use a single file for storing persistent properties

We have seen that storing persistent properties in separate files
causes increased boot latency compared to if they were stored in a
single contiguous file.

This change creates a simple format for a contiguously stored property
file, and adds the support for arbitrary characters in the names of
persistent properties, which previously had been restricted.  It has a
mechanism for converting older devices to the new format as well.

Bug: 64392887
Test: boot bullhead with new properties
Test: boot bullhead and verify old properties are converted to the new
      property file
Test: corrupt property file and ensure that it gets recovered from memory
Test: new unit tests
Change-Id: I60d8201d655ce5c97b33faae81d5ca8dbbb21a14

5 files changed, 566 insertions, 83 deletions

diff --git a/init/Android.bp b/init/Android.bp
index 33dfe566c..8737defae 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -72,6 +72,7 @@ cc_library_static {
         "import_parser.cpp",
         "log.cpp",
         "parser.cpp",
+        "persistent_properties.cpp",
         "property_service.cpp",
         "security.cpp",
         "selinux.cpp",
@@ -162,6 +163,7 @@ cc_test {
     srcs: [
         "devices_test.cpp",
         "init_test.cpp",
+        "persistent_properties_test.cpp",
         "property_service_test.cpp",
         "result_test.cpp",
         "rlimit_parser_test.cpp",
diff --git a/init/persistent_properties.cpp b/init/persistent_properties.cpp
new file mode 100644
index 000000000..66fa011b0
--- /dev/null
+++ b/init/persistent_properties.cpp
@@ -0,0 +1,341 @@
+/*
+ * Copyright (C) 2017 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 "persistent_properties.h"
+
+#include <dirent.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/system_properties.h>
+#include <sys/types.h>
+
+#include <memory>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/strings.h>
+#include <android-base/unique_fd.h>
+
+#include "util.h"
+
+using android::base::ReadFdToString;
+using android::base::StartsWith;
+using android::base::WriteStringToFd;
+using android::base::unique_fd;
+
+namespace android {
+namespace init {
+
+std::string persistent_property_filename = "/data/property/persistent_properties";
+
+namespace {
+
+constexpr const uint32_t kMagic = 0x8495E0B4;
+constexpr const char kLegacyPersistentPropertyDir[] = "/data/property";
+
+Result<std::vector<std::pair<std::string, std::string>>> LoadLegacyPersistentProperties() {
+    std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(kLegacyPersistentPropertyDir), closedir);
+    if (!dir) {
+        return ErrnoError() << "Unable to open persistent property directory \""
+                            << kLegacyPersistentPropertyDir << "\"";
+    }
+
+    std::vector<std::pair<std::string, std::string>> persistent_properties;
+    dirent* entry;
+    while ((entry = readdir(dir.get())) != nullptr) {
+        if (!StartsWith(entry->d_name, "persist.")) {
+            continue;
+        }
+        if (entry->d_type != DT_REG) {
+            continue;
+        }
+
+        unique_fd fd(openat(dirfd(dir.get()), entry->d_name, O_RDONLY | O_NOFOLLOW));
+        if (fd == -1) {
+            PLOG(ERROR) << "Unable to open persistent property file \"" << entry->d_name << "\"";
+            continue;
+        }
+
+        struct stat sb;
+        if (fstat(fd, &sb) == -1) {
+            PLOG(ERROR) << "fstat on property file \"" << entry->d_name << "\" failed";
+            continue;
+        }
+
+        // File must not be accessible to others, be owned by root/root, and
+        // not be a hard link to any other file.
+        if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0) || sb.st_uid != 0 || sb.st_gid != 0 ||
+            sb.st_nlink != 1) {
+            PLOG(ERROR) << "skipping insecure property file " << entry->d_name
+                        << " (uid=" << sb.st_uid << " gid=" << sb.st_gid << " nlink=" << sb.st_nlink
+                        << " mode=" << std::oct << sb.st_mode << ")";
+            continue;
+        }
+
+        std::string value;
+        if (ReadFdToString(fd, &value)) {
+            persistent_properties.emplace_back(entry->d_name, value);
+        } else {
+            PLOG(ERROR) << "Unable to read persistent property file " << entry->d_name;
+        }
+    }
+    return persistent_properties;
+}
+
+void RemoveLegacyPersistentPropertyFiles() {
+    std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(kLegacyPersistentPropertyDir), closedir);
+    if (!dir) {
+        PLOG(ERROR) << "Unable to open persistent property directory \""
+                    << kLegacyPersistentPropertyDir << "\"";
+        return;
+    }
+
+    dirent* entry;
+    while ((entry = readdir(dir.get())) != nullptr) {
+        if (!StartsWith(entry->d_name, "persist.")) {
+            continue;
+        }
+        if (entry->d_type != DT_REG) {
+            continue;
+        }
+        unlinkat(dirfd(dir.get()), entry->d_name, 0);
+    }
+}
+
+std::vector<std::pair<std::string, std::string>> LoadPersistentPropertiesFromMemory() {
+    std::vector<std::pair<std::string, std::string>> properties;
+    __system_property_foreach(
+        [](const prop_info* pi, void* cookie) {
+            __system_property_read_callback(
+                pi,
+                [](void* cookie, const char* name, const char* value, unsigned serial) {
+                    if (StartsWith(name, "persist.")) {
+                        auto properties =
+                            reinterpret_cast<std::vector<std::pair<std::string, std::string>>*>(
+                                cookie);
+                        properties->emplace_back(name, value);
+                    }
+                },
+                cookie);
+        },
+        &properties);
+    return properties;
+}
+
+class PersistentPropertyFileParser {
+  public:
+    PersistentPropertyFileParser(const std::string& contents) : contents_(contents), position_(0) {}
+    Result<std::vector<std::pair<std::string, std::string>>> Parse();
+
+  private:
+    Result<std::string> ReadString();
+    Result<uint32_t> ReadUint32();
+
+    const std::string& contents_;
+    size_t position_;
+};
+
+Result<std::vector<std::pair<std::string, std::string>>> PersistentPropertyFileParser::Parse() {
+    std::vector<std::pair<std::string, std::string>> result;
+
+    if (auto magic = ReadUint32(); magic) {
+        if (*magic != kMagic) {
+            return Error() << "Magic value '0x" << std::hex << *magic
+                           << "' does not match expected value '0x" << kMagic << "'";
+        }
+    } else {
+        return Error() << "Could not read magic value: " << magic.error();
+    }
+
+    if (auto version = ReadUint32(); version) {
+        if (*version != 1) {
+            return Error() << "Version '" << *version
+                           << "' does not match any compatible version: (1)";
+        }
+    } else {
+        return Error() << "Could not read version: " << version.error();
+    }
+
+    auto num_properties = ReadUint32();
+    if (!num_properties) {
+        return Error() << "Could not read num_properties: " << num_properties.error();
+    }
+
+    while (position_ < contents_.size()) {
+        auto key = ReadString();
+        if (!key) {
+            return Error() << "Could not read key: " << key.error();
+        }
+        if (!StartsWith(*key, "persist.")) {
+            return Error() << "Property '" << *key << "' does not starts with 'persist.'";
+        }
+        auto value = ReadString();
+        if (!value) {
+            return Error() << "Could not read value: " << value.error();
+        }
+        result.emplace_back(*key, *value);
+    }
+
+    if (result.size() != *num_properties) {
+        return Error() << "Mismatch of number of persistent properties read, " << result.size()
+                       << " and number of persistent properties expected, " << *num_properties;
+    }
+
+    return result;
+}
+
+Result<std::string> PersistentPropertyFileParser::ReadString() {
+    auto string_length = ReadUint32();
+    if (!string_length) {
+        return Error() << "Could not read size for string";
+    }
+
+    if (position_ + *string_length > contents_.size()) {
+        return Error() << "String size would cause it to overflow the input buffer";
+    }
+    auto result = std::string(contents_, position_, *string_length);
+    position_ += *string_length;
+    return result;
+}
+
+Result<uint32_t> PersistentPropertyFileParser::ReadUint32() {
+    if (position_ + 3 > contents_.size()) {
+        return Error() << "Input buffer not large enough to read uint32_t";
+    }
+    uint32_t result = *reinterpret_cast<const uint32_t*>(&contents_[position_]);
+    position_ += sizeof(uint32_t);
+    return result;
+}
+
+}  // namespace
+
+Result<std::vector<std::pair<std::string, std::string>>> LoadPersistentPropertyFile() {
+    const std::string temp_filename = persistent_property_filename + ".tmp";
+    if (access(temp_filename.c_str(), F_OK) == 0) {
+        LOG(INFO)
+            << "Found temporary property file while attempting to persistent system properties"
+               " a previous persistent property write may have failed";
+        unlink(temp_filename.c_str());
+    }
+    auto file_contents = ReadFile(persistent_property_filename);
+    if (!file_contents) {
+        return Error() << "Unable to read persistent property file: " << file_contents.error();
+    }
+    auto parsed_contents = PersistentPropertyFileParser(*file_contents).Parse();
+    if (!parsed_contents) {
+        // If the file cannot be parsed, then we don't have any recovery mechanisms, so we delete
+        // it to allow for future writes to take place successfully.
+        unlink(persistent_property_filename.c_str());
+        return Error() << "Unable to parse persistent property file: " << parsed_contents.error();
+    }
+    return parsed_contents;
+}
+
+std::string GenerateFileContents(
+    const std::vector<std::pair<std::string, std::string>>& persistent_properties) {
+    std::string result;
+
+    uint32_t magic = kMagic;
+    result.append(reinterpret_cast<char*>(&magic), sizeof(uint32_t));
+
+    uint32_t version = 1;
+    result.append(reinterpret_cast<char*>(&version), sizeof(uint32_t));
+
+    uint32_t num_properties = persistent_properties.size();
+    result.append(reinterpret_cast<char*>(&num_properties), sizeof(uint32_t));
+
+    for (const auto& [key, value] : persistent_properties) {
+        uint32_t key_length = key.length();
+        result.append(reinterpret_cast<char*>(&key_length), sizeof(uint32_t));
+        result.append(key);
+        uint32_t value_length = value.length();
+        result.append(reinterpret_cast<char*>(&value_length), sizeof(uint32_t));
+        result.append(value);
+    }
+    return result;
+}
+
+Result<Success> WritePersistentPropertyFile(
+    const std::vector<std::pair<std::string, std::string>>& persistent_properties) {
+    auto file_contents = GenerateFileContents(persistent_properties);
+
+    const std::string temp_filename = persistent_property_filename + ".tmp";
+    unique_fd fd(TEMP_FAILURE_RETRY(
+        open(temp_filename.c_str(), O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC | O_CLOEXEC, 0600)));
+    if (fd == -1) {
+        return ErrnoError() << "Could not open temporary properties file";
+    }
+    if (!WriteStringToFd(file_contents, fd)) {
+        return ErrnoError() << "Unable to write file contents";
+    }
+    fsync(fd);
+    fd.reset();
+
+    if (rename(temp_filename.c_str(), persistent_property_filename.c_str())) {
+        int saved_errno = errno;
+        unlink(temp_filename.c_str());
+        return Error(saved_errno) << "Unable to rename persistent property file";
+    }
+    return Success();
+}
+
+// Persistent properties are not written often, so we rather not keep any data in memory and read
+// then rewrite the persistent property file for each update.
+void WritePersistentProperty(const std::string& name, const std::string& value) {
+    auto persistent_properties = LoadPersistentPropertyFile();
+    if (!persistent_properties) {
+        LOG(ERROR) << "Recovering persistent properties from memory: "
+                   << persistent_properties.error();
+        persistent_properties = LoadPersistentPropertiesFromMemory();
+    }
+    auto it = std::find_if(persistent_properties->begin(), persistent_properties->end(),
+                           [&name](const auto& entry) { return entry.first == name; });
+    if (it != persistent_properties->end()) {
+        *it = {name, value};
+    } else {
+        persistent_properties->emplace_back(name, value);
+    }
+
+    if (auto result = WritePersistentPropertyFile(*persistent_properties); !result) {
+        LOG(ERROR) << "Could not store persistent property: " << result.error();
+    }
+}
+
+std::vector<std::pair<std::string, std::string>> LoadPersistentProperties() {
+    auto persistent_properties = LoadPersistentPropertyFile();
+
+    if (!persistent_properties) {
+        LOG(ERROR) << "Could not load single persistent property file, trying legacy directory: "
+                   << persistent_properties.error();
+        persistent_properties = LoadLegacyPersistentProperties();
+        if (!persistent_properties) {
+            LOG(ERROR) << "Unable to load legacy persistent properties: "
+                       << persistent_properties.error();
+            return {};
+        }
+        if (auto result = WritePersistentPropertyFile(*persistent_properties); result) {
+            RemoveLegacyPersistentPropertyFiles();
+        } else {
+            LOG(ERROR) << "Unable to write single persistent property file: " << result.error();
+            // Fall through so that we still set the properties that we've read.
+        }
+    }
+
+    return *persistent_properties;
+}
+
+}  // namespace init
+}  // namespace android
diff --git a/init/persistent_properties.h b/init/persistent_properties.h
new file mode 100644
index 000000000..d84d9db4f
--- /dev/null
+++ b/init/persistent_properties.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#ifndef _INIT_PERSISTENT_PROPERTIES_H
+#define _INIT_PERSISTENT_PROPERTIES_H
+
+#include <string>
+#include <vector>
+
+#include "result.h"
+
+namespace android {
+namespace init {
+
+std::vector<std::pair<std::string, std::string>> LoadPersistentProperties();
+void WritePersistentProperty(const std::string& name, const std::string& value);
+
+// Exposed only for testing
+Result<std::vector<std::pair<std::string, std::string>>> LoadPersistentPropertyFile();
+std::string GenerateFileContents(
+    const std::vector<std::pair<std::string, std::string>>& persistent_properties);
+Result<Success> WritePersistentPropertyFile(
+    const std::vector<std::pair<std::string, std::string>>& persistent_properties);
+extern std::string persistent_property_filename;
+
+}  // namespace init
+}  // namespace android
+
+#endif
diff --git a/init/persistent_properties_test.cpp b/init/persistent_properties_test.cpp
new file mode 100644
index 000000000..9ab5b229c
--- /dev/null
+++ b/init/persistent_properties_test.cpp
@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2017 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 "persistent_properties.h"
+
+#include <errno.h>
+
+#include <android-base/test_utils.h>
+#include <gtest/gtest.h>
+
+#include "util.h"
+
+using namespace std::string_literals;
+
+namespace android {
+namespace init {
+
+TEST(persistent_properties, GeneratedContents) {
+    const std::vector<std::pair<std::string, std::string>> persistent_properties = {
+        {"persist.abc", ""},
+        {"persist.def", "test_success"},
+    };
+    auto generated_contents = GenerateFileContents(persistent_properties);
+
+    // Manually serialized contents below:
+    std::string file_contents;
+    // All values below are written and read as little endian.
+    // Add magic value: 0x8495E0B4
+    file_contents += "\xB4\xE0\x95\x84"s;
+    // Add version: 1
+    file_contents += "\x01\x00\x00\x00"s;
+    // Add number of properties: 2
+    file_contents += "\x02\x00\x00\x00"s;
+
+    // Add first key: persist.abc
+    file_contents += "\x0B\x00\x00\x00persist.abc"s;
+    // Add first value: (empty string)
+    file_contents += "\x00\x00\x00\x00"s;
+
+    // Add second key: persist.def
+    file_contents += "\x0B\x00\x00\x00persist.def"s;
+    // Add second value: test_success
+    file_contents += "\x0C\x00\x00\x00test_success"s;
+
+    EXPECT_EQ(file_contents, generated_contents);
+}
+
+TEST(persistent_properties, EndToEnd) {
+    TemporaryFile tf;
+    ASSERT_TRUE(tf.fd != -1);
+    persistent_property_filename = tf.path;
+
+    std::vector<std::pair<std::string, std::string>> persistent_properties = {
+        {"persist.sys.locale", "en-US"},
+        {"persist.sys.timezone", "America/Los_Angeles"},
+        {"persist.test.empty.value", ""},
+        {"persist.test.new.line", "abc\n\n\nabc"},
+        {"persist.test.numbers", "1234567890"},
+        {"persist.test.non.ascii", "\x00\x01\x02\xFF\xFE\xFD\x7F\x8F\x9F"},
+        // We don't currently allow for non-ascii keys for system properties, but this is a policy
+        // decision, not a technical limitation.
+        {"persist.\x00\x01\x02\xFF\xFE\xFD\x7F\x8F\x9F", "non-ascii-key"},
+    };
+
+    ASSERT_TRUE(WritePersistentPropertyFile(persistent_properties));
+
+    auto read_back_properties = LoadPersistentProperties();
+    EXPECT_EQ(persistent_properties, read_back_properties);
+}
+
+TEST(persistent_properties, BadMagic) {
+    TemporaryFile tf;
+    ASSERT_TRUE(tf.fd != -1);
+    persistent_property_filename = tf.path;
+
+    ASSERT_TRUE(WriteFile(tf.path, "ab"));
+
+    auto read_back_properties = LoadPersistentPropertyFile();
+
+    ASSERT_FALSE(read_back_properties);
+    EXPECT_EQ(
+        "Unable to parse persistent property file: Could not read magic value: Input buffer not "
+        "large enough to read uint32_t",
+        read_back_properties.error_string());
+
+    ASSERT_TRUE(WriteFile(tf.path, "\xFF\xFF\xFF\xFF"));
+
+    read_back_properties = LoadPersistentPropertyFile();
+
+    ASSERT_FALSE(read_back_properties);
+    EXPECT_EQ(
+        "Unable to parse persistent property file: Magic value '0xffffffff' does not match "
+        "expected value '0x8495e0b4'",
+        read_back_properties.error_string());
+}
+
+TEST(persistent_properties, AddProperty) {
+    TemporaryFile tf;
+    ASSERT_TRUE(tf.fd != -1);
+    persistent_property_filename = tf.path;
+
+    std::vector<std::pair<std::string, std::string>> persistent_properties = {
+        {"persist.sys.timezone", "America/Los_Angeles"},
+    };
+    ASSERT_TRUE(WritePersistentPropertyFile(persistent_properties));
+
+    WritePersistentProperty("persist.sys.locale", "pt-BR");
+
+    std::vector<std::pair<std::string, std::string>> persistent_properties_expected = {
+        {"persist.sys.timezone", "America/Los_Angeles"},
+        {"persist.sys.locale", "pt-BR"},
+    };
+
+    auto read_back_properties = LoadPersistentProperties();
+    EXPECT_EQ(persistent_properties_expected, read_back_properties);
+}
+
+TEST(persistent_properties, UpdateProperty) {
+    TemporaryFile tf;
+    ASSERT_TRUE(tf.fd != -1);
+    persistent_property_filename = tf.path;
+
+    std::vector<std::pair<std::string, std::string>> persistent_properties = {
+        {"persist.sys.locale", "en-US"},
+        {"persist.sys.timezone", "America/Los_Angeles"},
+    };
+    ASSERT_TRUE(WritePersistentPropertyFile(persistent_properties));
+
+    WritePersistentProperty("persist.sys.locale", "pt-BR");
+
+    std::vector<std::pair<std::string, std::string>> persistent_properties_expected = {
+        {"persist.sys.locale", "pt-BR"},
+        {"persist.sys.timezone", "America/Los_Angeles"},
+    };
+
+    auto read_back_properties = LoadPersistentProperties();
+    EXPECT_EQ(persistent_properties_expected, read_back_properties);
+}
+
+TEST(persistent_properties, UpdatePropertyBadParse) {
+    TemporaryFile tf;
+    ASSERT_TRUE(tf.fd != -1);
+    persistent_property_filename = tf.path;
+
+    ASSERT_TRUE(WriteFile(tf.path, "ab"));
+
+    WritePersistentProperty("persist.sys.locale", "pt-BR");
+
+    auto read_back_properties = LoadPersistentProperties();
+    EXPECT_GT(read_back_properties.size(), 0U);
+
+    auto it = std::find_if(
+        read_back_properties.begin(), read_back_properties.end(), [](const auto& entry) {
+            return entry.first == "persist.sys.locale" && entry.second == "pt-BR";
+        });
+    EXPECT_FALSE(it == read_back_properties.end());
+}
+
+}  // namespace init
+}  // namespace android
diff --git a/init/property_service.cpp b/init/property_service.cpp
index f0e4d2e96..8c592cb41 100644
--- a/init/property_service.cpp
+++ b/init/property_service.cpp
@@ -17,7 +17,6 @@
 #include "property_service.h"
 
 #include <ctype.h>
-#include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
@@ -54,17 +53,17 @@
 #include <selinux/selinux.h>
 
 #include "init.h"
+#include "persistent_properties.h"
 #include "util.h"
 
 using android::base::Timer;
 
-#define PERSISTENT_PROPERTY_DIR  "/data/property"
 #define RECOVERY_MOUNT_POINT "/recovery"
 
 namespace android {
 namespace init {
 
-static int persistent_properties_loaded = 0;
+static bool persistent_properties_loaded = false;
 
 static int property_set_fd = -1;
 
@@ -120,29 +119,6 @@ static int check_control_mac_perms(const char *name, char *sctx, struct ucred *c
     return check_mac_perms(ctl_name, sctx, cr);
 }
 
-static void write_persistent_property(const char *name, const char *value)
-{
-    char tempPath[PATH_MAX];
-    char path[PATH_MAX];
-    int fd;
-
-    snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
-    fd = mkstemp(tempPath);
-    if (fd < 0) {
-        PLOG(ERROR) << "Unable to write persistent property to temp file " << tempPath;
-        return;
-    }
-    write(fd, value, strlen(value));
-    fsync(fd);
-    close(fd);
-
-    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
-    if (rename(tempPath, path)) {
-        PLOG(ERROR) << "Unable to rename persistent property file " << tempPath << " to " << path;
-        unlink(tempPath);
-    }
-}
-
 bool is_legal_property_name(const std::string& name) {
     size_t namelen = name.size();
 
@@ -204,7 +180,7 @@ static uint32_t PropertySetImpl(const std::string& name, const std::string& valu
     // Don't write properties to disk until after we have read all default
     // properties to prevent them from being overwritten by default values.
     if (persistent_properties_loaded && android::base::StartsWith(name, "persist.")) {
-        write_persistent_property(name.c_str(), value.c_str());
+        WritePersistentProperty(name, value);
     }
     property_changed(name, value);
     return PROP_SUCCESS;
@@ -599,61 +575,6 @@ static void load_properties_from_file(const char* filename, const char* filter)
     LOG(VERBOSE) << "(Loading properties from " << filename << " took " << t << ".)";
 }
 
-static void load_persistent_properties() {
-    persistent_properties_loaded = 1;
-
-    std::unique_ptr<DIR, int(*)(DIR*)> dir(opendir(PERSISTENT_PROPERTY_DIR), closedir);
-    if (!dir) {
-        PLOG(ERROR) << "Unable to open persistent property directory \""
-                    << PERSISTENT_PROPERTY_DIR << "\"";
-        return;
-    }
-
-    struct dirent* entry;
-    while ((entry = readdir(dir.get())) != NULL) {
-        if (strncmp("persist.", entry->d_name, strlen("persist."))) {
-            continue;
-        }
-        if (entry->d_type != DT_REG) {
-            continue;
-        }
-
-        // Open the file and read the property value.
-        int fd = openat(dirfd(dir.get()), entry->d_name, O_RDONLY | O_NOFOLLOW);
-        if (fd == -1) {
-            PLOG(ERROR) << "Unable to open persistent property file \"" << entry->d_name << "\"";
-            continue;
-        }
-
-        struct stat sb;
-        if (fstat(fd, &sb) == -1) {
-            PLOG(ERROR) << "fstat on property file \"" << entry->d_name << "\" failed";
-            close(fd);
-            continue;
-        }
-
-        // File must not be accessible to others, be owned by root/root, and
-        // not be a hard link to any other file.
-        if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0) || sb.st_uid != 0 || sb.st_gid != 0 || sb.st_nlink != 1) {
-            PLOG(ERROR) << "skipping insecure property file " << entry->d_name
-                        << " (uid=" << sb.st_uid << " gid=" << sb.st_gid
-                        << " nlink=" << sb.st_nlink << " mode=" << std::oct << sb.st_mode << ")";
-            close(fd);
-            continue;
-        }
-
-        char value[PROP_VALUE_MAX];
-        int length = read(fd, value, sizeof(value) - 1);
-        if (length >= 0) {
-            value[length] = 0;
-            property_set(entry->d_name, value);
-        } else {
-            PLOG(ERROR) << "Unable to read persistent property file " << entry->d_name;
-        }
-        close(fd);
-    }
-}
-
 // persist.sys.usb.config values can't be combined on build-time when property
 // files are split into each partition.
 // So we need to apply the same rule of build/make/tools/post_process_props.py
@@ -703,7 +624,11 @@ void load_persist_props(void) {
 
     load_override_properties();
     /* Read persistent properties after all default values have been loaded. */
-    load_persistent_properties();
+    auto persistent_properties = LoadPersistentProperties();
+    for (const auto& [name, value] : persistent_properties) {
+        property_set(name, value);
+    }
+    persistent_properties_loaded = true;
     property_set("ro.persistent_properties.ready", "true");
 }