CURLOPT_RESUME_FROM_LARGE - Man Page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_RESUME_FROM_LARGE,
                          curl_off_t from);

Pass a curl_off_t as parameter. It contains the offset in number of bytes that you want the transfer to start from. Set this option to 0 to make the transfer start from the beginning (effectively disabling resume). For FTP, set this option to -1 to make the transfer start from the end of the target file (useful to continue an interrupted upload).

When doing uploads with FTP, the resume position is where in the local/source file libcurl should try to resume the upload from and it appends the source file to the remote target file.

0, not used

This functionality affects all supported protocols

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_off_t resume_position; /* get it somehow */
    curl_off_t file_size; /* get it somehow as well */

    curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com");

    /* resuming upload at this position, possibly beyond 2GB */
    curl_easy_setopt(curl, CURLOPT_RESUME_FROM_LARGE, resume_position);

    /* ask for upload */
    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);

    /* set total data amount to expect */
    curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE, file_size);

    /* Perform the request */
    curl_easy_perform(curl);
  }
}

Added in curl 7.11.0

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

CURLOPT_INFILESIZE_LARGE(3), CURLOPT_RANGE(3), CURLOPT_RESUME_FROM(3)

curl_easy_setopt(3), CURLOPT_RESUME_FROM(3), libcurl-symbols(3).