mirror of
https://github.com/moparisthebest/curl
synced 2024-12-23 00:28:48 -05:00
79 lines
3.4 KiB
Groff
79 lines
3.4 KiB
Groff
.\" **************************************************************************
|
|
.\" * _ _ ____ _
|
|
.\" * Project ___| | | | _ \| |
|
|
.\" * / __| | | | |_) | |
|
|
.\" * | (__| |_| | _ <| |___
|
|
.\" * \___|\___/|_| \_\_____|
|
|
.\" *
|
|
.\" * Copyright (C) 1998 - 2014, Daniel Stenberg, <daniel@haxx.se>, et al.
|
|
.\" *
|
|
.\" * This software is licensed as described in the file COPYING, which
|
|
.\" * you should have received as part of this distribution. The terms
|
|
.\" * are also available at http://curl.haxx.se/docs/copyright.html.
|
|
.\" *
|
|
.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
|
|
.\" * copies of the Software, and permit persons to whom the Software is
|
|
.\" * furnished to do so, under the terms of the COPYING file.
|
|
.\" *
|
|
.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
|
|
.\" * KIND, either express or implied.
|
|
.\" *
|
|
.\" **************************************************************************
|
|
.\"
|
|
.TH CURLOPT_READFUNCTION 3 "16 Jun 2014" "libcurl 7.37.0" "curl_easy_setopt options"
|
|
.SH NAME
|
|
CURLOPT_READFUNCTION \- read callback for data uploads
|
|
.SH SYNOPSIS
|
|
#include <curl/curl.h>
|
|
|
|
size_t read_callback(char *buffer, size_t size, size_t nitems, void *instream);
|
|
|
|
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_READFUNCTION, read_callback);
|
|
|
|
.SH DESCRIPTION
|
|
Pass a pointer to your callback function, as the prototype shows above.
|
|
|
|
This callback function gets called by libcurl as soon as it needs to read data
|
|
in order to send it to the peer. The data area pointed at by the pointer
|
|
\fIbuffer\fP should be filled up with at most \fIsize\fP multiplied with
|
|
\fInmemb\fP number of bytes by your function.
|
|
|
|
Your function must then return the actual number of bytes that it stored in
|
|
that memory area. Returning 0 will signal end-of-file to the library and cause
|
|
it to stop the current transfer.
|
|
|
|
If you stop the current transfer by returning 0 "pre-maturely" (i.e before the
|
|
server expected it, like when you've said you will upload N bytes and you
|
|
upload less than N bytes), you may experience that the server "hangs" waiting
|
|
for the rest of the data that won't come.
|
|
|
|
The read callback may return \fICURL_READFUNC_ABORT\fP to stop the current
|
|
operation immediately, resulting in a \fICURLE_ABORTED_BY_CALLBACK\fP error
|
|
code from the transfer.
|
|
|
|
The callback can return \fICURL_READFUNC_PAUSE\fP to cause reading from this
|
|
connection to pause. See \fIcurl_easy_pause(3)\fP for further details.
|
|
|
|
\fBBugs\fP: when doing TFTP uploads, you must return the exact amount of data
|
|
that the callback wants, or it will be considered the final packet by the
|
|
server end and the transfer will end there.
|
|
|
|
If you set this callback pointer to NULL, or don't set it at all, the default
|
|
internal read function will be used. It is doing an fread() on the FILE *
|
|
userdata set with \fICURLOPT_READDATA(3)\fP.
|
|
.SH DEFAULT
|
|
The default internal read callback is fread().
|
|
.SH PROTOCOLS
|
|
This is used for all protocols when doing uploads.
|
|
.SH EXAMPLE
|
|
Here's an example setting a read callback for reading that to upload to an FTP
|
|
site: http://curl.haxx.se/libcurl/c/ftpupload.html
|
|
.SH AVAILABILITY
|
|
CURL_READFUNC_PAUSE return code was added in 7.18.0 and CURL_READFUNC_ABORT
|
|
was added in 7.12.1.
|
|
.SH RETURN VALUE
|
|
This will return CURLE_OK.
|
|
.SH "SEE ALSO"
|
|
.BR CURLOPT_READDATA "(3), " CURLOPT_WRITEFUNCTION "(3), "
|
|
.BR CURLOPT_SEEKFUNCTION "(3), "
|