#!/usr/bin/env python3
"""fix_pe_simple.py — PE header fixup for PIE-built UEFI bootloader

The -fPIE-built bootloader uses only PC-relative addressing, so it needs
zero absolute fixups.  This script just sets proper PE flags:

  - ImageBase         (env IMAGE_BASE, default 0x10000000)
  - Characteristics   = 0x022e (RELOCS_STRIPPED)
  - DllChar           = 0x0160 (NX | DYNAMIC_BASE | HIGH_ENTROPY_VA)
  - Clears .reloc DD  (no relocations needed)
  - Clears checksum   (not signed)
"""

import struct, os, sys

def fix_pe(path):
    try:
        with open(path, 'rb') as f:
            d = bytearray(f.read())
    except IOError as e:
        print(f"  ERROR: cannot read {path}: {e}")
        return False

    po = struct.unpack('<I', d[0x3C:0x40])[0]
    if d[po:po+4] != b'PE\x00\x00':
        print(f"  Not a PE file")
        return False

    coff = po + 4
    opt = po + 24

    magic = struct.unpack('<H', d[opt:opt+2])[0]
    if magic != 0x20b:
        print(f"  Not PE32+")
        return False

    ib_env = os.environ.get('IMAGE_BASE', '0x10000000')
    img_base = int(ib_env, 16) if ib_env.startswith('0x') else 0x10000000
    struct.pack_into('<Q', d, opt+24, img_base)
    struct.pack_into('<H', d, coff+18, 0x022e)
    struct.pack_into('<H', d, opt+70, 0x0160)
    struct.pack_into('<I', d, coff+8, 0)
    struct.pack_into('<I', d, coff+12, 0)
    struct.pack_into('<I', d, opt+64, 0)

    dd = opt + 112
    struct.pack_into('<II', d, dd + 5*8, 0, 0)

    try:
        with open(path, 'wb') as f:
            f.write(d)
    except IOError as e:
        print(f"  ERROR: cannot write {path}: {e}")
        return False

    print(f"  Fixed: ImageBase={img_base:#010x} char=0x022e dll=0x0160 reloc=cleared")
    return True

if __name__ == '__main__':
    if len(sys.argv) < 2:
        print(f"Usage: IMAGE_BASE=0x... {sys.argv[0]} <pe-path>")
        sys.exit(1)
    if not fix_pe(sys.argv[1]):
        sys.exit(1)