curl_easy_perform(3) Library Functions Manual curl_easy_perform(3)

curl_easy_perform - perform a blocking file transfer

#include <curl/curl.h>
CURLcode curl_easy_perform(CURL *easy_handle);

curl_easy_perform(3) performs a network transfer in a blocking manner and returns when done, or earlier if it fails. For non-blocking behavior, see curl_multi_perform(3).

Invoke this function after curl_easy_init(3) and all the curl_easy_setopt(3) calls are made, and it performs the transfer as described in the options. It must be called with the same easy_handle as input as the curl_easy_init(3) call returned.

You can do any amount of calls to curl_easy_perform(3) while using the same easy_handle. If you intend to transfer more than one file, you are even encouraged to do so. libcurl attempts to reuse existing connections for the following transfers, thus making the operations faster, less CPU intense and using less network resources. You probably want to use curl_easy_setopt(3) between the invokes to set options for the following curl_easy_perform(3) call.

You must never call this function simultaneously from two places using the same easy_handle. Let the function return first before invoking it another time. If you want parallel transfers, you must use several curl easy_handles.

A network transfer moves data to a peer or from a peer. An application tells libcurl how to receive data by setting the CURLOPT_WRITEFUNCTION(3) and CURLOPT_WRITEDATA(3) options. To tell libcurl what data to send, there are a few more alternatives but two common ones are CURLOPT_READFUNCTION(3) and CURLOPT_POSTFIELDS(3).

While the easy_handle is added to a multi handle, it cannot be used by curl_easy_perform(3).

All

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

Always

CURLE_OK (0) means everything was OK, non-zero means an error occurred as <curl/curl.h> defines - see libcurl-errors(3). If CURLOPT_ERRORBUFFER(3) was set with curl_easy_setopt(3) there is an error message stored in the error buffer when non-zero is returned.

curl_easy_init(3), curl_easy_setopt(3), curl_multi_add_handle(3), curl_multi_perform(3), libcurl-errors(3)

2024-05-22 libcurl