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

3 files changed, 6 insertions, 5 deletions

diff --git a/tools/dbus-launch-win.c b/tools/dbus-launch-win.c
index 1dfd0954c..34837c12b 100644
--- 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 198884868..e8b29f882 100644
--- 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 03ce55360..744bbeb0e 100644
--- 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";