curl-w32/docs/libcurl/opts/CURLOPT_READDATA.md

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---
c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_READDATA
Section: 3
Source: libcurl
See-also:
- CURLOPT_HEADERDATA (3)
- CURLOPT_READFUNCTION (3)
- CURLOPT_WRITEDATA (3)
- CURLOPT_WRITEFUNCTION (3)
---
# NAME
CURLOPT_READDATA - pointer passed to the read callback
# SYNOPSIS
~~~c
#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
CURLOPT_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
CURLOPT_READFUNCTION(3) callback if you set this option, otherwise you
might experience crashes.
# DEFAULT
By default, this is a FILE * to stdin.
# PROTOCOLS
This is used for all protocols when sending data.
# EXAMPLE
~~~c
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);
}
}
~~~
# AVAILABILITY
This option was once known by the older name CURLOPT_INFILE, the name
CURLOPT_READDATA(3) was introduced in 7.9.7.
# RETURN VALUE
This returns CURLE_OK.