}

var etagRegex = regexp.MustCompile("\"*?([^\"]*?)\"*?$")

// canonicalizeETag returns ETag with leading and trailing double-quotes removed,
// if any present
func canonicalizeETag(etag string) string {
	return etagRegex.ReplaceAllString(etag, "$1")
}

// Init - populates the input values, initializes CondCheck

	// The extended form disables evaluation of . and .. path
	// elements and disables the interpretation of / as equivalent
	// to \. The conversion here rewrites / to \ and elides
	// . elements as well as trailing or duplicate separators. For
	// simplicity it avoids the conversion entirely for relative
	// paths or paths containing .. elements. For now,
	// \\server\share paths are not converted to

		"substring('abcd' , 2 , 2)",

		"substring('abcd' , 22 )",
		"trim('  aab  ')",
		"trim(leading from '  aab  ')",
		"trim(trailing from '  aab  ')",
		"trim(both from '  aab  ')",

		"trim(both '12' from '  aab  ')",
		"trim(leading '12' from '  aab  ')",
		"trim(trailing '12' from '  aab  ')",
		"count(23)",
	}
	for i, tc := range validCases {
		err := p.ParseString(tc, &fex)
		if err != nil {

		if strings.HasPrefix(baseDir, dirPath) {
			return nil
		}
	}

	// Slow path: make sure parent exists and then call Mkdir for path.
	i := len(dirPath)
	for i > 0 && os.IsPathSeparator(dirPath[i-1]) { // Skip trailing path separator.
		i--
	}

	j := i
	for j > 0 && !os.IsPathSeparator(dirPath[j-1]) { // Scan backward over element.
		j--
	}

	if j > 1 {
		// Create parent.

		b[len(s)] = 0
	}

	// Some buggy readers treat regular files with a trailing slash
	// in the V7 path field as a directory even though the full path
	// recorded elsewhere (e.g., via PAX record) contains no trailing slash.
	if len(s) > len(b) && b[len(b)-1] == '/' {
		n := len(strings.TrimRight(s[:len(b)-1], "/"))
		b[n] = 0 // Replace trailing slash with NUL terminator
	}
}

			extractedSignedHeaders.Set(header, strconv.FormatInt(r.ContentLength, 10))
		default:
			return nil, ErrUnsignedHeaders
		}
	}
	return extractedSignedHeaders, ErrNone
}

// Trim leading and trailing spaces and replace sequential spaces with one space, following Trimall()
// in http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
func signV4TrimAll(input string) string {