Ventoy 1.1.18 sources and Paravis patches

paravis/patch_vtoyjump.py

@@ -0,0 +1,98 @@
+#!/usr/bin/env python3
+"""
+Patch Ventoy 1.1.18 vtoyjump32.exe / vtoyjump64.exe to skip the "Ventoy disk"
+MBR marker check (CheckVentoyDisk), so the ISO can be mounted when the USB
+stick uses a third-party MBR (Xorboot) instead of Ventoy's own MBR.
+
+CheckVentoyDisk() in vtoyjump.c does:
+    UINT8 check[8] = { 0x56,0x54,0x00,0x47,0x65,0x00,0x48,0x44 };
+    ...
+    if (memcmp(SectorBuf + 0x190, check, 8) == 0)
+        return TRUE;
+    return FALSE;
+
+Patches (always return TRUE, code size unchanged):
+
+  vtoyjump64.exe (PE32+, .text VMA 0x140001000, file off 0x400)
+    0x140008D0E  0F 94 C3   sete %bl
+              ->  B3 01 90   mov $1,%bl ; nop
+    (ebx is zeroed at function entry, then copied to eax at 0x140008D11)
+
+  vtoyjump32.exe (PE32, .text VMA 0x00401000, file off 0x400)
+    0x00407BEB  75 87              jne  -> false
+              ->  90 90              nop nop
+    0x00407BF3  0F 85 7B FF FF FF  jne  -> false
+              ->  90 90 90 90 90 90  nop x6
+
+Usage:
+    python3 patch_vtoyjump.py <dir-with-vtoyjump32.exe-and-vtoyjump64.exe>
+
+Re-running is safe: already patched files are detected and skipped.
+"""
+
+import os
+import sys
+
+PATCHES = {
+    "vtoyjump64.exe": [
+        (0x810E, bytes([0x0F, 0x94, 0xC3]), bytes([0xB3, 0x01, 0x90])),
+    ],
+    "vtoyjump32.exe": [
+        (0x6FEB, bytes([0x75, 0x87]), bytes([0x90, 0x90])),
+        (0x6FF3, bytes([0x0F, 0x85, 0x7B, 0xFF, 0xFF, 0xFF]),
+                 bytes([0x90, 0x90, 0x90, 0x90, 0x90, 0x90])),
+    ],
+}
+
+
+def patch_file(path, patches):
+    with open(path, "rb") as f:
+        data = bytearray(f.read())
+
+    changed = False
+    for off, orig, new in patches:
+        cur = bytes(data[off:off + len(orig)])
+        if cur == new:
+            print("  %s @0x%X already patched" % (os.path.basename(path), off))
+            continue
+        if cur != orig:
+            raise SystemExit(
+                "  %s @0x%X unexpected bytes: %s (expected %s)" % (
+                    os.path.basename(path), off, cur.hex(" "), orig.hex(" ")))
+        data[off:off + len(new)] = new
+        print("  %s @0x%X patched: %s -> %s" % (
+            os.path.basename(path), off, orig.hex(" "), new.hex(" ")))
+        changed = True
+
+    if changed:
+        with open(path, "wb") as f:
+            f.write(data)
+    return changed
+
+
+def main():
+    if len(sys.argv) != 2:
+        print(__doc__)
+        return 1
+
+    d = sys.argv[1]
+    rc = 0
+    for name, patches in PATCHES.items():
+        path = os.path.join(d, name)
+        if not os.path.isfile(path):
+            print("MISSING: %s" % path)
+            rc = 1
+            continue
+        print("%s (%d bytes)" % (path, os.path.getsize(path)))
+        try:
+            patch_file(path, patches)
+        except SystemExit as e:
+            print(e)
+            rc = 1
+
+    print("DONE" if rc == 0 else "FAILED")
+    return rc
+
+
+if __name__ == "__main__":
+    sys.exit(main())