Manpages - CURLINFO_CONDITION_UNMET.3

CURLINFO_CONDITION_UNMET - get info on unmet time conditional or 304 HTTP response.

#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_CONDITION_UNMET, long *unmet);

Pass a pointer to a long to receive the number 1 if the condition provided in the previous request did not match (see CURLOPT_TIMECONDITION(3)). Alas, if this returns a 1 you know that the reason you did not get data in return is because it did not fulfill the condition. The long this argument points to will get a zero stored if the condition instead was met. This can also return 1 if the server responded with a 304 HTTP status code, for example after sending a custom “If-Match-*” header.

HTTP and some

  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

    /* January 1, 2020 is 1577833200 */
    curl_easy_setopt(curl, CURLOPT_TIMEVALUE, 1577833200L);

    /* If-Modified-Since the above time stamp */
    curl_easy_setopt(curl, CURLOPT_TIMECONDITION, CURL_TIMECOND_IFMODSINCE);

    /* Perform the request */
    res = curl_easy_perform(curl);

    if(!res) {
      /* check the time condition */
      long unmet;
      res = curl_easy_getinfo(curl, CURLINFO_CONDITION_UNMET, &unmet);
      if(!res) {
        printf("The time condition was %sfulfilled\n", unmet?"NOT":"");
      }
    }
  }

Added in 7.19.4

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

*curl_easy_getinfo*(3), *curl_easy_setopt*(3),