def does_file_need_update()

in build/fbcode_builder/getdeps/fetcher.py [0:0]

• 25 lines of code
• 10 McCabe index (conditional complexity)

def does_file_need_update(src_name, src_st, dest_name):
    try:
        target_st = os.lstat(dest_name)
    except OSError as exc:
        if exc.errno != errno.ENOENT:
            raise
        return True

    if src_st.st_size != target_st.st_size:
        return True

    if stat.S_IFMT(src_st.st_mode) != stat.S_IFMT(target_st.st_mode):
        return True
    if stat.S_ISLNK(src_st.st_mode):
        return os.readlink(src_name) != os.readlink(dest_name)
    if not stat.S_ISREG(src_st.st_mode):
        return True

    # They might have the same content; compare.
    with open(src_name, "rb") as sf, open(dest_name, "rb") as df:
        chunk_size = 8192
        while True:
            src_data = sf.read(chunk_size)
            dest_data = df.read(chunk_size)
            if src_data != dest_data:
                return True
            if len(src_data) < chunk_size:
                # EOF
                break
    return False