[PATCH v5 0/1] MR7049: vbscript: fix Mid() empty and null handling

[Francis De Brabandere (＠francisdb)]

Fixes https://bugs.winehq.org/show_bug.cgi?id=57563

--
  v5: vbscript: Mid() empty and null handling

https://gitlab.winehq.org/wine/wine/-/merge_requests/7049

[PATCH v5 1/1] vbscript: Mid() empty and null handling

[Francis De Brabandere]

From: Francis De Brabandere

---
 dlls/vbscript/global.c      | 11 +++--
 dlls/vbscript/tests/api.vbs | 86 +++++++++++++++++--------------------
 2 files changed, 47 insertions(+), 50 deletions(-)

diff --git a/dlls/vbscript/global.c b/dlls/vbscript/global.c
index 058ddabcde1..972d0d2ea0b 100644
--- a/dlls/vbscript/global.c
+++ b/dlls/vbscript/global.c
@@ -1404,9 +1404,6 @@ static HRESULT Global_Mid(BuiltinDisp *This, VARIANT *args, unsigned args_cnt, V

assert(args_cnt == 2 || args_cnt == 3);

-    if(V_VT(args) == VT_EMPTY)
-        return MAKE_VBSERROR(VBSE_ILLEGAL_FUNC_CALL);
-
     if(V_VT(args+1) == VT_NULL || (args_cnt == 3 && V_VT(args+2) == VT_NULL))
         return MAKE_VBSERROR(VBSE_ILLEGAL_NULL_USE);

@@ -1417,7 +1414,7 @@ static HRESULT Global_Mid(BuiltinDisp *This, VARIANT *args, unsigned args_cnt, V
     if(FAILED(hres))
         return hres;

-    if(start < 0)
+    if(start <= 0)
         return MAKE_VBSERROR(VBSE_ILLEGAL_FUNC_CALL);

if(args_cnt == 3) {
@@ -1432,6 +1429,12 @@ static HRESULT Global_Mid(BuiltinDisp *This, VARIANT *args, unsigned args_cnt, V
             return MAKE_VBSERROR(VBSE_ILLEGAL_FUNC_CALL);
     }

+    if(V_VT(args) == VT_EMPTY)
+        return return_string(res, L"");
+
+    if(V_VT(args) == VT_NULL)
+        return return_null(res);
+
     if(V_VT(args) == VT_BSTR) {
         str = V_BSTR(args);
     }else {
diff --git a/dlls/vbscript/tests/api.vbs b/dlls/vbscript/tests/api.vbs
index 7b8744f4c74..025d9ec9232 100644
--- a/dlls/vbscript/tests/api.vbs
+++ b/dlls/vbscript/tests/api.vbs
@@ -632,6 +632,25 @@ Sub TestMid2(str, start, ex)
     Call ok(x = ex, "Mid(" & str & ", " & start & ") = " & x & " expected " & ex)
 End Sub

+Sub TestMidNull(str, start, len)
+    x = Mid(str, start, len)
+    Call ok(IsNull(x), "Mid(" & str & ", " & start & ", " & len & ") = " & x & " expected Null")
+End Sub
+
+Sub TestMidNull2(str, start)
+    x = Mid(str, start)
+    Call ok(IsNull(x), "Mid(" & str & ", " & start & ") = " & x & " expected Null")
+End Sub
+
+Sub TestMidError(str, start, len, number)
+    On Error Resume Next
+    Call Mid(str, start, len)
+    Dim err_num: err_num = Err.number
+    Call Err.clear()
+    On Error GoTo 0
+    Call ok(err_num = number, "Mid(" & str & ", " & start & ", " & len & ") " & " expected Err.number = " & number)
+End Sub
+
 TestMid "test", 2, 2, "es"
 TestMid "test", 2, 4, "est"
 TestMid "test", 1, 2, "te"
@@ -640,57 +659,32 @@ TestMid "test", 1, 0, ""
 TestMid "test", 5, 2, ""
 TestMid 1234, 1, 2, "12"
 TestMid 1234, 5, 2, ""
+TestMid empty, 5, 2, ""
+
 TestMid2 "test", 1, "test"
 TestMid2 "test", 2, "est"
 TestMid2 "test", 4, "t"
 TestMid2 "test", 5, ""
 TestMid2 1234, 5, ""
-
-sub TestMidError()
-    on error resume next
-    call Err.clear()
-    call Mid("test", "a", 1)
-    call ok(Err.number = 13, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid("test", "a", null)
-    call ok(Err.number = 94, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid("test", "a", empty)
-    call ok(Err.number = 13, "Err.number = " & Err.number)
-    call Mid("test", 0, -1)
-    call ok(Err.number = 5, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid("test", -1, -1)
-    call ok(Err.number = 5, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid(null, -1, -1)
-    call ok(Err.number = 5, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid("test", 0, null)
-    call ok(Err.number = 94, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid("test", -1, null)
-    call ok(Err.number = 94, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid("test", null, 2)
-    call ok(Err.number = 94, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid("test", null, -1)
-    call ok(Err.number = 94, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid(null, -1, -1)
-    call ok(Err.number = 5, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid("test", empty, 1)
-    call ok(Err.number = 5, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid("test", 0, empty)
-    call ok(Err.number = 5, "Err.number = " & Err.number)
-    call Err.clear()
-    call Mid(empty, 0, 0)
-    call ok(Err.number = 5, "Err.number = " & Err.number)
-end sub
-call TestMidError()
+TestMid2 empty, 5, ""
+
+TestMidNull null, 5, 2
+TestMidNull2 null, 5
+
+TestMidError "test", "a", 1, 13
+TestMidError "test", "a", null, 94
+TestMidError "test", "a", empty, 13
+TestMidError "test", 0, 3, 5
+TestMidError "test", 0, -1, 5
+TestMidError "test", -1, -1, 5
+TestMidError "test", 0, null, 94
+TestMidError "test", -1, null, 94
+TestMidError "test", null, 2, 94
+TestMidError "test", null, -1, 94
+TestMidError null, -1, -1, 5
+TestMidError "test", empty, 1, 5
+TestMidError "test", 0, empty, 5
+TestMidError empty, 0, 0, 5

Sub TestUCase(str, ex)
     x = UCase(str)

[Francis De Brabandere (＠francisdb)]

On Fri Dec 20 11:35:09 2024 +0000, Jacek Caban wrote:
> Yes, it's ran on Windows in addition to Wine.
> `dlls/vbscript/tests/run.c` implements its own script host that provides
> additional functionality like `ok()` function, so it uses the script
> engine directly, without cscript involvement. If you'd have mingw
> installed, you'd have `vbscript_test.exe` in your build that you can
> just copy to Windows and run. CI also runs it on Windows, see https://gitlab.winehq.org/francisdb/wine/-/jobs/124440.

Put that test back, made sure mid fails for 0 start, improved error testing, removed duplicate error test case