FIX: better results from change-dir function (on error and also on …

…success).

resolves: Oldes/Rebol-issues#2446

src/core/n-io.c

@@ -551,17 +551,26 @@ static REBSER *Read_All_File(char *fname)
 	REBVAL *arg = D_ARG(1);
 	REBSER *ser;
 	REBINT n;
-	REBVAL val;
+	REBVAL val, reason;
 
 	ser = Value_To_OS_Path(arg, TRUE);
-	if (!ser) Trap_Arg(arg); // !!! ERROR MSG
+	// it should be safe not to check result from Value_To_OS_Path (it always succeeds)
+	//if (!ser) Trap_Arg(arg); // !!! ERROR MSG
 
 	Set_String(&val, ser); // may be unicode or utf-8
 	Check_Security(SYM_FILE, POL_EXEC, &val);
 
 	n = OS_SET_CURRENT_DIR((void*)ser->data);  // use len for bool
-	if (!n) Trap_Arg(arg); // !!! ERROR MSG
 
+	// convert the full OS path back to Rebol format
+	// used in error or as a result
+	ser = Value_To_REBOL_Path(&val, TRUE);
+	SET_FILE(arg, ser);
+
+	if (NZ(n)) {
+		SET_INTEGER(&reason, n);
+		Trap2(RE_CANNOT_OPEN, arg, &reason);
+	}
 	return R_ARG1;
 }
 

src/os/posix/host-lib.c

@@ -646,14 +646,14 @@ int pipe2(int pipefd[2], int flags); //to avoid "implicit-function-declaration"
 
 /***********************************************************************
 **
-*/	REBOOL OS_Set_Current_Dir(REBCHR *path)
+*/	int OS_Set_Current_Dir(REBCHR *path)
 /*
-**		Set the current directory to local path. Return FALSE
-**		on failure.
+**		Set the current directory to local path.
+**		Return 0 on success else error number.
 **
 ***********************************************************************/
 {
-	return chdir(path) == 0;
+	return (chdir(path) == 0) ? 0 : errno;
 }
 
 

src/os/win32/host-lib.c

@@ -642,14 +642,14 @@ static void *Task_Ready;
 
 /***********************************************************************
 **
-*/	REBOOL OS_Set_Current_Dir(REBCHR *path)
+*/	int OS_Set_Current_Dir(REBCHR *path)
 /*
-**		Set the current directory to local path. Return FALSE
-**		on failure.
+**		Set the current directory to local path.
+**		Return 0 on success else error number.
 **
 ***********************************************************************/
 {
-	return SetCurrentDirectory( path[0]==0 ? L"\\" : path );
+	return (SetCurrentDirectory(path[0] == 0 ? L"\\" : path)) ? 0 : GetLastError();
 }
 
 

src/tests/units/port-test.r3

@@ -135,6 +135,15 @@ Rebol [
 			not error?      delete-dir %units/temp-dir/
 			not exists? %units/temp-dir/
 		]
+	--test-- "CHANGE-DIR"
+		;@@ https://github.com/Oldes/Rebol-issues/issues/2446
+		--assert what-dir = change-dir %.
+		--assert all [
+			error? e: try [change-dir %issues/2446]
+			e/id = 'cannot-open
+			e/arg1 = join what-dir %issues/2446/
+		]
+
 if system/platform = 'Windows [
 ;@@ it looks that on Linux there is no lock on opened file
 		--assert all [