fdt: Add a function to get the index of a string

The new fdt_stringlist_search() function will look up a given string in
the list contained in the value of a named property of a given device
tree node and return its index.

Signed-off-by: Thierry Reding <treding@nvidia.com>
[Fix some -Wshadow warnings --dwg]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 30 insertions, 0 deletions

diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
index 4cde931..2d74c37 100644
--- a/libfdt/fdt_ro.c
+++ b/libfdt/fdt_ro.c
@@ -563,6 +563,36 @@ int fdt_stringlist_count(const void *fdt, int nodeoffset, const char *property)
 	return count;
 }
 
+int fdt_stringlist_search(const void *fdt, int nodeoffset, const char *property,
+			  const char *string)
+{
+	int length, len, idx = 0;
+	const char *list, *end;
+
+	list = fdt_getprop(fdt, nodeoffset, property, &length);
+	if (!list)
+		return -length;
+
+	len = strlen(string) + 1;
+	end = list + length;
+
+	while (list < end) {
+		length = strnlen(list, end - list) + 1;
+
+		/* Abort if the last string isn't properly NUL-terminated. */
+		if (list + length > end)
+			return -FDT_ERR_BADVALUE;
+
+		if (length == len && memcmp(list, string, length) == 0)
+			return idx;
+
+		list += length;
+		idx++;
+	}
+
+	return -FDT_ERR_NOTFOUND;
+}
+
 int fdt_node_check_compatible(const void *fdt, int nodeoffset,
 			      const char *compatible)
 {