[tracker/tracker-0.10] tracker-writeback: Use g_mkstemp_full() and preserve permissions on copy

[Martyn James Russell <mr src gnome org>]

commit 806fba3286ae498c1717a59719c32a6380bda4b3
Author: Carlos Garnacho <carlos lanedo com>
Date:   Fri Jul 15 17:13:11 2011 +0200

    tracker-writeback: Use g_mkstemp_full() and preserve permissions on copy
    
    This way we ensure there is no intromission on the temporary file,
    plus we don't potentially change permissions on the final file.
    writeback usually happens on a copy, which is moved atomically onto
    of the original file, so we now ensure there are

 src/tracker-writeback/tracker-writeback-file.c |   74 +++++++++++++++++++----
 1 files changed, 61 insertions(+), 13 deletions(-)
---
diff --git a/src/tracker-writeback/tracker-writeback-file.c b/src/tracker-writeback/tracker-writeback-file.c
index 69356c3..a837ed9 100644
--- a/src/tracker-writeback/tracker-writeback-file.c
+++ b/src/tracker-writeback/tracker-writeback-file.c
@@ -22,6 +22,8 @@
 #include <stdio.h>
 
 #include <libtracker-common/tracker-file-utils.h>
+#include <gio/gunixoutputstream.h>
+#include <fcntl.h> /* O_WRONLY */
 
 #include "tracker-writeback-file.h"
 
@@ -63,23 +65,69 @@ file_unlock_cb (gpointer user_data)
 }
 
 static GFile *
-get_tmp_file (GFile *file)
+create_temporary_file (GFile     *file,
+                       GFileInfo *file_info)
 {
+	GInputStream *input_stream;
+	GOutputStream *output_stream;
 	GFile *tmp_file, *parent;
-	gchar *tmp_name, *dir;
+	gchar *dir, *name, *tmp_path;
+	guint32 mode;
+	gint fd;
+	GError *error = NULL;
 
-	/* Create a temporary, hidden file
-	 * within the same directory */
+	if (!g_file_is_native (file)) {
+		return NULL;
+	}
+
+	/* Create input stream */
+	input_stream = G_INPUT_STREAM (g_file_read (file, NULL, &error));
+
+	if (error) {
+		g_critical ("Could not read the file: %s", error->message);
+		g_error_free (error);
+		return NULL;
+	}
+
+	/* Create output stream in a tmp file */
 	parent = g_file_get_parent (file);
 	dir = g_file_get_path (parent);
-
-	tmp_name = tempnam (dir, "._trk");
 	g_object_unref (parent);
 
-	tmp_file = g_file_new_for_path (tmp_name);
-
-	g_free (tmp_name);
+	name = g_file_get_basename (file);
+	tmp_path = g_strdup_printf ("%s" G_DIR_SEPARATOR_S ".tracker-XXXXXX.%s",
+	                            dir, name);
 	g_free (dir);
+	g_free (name);
+
+	mode = g_file_info_get_attribute_uint32 (file_info,
+	                                         G_FILE_ATTRIBUTE_UNIX_MODE);
+	fd = g_mkstemp_full (tmp_path, O_WRONLY, mode);
+
+	output_stream = g_unix_output_stream_new (fd, TRUE);
+
+	/* Splice the original file into the tmp file */
+	g_output_stream_splice (output_stream,
+	                        input_stream,
+	                        G_OUTPUT_STREAM_SPLICE_CLOSE_SOURCE |
+	                        G_OUTPUT_STREAM_SPLICE_CLOSE_TARGET,
+	                        NULL, &error);
+
+	g_object_unref (output_stream);
+	g_object_unref (input_stream);
+
+	tmp_file = g_file_new_for_path (tmp_path);
+	g_free (tmp_path);
+
+	if (error) {
+		g_critical ("Could not copy file: %s\n", error->message);
+		g_error_free (error);
+
+		g_file_delete (tmp_file, NULL, NULL);
+		g_object_unref (tmp_file);
+
+		return NULL;
+	}
 
 	return tmp_file;
 }
@@ -119,6 +167,7 @@ tracker_writeback_file_update_metadata (TrackerWriteback        *writeback,
 	file = g_file_new_for_uri (row[0]);
 
 	file_info = g_file_query_info (file,
+	                               G_FILE_ATTRIBUTE_UNIX_MODE ","
 	                               G_FILE_ATTRIBUTE_STANDARD_CONTENT_TYPE,
 	                               G_FILE_QUERY_INFO_NOFOLLOW_SYMLINKS,
 	                               NULL, NULL);
@@ -129,11 +178,10 @@ tracker_writeback_file_update_metadata (TrackerWriteback        *writeback,
 	}
 
 	/* Copy to a temporary file so we can perform an atomic write on move */
-	tmp_file = get_tmp_file (file);
-	if (!g_file_copy (file, tmp_file, 0,
-			  NULL, NULL, NULL, NULL)) {
+	tmp_file = create_temporary_file (file, file_info);
+
+	if (!tmp_file) {
 		g_object_unref (file);
-		g_object_unref (tmp_file);
 		return FALSE;
 	}