CURLOPT_SEEKDATA - pointer passed to the seek callback

Added in curl 7.18.0

If you do not set this, NULL is passed to the callback.

Data pointer to pass to the seek callback function. If you use the CURLOPT_SEEKFUNCTION(3) option, this is the pointer you get as input.

#include <unistd.h> /* for lseek() */ struct data { int our_fd; }; static int seek_cb(void *clientp, curl_off_t offset, int origin) { struct data *d = (struct data *)clientp; lseek(d->our_fd, offset, origin); return CURL_SEEKFUNC_OK; } int main(void) { struct data seek_data; CURL *curl = curl_easy_init(); if(curl) { curl_easy_setopt(curl, CURLOPT_SEEKFUNCTION, seek_cb); curl_easy_setopt(curl, CURLOPT_SEEKDATA, &seek_data); } }

CURLOPT_SEEKDATA - pointer passed to the seek callback

This functionality affects ftp, http and sftp

CURLOPT_DEBUGFUNCTION(3), CURLOPT_IOCTLFUNCTION(3), CURLOPT_SEEKFUNCTION(3), CURLOPT_STDERR(3) libcurl 2025-06-16 CURLOPT_SEEKDATA(3)

#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SEEKDATA, void *pointer);