/* dll.c - wrapper for loading modules */
/* PUBLIC DOMAIN - July 23, 2007 - Jon Mayo */

/* see:
 * http://msdn2.microsoft.com/en-us/library/ms686944.aspx
 * http://msdn2.microsoft.com/en-us/library/ms683212.aspx
 */

#include <assert.h>
#include <stdio.h>
#include "dll.h"

#ifdef WIN32
static void dll_show_error(const char *reason)
{
	LPTSTR lpMsgBuf;
	FormatMessage(
	        FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM
	        | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, GetLastError(),
	        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), &lpMsgBuf, 0, NULL);

	if (reason) {
		fprintf(stderr, "%s:%s\n", reason, lpMsgBuf);
	} else {
		fprintf(stderr, "%s\n", lpMsgBuf);
	}

	LocalFree(lpMsgBuf);
}

/* return zero on success, non-zero on error */
int dll_open(dll_handle_t *h, const char *filename)
{
	/* TODO: convert filename to windows text encoding */
	*h = LoadLibrary(filename);

	if (!*h) {
		dll_show_error(filename);
		return -1;
	}

	return 0;
}

void dll_close(dll_handle_t h)
{
	if (!FreeLibrary(h)) {
		dll_show_error("FreeLibrary()");
	}
}

/* return NULL on error. address of exported symbol on success */
void *dll_func(dll_handle_t h, const char *name)
{
	void *ret = GetProcAddress(h, name);

	if (!ret) {
		dll_show_error(name);
	}

	return ret;
}
#else
static void dll_show_error(const char *reason)
{
	const char *msg = dlerror();

	if (msg) {
		if (reason) {
			fprintf(stderr, "%s:%s\n", reason, msg);
		} else {
			fprintf(stderr, "%s\n", msg);
		}
	}
}

/* return zero on success, non-zero on error */
int dll_open(dll_handle_t *h, const char *filename)
{
	*h = dlopen(filename, RTLD_LOCAL | RTLD_NOW);

	if (!*h) {
		dll_show_error(filename);
		return -1;
	}

	return 0;
}

void dll_close(dll_handle_t h)
{
	if (dlclose(h)) {
		dll_show_error("dlclose()");
	}
}

/* return NULL on error. address of exported symbol on success */
void *dll_func(dll_handle_t h, const char *name)
{
	void *ret = dlsym(h, name);

	if (!ret) {
		dll_show_error(name);
		return NULL;
	}
	return ret;
}
#endif