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Sortix volatile manual

This manual documents Sortix volatile, a development build that has not been officially released. You can instead view this document in the latest official manual.

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 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

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)
2025-05-13 libcurl
Copyright 2011-2025 Jonas 'Sortie' Termansen and contributors.
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