repo/core/curl/files/CURLOPT_READDATA.3

.\" generated by cd2nroff 0.1 from CURLOPT_READDATA.md
.TH CURLOPT_READDATA 3 "2024-07-29" libcurl
.SH NAME
CURLOPT_READDATA \- pointer passed to the read callback
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_READDATA, void *pointer);
.fi
.SH DESCRIPTION
Data \fIpointer\fP to pass to the file read function. If you use the
\fICURLOPT_READFUNCTION(3)\fP 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 \(aqvoid *\(aq).

If you are using libcurl as a DLL on Windows, you must use the
\fICURLOPT_READFUNCTION(3)\fP callback if you set this option, otherwise you
might experience crashes.
.SH DEFAULT
stdin
.SH PROTOCOLS
This functionality affects all supported protocols
.SH EXAMPLE
.nf
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);
  }
}
.fi
.SH HISTORY
This option was once known by the older name CURLOPT_INFILE, the name
\fICURLOPT_READDATA(3)\fP was introduced in 7.9.7.
.SH AVAILABILITY
Added in curl 7.9.7
.SH RETURN VALUE
This returns CURLE_OK.
.SH SEE ALSO
.BR CURLOPT_HEADERDATA (3),
.BR CURLOPT_READFUNCTION (3),
.BR CURLOPT_WRITEDATA (3),
.BR CURLOPT_WRITEFUNCTION (3)