[PATCH] cmd: Set errorlevel to 0 when 'call' is invoked with an empty string.

[Aaron Hill]

Previously, invoking 'call' with an empty string would leave errorlevel
unchanged. Reset errorlevel to 0 to match the behavior of
the Windows 'cmd.exe'.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=49982
Signed-off-by: Aaron Hill 
---
 programs/cmd/tests/test_builtins.cmd |  3 +++
 programs/cmd/wcmdmain.c              | 10 +++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/programs/cmd/tests/test_builtins.cmd b/programs/cmd/tests/test_builtins.cmd
index 73b0917c275..c7418b759e4 100644
--- a/programs/cmd/tests/test_builtins.cmd
+++ b/programs/cmd/tests/test_builtins.cmd
@@ -3149,6 +3149,9 @@ echo %ErrorLevel% should be 7
 if errorlevel 7 echo setting var worked too well, bad
 call :setError 3
 echo %ErrorLevel% should still be 7
+rem Verify that (call ) sets errorlevel to 0
+(call )
+if errorlevel 1 echo errorlevel should have been 0

echo ------------ Testing GOTO ------------
 if a==a goto dest1
diff --git a/programs/cmd/wcmdmain.c b/programs/cmd/wcmdmain.c
index 47e43fcd675..78f07b1b7b4 100644
--- a/programs/cmd/wcmdmain.c
+++ b/programs/cmd/wcmdmain.c
@@ -1041,6 +1041,7 @@ void WCMD_run_program (WCHAR *command, BOOL called)
   WCHAR *lastSlash;
   WCHAR  pathext[MAXSTRING];
   WCHAR *firstParam;
+  DWORD firstParamLen;
   BOOL  extensionsupplied = FALSE;
   BOOL  explicit_path = FALSE;
   BOOL  status;
@@ -1053,6 +1054,13 @@ void WCMD_run_program (WCHAR *command, BOOL called)
   firstParam = WCMD_parameter(command, 0, NULL, FALSE, TRUE);
   if (!firstParam) return;

+  firstParamLen = lstrlenW(firstParam);
+  if (firstParamLen == 0) {
+      // Windows sets errorlevel to 0 when invoking 'call' on an empty string
+      errorlevel = 0;
+      return;
+  }
+
   /* Calculate the search path and stem to search for */
   if (wcspbrk (firstParam, delims) == NULL) {  /* No explicit path given, search path */
     static const WCHAR curDir[] = {'.',';','\0'};
@@ -1063,7 +1071,7 @@ void WCMD_run_program (WCHAR *command, BOOL called)
       lstrcpyW (pathtosearch, curDir);
     }
     if (wcschr(firstParam, '.') != NULL) extensionsupplied = TRUE;
-    if (lstrlenW(firstParam) >= MAX_PATH)
+    if (firstParamLen >= MAX_PATH)
     {
         WCMD_output_asis_stderr(WCMD_LoadMessage(WCMD_LINETOOLONG));
         return;