util: Add helper to print a string as hex bytes

src/util/output.hpp

@@ -143,6 +143,30 @@ std::ostream & operator<<(std::ostream & os, const print_hex<T> & s) {
 	return os;
 }
 
+struct print_hex_string {
+	
+	const char * data;
+	size_t size;
+	
+	explicit print_hex_string(const char * data, size_t size) : data(data), size(size) { }
+	
+};
+
+inline std::ostream & operator<<(std::ostream & os, const print_hex_string & s) {
+	
+	std::ios_base::fmtflags old = os.flags();
+	char oldfill = os.fill('0');
+	
+	os << std::hex;
+	for(size_t i = 0; i < s.size; i++) {
+		os << std::setw(2) << int(boost::uint8_t(s.data[i]));
+	}
+	
+	os.fill(oldfill);
+	os.setf(old, std::ios_base::basefield);
+	return os;
+}
+
 } // namespace detail
 
 template <class T>
@@ -150,6 +174,14 @@ detail::print_hex<T> print_hex(T value) {
 	return detail::print_hex<T>(value);
 }
 
+inline detail::print_hex_string print_hex(const char * data, size_t size) {
+	return detail::print_hex_string(data, size);
+}
+
+inline detail::print_hex_string print_hex(const std::string & data) {
+	return print_hex(data.c_str(), data.size());
+}
+
 const char * const byte_size_units[] = {
 	"B",
 	"KiB",