--- /dev/null
+/* fchdir replacement.
+ Copyright (C) 2006-2016 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 <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>
+
+#include "assure.h"
+#include "dosname.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. */
+ /* 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 an absolute name of DIR in malloc'd storage. */
+static char *
+get_name (char const *dir)
+{
+ char *cwd;
+ char *result;
+ int saved_errno;
+
+ 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);
+ saved_errno = errno;
+ free (cwd);
+ errno = saved_errno;
+ 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;
+
+ 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;
+}
projects / deliverable / binutils-gdb.git / blobdiff