Add std::string system property functions.
Makes it easier to write correct code in a world where the maximum
property key/value lengths change.
Bug: http://b/23102347
Test: libbase_test64
Change-Id: I100f00904221bbcef9e8786a4e6e30428039bb49
diff --git a/base/properties.cpp b/base/properties.cpp
new file mode 100644
index 0000000..fab3005
--- /dev/null
+++ b/base/properties.cpp
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * 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 "android-base/properties.h"
+
+#include <sys/system_properties.h>
+
+#include <string>
+
+#include <android-base/parseint.h>
+
+namespace android {
+namespace base {
+
+std::string GetProperty(const std::string& key, const std::string& default_value) {
+ const prop_info* pi = __system_property_find(key.c_str());
+ if (pi == nullptr) return default_value;
+
+ char buf[PROP_VALUE_MAX];
+ if (__system_property_read(pi, nullptr, buf) > 0) return buf;
+
+ // If the property exists but is empty, also return the default value.
+ // Since we can't remove system properties, "empty" is traditionally
+ // the same as "missing" (this was true for cutils' property_get).
+ return default_value;
+}
+
+bool GetBoolProperty(const std::string& key, bool default_value) {
+ std::string value = GetProperty(key, "");
+ if (value == "1" || value == "y" || value == "yes" || value == "on" || value == "true") {
+ return true;
+ } else if (value == "0" || value == "n" || value == "no" || value == "off" || value == "false") {
+ return false;
+ }
+ return default_value;
+}
+
+template <typename T>
+T GetIntProperty(const std::string& key, T default_value, T min, T max) {
+ T result;
+ std::string value = GetProperty(key, "");
+ if (!value.empty() && android::base::ParseInt(value.c_str(), &result, min, max)) return result;
+ return default_value;
+}
+
+template <typename T>
+T GetUintProperty(const std::string& key, T default_value, T max) {
+ T result;
+ std::string value = GetProperty(key, "");
+ if (!value.empty() && android::base::ParseUint(value.c_str(), &result, max)) return result;
+ return default_value;
+}
+
+template int8_t GetIntProperty(const std::string&, int8_t, int8_t, int8_t);
+template int16_t GetIntProperty(const std::string&, int16_t, int16_t, int16_t);
+template int32_t GetIntProperty(const std::string&, int32_t, int32_t, int32_t);
+template int64_t GetIntProperty(const std::string&, int64_t, int64_t, int64_t);
+
+template uint8_t GetUintProperty(const std::string&, uint8_t, uint8_t);
+template uint16_t GetUintProperty(const std::string&, uint16_t, uint16_t);
+template uint32_t GetUintProperty(const std::string&, uint32_t, uint32_t);
+template uint64_t GetUintProperty(const std::string&, uint64_t, uint64_t);
+
+bool SetProperty(const std::string& key, const std::string& value) {
+ return (__system_property_set(key.c_str(), value.c_str()) == 0);
+}
+
+} // namespace base
+} // namespace android