case, but we ensure
+         we can get back to where we started before using it.  Treat
+         "." as a special case, as it is frequently encountered.  */
+      char *cwd = getcwd (NULL, 0);
+      int saved_errno;
+      if (dir[0] == '.' && dir[1] == '\0')
+        return cwd;
+      if (chdir (cwd))
+        return NULL;
+      result = chdir (dir) ? NULL : getcwd (NULL, 0);
+      saved_errno = errno;
+      if (chdir (cwd))
+        abort ();
+      free (cwd);
+      errno = saved_errno;
+    }
+  else
+    {
+      /* Avoid changing the directory.  */
+      result = canonicalize_file_name (dir);
+    }
+  return result;
+}
+
+/* Hook into the gnulib replacements for open() and close() to keep track
+   of the open file descriptors.  */
+
+/* Close FD, cleaning up any fd to name mapping if fd was visiting a
+   directory.  */
+void
+_gl_unregister_fd (int fd)
+{
+  if (fd >= 0 && fd < dirs_allocated)
+    {
+      free (dirs[fd].name);
+      dirs[fd].name = NULL;
+    }
+}
+
+/* Mark FD as visiting FILENAME.  FD must be non-negative, and refer
+   to an open file descriptor.  If REPLACE_OPEN_DIRECTORY is non-zero,
+   this should only be called if FD is visiting a directory.  Close FD
+   and return -1 if there is insufficient memory to track the
+   directory name; otherwise return FD.  */
+int
+_gl_register_fd (int fd, const char *filename)
+{
+  struct stat statbuf;
+
+  assert (0 <= fd);
+  if (REPLACE_OPEN_DIRECTORY
+      || (fstat (fd, &statbuf) == 0 && S_ISDIR (statbuf.st_mode)))
+    {
+      if (!ensure_dirs_slot (fd)
+          || (dirs[fd].name = get_name (filename)) == NULL)
+        {
+          int saved_errno = errno;
+          close (fd);
+          errno = saved_errno;
+          return -1;
+        }
+    }
+  return fd;
+}
+
+/* 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
+
+/* Override opendir() and closedir(), to keep track of the open file
+   descriptors.  Needed because there is a function dirfd().  */
+
+int
+rpl_closedir (DIR *dp)
+#undef closedir
+{
+  int fd = dirfd (dp);
+  int retval = closedir (dp);
+
+  if (retval >= 0)
+    _gl_unregister_fd (fd);
+  return retval;
+}
+
+DIR *
+rpl_opendir (const char *filename)
+#undef opendir
+{
+  DIR *dp;
+
+  dp = opendir (filename);
+  if (dp != NULL)
+    {
+      int fd = dirfd (dp);
+      if (0 <= fd && _gl_register_fd (fd, filename) != fd)
+        {
+          int saved_errno = errno;
+          closedir (dp);
+          errno = saved_errno;
+          return NULL;
+        }
+    }
+  return dp;
+}
+
+/* Override dup(), to keep track of open file descriptors.  */
+
+int
+rpl_dup (int oldfd)
+#undef dup
+{
+  int newfd = dup (oldfd);
+
+  if (0 <= newfd)
+    newfd = _gl_register_dup (oldfd, newfd);
+  return newfd;
+}
+
+
+/* Implement fchdir() in terms of chdir().  */
+
+int
+fchdir (int fd)
+{
+  const char *name = _gl_directory_name (fd);
+  return name ? chdir (name) : -1;
+}