windows: Provide wrappers for dlopen() function family

src/libstrongswan/plugins/plugin_loader.c

@@ -21,7 +21,9 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <string.h>
+#ifdef HAVE_DLADDR
 #include <dlfcn.h>
+#endif
 #include <limits.h>
 #include <stdio.h>
 

src/libstrongswan/utils/windows.h

@@ -150,4 +150,85 @@ static inline struct tm *localtime_r(const time_t *timep, struct tm *result)
 	return NULL;
 }
 
+/**
+ * dlerror(3) from <dlfcn.h>, printing error to an alloca() buffer
+ */
+#define dlerror() \
+({ \
+	char buf[128], *out;\
+	ssize_t len; \
+	DWORD err; \
+	err = GetLastError(); \
+	len = FormatMessage(0, NULL, err, 0, buf, sizeof(buf), NULL); \
+	if (len <= 0) \
+	{ \
+		len = snprintf(buf, sizeof(buf), "(%u)", err); \
+	} \
+	len++; \
+	out = alloca(len); \
+	memcpy(out, buf, len); \
+	out; \
+})
+
+/**
+ * Lazy binding, ignored on Windows
+ */
+#define RTLD_LAZY 1
+
+/**
+ * dlopen(3) from <dlfcn.h>
+ */
+static inline void *dlopen(const char *filename, int flag)
+{
+	return LoadLibrary(filename);
+}
+
+/**
+ * Default handle targeting .exe
+ */
+#define RTLD_DEFAULT (NULL)
+
+/**
+ * Find symbol in next library
+ */
+#define RTLD_NEXT ((void*)~(uintptr_t)0)
+
+/**
+ * dlsym() from <dlfcn.h>
+ */
+static inline void *dlsym(void *handle, const char *symbol)
+{
+	if (handle == RTLD_DEFAULT)
+	{
+		handle = GetModuleHandle(NULL);
+	}
+	else if (handle == RTLD_NEXT)
+	{
+		if (strcmp(symbol, "malloc") == 0 ||
+			strcmp(symbol, "realloc") == 0 ||
+			strcmp(symbol, "free") == 0)
+		{
+			/* for leak-detective */
+			handle = GetModuleHandle("msvcrt");
+		}
+		else
+		{
+			return NULL;
+		}
+	}
+	if (handle)
+	{
+		return GetProcAddress((HMODULE)handle, symbol);
+	}
+	return NULL;
+}
+
+/**
+ * dlclose() from <dlfcn.h>
+ */
+static inline int dlclose(void *handle)
+{
+	return FreeLibrary((HMODULE)handle);
+}
+
 #endif /** WINDOWS_H_ @}*/