dtc: cpp co-existence: allow names starting with # to be escaped

The device tree language as currently defined conflicts with the C pre-
processor in one aspect - when a property or node name begins with a #
character, a pre-processor would attempt to interpret it as a directive,
fail, and most likely error out.

This change allows a property/node name to be prefixed with \. This
prevents a pre-processor from seeing # as the first non-whitespace
character on the line, and hence prevents the conflict. \ was previously
an illegal character in property/node names, so this change is
backwards compatible. The \ is stripped from the name during parsing
by dtc.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>

dtc-lexer.l

@@ -162,9 +162,10 @@ static int pop_input_file(void);
 			return ']';
 		}
 
-<PROPNODENAME>{PROPNODECHAR}+ {
+<PROPNODENAME>\\?{PROPNODECHAR}+ {
 			DPRINT("PropNodeName: %s\n", yytext);
-			yylval.propnodename = xstrdup(yytext);
+			yylval.propnodename = xstrdup((yytext[0] == '\\') ?
+							yytext + 1 : yytext);
 			BEGIN_DEFAULT();
 			return DT_PROPNODENAME;
 		}

tests/.gitignore

@@ -39,6 +39,7 @@ tmp.*
 /path_offset
 /path_offset_aliases
 /phandle_format
+/propname_escapes
 /references
 /root_node
 /rw_tree1

tests/Makefile.tests

@@ -12,7 +12,7 @@ LIB_TESTS_L = get_mem_rsv \
 	sw_tree1 \
 	move_and_save mangle-layout nopulate \
 	open_pack rw_tree1 set_name setprop del_property del_node \
-	appendprop1 appendprop2 \
+	appendprop1 appendprop2 propname_escapes \
 	string_escapes references path-references phandle_format \
 	boot-cpuid incbin \
 	extra-terminating-null \

tests/propname_escapes.c

@@ -0,0 +1,43 @@
+/*
+ * libfdt - Flat Device Tree manipulation
+ *	Testcase for fdt_getprop()
+ * Copyright (C) 2006 David Gibson, IBM Corporation.
+ * Copyright (C) 2012 NVIDIA CORPORATION. All rights reserved.
+ *
+ * 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"
+
+int main(int argc, char *argv[])
+{
+	void *fdt;
+
+	test_init(argc, argv);
+	fdt = load_blob_arg(argc, argv);
+
+	check_getprop_cell(fdt, 0, "#address-cells", 1);
+	check_getprop_cell(fdt, 0, "#gpio-cells", 2);
+
+	PASS();
+}

tests/propname_escapes.dts

@@ -0,0 +1,6 @@
+/dts-v1/;
+
+/ {
+	#address-cells = <1>;
+	\#gpio-cells = <2>;
+};

tests/run_tests.sh

@@ -254,6 +254,9 @@ dtc_tests () {
     tree1_tests_rw dtc_tree1.test.dtb
     run_test dtbs_equal_ordered dtc_tree1.test.dtb test_tree1.dtb
 
+    run_dtc_test -I dts -O dtb -o dtc_escapes.test.dtb propname_escapes.dts
+    run_test propname_escapes dtc_escapes.test.dtb
+
     run_dtc_test -I dts -O dtb -o dtc_escapes.test.dtb escapes.dts
     run_test string_escapes dtc_escapes.test.dtb