Add `struct string` for strings parsed from FDT
Just a small wrapper around a char array to make things simpler.
Bug: 117551352
Change-Id: I0880ebbb81258830290ce49bf3772280551d3483
diff --git a/src/string.c b/src/string.c
new file mode 100644
index 0000000..4876a3f
--- /dev/null
+++ b/src/string.c
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2019 The Hafnium Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "hf/string.h"
+
+#include "hf/static_assert.h"
+#include "hf/std.h"
+
+void string_init_empty(struct string *str)
+{
+ static_assert(sizeof(str->data) >= 1, "String buffer too small");
+ str->data[0] = '\0';
+}
+
+/**
+ * Caller must guarantee that `data` points to a NULL-terminated string.
+ * The constructor checks that it fits into the internal buffer and copies
+ * the string there.
+ */
+enum string_return_code string_init(struct string *str, const char *data,
+ size_t size)
+{
+ /*
+ * Require that the value contains exactly one NULL character and that
+ * it is the last byte.
+ */
+ if (size < 1 || memchr(data, '\0', size) != &data[size - 1]) {
+ return STRING_ERROR_INVALID_INPUT;
+ }
+
+ if (size > sizeof(str->data)) {
+ return STRING_ERROR_TOO_LONG;
+ }
+
+ memcpy_s(str->data, sizeof(str->data), data, size);
+ return STRING_SUCCESS;
+}
+
+bool string_is_empty(const struct string *str)
+{
+ return str->data[0] == '\0';
+}
+
+const char *string_data(const struct string *str)
+{
+ return str->data;
+}