Index: generic/vlerq.c
===================================================================
--- generic/vlerq.c	(revision 1848)
+++ generic/vlerq.c	(working copy)
@@ -1974,6 +1974,52 @@
 #endif
 }
 
+#if WIN32+0
+/*
+ * If we are opening a Windows PE executable with an attached metakit
+ * then we must check for the presence of an Authenticode certificate
+ * and reduce the length of our mapped region accordingly
+ */
+
+static DWORD
+AuthenticodeOffset(LPBYTE pData, DWORD cbData)
+{
+    if (pData[0] == 'M' && pData[1] == 'Z')              /* IMAGE_DOS_SIGNATURE */
+    {
+        LPBYTE pNT = pData + *(LONG *)(pData + 0x3c);    /* e_lfanew */
+        if (pNT[0] == 'P' && pNT[1] == 'E' && pNT[2] == 0 && pNT[3] == 0)
+        {                                                /* IMAGE_NT_SIGNATURE */
+            DWORD dwCheckSum = 0, dwDirectories = 0;
+            LPBYTE pOpt = pNT + 0x18;                    /* OptionalHeader */
+            LPDWORD pCertDir = NULL;
+            if (pOpt[0] == 0x0b && pOpt[1] == 0x01) {    /* IMAGE_NT_OPTIONAL_HDR_MAGIC */
+                dwCheckSum = *(DWORD *)(pOpt + 0x40);    /* Checksum */
+                dwDirectories = *(DWORD *)(pOpt + 0x5c); /* NumberOfRvaAndSizes */
+                if (dwDirectories > 4) {                 /* DataDirectory[] */
+                    pCertDir = (DWORD *)(pOpt + 0x60 + (4 * 8));
+                }
+            } else {
+                dwCheckSum = *(DWORD *)(pOpt + 0x40);    /* Checksum */
+                dwDirectories = *(DWORD *)(pOpt + 0x6c); /* NumberOfRvaAndSizes */
+                if (dwDirectories > 4) {                 /* DataDirectory[] */
+                    pCertDir = (DWORD *)(pOpt + 0x70 + (4 * 8));
+                }
+            }
+
+            if (pCertDir && pCertDir[1] > 0) {
+                int n = 0;
+                cbData = pCertDir[0];
+                /* need to eliminate any zero padding - up to 8 bytes */
+                while (pData[cbData - 16] != 0x80 && pData[cbData-1] == 0 && n < 16) {
+                    --cbData, ++n;
+                }
+            }
+        }
+    }
+    return cbData;
+}
+#endif /* WIN32 */
+
 static MappedFile_p OpenMappedFile (const char *filename) {
     const char *data = NULL;
     Int_t length = -1;
@@ -1988,8 +2034,9 @@
             if (h != INVALID_HANDLE_VALUE) {
                 n = GetFileSize(f, 0);
                 data = MapViewOfFile(h, FILE_MAP_READ, 0, 0, n);
-                if (data != NULL)
-                    length = n;
+                if (data != NULL) {
+                    length = AuthenticodeOffset((LPBYTE)data, n);
+                }
                 CloseHandle(h);
             }
             CloseHandle(f);