Move XML util from os to base repository

Since the dynamic linker depends on the XML utils and we plan to replace
the ancient 'Arg_string' with XML, it is time to move the 'Xml_node' and
'Xml_generator' to base/include.

repos/base/include/util/print_lines.h

@@ -0,0 +1,96 @@
+/*
+ * \brief  Utility for safely writing multi-line text
+ * \author Norman Feske
+ * \date   2014-01-11
+ */
+
+/*
+ * Copyright (C) 2014 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef _INCLUDE__UTIL__PRINT_LINES_H_
+#define _INCLUDE__UTIL__PRINT_LINES_H_
+
+#include <util/string.h>
+
+namespace Genode {
+
+	template <size_t, typename FUNC>
+	static inline void print_lines(char const *, size_t, FUNC const &);
+}
+
+
+/**
+ * Print multi-line string
+ *
+ * \param MAX_LINE_LEN  maximum line length, used to dimension a line buffer
+ *                      on the stack
+ * \param string        character buffer, not necessarily null-terminated
+ * \param len           number of characters to print
+ * \param func          functor called for each line with 'char const *' as
+ *                      argument
+ *
+ * In situations where a string is supplied by an untrusted client, we cannot
+ * simply print the client-provided content as a single string becausewe cannot
+ * expect the client to null-terminate the string properly. The 'Log_multiline'
+ * class outputs the content line by line while keeping track of the content
+ * size.
+ *
+ * The output stops when reaching the end of the buffer or when a null
+ * character is encountered.
+ */
+template <Genode::size_t MAX_LINE_LEN, typename FUNC>
+void Genode::print_lines(char const *string, size_t len, FUNC const &func)
+{
+	/* skip leading line breaks */
+	for (; *string == '\n'; string++);
+
+	/* number of space and tab characters used for indentation */
+	size_t const num_indent_chars =
+		({
+			size_t n = 0;
+			for (; string[n] == ' ' || string[n] == '\t'; n++);
+			n;
+		});
+
+	char const * const first_line = string;
+
+	while (*string && len) {
+
+		/*
+		 * Skip indentation if the pattern is the same as for the first line.
+		 */
+		if (Genode::strcmp(first_line, string, num_indent_chars) == 0)
+			string += num_indent_chars;
+
+		size_t const line_len =
+			({
+				size_t i = 0;
+				for (; string[i] && i < len && string[i] != '\n'; i++);
+
+				/* the newline character belongs to the line */
+				if (string[i] == '\n')
+					i++;
+
+				i;
+			});
+
+		if (!line_len)
+			break;
+
+		/*
+		 * Copy line from (untrusted) caller to local line buffer
+		 */
+		char line_buf[MAX_LINE_LEN];
+		Genode::strncpy(line_buf, string, Genode::min(line_len + 1, sizeof(line_buf)));
+		func(line_buf);
+
+		string += line_len;
+		len    -= line_len;
+	}
+}
+
+#endif /* _INCLUDE__UTIL__PRINT_LINES_H_ */