Use Pascal strings in place of null-termination; update documentation

global.go

@@ -2,62 +2,68 @@ package main
 
 /*
 #include <stdlib.h>
+typedef struct {
+    char* data;
+    int len;
+} PascalString;
 */
 import "C"
 import (
 	"github.com/rwinkhart/libmutton/global"
 )
 
+// TODO Use a nil pointer for blank deviceIDs, not FSMisc (requires changes to libmutton)
+
 // DirInit returns:
-// r0: oldDeviceID (FSMisc if none)
+// r0: err
 //
-// r1: err
+// r1: oldDeviceID (FSMisc if none)
 //
 //export DirInit
-func DirInit(preserveOldCfgDir bool) (*C.char, *C.char) {
+func DirInit(preserveOldCfgDir bool) (*C.char, C.PascalString) {
 	oldDeviceID, err := global.DirInit(preserveOldCfgDir)
 	if err != nil {
-		return nil, C.CString(err.Error())
+		return C.CString(err.Error()), C.PascalString{data: nil, len: 0}
 	}
-	return C.CString(oldDeviceID), nil
+	return nil, getPascalString(oldDeviceID)
 }
 
 // GetCurrentDeviceID returns:
-// r0: currentDeviceID (FSMisc if none)
+// r0: err
 //
-// r1: err
+// r1: currentDeviceID (FSMisc if none)
 //
 //export GetCurrentDeviceID
-func GetCurrentDeviceID() (*C.char, *C.char) {
+func GetCurrentDeviceID() (*C.char, C.PascalString) {
 	currentDeviceID, err := global.GetCurrentDeviceID()
 	if err != nil {
-		return nil, C.CString(err.Error())
+		return C.CString(err.Error()), C.PascalString{data: nil, len: 0}
 	}
-	return C.CString(currentDeviceID), nil
+	return nil, getPascalString(currentDeviceID)
 }
 
 // GetRealAgePath returns:
 // realAgePath
 //
 //export GetRealAgePath
-func GetRealAgePath(vanityPath *C.char) *C.char {
-	return C.CString(global.GetRealAgePath(C.GoString(vanityPath)))
+func GetRealAgePath(vanityPath *C.char) C.PascalString {
+	return getPascalString(global.GetRealAgePath(C.GoString(vanityPath)))
 }
 
 // GetRealPath returns:
 // realPath
 //
 //export GetRealPath
-func GetRealPath(vanityPath *C.char) *C.char {
-	return C.CString(global.GetRealPath(C.GoString(vanityPath)))
+func GetRealPath(vanityPath *C.char) C.PascalString {
+	return getPascalString(global.GetRealPath(C.GoString(vanityPath)))
 }
 
 // GetVanityPath returns:
 // vanityPath
 //
 //export GetVanityPath
-func GetVanityPath(realPath *C.char) *C.char {
-	return C.CString(global.GetVanityPath(C.GoString(realPath)))
+func GetVanityPath(realPath *C.char) C.PascalString {
+	return getPascalString(global.GetVanityPath(C.GoString(realPath)))
 }
 
 func main() {}