clientETag, err := etag.FromContentMD5(r.Header)
	if err != nil {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrInvalidDigest), r.URL)
		return
	}

	// if Content-Length is unknown/missing, deny the request
	size := r.ContentLength
	rAuthType := getRequestAuthType(r)
	switch rAuthType {
	// Check signature types that must have content length

	{
		h := sha256.New()
		h.Write([]byte("openid:" + subFromToken + ":" + issFromToken))
		bs := h.Sum(nil)
		cred.ParentUser = base64.RawURLEncoding.EncodeToString(bs)
	}

	// Deny this assume role request if the policy that the user intends to bind
	// has a sts:DurationSeconds condition, which is not satisfied as well
	{
		p := policyName
		if p == "" {
			var err error

	if s3Err != ErrNone {
		writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErr(s3Err), r.URL)
		return
	}

	checkDenyOnly := false
	if name == cred.AccessKey {
		// Check that there is no explicit deny - otherwise it's allowed
		// to view one's own info.
		checkDenyOnly = true
	}

	if !globalIAMSys.IsAllowed(policy.Args{
		AccountName:     cred.AccessKey,
		Groups:          cred.Groups,

github.com/jessevdk/go-flags
https://github.com/jessevdk/go-flags
----------------------------------------------------------------
Copyright (c) 2012 Jesse van den Kieboom. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met: