/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- * * Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>. * * This library 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 2 of the License, or (at your option) any later version. * * This library 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 library; if not, write to the * Free Software Foundation, Inc., 59 Temple Place - Suite 330, * Boston, MA 02111-1307, USA. */ #include "config.h" #include <string.h> #include <glnx-dirfd.h> #include <glnx-errors.h> #include <glnx-local-alloc.h> /** * glnx_opendirat_with_errno: * @dfd: File descriptor for origin directory * @name: Pathname, relative to @dfd * @follow: Whether or not to follow symbolic links * * Use openat() to open a directory, using a standard set of flags. * This function sets errno. */ int glnx_opendirat_with_errno (int dfd, const char *path, gboolean follow) { int flags = O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC | O_NOCTTY; if (!follow) flags |= O_NOFOLLOW; dfd = glnx_dirfd_canonicalize (dfd); return openat (dfd, path, flags); } /** * glnx_opendirat: * @dfd: File descriptor for origin directory * @path: Pathname, relative to @dfd * @follow: Whether or not to follow symbolic links * @error: Error * * Use openat() to open a directory, using a standard set of flags. */ gboolean glnx_opendirat (int dfd, const char *path, gboolean follow, int *out_fd, GError **error) { int ret = glnx_opendirat_with_errno (dfd, path, follow); if (ret == -1) { glnx_set_prefix_error_from_errno (error, "%s", "openat"); return FALSE; } *out_fd = ret; return TRUE; } struct GLnxRealDirfdIterator { gboolean initialized; int fd; DIR *d; }; typedef struct GLnxRealDirfdIterator GLnxRealDirfdIterator; /** * glnx_dirfd_iterator_init_at: * @dfd: File descriptor, may be AT_FDCWD or -1 * @path: Path, may be relative to @df * @follow: If %TRUE and the last component of @path is a symlink, follow it * @out_dfd_iter: (out caller-allocates): A directory iterator, will be initialized * @error: Error * * Initialize @out_dfd_iter from @dfd and @path. */ gboolean glnx_dirfd_iterator_init_at (int dfd, const char *path, gboolean follow, GLnxDirFdIterator *out_dfd_iter, GError **error) { gboolean ret = FALSE; glnx_fd_close int fd = -1; if (!glnx_opendirat (dfd, path, follow, &fd, error)) goto out; if (!glnx_dirfd_iterator_init_take_fd (fd, out_dfd_iter, error)) goto out; fd = -1; /* Transfer ownership */ ret = TRUE; out: return ret; } /** * glnx_dirfd_iterator_init_take_fd: * @dfd: File descriptor - ownership is taken * @dfd_iter: A directory iterator * @error: Error * * Steal ownership of @dfd, using it to initialize @dfd_iter for * iteration. */ gboolean glnx_dirfd_iterator_init_take_fd (int dfd, GLnxDirFdIterator *dfd_iter, GError **error) { gboolean ret = FALSE; GLnxRealDirfdIterator *real_dfd_iter = (GLnxRealDirfdIterator*) dfd_iter; DIR *d = NULL; d = fdopendir (dfd); if (!d) { glnx_set_prefix_error_from_errno (error, "%s", "fdopendir"); goto out; } real_dfd_iter->fd = dfd; real_dfd_iter->d = d; real_dfd_iter->initialized = TRUE; ret = TRUE; out: return ret; } /** * glnx_dirfd_iterator_next_dent: * @dfd_iter: A directory iterator * @out_dent: (out) (transfer none): Pointer to dirent; do not free * @cancellable: Cancellable * @error: Error * * Read the next value from @dfd_iter, causing @out_dent to be * updated. If end of stream is reached, @out_dent will be set * to %NULL, and %TRUE will be returned. */ gboolean glnx_dirfd_iterator_next_dent (GLnxDirFdIterator *dfd_iter, struct dirent **out_dent, GCancellable *cancellable, GError **error) { gboolean ret = FALSE; GLnxRealDirfdIterator *real_dfd_iter = (GLnxRealDirfdIterator*) dfd_iter; g_return_val_if_fail (out_dent, FALSE); g_return_val_if_fail (dfd_iter->initialized, FALSE); if (g_cancellable_set_error_if_cancelled (cancellable, error)) goto out; do { errno = 0; *out_dent = readdir (real_dfd_iter->d); if (*out_dent == NULL && errno != 0) { glnx_set_prefix_error_from_errno (error, "%s", "fdopendir"); goto out; } } while (*out_dent && (strcmp ((*out_dent)->d_name, ".") == 0 || strcmp ((*out_dent)->d_name, "..") == 0)); ret = TRUE; out: return ret; } /** * glnx_dirfd_iterator_next_dent_ensure_dtype: * @dfd_iter: A directory iterator * @out_dent: (out) (transfer none): Pointer to dirent; do not free * @cancellable: Cancellable * @error: Error * * A variant of @glnx_dirfd_iterator_next_dent, which will ensure the * `dent->d_type` member is filled in by calling `fstatat` * automatically if the underlying filesystem type sets `DT_UNKNOWN`. */ gboolean glnx_dirfd_iterator_next_dent_ensure_dtype (GLnxDirFdIterator *dfd_iter, struct dirent **out_dent, GCancellable *cancellable, GError **error) { gboolean ret = FALSE; struct dirent *ret_dent; g_return_val_if_fail (out_dent, FALSE); if (!glnx_dirfd_iterator_next_dent (dfd_iter, out_dent, cancellable, error)) goto out; ret_dent = *out_dent; if (ret_dent) { if (ret_dent->d_type == DT_UNKNOWN) { struct stat stbuf; if (TEMP_FAILURE_RETRY (fstatat (dfd_iter->fd, ret_dent->d_name, &stbuf, AT_SYMLINK_NOFOLLOW)) != 0) { glnx_set_error_from_errno (error); goto out; } ret_dent->d_type = IFTODT (stbuf.st_mode); } } ret = TRUE; out: return ret; } /** * glnx_dirfd_iterator_clear: * @dfd_iter: Iterator, will be de-initialized * * Unset @dfd_iter, freeing any resources. If @dfd_iter is not * initialized, do nothing. */ void glnx_dirfd_iterator_clear (GLnxDirFdIterator *dfd_iter) { GLnxRealDirfdIterator *real_dfd_iter = (GLnxRealDirfdIterator*) dfd_iter; /* fd is owned by dfd_iter */ if (!real_dfd_iter->initialized) return; (void) closedir (real_dfd_iter->d); real_dfd_iter->initialized = FALSE; } /** * glnx_fdrel_abspath: * @dfd: Directory fd * @path: Path * * Turn a fd-relative pair into something that can be used for legacy * APIs expecting absolute paths. * * This is Linux specific, and only valid inside this process (unless * you set up the child process to have the exact same fd number, but * don't try that). */ char * glnx_fdrel_abspath (int dfd, const char *path) { dfd = glnx_dirfd_canonicalize (dfd); if (dfd == AT_FDCWD) return g_strdup (path); return g_strdup_printf ("/proc/self/fd/%d/%s", dfd, path); } /** * glnx_gen_temp_name: * @tmpl: (type filename): template directory name, the last 6 characters will be replaced * * Replace the last 6 characters of @tmpl with random ASCII. You must * use this in combination with a mechanism to ensure race-free file * creation such as `O_EXCL`. */ void glnx_gen_temp_name (gchar *tmpl) { size_t len; char *XXXXXX; int count; static const char letters[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; static const int NLETTERS = sizeof (letters) - 1; glong value; GTimeVal tv; static int counter = 0; g_return_if_fail (tmpl != NULL); len = strlen (tmpl); g_return_if_fail (len >= 6); XXXXXX = tmpl + (len - 6); /* Get some more or less random data. */ g_get_current_time (&tv); value = (tv.tv_usec ^ tv.tv_sec) + counter++; for (count = 0; count < 100; value += 7777, ++count) { glong v = value; /* Fill in the random bits. */ XXXXXX[0] = letters[v % NLETTERS]; v /= NLETTERS; XXXXXX[1] = letters[v % NLETTERS]; v /= NLETTERS; XXXXXX[2] = letters[v % NLETTERS]; v /= NLETTERS; XXXXXX[3] = letters[v % NLETTERS]; v /= NLETTERS; XXXXXX[4] = letters[v % NLETTERS]; v /= NLETTERS; XXXXXX[5] = letters[v % NLETTERS]; } } /** * glnx_mkdtempat: * @dfd: Directory fd * @tmpl: (type filename): template directory name, last 6 characters will be replaced * @mode: permissions to create the temporary directory with * @error: Error * * Similar to g_mkdtemp_full, but using openat. */ gboolean glnx_mkdtempat (int dfd, gchar *tmpl, int mode, GError **error) { int count; g_return_val_if_fail (tmpl != NULL, -1); for (count = 0; count < 100; count++) { glnx_gen_temp_name (tmpl); if (mkdirat (dfd, tmpl, mode) == -1) { if (errno == EEXIST) continue; /* Any other error will apply also to other names we might * try, and there are 2^32 or so of them, so give up now. */ glnx_set_prefix_error_from_errno (error, "%s", "mkdirat"); return FALSE; } return TRUE; } g_set_error (error, G_IO_ERROR, G_IO_ERROR_EXISTS, "mkstempat ran out of combinations to try."); return FALSE; }