[MLton-commit] r4862

[Vesa Karvonen]

Added minimal implementations of dlopen, dlclose, dlsym, and dlerror for
MinGW.

Emulation of dlopen(NULL, ...) behavior is problematic.  The current
implementation just returns GetModuleHandle(NULL) which has a similar
meaning.  Unfortunately, you can't access the C runtime from the returned
handle nor can you access symbols that have not been explicitly exported.

----------------------------------------------------------------------

U   mlton/trunk/runtime/platform/mingw.c

----------------------------------------------------------------------

Modified: mlton/trunk/runtime/platform/mingw.c
===================================================================
--- mlton/trunk/runtime/platform/mingw.c	2006-11-27 09:36:16 UTC (rev 4861)
+++ mlton/trunk/runtime/platform/mingw.c	2006-11-27 12:37:26 UTC (rev 4862)
@@ -748,3 +748,91 @@
                 WSAStartup (version, &wsaData);
         }
 }
+
+/* ------------------------------------------------- */
+/*                      libdl                        */
+/* ------------------------------------------------- */
+
+static DWORD dlerror_last = ERROR_SUCCESS;
+/* This is for emulating the ugly stateful behavior of dlerror. */
+
+static HMODULE dl_main_module = NULL;
+/* Handle to the main module returned by GetModuleHandle(NULL).  It is
+ * assumed that the main module isn't freed during the lifetime of the
+ * process.
+ */
+
+void *dlopen(const char *filename, int flag_IGNORED) {
+        if (!filename) {
+                if (!dl_main_module)
+                        dl_main_module = GetModuleHandle(NULL);
+
+                if (!dl_main_module)
+                        dlerror_last = GetLastError();
+
+                return dl_main_module;
+        }
+
+        {
+                HMODULE result = LoadLibrary(filename);
+
+                if (!result)
+                        dlerror_last = GetLastError();
+
+                return result;
+        }
+}
+
+const char *dlerror(void) {
+        if (ERROR_SUCCESS == dlerror_last) {
+                return NULL;
+        } else {
+                static char buffer[256];
+
+                if (!FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS |
+                                   FORMAT_MESSAGE_FROM_SYSTEM,
+                                   NULL, dlerror_last, 0,
+                                   buffer, sizeof(buffer),
+                                   NULL))
+                        snprintf(buffer, sizeof(buffer),
+                                 "Failed to format error message");
+
+                dlerror_last = ERROR_SUCCESS;
+
+                return buffer;
+        }
+}
+
+void *dlsym(void *void_hmodule, const char *symbol) {
+        HMODULE hmodule = void_hmodule;
+
+        if (!hmodule) {
+                dlerror_last = ERROR_INVALID_HANDLE;
+                return NULL;
+        }
+
+        {
+                void* result = GetProcAddress(hmodule, symbol);
+
+                if (!result)
+                        dlerror_last = GetLastError();
+
+                return result;
+        }
+}
+
+int dlclose(void *void_hmodule) {
+        HMODULE hmodule = void_hmodule;
+
+        if (!hmodule || hmodule == dl_main_module)
+                return 0;
+
+        {
+                int result = !FreeLibrary(hmodule);
+
+                if (result)
+                        dlerror_last = GetLastError();
+
+                return result;
+        }
+}