fileform.py 文件源码

def _find_firstheader(nsis_file):
    firstheader_offset = 0
    pos = 0
    while True:
        chunk = nsis_file.read(32768 if firstheader_offset else 512)
        if len(chunk) < _firstheader_pack.size:
            return None

        if firstheader_offset == 0:
            firstheader = FirstHeader._make(
                    _firstheader_pack.unpack_from(chunk))
            firstheader.header_offset = pos
            firstheader.data_offset = pos + _firstheader_pack.size

            if firstheader.siginfo == FH_SIG and \
                    firstheader.magics == FH_MAGICS:
                # NSIS header found.
                return firstheader

        pos += len(chunk)