curl / libcurl / API / curl_easy_setopt / CURLOPT_COPYPOSTFIELDS

CURLOPT_COPYPOSTFIELDS explained

Name

CURLOPT_COPYPOSTFIELDS - have libcurl copy data to POST

Synopsis

#include <curl/curl.h>
 
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_COPYPOSTFIELDS, char *data);

Description

Pass a char pointer as parameter, which should be the full data to post in a HTTP POST operation. It behaves as the CURLOPT_POSTFIELDS option, but the original data is instead copied by the library, allowing the application to overwrite the original data after setting this option.

Because data is copied, care must be taken when using this option in conjunction with CURLOPT_POSTFIELDSIZE or CURLOPT_POSTFIELDSIZE_LARGE. If the size has not been set prior to CURLOPT_COPYPOSTFIELDS, the data is assumed to be a null-terminated string; else the stored size informs the library about the byte count to copy. In any case, the size must not be changed after CURLOPT_COPYPOSTFIELDS, unless another CURLOPT_POSTFIELDS or CURLOPT_COPYPOSTFIELDS option is set.

The application does not have to keep the string around after setting this option.

Using this option multiple times makes the last set string override the previous ones. Set it to NULL to disable its use again.

Default

NULL

Protocols

This functionality affects http only

Example

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    char local_buffer[1024]="data to send";
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
 
    /* size of the data to copy from the buffer and send in the request */
    curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, 12L);
 
    /* send data from the local stack */
    curl_easy_setopt(curl, CURLOPT_COPYPOSTFIELDS, local_buffer);
 
    curl_easy_perform(curl);
  }
}

Availability

Added in curl 7.17.1

Return value

Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space.