Function streamBodyToFile

switch/source/server.cpp:189–228

Streams the body of an upload request to `tmpPath`, tracking progress and honouring a receive cancel. `leftover` is the body bytes already read while parsing the header. Returns true when the full body was written.

    // honouring a receive cancel. `leftover` is the body bytes already read while
    // parsing the header. Returns true when the full body was written.
    bool streamBodyToFile(s32 clientSocket, const std::string& tmpPath, size_t contentLength, const char* leftover, size_t leftoverLen)
    {
        FILE* out = fopen(tmpPath.c_str(), "wb");
        if (out == nullptr) {
            Logging::error("Failed to open upload temp file {} with errno {}.", tmpPath, errno);
            return false;
        }

        TransferStatus::beginNetwork(i18n::t("transfer.downloading"), contentLength);

        size_t written = 0;
        if (leftoverLen > 0) {
            size_t toWrite = leftoverLen > contentLength ? contentLength : leftoverLen;
            fwrite(leftover, 1, toWrite, out);
            written += toWrite;
            TransferStatus::setBytesDone(written);
        }

        constexpr size_t RECV_CHUNK = 64 * 1024;
        std::vector<char> buffer(RECV_CHUNK);
        int idleMs = 0;
        bool ok    = true;
        while (written < contentLength) {
            ssize_t received = pollRecv(clientSocket, buffer.data(), buffer.size(), idleMs, true);
            if (received <= 0) {
                ok = false; // clean close, idle timeout, or cancel: incomplete body
                break;
            }
            size_t toWrite = (size_t)received;
            if (written + toWrite > contentLength) {
                toWrite = contentLength - written;
            }
            fwrite(buffer.data(), 1, toWrite, out);
            written += toWrite;
            TransferStatus::setBytesDone(written);
        }

        fclose(out);
        return ok && written == contentLength;
    }

    void handleHttpRequest(s32 clientSocket)
    {