Import of the watch repository from Pebble

src/fw/util/stringlist.c

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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
+ *
+ *     http://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 "stringlist.h"
+
+#include "util/math.h"
+#include "util/string.h"
+
+#include <stdbool.h>
+#include <string.h>
+
+size_t string_list_count(StringList *list) {
+  if (!list || list->serialized_byte_length == 0) {
+    return 0;
+  }
+
+  size_t result = 1;
+  for (int i = 0; i < list->serialized_byte_length; i++) {
+    if (list->data[i] == '\0') {
+      result++;
+    }
+  }
+  return result;
+}
+
+char *string_list_get_at(StringList *list, size_t index) {
+  if (!list) {
+    return NULL;
+  }
+
+  char *ptr = list->data;
+  const char *max_ptr = ptr + list->serialized_byte_length;
+  while (index > 0 && ptr < max_ptr) {
+    ptr += strlen(ptr) + 1;
+    index--;
+  }
+
+  if (index > 0) {
+    return NULL;
+  } else {
+    return ptr;
+  }
+}
+
+int string_list_add_string(StringList *list, size_t max_list_size, const char *buffer,
+                           size_t max_str_size) {
+  if (!list) {
+    return 0;
+  }
+
+  const size_t str_length = strnlen(buffer, max_str_size);
+  const int size_remaining =
+      max_list_size - (sizeof(StringList) + list->serialized_byte_length + 1);
+  if (size_remaining <= 0) {
+    return 0;
+  }
+  const bool has_last_terminator = (list->serialized_byte_length > 0);
+  char *cursor = &list->data[list->serialized_byte_length + (has_last_terminator ? 1 : 0)];
+  const size_t bytes_written = MIN(str_length, (size_t)size_remaining - 1);
+  strncpy(cursor, buffer, bytes_written);
+  cursor[bytes_written] = '\0';
+  list->serialized_byte_length += (has_last_terminator ? 1 : 0) + bytes_written;
+  return bytes_written;
+}