CURLOPT_UPLOAD − enable data upload
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_UPLOAD, long upload);
The long parameter upload set to 1 tells the library to prepare for and perform an upload. The CURLOPT_READDATA(3) and CURLOPT_INFILESIZE(3) or CURLOPT_INFILESIZE_LARGE(3) options are also interesting for uploads. If the protocol is HTTP, uploading means using the PUT request unless you tell libcurl otherwise.
Using PUT with HTTP 1.1 implies the use of a "Expect: 100-continue" header. You can disable this header with CURLOPT_HTTPHEADER(3) as usual.
If you use PUT to an HTTP 1.1 server, you can upload data without knowing the size before starting the transfer if you use chunked encoding. You enable this by adding a header like "Transfer-Encoding: chunked" with CURLOPT_HTTPHEADER(3). With HTTP 1.0 or without chunked transfer, you must specify the size.
0, default is download
CURL *curl =
/* we want to use our own read function */
curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);
curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/dir/to/newfile");
/* now specify
which pointer to pass to our callback */
curl_easy_setopt(curl, CURLOPT_READDATA, hd_src);
/* Set the size
of the file to upload */
curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE, (curl_off_t)fsize);
/* Now run off
and do what you’ve been told! */
CURLOPT_PUT(3), CURLOPT_READFUNCTION(3), CURLOPT_INFILESIZE_LARGE(3),