Reimplement the argument passing mechanism using varargs.

libpkg/pkg.h

@@ -1,6 +1,7 @@
 #ifndef _PKG_H
 #define _PKG_H
 
+#include <stdarg.h>
 #include <sys/types.h>
 #include <openssl/pem.h>
 
@@ -591,7 +592,7 @@ typedef enum {
  * Event callback mechanism.  Events will be reported using this callback,
  * providing an event identifier and up to two event-specific pointers.
  */
-typedef int(*pkg_event_cb)(pkg_event_t, void *, void *);
+typedef int(*pkg_event_cb)(pkg_event_t, void **);
 
 struct pkg_handle {
 	pkg_event_cb event_cb;
@@ -604,9 +605,9 @@ void pkg_handle_set_event_callback(struct pkg_handle *, pkg_event_cb);
 /* XXX maybe the event callback should also get a pointer to the handle, and
  * just drop arg1 altogether..? */
 
-#define	pkg_emit_event(ev, arg0, arg1) \
-	__pkg_emit_event(pkg_get_handle(), ev, arg0, arg1)
+#define	pkg_emit_event(ev, argc, ...) \
+	__pkg_emit_event(pkg_get_handle(), ev, argc, ...)
 
-void __pkg_emit_event(struct pkg_handle *, pkg_event_t, void *, void *);
+void __pkg_emit_event(struct pkg_handle *, pkg_event_t, int, ...);
 
 #endif

libpkg/pkg_handle.c

@@ -1,3 +1,4 @@
+#include <assert.h>
 #include "pkg.h"
 
 struct pkg_handle __pkg_handle_singleton;
@@ -21,9 +22,33 @@ pkg_handle_get_event_callback(struct pkg_handle *hdl)
 }
 
 void
-__pkg_emit_event(struct pkg_handle *hdl, pkg_event_t ev, void *arg0, void *arg1)
+__pkg_emit_event(struct pkg_handle *hdl, pkg_event_t ev, int argc, ...)
 {
+	va_list ap;
+	void **argv;
+	int i;
+
 	if (hdl == NULL || hdl->event_cb == NULL)
 		return;
-	hdl->event_cb(ev, arg0, arg1);
+
+	/* Guard-rail against incorrect number of arguments */
+	switch(ev) {
+	case PKG_EVENT_INSTALL_BEGIN:
+		assert(argc == 1);
+		break;
+	case PKG_EVENT_ARCHIVE_ERROR:
+		assert(argc == 2);
+		break;
+	default:
+		break;
+	}
+
+	/* Generate the argument vector to pass in. */
+	argv = calloc(argc, sizeof(void *));
+	va_start(ap, argc);
+	for (i = 0;i < argc; i++)
+		argv[i] = va_arg(ap, void *);
+	va_end(ap);
+
+	hdl->event_cb(ev, argv);
 }

pkg/event.c

@@ -3,22 +3,17 @@
 #include "pkg.h"
 #include "event.h"
 
-/* XXX: use varargs? */
 int
-event_callback(pkg_event_t ev, void *arg0, void *arg1)
+event_callback(pkg_event_t ev, void **argv)
 {
-	struct pkg *pkg;
-	const char *str0, *str1;
 
 	switch(ev) {
 	case PKG_EVENT_INSTALL_BEGIN:
-		pkg = (struct pkg *)arg0;
-		printf("Installing %s\n", pkg_get(pkg, PKG_NAME));
+		printf("Installing %s\n", pkg_get((struct pkg *)argv[0], PKG_NAME));
 		break;
 	case PKG_EVENT_ARCHIVE_ERROR:
-		str0 = (const char *)arg0; /* file path */
-		str1 = archive_error_string(arg1);
-		fprintf(stderr, "archive error on %s: %s\n", str0, str1);
+		fprintf(stderr, "archive error on %s: %s\n",
+		    (const char *)argv[0], archive_error_string(argv[1]));
 		break;
 	default:
 		break;

pkg/event.h

@@ -1,6 +1,6 @@
 #ifndef __PKG_EVENT_H__
 #define	__PKG_EVENT_H__
 
-int event_callback(pkg_event_t ev, void *arg0, void *arg1);
+int event_callback(pkg_event_t ev, void **argv);
 
 #endif