protect Tcl_WinUtfToTChar/Tcl_WinTCharToUtf against NULL input values: return empty string in that case.

Add TIP #494-compatible definitions of TCL_IO_FAILURE/TCL_AUTO_LENGTH, and use it in some appropriate places.

1 files changed, 7 insertions, 1 deletions

diff --git a/win/tclWin32Dll.c b/win/tclWin32Dll.c
index 1a33514..04d27dd 100644
--- a/win/tclWin32Dll.c
+++ b/win/tclWin32Dll.c
@@ -472,6 +472,9 @@ Tcl_WinUtfToTChar(
 				 * converted string is stored. */
 {
     Tcl_DStringInit(dsPtr);
+    if (!string) {
+	return (TCHAR *)Tcl_DStringValue(dsPtr);
+    }
     return Tcl_UtfToUniCharDString(string, len, dsPtr);
 }
 
@@ -483,12 +486,15 @@ Tcl_WinTCharToUtf(
     Tcl_DString *dsPtr)		/* Uninitialized or free DString in which the
 				 * converted string is stored. */
 {
+    Tcl_DStringInit(dsPtr);
+    if (!string) {
+	return Tcl_DStringValue(dsPtr);
+    }
     if (len > 0) {
 	len /= 2;
     } else if (len < 0) {
 	len = wcslen(string);
     }
-    Tcl_DStringInit(dsPtr);
     return Tcl_UniCharToUtfDString(string, len, dsPtr);
 }