Function copyFile

Core/MemoryFile.cpp:582–611

copy to a temp file then rename it this is the best we can do under the POSIX standard

// copy to a temp file then rename it
// this is the best we can do under the POSIX standard
bool copyFile(const MMKVPath_t &srcPath, const MMKVPath_t &dstPath) {
    auto pair = createUniqueTempFile("MMKV");
    auto tmpFD = pair.second;
    auto &tmpPath = pair.first;
    if (tmpFD < 0) {
        return false;
    }

    bool renamed = false;
    if (copyFileContent(srcPath, tmpFD, false)) {
        MMKVInfo("copyfile [%s] to [%s]", srcPath.c_str(), tmpPath.c_str());
        renamed = tryAtomicRename(tmpPath, dstPath);
        if (!renamed) {
            MMKVInfo("rename fail, try copy file content instead.");
            if (copyFileContent(tmpPath, dstPath)) {
                renamed = true;
                ::unlink(tmpPath.c_str());
            }
        }
        if (renamed) {
            MMKVInfo("copyfile [%s] to [%s] finish.", srcPath.c_str(), dstPath.c_str());
        }
    }

    ::close(tmpFD);
    if (!renamed) {
        ::unlink(tmpPath.c_str());
    }
    return renamed;
}

bool copyFileContent(const MMKVPath_t &srcPath, const MMKVPath_t &dstPath) {
    File dstFile(dstPath, OpenFlag::WriteOnly | OpenFlag::Create | OpenFlag::Truncate);