dtc: Improve support for string escapes

dtc supports the use of C-style escapes (\n, \t and so forth) in
string property definitions via the data_copy_escape_string()
function.  However, while it supports the most common escape
characters, it doesn't support the full set that C does, which is a
potential gotcha.

Worse, a bug in the lexer means that while data_copy_escape_string()
can handle the \" escape, a string with such an escape won't lex
correctly.

This patch fixes both problems, extending data_copy_escape_string() to
support the missing escapes, and fixing the regex for strings in the
lexer to handle internal escaped quotes.

This also adds a testcase for string escape functionality.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/tests/string_escapes.c b/tests/string_escapes.c
new file mode 100644
index 0000000..0238502
--- /dev/null
+++ b/tests/string_escapes.c
@@ -0,0 +1,42 @@
+/*
+ * libfdt - Flat Device Tree manipulation
+ *	Testcase for string escapes in dtc
+ * Copyright (C) 2006 David Gibson, IBM Corporation.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+
+#include <fdt.h>
+#include <libfdt.h>
+
+#include "tests.h"
+#include "testdata.h"
+
+int main(int argc, char *argv[])
+{
+	void *fdt;
+
+	test_init(argc, argv);
+	fdt = load_blob_arg(argc, argv);
+
+	check_getprop(fdt, 0, "escape-str",
+		      strlen(TEST_STRING_2)+1, TEST_STRING_2);
+
+	PASS();
+}