lass="bold">*n</span>. 
<p class="level0">On failure, returns the appropriate error code. 
<p class="level0">If there is no data to read, the function returns <span Class="bold">CURLE_AGAIN</span>. Use your operating system facilities to wait until the data is ready, and retry. 
<p class="level0">Reading exactly 0 bytes would indicate a closed connection. 
<p class="level0">If there's no socket available to use from the previous transfer, this function returns CURLE_UNSUPPORTED_PROTOCOL. <a name="EXAMPLE"><