Re: [AD] Re: binary compatibility check

[Elias Pschernig <elias@xxxxxxxxxx>]

On Wed, 2006-02-08 at 11:29 +0100, Elias Pschernig wrote:
> Since this code looks so ugly now though, I'm wondering about changing
> _install_allegro to get a 4th parameter with the compile-time version,
> and then simply have this:
> 
> #define allegro_init _install_allegro(SYSTEM_AUTODETECT, errno, atexit, MAKE_VERSION(...))
> 
> And let install_allegro again be a normal function, which simply calls
> _install_allegro. It would mean, only allegro_init could do the version
> check, but that should be enough, and all involved code stays clean.

The attached patch does just that. I left the current allegro_install
intact, since I'm not sure how changing an AL_INLINE function to a
normal function affects binary compatibility.

-- 
Elias Pschernig

Index: include/allegro/system.h
===================================================================
--- include/allegro/system.h	(revision 5704)
+++ include/allegro/system.h	(working copy)
@@ -75,37 +75,20 @@
 
 AL_FUNC(int, _get_allegro_version, (void));
 AL_FUNC(int, _install_allegro, (int system_id, int *errno_ptr, AL_METHOD(int, atexit_ptr, (AL_METHOD(void, func, (void))))));
+AL_FUNC(int, _install_allegro_version_check, (int system_id, int *errno_ptr,
+   AL_METHOD(int, atexit_ptr, (AL_METHOD(void, func, (void)))), int version));
 
+/* This is only here because of binary compatibility with 4.2.0. */
 AL_INLINE(int, install_allegro, (int system_id, int *errno_ptr,
    AL_METHOD(int, atexit_ptr, (AL_METHOD(void, func, (void))))),
 {
-   int r = _install_allegro(system_id, errno_ptr, atexit_ptr);
-   int dll_v = _get_allegro_version(); /* This comes from the DLL. */
-   int dll_wip = dll_v & 255;
-   int dll_ver = dll_v & ~255;
-
-#if ((ALLEGRO_SUB_VERSION&1) == 0)
-
-   /* Check that the x.y versions match (eg. 4.2 = 4.2) and that the DLL WIP
-    * version is at least as new as the headers we were compiled with */
-   if ((dll_ver != MAKE_VERSION(ALLEGRO_VERSION, ALLEGRO_SUB_VERSION, 0)) ||
-       (dll_wip < ALLEGRO_WIP_VERSION)) {
-#else
-   /* Enforce strict header x.y.z == lib x.y.z for WIP branches */
-   if (dll_v != MAKE_VERSION(ALLEGRO_VERSION, ALLEGRO_SUB_VERSION, 
-      ALLEGRO_WIP_VERSION)) {
-#endif
-      uszprintf(allegro_error, ALLEGRO_ERROR_SIZE, get_config_text(
-         "The detected dynamic Allegro library (%d.%d.%d) is "
-         "not compatible with this program (%d.%d.%d)."),
-         dll_ver >> 16, (dll_ver >> 8) & 255, dll_wip,
-         ALLEGRO_VERSION, ALLEGRO_SUB_VERSION, ALLEGRO_WIP_VERSION);
-      return !0;
-   }
-   return r;
+   return _install_allegro(system_id, errno_ptr, atexit_ptr);
 })
 
-#define allegro_init()  install_allegro(SYSTEM_AUTODETECT, &errno, (int (*)(void (*)(void)))atexit)
+
+#define allegro_init()  _install_allegro_version_check(SYSTEM_AUTODETECT, &errno, \
+   (int (*)(void (*)(void)))atexit, \
+   MAKE_VERSION(ALLEGRO_VERSION, ALLEGRO_SUB_VERSION, ALLEGRO_WIP_VERSION))
 AL_FUNC(void, allegro_exit, (void));
 
 AL_PRINTFUNC(void, allegro_message, (AL_CONST char *msg, ...), 1, 2);
Index: src/allegro.c
===================================================================
--- src/allegro.c	(revision 5704)
+++ src/allegro.c	(working copy)
@@ -411,6 +411,48 @@
 
 
 
+/* _install_allegro_version_check:
+ *  Initialises the Allegro library, but return with an error if an incompatible version
+ *  is found.
+ */
+int _install_allegro_version_check(int system_id, int *errno_ptr,
+   int (*atexit_ptr)(void (*func)(void)), int version)
+{
+   int r = _install_allegro(system_id, errno_ptr, atexit_ptr);
+
+   int build_wip = version & 255;
+   int build_ver = version & ~255;
+
+   int version_ok;
+
+   if (r)
+      return r;
+
+#if ALLEGRO_SUB_VERSION&1
+   /* This is a WIP runtime, so enforce strict compatibility. */
+   version_ok = version == _get_allegro_version();
+#else
+   /* This is a stable runtime, so the runtime should be at least as new
+    * as the build headers (otherwise we may get a crash, since some
+    * functions may have been used which aren't available in this runtime).
+    */
+   version_ok = (MAKE_VERSION(ALLEGRO_VERSION, ALLEGRO_SUB_VERSION, 0) == build_ver) &&
+      (ALLEGRO_WIP_VERSION >= build_wip);
+#endif
+
+   if (!version_ok) {
+      uszprintf(allegro_error, ALLEGRO_ERROR_SIZE, get_config_text(
+         "The detected dynamic Allegro library (%d.%d.%d) is "
+         "not compatible with this program (%d.%d.%d)."),
+         ALLEGRO_VERSION, ALLEGRO_SUB_VERSION, ALLEGRO_WIP_VERSION,
+         build_ver >> 16, (build_ver >> 8) & 255, build_wip);
+      return -1;
+   }
+   return 0;
+}
+
+
+
 /* allegro_exit:
  *  Closes down the Allegro system.
  */