Be more const-correct

As a general design principle, strings that we aren't going to modify
should usually be const. When compiling with -Wwrite-strings, quoted
string constants are of type "const char *", causing compiler warnings
when they are assigned to char * variables.

Unfortunately, we need to add casts in a few places:

* _dbus_list_append(), _dbus_test_oom_handling() and similar generic
  "user-data" APIs take a void *, not a const void *, so we have
  to cast
* For historical reasons the execve() family of functions take a
  (char * const *), i.e. a constant pointer to an array of mutable
  strings, so again we have to cast
* _dbus_spawn_async_with_babysitter similarly takes a char **,
  although we can make it a little more const-correct by making it
  take (char * const *) like execve() does

This also incorporates a subsequent patch by Thomas Zimmermann to
put various string constants in static storage, which is a little
more efficient.

Signed-off-by: Simon McVittie <smcv@debian.org>
Reviewed-by: Thomas Zimmermann <tdz@users.sourceforge.net>
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=97357

diff --git a/bus/config-parser.c b/bus/config-parser.c
index 5af1024..b776a2d 100644 (file)
--- a/bus/config-parser.c
+++ b/bus/config-parser.c
@@ -2810,7 +2810,7 @@ static dbus_bool_t
 do_check_own_rules (BusPolicy  *policy)
 {
   const struct {
-    char *name;
+    const char *name;
     dbus_bool_t allowed;
   } checks[] = {
     {"org.freedesktop", FALSE},

diff --git a/bus/desktop-file.c b/bus/desktop-file.c
index bfeb72e..4459858 100644 (file)
--- a/bus/desktop-file.c
+++ b/bus/desktop-file.c
@@ -88,7 +88,7 @@ static unsigned char valid[256] = {
 };
 
 static void report_error (BusDesktopFileParser *parser,
-                         char                 *message,
+                         const char           *message,
                          const char           *error_name,
                          DBusError            *error);
 
@@ -579,7 +579,7 @@ parse_key_value (BusDesktopFileParser *parser, DBusError *error)
 
 static void
 report_error (BusDesktopFileParser *parser,
-             char                 *message,
+             const char           *message,
              const char           *error_name,
              DBusError            *error)
 {

diff --git a/bus/driver.c b/bus/driver.c
index 41ca445..83e8ead 100644 (file)
--- a/bus/driver.c
+++ b/bus/driver.c
@@ -1528,6 +1528,8 @@ bus_driver_handle_list_queued_owners (DBusConnection *connection,
                                      DBusMessage    *message,
                                      DBusError      *error)
 {
+  static const char dbus_service_name[] = DBUS_SERVICE_DBUS;
+
   const char *text;
   DBusList *base_names;
   DBusList *link;
@@ -1536,7 +1538,6 @@ bus_driver_handle_list_queued_owners (DBusConnection *connection,
   BusService *service;
   DBusMessage *reply;
   DBusMessageIter iter, array_iter;
-  char *dbus_service_name = DBUS_SERVICE_DBUS;
 
   _DBUS_ASSERT_ERROR_IS_CLEAR (error);
 
@@ -1557,7 +1558,7 @@ bus_driver_handle_list_queued_owners (DBusConnection *connection,
       _dbus_string_equal_c_str (&str, DBUS_SERVICE_DBUS))
     {
       /* ORG_FREEDESKTOP_DBUS owns itself */
-      if (! _dbus_list_append (&base_names, dbus_service_name))
+      if (! _dbus_list_append (&base_names, (char *) dbus_service_name))
         goto oom;
     }
   else if (service == NULL)

diff --git a/bus/test-launch-helper.c b/bus/test-launch-helper.c
index e9ec7b9..5d025f5 100644 (file)
--- a/bus/test-launch-helper.c
+++ b/bus/test-launch-helper.c
@@ -130,7 +130,7 @@ main (int argc, char **argv)
 
   if (!_dbus_test_oom_handling ("dbus-daemon-launch-helper",
                                 bus_activation_helper_oom_test,
-                                "org.freedesktop.DBus.TestSuiteEchoService"))
+                                (char *) "org.freedesktop.DBus.TestSuiteEchoService"))
     die ("OOM failed");
 
   test_post_hook (argv[0]);

diff --git a/bus/test-main.c b/bus/test-main.c
index e4ba0ad..9496dd2 100644 (file)
--- a/bus/test-main.c
+++ b/bus/test-main.c
@@ -74,7 +74,7 @@ test_pre_hook (void)
   initial_fds = _dbus_check_fdleaks_enter ();
 }
 
-static char *progname = "";
+static const char *progname = "";
 
 static void
 test_post_hook (void)

diff --git a/bus/test-system.c b/bus/test-system.c
index e03e677..7d5c3df 100644 (file)
--- a/bus/test-system.c
+++ b/bus/test-system.c
@@ -59,7 +59,7 @@ test_pre_hook (void)
 {
 }
 
-static char *progname = "";
+static const char *progname = "";
 static void
 test_post_hook (void)
 {

diff --git a/dbus/dbus-connection.c b/dbus/dbus-connection.c
index 365fd45..319987e 100644 (file)
--- a/dbus/dbus-connection.c
+++ b/dbus/dbus-connection.c
@@ -2183,9 +2183,9 @@ _dbus_memory_pause_based_on_timeout (int timeout_milliseconds)
 }
 
 static DBusMessage *
-generate_local_error_message (dbus_uint32_t serial, 
-                              char *error_name, 
-                              char *error_msg)
+generate_local_error_message (dbus_uint32_t serial,
+                              const char *error_name,
+                              const char *error_msg)
 {
   DBusMessage *message;
   message = dbus_message_new (DBUS_MESSAGE_TYPE_ERROR);

diff --git a/dbus/dbus-spawn-test.c b/dbus/dbus-spawn-test.c
index 5cb2cf4..bffb33e 100644 (file)
--- a/dbus/dbus-spawn-test.c
+++ b/dbus/dbus-spawn-test.c
@@ -56,14 +56,17 @@ get_test_exec (const char *exe,
 static dbus_bool_t
 check_spawn_nonexistent (void *data)
 {
-  char *argv[4] = { NULL, NULL, NULL, NULL };
+  static const char arg_does_not_exist[] = "/this/does/not/exist/32542sdgafgafdg";
+
+  const char *argv[4] = { NULL, NULL, NULL, NULL };
   DBusBabysitter *sitter = NULL;
   DBusError error = DBUS_ERROR_INIT;
 
   /*** Test launching nonexistent binary */
 
-  argv[0] = "/this/does/not/exist/32542sdgafgafdg";
-  if (_dbus_spawn_async_with_babysitter (&sitter, "spawn_nonexistent", argv,
+  argv[0] = arg_does_not_exist;
+  if (_dbus_spawn_async_with_babysitter (&sitter, "spawn_nonexistent",
+                                         (char * const *) argv,
                                          NULL, DBUS_SPAWN_NONE, NULL, NULL,
                                          &error))
     {

diff --git a/dbus/dbus-spawn-win.c b/dbus/dbus-spawn-win.c
index 564f61d..cc5bfc3 100644 (file)
--- a/dbus/dbus-spawn-win.c
+++ b/dbus/dbus-spawn-win.c
@@ -412,8 +412,8 @@ handle_watch (DBusWatch       *watch,
 
 /* protect_argv lifted from GLib, relicensed by author, Tor Lillqvist */
 static int
-protect_argv (char  **argv,
-              char ***new_argv)
+protect_argv (char  * const *argv,
+              char        ***new_argv)
 {
   int i;
   int argc = 0;
@@ -440,7 +440,7 @@ protect_argv (char  **argv,
    */
   for (i = 0; i < argc; i++)
     {
-      char *p = argv[i];
+      const char *p = argv[i];
       char *q;
       int len = 0;
       int need_dblquotes = FALSE;
@@ -452,7 +452,7 @@ protect_argv (char  **argv,
             len++;
           else if (*p == '\\')
             {
-              char *pp = p;
+              const char *pp = p;
               while (*pp && *pp == '\\')
                 pp++;
               if (*pp == '"')
@@ -479,7 +479,7 @@ protect_argv (char  **argv,
             *q++ = '\\';
           else if (*p == '\\')
             {
-              char *pp = p;
+              const char *pp = p;
               while (*pp && *pp == '\\')
                 pp++;
               if (*pp == '"')
@@ -643,7 +643,7 @@ babysitter (void *parameter)
 dbus_bool_t
 _dbus_spawn_async_with_babysitter (DBusBabysitter           **sitter_p,
                                    const char                *log_name,
-                                   char                     **argv,
+                                   char              * const *argv,
                                    char                     **envp,
                                    DBusSpawnFlags             flags _DBUS_GNUC_UNUSED,
                                    DBusSpawnChildSetupFunc    child_setup _DBUS_GNUC_UNUSED,

diff --git a/dbus/dbus-spawn.c b/dbus/dbus-spawn.c
index 04245b4..df6eafd 100644 (file)
--- a/dbus/dbus-spawn.c
+++ b/dbus/dbus-spawn.c
@@ -1004,8 +1004,8 @@ write_status_and_exit (int fd, int status)
 
 static void
 do_exec (int                       child_err_report_fd,
-        char                    **argv,
-        char                    **envp,
+        char             * const *argv,
+        char             * const *envp,
         DBusSpawnChildSetupFunc   child_setup,
         void                     *user_data)
 {
@@ -1214,7 +1214,7 @@ babysit (pid_t grandchild_pid,
 dbus_bool_t
 _dbus_spawn_async_with_babysitter (DBusBabysitter          **sitter_p,
                                    const char               *log_name,
-                                   char                    **argv,
+                                   char             * const *argv,
                                    char                    **env,
                                    DBusSpawnFlags            flags,
                                    DBusSpawnChildSetupFunc   child_setup,

diff --git a/dbus/dbus-spawn.h b/dbus/dbus-spawn.h
index dc04dc7..b34324d 100644 (file)
--- a/dbus/dbus-spawn.h
+++ b/dbus/dbus-spawn.h
@@ -45,7 +45,7 @@ typedef enum {
 
 dbus_bool_t _dbus_spawn_async_with_babysitter     (DBusBabysitter           **sitter_p,
                                                    const char                *log_name,
-                                                   char                     **argv,
+                                                   char              * const *argv,
                                                    char                     **env,
                                                    DBusSpawnFlags             flags,
                                                    DBusSpawnChildSetupFunc    child_setup,

diff --git a/dbus/dbus-sysdeps-unix.c b/dbus/dbus-sysdeps-unix.c
index 5d9062f..fda5d8e 100644 (file)
--- a/dbus/dbus-sysdeps-unix.c
+++ b/dbus/dbus-sysdeps-unix.c
@@ -1069,7 +1069,7 @@ _dbus_connect_exec (const char     *path,
 
       _dbus_close_all ();
 
-      execvp (path, argv);
+      execvp (path, (char * const *) argv);
 
       fprintf (stderr, "Failed to execute process %s: %s\n", path, _dbus_strerror (errno));
 
@@ -3545,7 +3545,7 @@ _dbus_get_tmpdir(void)
 static dbus_bool_t
 _read_subprocess_line_argv (const char *progpath,
                             dbus_bool_t path_fallback,
-                            char       * const *argv,
+                            const char * const *argv,
                             DBusString *result,
                             DBusError  *error)
 {
@@ -3648,7 +3648,7 @@ _read_subprocess_line_argv (const char *progpath,
       /* If it looks fully-qualified, try execv first */
       if (progpath[0] == '/')
         {
-          execv (progpath, argv);
+          execv (progpath, (char * const *) argv);
           /* Ok, that failed.  Now if path_fallback is given, let's
            * try unqualified.  This is mostly a hack to work
            * around systems which ship dbus-launch in /usr/bin
@@ -3657,10 +3657,10 @@ _read_subprocess_line_argv (const char *progpath,
            */
           if (path_fallback)
             /* We must have a slash, because we checked above */
-            execvp (strrchr (progpath, '/')+1, argv);
+            execvp (strrchr (progpath, '/')+1, (char * const *) argv);
         }
       else
-        execvp (progpath, argv);
+        execvp (progpath, (char * const *) argv);
 
       /* still nothing, we failed */
       _exit (1);
@@ -3758,12 +3758,17 @@ _dbus_get_autolaunch_address (const char *scope,
                               DBusError  *error)
 {
 #ifdef DBUS_ENABLE_X11_AUTOLAUNCH
+  static const char arg_dbus_launch[] = "dbus-launch";
+  static const char arg_autolaunch[] = "--autolaunch";
+  static const char arg_binary_syntax[] = "--binary-syntax";
+  static const char arg_close_stderr[] = "--close-stderr";
+
   /* Perform X11-based autolaunch. (We also support launchd-based autolaunch,
    * but that's done elsewhere, and if it worked, this function wouldn't
    * be called.) */
   const char *display;
   const char *progpath;
-  char *argv[6];
+  const char *argv[6];
   int i;
   DBusString uuid;
   dbus_bool_t retval;
@@ -3818,15 +3823,15 @@ _dbus_get_autolaunch_address (const char *scope,
    * see fd.o#69716
    */
   i = 0;
-  argv[i] = "dbus-launch";
+  argv[i] = arg_dbus_launch;
   ++i;
-  argv[i] = "--autolaunch";
+  argv[i] = arg_autolaunch;
   ++i;
   argv[i] = _dbus_string_get_data (&uuid);
   ++i;
-  argv[i] = "--binary-syntax";
+  argv[i] = arg_binary_syntax;
   ++i;
-  argv[i] = "--close-stderr";
+  argv[i] = arg_close_stderr;
   ++i;
   argv[i] = NULL;
   ++i;

diff --git a/dbus/dbus-sysdeps-win.c b/dbus/dbus-sysdeps-win.c
index 62e7023..c68c6ca 100644 (file)
--- a/dbus/dbus-sysdeps-win.c
+++ b/dbus/dbus-sysdeps-win.c
@@ -3678,7 +3678,7 @@ _dbus_logv (DBusSystemLogSeverity  severity,
             const char            *msg,
             va_list                args)
 {
-  char *s = "";
+  const char *s = "";
   va_list tmp;
 
   switch(severity)

diff --git a/test/name-test/test-pending-call-dispatch.c b/test/name-test/test-pending-call-dispatch.c
index 7785564..c8462d0 100644 (file)
--- a/test/name-test/test-pending-call-dispatch.c
+++ b/test/name-test/test-pending-call-dispatch.c
@@ -20,7 +20,7 @@ _run_iteration (DBusConnection *conn)
   DBusPendingCall *dbus_pending;
   DBusMessage *method;
   DBusMessage *reply;
-  char *echo = "echo";
+  const char *echo = "echo";
 
   /* send the first message */
   method = dbus_message_new_method_call ("org.freedesktop.DBus.TestSuiteEchoService",

diff --git a/test/name-test/test-pending-call-timeout.c b/test/name-test/test-pending-call-timeout.c
index be6b849..6035df8 100644 (file)
--- a/test/name-test/test-pending-call-timeout.c
+++ b/test/name-test/test-pending-call-timeout.c
@@ -17,7 +17,7 @@ _method_call (DBusConnection *conn,
   DBusPendingCall *pending;
   DBusMessage *method;
   DBusMessage *reply;
-  char *echo = "echo";
+  const char *echo = "echo";
 
   /* send the message */
   method = dbus_message_new_method_call ("org.freedesktop.DBus.TestSuiteEchoService",

diff --git a/test/name-test/test-threads-init.c b/test/name-test/test-threads-init.c
index 6285715..eb0ff96 100644 (file)
--- a/test/name-test/test-threads-init.c
+++ b/test/name-test/test-threads-init.c
@@ -18,7 +18,7 @@ _run_iteration (DBusConnection *conn)
   DBusPendingCall *dbus_pending;
   DBusMessage *method;
   DBusMessage *reply;
-  char *echo = "echo";
+  const char *echo = "echo";
 
   /* send the first message */
   method = dbus_message_new_method_call ("org.freedesktop.DBus.TestSuiteEchoService",

diff --git a/tools/dbus-launch-win.c b/tools/dbus-launch-win.c
index 1dfd095..34837c1 100644 (file)
--- a/tools/dbus-launch-win.c
+++ b/tools/dbus-launch-win.c
@@ -38,7 +38,7 @@
 #define wcscpy_s my_wcscpy_s
 
 static errno_t
-wcscat_s (wchar_t *dest, size_t size, wchar_t *src) 
+wcscat_s (wchar_t *dest, size_t size, const wchar_t *src)
 {
   assert (sizeof (wchar_t) * (wcslen (dest) + wcslen (src) + 1) <= size);
   wcscat (dest, src);
@@ -47,7 +47,7 @@ wcscat_s (wchar_t *dest, size_t size, wchar_t *src)
 
 
 static errno_t
-wcscpy_s (wchar_t *dest, size_t size, wchar_t *src)
+wcscpy_s (wchar_t *dest, size_t size, const wchar_t *src)
 {
   assert (sizeof (wchar_t) * (wcslen (src) + 1) <= size);
   wcscpy (dest, src);
@@ -87,7 +87,7 @@ main (int argc, char **argv)
   wchar_t dbusDaemonPath[MAX_PATH * 2 + 1];
   wchar_t command[MAX_PATH * 2 + 1];
   wchar_t *p;
-  wchar_t *daemon_name;
+  const wchar_t *daemon_name;
   int result;
 
 #ifdef DBUS_WINCE

diff --git a/tools/dbus-launch-x11.c b/tools/dbus-launch-x11.c
index 1988848..e8b29f8 100644 (file)
--- a/tools/dbus-launch-x11.c
+++ b/tools/dbus-launch-x11.c
@@ -52,7 +52,7 @@ x_io_error_handler (Display *local_xdisplay)
 
 static void
 remove_prefix (char *s,
-               char *prefix)
+               const char *prefix)
 {
   int plen;
 

diff --git a/tools/dbus-uuidgen.c b/tools/dbus-uuidgen.c
index 03ce553..744bbeb 100644 (file)
--- a/tools/dbus-uuidgen.c
+++ b/tools/dbus-uuidgen.c
@@ -28,7 +28,8 @@
 #include <dbus/dbus.h>
 
 static void
-usage (char *name, int ecode)
+usage (const char *name,
+       int ecode)
 {
   if (name == NULL)
     name = "dbus-uuidgen";