CURLINFO_OS_ERRNO - Man Page

#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_OS_ERRNO, long *errnop);

Pass a pointer to a long to receive the errno variable from a connect failure. Note that the value is only set on failure, it is not reset upon a successful operation. The number is OS and system specific.

libcurl network-related errors that may have a saved errno are: CURLE_COULDNT_CONNECT, CURLE_FAILED_INIT, CURLE_INTERFACE_FAILED, CURLE_OPERATION_TIMEDOUT, CURLE_RECV_ERROR, CURLE_SEND_ERROR.

Since 8.8.0 libcurl clears the easy handle's saved errno before performing the transfer. Prior versions did not clear the saved errno, which means if a saved errno is retrieved it could be from a previous transfer on the same handle.

This functionality affects all supported protocols

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);
    if(res != CURLE_OK) {
      long error;
      res = curl_easy_getinfo(curl, CURLINFO_OS_ERRNO, &error);
      if(!res && error) {
        printf("Errno: %ld\n", error);
      }
    }
    curl_easy_cleanup(curl);
  }
}

Added in curl 7.12.2

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.

curl_easy_getinfo(3), curl_easy_setopt(3)

curl_easy_getinfo(3).