371 lines
9.8 KiB
C
371 lines
9.8 KiB
C
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
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*
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* Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include "config.h"
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#include <string.h>
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#include <glnx-dirfd.h>
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#include <glnx-errors.h>
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#include <glnx-local-alloc.h>
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/**
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* glnx_opendirat_with_errno:
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* @dfd: File descriptor for origin directory
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* @name: Pathname, relative to @dfd
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* @follow: Whether or not to follow symbolic links
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*
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* Use openat() to open a directory, using a standard set of flags.
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* This function sets errno.
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*/
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int
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glnx_opendirat_with_errno (int dfd,
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const char *path,
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gboolean follow)
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{
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int flags = O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC | O_NOCTTY;
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if (!follow)
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flags |= O_NOFOLLOW;
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dfd = glnx_dirfd_canonicalize (dfd);
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return openat (dfd, path, flags);
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}
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/**
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* glnx_opendirat:
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* @dfd: File descriptor for origin directory
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* @path: Pathname, relative to @dfd
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* @follow: Whether or not to follow symbolic links
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* @error: Error
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*
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* Use openat() to open a directory, using a standard set of flags.
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*/
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gboolean
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glnx_opendirat (int dfd,
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const char *path,
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gboolean follow,
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int *out_fd,
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GError **error)
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{
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int ret = glnx_opendirat_with_errno (dfd, path, follow);
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if (ret == -1)
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{
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glnx_set_prefix_error_from_errno (error, "%s", "openat");
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return FALSE;
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}
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*out_fd = ret;
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return TRUE;
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}
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struct GLnxRealDirfdIterator
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{
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gboolean initialized;
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int fd;
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DIR *d;
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};
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typedef struct GLnxRealDirfdIterator GLnxRealDirfdIterator;
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/**
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* glnx_dirfd_iterator_init_at:
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* @dfd: File descriptor, may be AT_FDCWD or -1
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* @path: Path, may be relative to @df
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* @follow: If %TRUE and the last component of @path is a symlink, follow it
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* @out_dfd_iter: (out caller-allocates): A directory iterator, will be initialized
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* @error: Error
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*
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* Initialize @out_dfd_iter from @dfd and @path.
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*/
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gboolean
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glnx_dirfd_iterator_init_at (int dfd,
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const char *path,
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gboolean follow,
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GLnxDirFdIterator *out_dfd_iter,
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GError **error)
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{
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gboolean ret = FALSE;
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glnx_fd_close int fd = -1;
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if (!glnx_opendirat (dfd, path, follow, &fd, error))
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goto out;
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if (!glnx_dirfd_iterator_init_take_fd (fd, out_dfd_iter, error))
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goto out;
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fd = -1; /* Transfer ownership */
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ret = TRUE;
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out:
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return ret;
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}
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/**
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* glnx_dirfd_iterator_init_take_fd:
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* @dfd: File descriptor - ownership is taken
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* @dfd_iter: A directory iterator
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* @error: Error
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*
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* Steal ownership of @dfd, using it to initialize @dfd_iter for
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* iteration.
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*/
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gboolean
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glnx_dirfd_iterator_init_take_fd (int dfd,
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GLnxDirFdIterator *dfd_iter,
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GError **error)
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{
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gboolean ret = FALSE;
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GLnxRealDirfdIterator *real_dfd_iter = (GLnxRealDirfdIterator*) dfd_iter;
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DIR *d = NULL;
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d = fdopendir (dfd);
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if (!d)
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{
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glnx_set_prefix_error_from_errno (error, "%s", "fdopendir");
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goto out;
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}
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real_dfd_iter->fd = dfd;
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real_dfd_iter->d = d;
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ret = TRUE;
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out:
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return ret;
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}
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/**
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* glnx_dirfd_iterator_next_dent:
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* @dfd_iter: A directory iterator
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* @out_dent: (out) (transfer none): Pointer to dirent; do not free
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* @cancellable: Cancellable
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* @error: Error
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*
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* Read the next value from @dfd_iter, causing @out_dent to be
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* updated. If end of stream is reached, @out_dent will be set
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* to %NULL, and %TRUE will be returned.
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*/
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gboolean
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glnx_dirfd_iterator_next_dent (GLnxDirFdIterator *dfd_iter,
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struct dirent **out_dent,
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GCancellable *cancellable,
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GError **error)
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{
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gboolean ret = FALSE;
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GLnxRealDirfdIterator *real_dfd_iter = (GLnxRealDirfdIterator*) dfd_iter;
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g_return_val_if_fail (out_dent, FALSE);
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if (g_cancellable_set_error_if_cancelled (cancellable, error))
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goto out;
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do
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{
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errno = 0;
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*out_dent = readdir (real_dfd_iter->d);
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if (*out_dent == NULL && errno != 0)
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{
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glnx_set_prefix_error_from_errno (error, "%s", "fdopendir");
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goto out;
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}
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} while (*out_dent &&
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(strcmp ((*out_dent)->d_name, ".") == 0 ||
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strcmp ((*out_dent)->d_name, "..") == 0));
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ret = TRUE;
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out:
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return ret;
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}
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/**
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* glnx_dirfd_iterator_next_dent_ensure_dtype:
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* @dfd_iter: A directory iterator
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* @out_dent: (out) (transfer none): Pointer to dirent; do not free
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* @cancellable: Cancellable
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* @error: Error
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*
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* A variant of @glnx_dirfd_iterator_next_dent, which will ensure the
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* `dent->d_type` member is filled in by calling `fstatat`
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* automatically if the underlying filesystem type sets `DT_UNKNOWN`.
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*/
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gboolean
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glnx_dirfd_iterator_next_dent_ensure_dtype (GLnxDirFdIterator *dfd_iter,
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struct dirent **out_dent,
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GCancellable *cancellable,
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GError **error)
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{
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gboolean ret = FALSE;
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struct dirent *ret_dent;
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g_return_val_if_fail (out_dent, FALSE);
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if (!glnx_dirfd_iterator_next_dent (dfd_iter, out_dent, cancellable, error))
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goto out;
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ret_dent = *out_dent;
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if (ret_dent)
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{
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if (ret_dent->d_type == DT_UNKNOWN)
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{
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struct stat stbuf;
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if (TEMP_FAILURE_RETRY (fstatat (dfd_iter->fd, ret_dent->d_name, &stbuf, AT_SYMLINK_NOFOLLOW)) != 0)
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{
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glnx_set_error_from_errno (error);
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goto out;
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}
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ret_dent->d_type = IFTODT (stbuf.st_mode);
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}
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}
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ret = TRUE;
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out:
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return ret;
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}
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/**
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* glnx_dirfd_iterator_clear:
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* @dfd_iter: Iterator, will be de-initialized
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*
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* Unset @dfd_iter, freeing any resources. If @dfd_iter is not
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* initialized, do nothing.
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*/
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void
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glnx_dirfd_iterator_clear (GLnxDirFdIterator *dfd_iter)
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{
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GLnxRealDirfdIterator *real_dfd_iter = (GLnxRealDirfdIterator*) dfd_iter;
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/* fd is owned by dfd_iter */
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(void) closedir (real_dfd_iter->d);
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real_dfd_iter->initialized = FALSE;
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}
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/**
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* glnx_fdrel_abspath:
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* @dfd: Directory fd
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* @path: Path
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*
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* Turn a fd-relative pair into something that can be used for legacy
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* APIs expecting absolute paths.
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*
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* This is Linux specific, and only valid inside this process (unless
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* you set up the child process to have the exact same fd number, but
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* don't try that).
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*/
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char *
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glnx_fdrel_abspath (int dfd,
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const char *path)
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{
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dfd = glnx_dirfd_canonicalize (dfd);
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if (dfd == AT_FDCWD)
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return g_strdup (path);
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return g_strdup_printf ("/proc/self/fd/%d/%s", dfd, path);
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}
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/**
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* glnx_gen_temp_name:
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* @tmpl: (type filename): template directory name, the last 6 characters will be replaced
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*
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* Replace the last 6 characters of @tmpl with random ASCII. You must
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* use this in combination with a mechanism to ensure race-free file
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* creation such as `O_EXCL`.
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*/
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void
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glnx_gen_temp_name (gchar *tmpl)
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{
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size_t len;
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char *XXXXXX;
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int count;
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static const char letters[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
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static const int NLETTERS = sizeof (letters) - 1;
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glong value;
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GTimeVal tv;
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static int counter = 0;
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g_return_if_fail (tmpl != NULL);
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len = strlen (tmpl);
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g_return_if_fail (len >= 6);
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XXXXXX = tmpl + (len - 6);
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/* Get some more or less random data. */
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g_get_current_time (&tv);
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value = (tv.tv_usec ^ tv.tv_sec) + counter++;
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for (count = 0; count < 100; value += 7777, ++count)
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{
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glong v = value;
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/* Fill in the random bits. */
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XXXXXX[0] = letters[v % NLETTERS];
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v /= NLETTERS;
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XXXXXX[1] = letters[v % NLETTERS];
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v /= NLETTERS;
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XXXXXX[2] = letters[v % NLETTERS];
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v /= NLETTERS;
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XXXXXX[3] = letters[v % NLETTERS];
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v /= NLETTERS;
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XXXXXX[4] = letters[v % NLETTERS];
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v /= NLETTERS;
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XXXXXX[5] = letters[v % NLETTERS];
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}
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}
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/**
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* glnx_mkdtempat:
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* @dfd: Directory fd
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* @tmpl: (type filename): template directory name, last 6 characters will be replaced
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* @mode: permissions to create the temporary directory with
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* @error: Error
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*
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* Similar to g_mkdtemp_full, but using openat.
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*/
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gboolean
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glnx_mkdtempat (int dfd,
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gchar *tmpl,
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int mode,
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GError **error)
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{
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int count;
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g_return_val_if_fail (tmpl != NULL, -1);
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for (count = 0; count < 100; count++)
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{
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glnx_gen_temp_name (tmpl);
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if (mkdirat (dfd, tmpl, mode) == -1)
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{
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if (errno == EEXIST)
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continue;
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/* Any other error will apply also to other names we might
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* try, and there are 2^32 or so of them, so give up now.
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*/
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glnx_set_prefix_error_from_errno (error, "%s", "mkdirat");
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return FALSE;
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}
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return TRUE;
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}
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g_set_error (error, G_IO_ERROR, G_IO_ERROR_EXISTS,
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"mkstempat ran out of combinations to try.");
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return FALSE;
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}
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