CURLOPT_READDATA(3) Library Functions Manual CURLOPT_READDATA(3)
NAME
CURLOPT_READDATA - pointer passed to the read callback
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_READDATA, void *pointer);
DESCRIPTION
Data pointer to pass to the file read function. If you use the CUR-
LOPT_READFUNCTION(3) option, this is the pointer you get as input in the
fourth argument to the callback.
If you do not specify a read callback but instead rely on the default
internal read function, this data must be a valid readable FILE * (cast
to 'void *').
If you are using libcurl as a DLL on Windows, you must use the CUR-
LOPT_READFUNCTION(3) callback if you set this option, otherwise you
might experience crashes.
DEFAULT
stdin
PROTOCOLS
This functionality affects all supported protocols
EXAMPLE
struct MyData {
void *custom;
};
int main(void)
{
CURL *curl = curl_easy_init();
struct MyData this;
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
/* pass pointer that gets passed in to the
CURLOPT_READFUNCTION callback */
curl_easy_setopt(curl, CURLOPT_READDATA, &this);
curl_easy_perform(curl);
}
}
HISTORY
This option was once known by the older name CURLOPT_INFILE, the name
CURLOPT_READDATA(3) was introduced in 7.9.7.
AVAILABILITY
Added in curl 7.9.7
RETURN VALUE
This returns CURLE_OK.
SEE ALSO
CURLOPT_HEADERDATA(3), CURLOPT_READFUNCTION(3), CURLOPT_WRITEDATA(3),
CURLOPT_WRITEFUNCTION(3)
libcurl 2026-07-12 CURLOPT_READDATA(3)
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