diff options
Diffstat (limited to 'docs/libcurl')
| -rw-r--r-- | docs/libcurl/opts/CURLOPT_WRITEFUNCTION.3 | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/docs/libcurl/opts/CURLOPT_WRITEFUNCTION.3 b/docs/libcurl/opts/CURLOPT_WRITEFUNCTION.3 new file mode 100644 index 000000000..7e9bbb504 --- /dev/null +++ b/docs/libcurl/opts/CURLOPT_WRITEFUNCTION.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_WRITEFUNCTION 3 "16 Jun 2014" "libcurl 7.37.0" "curl_easy_setopt options" +.SH NAME +CURLOPT_WRITEFUNCTION \- set callback for writing received data +.SH SYNOPSIS +.nf +#include <curl/curl.h> + +size_t write_callback(char *ptr, size_t size, size_t nmemb, void *userdata); + +CURLcode curl_easy_setopt(CURL *handle, CURLOPT_WRITEFUNCTION, write_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 there is data +received that needs to be saved. \fIptr\fP points to the delivered data, and +the size of that data is \fIsize\fP multiplied with \fInmemb\fP. + +The received data will not be zero terminated! + +Return the number of bytes actually taken care of. If that amount differs from +the amount passed to your callback function, it'll signal an error condition +to the library. This will cause the transfer to get aborted and return +\fICURLE_WRITE_ERROR\fP. + +The callback function can return CURL_WRITEFUNC_PAUSE which then will cause +writing to this connection to become paused. See \fIcurl_easy_pause(3)\fP for +further details. + +This function may be called with zero bytes data if the transferred file is +empty. + +Set this option to NULL to get the internal default function used instead of +your callback. The internal default function will write the data to the FILE * +given with \fICURLOPT_WRITEDATA(3)\fP. + +Set the \fIuserdata\fP argument with the \fICURLOPT_WRITEDATA(3)\fP option. + +The callback function will be passed as much data as possible in all invokes, +but you cannot possibly make any assumptions. It may be one byte, it may be +thousands. The maximum amount of body data that can be passed to the write +callback is defined in the curl.h header file: CURL_MAX_WRITE_SIZE (the usual +default is 16K). If you however have \fICURLOPT_HEADER(3)\fP set, which sends +header data to the write callback, you can get up to +\fICURL_MAX_HTTP_HEADER\fP bytes of header data passed into it. This usually +means 100K. +.SH PROTOCOLS +For all protocols +.SH AVAILABILITY +Support for the CURL_WRITEFUNC_PAUSE return code was added in version 7.18.0. +.SH EXAMPLE +A common technique is to use this callback to store the incoming data into a +dynamically growing allocated buffer. Like in the getinmemory example: +http://curl.haxx.se/libcurl/c/getinmemory.html +.SH "SEE ALSO" +.BR CURLOPT_WRITEDATA "(3), " CURLOPT_READFUNCTION "(3), " |