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Diffstat (limited to 'docs/libcurl/opts/CURLOPT_READFUNCTION.3')
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diff --git a/docs/libcurl/opts/CURLOPT_READFUNCTION.3 b/docs/libcurl/opts/CURLOPT_READFUNCTION.3 new file mode 100644 index 000000000..6e7326e4b --- /dev/null +++ b/docs/libcurl/opts/CURLOPT_READFUNCTION.3 @@ -0,0 +1,77 @@ +.\" ************************************************************************** +.\" * _ _ ____ _ +.\" * 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 \- [short desc] +.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), " |