libfdt: Add function to explicitly expand aliases

Kumar has already added alias expansion to fdt_path_offset().
However, in some circumstances it may be convenient for the user of
libfdt to explicitly get the string expansion of an alias.  This patch
adds a function to do this, fdt_get_alias(), and uses it to implement
fdt_path_offset().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

3 files changed, 60 insertions, 0 deletions

diff --git a/tests/Makefile.tests b/tests/Makefile.tests
index 44021b0..5fd4d28 100644
--- a/tests/Makefile.tests
+++ b/tests/Makefile.tests
@@ -4,6 +4,7 @@ LIB_TESTS_L = get_mem_rsv \
 	get_path supernode_atdepth_offset parent_offset \
 	node_offset_by_prop_value node_offset_by_phandle \
 	node_check_compatible node_offset_by_compatible \
+	get_alias \
 	notfound \
 	setprop_inplace nop_property nop_node \
 	sw_tree1 \
diff --git a/tests/get_alias.c b/tests/get_alias.c
new file mode 100644
index 0000000..8eeaee4
--- /dev/null
+++ b/tests/get_alias.c
@@ -0,0 +1,58 @@
+/*
+ * libfdt - Flat Device Tree manipulation
+ *	Testcase for fdt_get_alias()
+ * 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"
+
+void check_alias(void *fdt, const char *path, const char *alias)
+{
+	const char *aliaspath;
+
+	aliaspath = fdt_get_alias(fdt, alias);
+
+	if (path && !aliaspath)
+		FAIL("fdt_get_alias(%s) failed\n", alias);
+
+	if (strcmp(aliaspath, path) != 0)
+		FAIL("fdt_get_alias(%s) returned %s instead of %s\n",
+		     alias, aliaspath, path);
+}
+
+int main(int argc, char *argv[])
+{
+	void *fdt;
+
+	test_init(argc, argv);
+	fdt = load_blob_arg(argc, argv);
+
+	check_alias(fdt, "/subnode@1", "s1");
+	check_alias(fdt, "/subnode@1/subsubnode", "ss1");
+	check_alias(fdt, "/subnode@1/subsubnode/subsubsubnode", "sss1");
+
+	PASS();
+}
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index eb29462..b424664 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -216,6 +216,7 @@ dtc_tests () {
 
     # Check aliases support in fdt_path_offset
     run_dtc_test -I dts -O dtb -o aliases.dtb aliases.dts
+    run_test get_alias aliases.dtb
     run_test path_offset_aliases aliases.dtb
 
     # Check /include/ directive