PolicyKit helper to copy a RANDR profile to a systemwide location
Signed-off-by: Federico Mena Quintero <federico@novell.com>
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Federico Mena Quintero
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268
capplets/display/gnome-display-properties-install-systemwide.c
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268
capplets/display/gnome-display-properties-install-systemwide.c
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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*-
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*
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* gnome-display-properties-install-systemwide - Install a RANDR profile for the whole system
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*
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* Copyright (C) 2010 Novell, Inc.
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*
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* Authors: Federico Mena Quintero <federico@novell.com>
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*
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* Licensed under the GNU General Public License Version 2
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "config.h"
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#include <locale.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <glib/gi18n.h>
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#include <glib.h>
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#define SYSTEM_RANDR_PATH "/etc/gnome-settings-daemon/xrandr"
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static void
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usage (const char *program_name)
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{
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g_print (_("Usage: %s SOURCE_FILE DEST_NAME\n"
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"\n"
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"This program installs a RANDR profile for multi-monitor setups into\n"
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"a systemwide location. The resulting profile will get used when\n"
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"the RANDR plug-in gets run in gnome-settings-daemon.\n"
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"\n"
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"SOURCE_FILE - a full pathname, typically /home/username/.config/monitors.xml\n"
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"\n"
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"DEST_NAME - relative name for the installed file. This will get put in\n"
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" the systemwide directory for RANDR configurations,\n"
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" so the result will typically be %s/DEST_NAME\n"),
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program_name,
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SYSTEM_RANDR_PATH);
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}
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static gboolean
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is_basename (const char *filename)
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{
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if (*filename == '\0')
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return FALSE; /* no empty strings, please */
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for (; *filename; filename++)
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if (G_IS_DIR_SEPARATOR (*filename))
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return FALSE;
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return TRUE;
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}
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static gboolean
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copy_file (int source_fd, int dest_fd)
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{
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char buf[1024];
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int num_read;
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int num_written;
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while (TRUE) {
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char *p;
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num_read = read (source_fd, buf, sizeof (buf));
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if (num_read == 0)
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break;
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if (num_read == -1) {
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if (errno == EINTR)
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continue;
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else
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return FALSE;
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}
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p = buf;
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while (num_read > 0) {
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num_written = write (dest_fd, p, num_read);
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if (num_written == -1) {
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if (errno == EINTR)
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continue;
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else
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return FALSE;
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}
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num_read -= num_written;
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p += num_written;
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}
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}
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return TRUE;
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}
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/* This is essentially a "please copy a file to a privileged location" program.
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* We try to be paranoid in the following ways:
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*
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* - We copy only regular files, owned by the user who called pkexec(1), to
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* avoid attacks like "copy a file that I'm not allowed to read into a
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* world-readable location".
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*
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* - We copy only to a well-known directory.
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*
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* - We try to avoid race conditions. We only fstat() files that we have open
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* to avoid files moving under our feet. We only create files in directories
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* that we have open.
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*
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* - We replace the destination file atomically.
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*/
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int
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main (int argc, char **argv)
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{
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const char *source_filename;
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const char *dest_name;
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const char *pkexec_uid_str;
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int pkexec_uid;
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struct stat statbuf;
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int err;
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int source_fd;
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int dest_fd;
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char template[100];
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setlocale (LC_ALL, "");
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bindtextdomain (GETTEXT_PACKAGE, LOCALEDIR);
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bind_textdomain_codeset (GETTEXT_PACKAGE, "UTF-8");
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textdomain (GETTEXT_PACKAGE);
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/* We only run as root */
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uid = getuid ();
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euid = geteuid ();
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if (uid != 0 || euid != 0) {
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/* Translators: only able to install RANDR profiles as root */
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g_print ("%s\n", _("This program can only be used by the root user"));
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return EXIT_FAILURE;
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}
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/* Usage: gsd-xrandr-install-systemwide SOURCE_FILE DEST_NAME */
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if (argc != 3) {
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usage (argv[0]);
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return EXIT_FAILURE;
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}
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source_filename = argv[1];
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dest_name = argv[2];
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/* Absolute source filenames only, please */
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if (!g_path_is_absolute (source_filename)) {
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g_print ("%s\n", _("The source filename must be absolute"));
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return EXIT_FAILURE;
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}
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/* We only copy regular files */
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source_fd = open (source_filename, O_RDONLY);
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if (source_fd == -1) {
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err = errno;
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/* Translators: first %s is a filename; second %s is an error message */
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g_print (_("Could not open %s: %s"),
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source_filename,
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g_strerror (err));
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return EXIT_FAILURE;
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}
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if (fstat (source_fd, &statbuf) != 0) {
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err = errno;
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/* Translators: first %s is a filename; second %s is an error message */
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g_print (_("Could not get information for %s: %s\n"),
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source_filename,
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g_strerror (err));
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return EXIT_FAILURE;
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}
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if (!S_ISREG (statbuf.st_mode)) {
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g_print (_("%s must be a regular file\n"),
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source_filename);
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return EXIT_FAILURE;
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}
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/* We only copy files that are really owned by the calling user */
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pkexec_uid_str = g_getenv ("PKEXEC_UID");
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if (pkexec_uid_str == NULL) {
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g_print ("%s\n", _("This program must only be run through pkexec(1)"));
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return EXIT_FAILURE;
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}
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if (sscanf (pkexec_uid_str, "%d", &pkexec_uid) != 1) {
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g_print ("%s\n", _("PKEXEC_UID must be set to an integer value"));
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return EXIT_FAILURE;
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}
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if (statbuf.st_uid != pkexec_uid) {
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/* Translators: we are complaining that a file must be really owned by the user who called this program */
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g_print (_("%s must be owned by you"), source_filename);
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return EXIT_FAILURE;
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}
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/* We only accept basenames for the destination */
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if (!is_basename (dest_name)) {
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/* Translators: here we are saying that a plain filename must look like "filename", not like "some_dir/filename" */
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g_print (_("%s must not have any directory components\n"),
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dest_name);
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return EXIT_FAILURE;
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}
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/* Chdir to the destination directory to keep it open... */
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if (chdir (SYSTEM_RANDR_PATH) != 0) {
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g_print (_("%s must be a directory"), SYSTEM_RANDR_PATH);
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return EXIT_FAILURE;
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}
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/* ... and open our temporary destination file right there */
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strcpy (template, "gsd-XXXXXX");
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dest_fd = g_mkstemp_full (template, 0, 0644);
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if (dest_fd == -1) {
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err = errno;
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/* Translators: the first %s/%s is a directory/filename; the last %s is an error message */
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g_print (_("Could not open %s/%s: %s"),
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SYSTEM_RANDR_PATH,
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template,
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g_strerror (err));
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return EXIT_FAILURE;
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}
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/* Do the copy */
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if (!copy_file (source_fd, dest_fd)) {
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/* If something went wrong, remove the destination file to avoid leaving trash around */
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unlink (template);
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return EXIT_FAILURE;
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}
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/* Rename to the final filename */
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if (rename (template, dest_name) != 0) {
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err = errno;
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unlink (template);
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g_print (_("Could not rename %s to %s: %s"),
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template,
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dest_name,
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g_strerror (err));
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return EXIT_FAILURE;
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}
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/* Whew! We'll leave the final closing of the files to the almighty kernel. */
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return EXIT_SUCCESS;
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}
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