Adding upstream version 1.21.4.upstream/1.21.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 204 insertions, 0 deletions

diff --git a/lib/fchdir.c b/lib/fchdir.c
new file mode 100644
index 0000000..880b137
--- /dev/null
+++ b/lib/fchdir.c
@@ -0,0 +1,204 @@
+/* fchdir replacement.
+   Copyright (C) 2006-2023 Free Software Foundation, Inc.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation, either version 3 of the
+   License, or (at your option) any later version.
+
+   This file 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 Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <unistd.h>
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "assure.h"
+#include "filename.h"
+#include "filenamecat.h"
+
+#ifndef REPLACE_OPEN_DIRECTORY
+# define REPLACE_OPEN_DIRECTORY 0
+#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.  */
+} 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 an absolute name of DIR in malloc'd storage.
+   Upon failure, return NULL with errno set.  */
+static char *
+get_name (char const *dir)
+{
+  char *cwd;
+  char *result;
+
+  if (IS_ABSOLUTE_FILE_NAME (dir))
+    return strdup (dir);
+
+  /* We often encounter "."; treat it as a special case.  */
+  cwd = getcwd (NULL, 0);
+  if (!cwd || (dir[0] == '.' && dir[1] == '\0'))
+    return cwd;
+
+  result = mfile_name_concat (cwd, dir, NULL);
+  free (cwd);
+  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 with errno set 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;
+
+  assure (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)
+{
+  assure (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;
+}
+
+
+/* Implement fchdir() in terms of chdir().  */
+
+int
+fchdir (int fd)
+{
+  const char *name = _gl_directory_name (fd);
+  return name ? chdir (name) : -1;
+}