Merge "init: fsync() persistent properties directory after rename()"

#include "util.h"

using android::base::Dirname;

using android::base::ReadFdToString;

using android::base::StartsWith;

using android::base::WriteStringToFd;

using android::base::unique_fd;

using android::base::WriteStringToFd;

namespace android {

namespace init {

        unlink(temp_filename.c_str());

        return Error(saved_errno) << "Unable to rename persistent property file";

    }

    // rename() is atomic with regards to the kernel's filesystem buffers, but the parent

    // directories must be fsync()'ed otherwise, the rename is not necessarily written to storage.

    // Note in this case, that the source and destination directories are the same, so only one

    // fsync() is required.

    auto dir = Dirname(persistent_property_filename);

    auto dir_fd = unique_fd{open(dir.c_str(), O_DIRECTORY | O_RDONLY)};

    if (dir_fd < 0) {

        return ErrnoError() << "Unable to open persistent properties directory for fsync()";

    }

    fsync(dir_fd);

    return {};

}