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116 lines
4.2 KiB
Groff
116 lines
4.2 KiB
Groff
.\" **************************************************************************
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.\" * _ _ ____ _
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.\" * Project ___| | | | _ \| |
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.\" * / __| | | | |_) | |
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.\" * | (__| |_| | _ <| |___
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.\" * \___|\___/|_| \_\_____|
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.\" *
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.\" * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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.\" *
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.\" * This software is licensed as described in the file COPYING, which
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.\" * you should have received as part of this distribution. The terms
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.\" * are also available at https://curl.se/docs/copyright.html.
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.\" *
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.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
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.\" * copies of the Software, and permit persons to whom the Software is
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.\" * furnished to do so, under the terms of the COPYING file.
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.\" *
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.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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.\" * KIND, either express or implied.
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.\" *
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.\" * SPDX-License-Identifier: curl
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.\" *
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.\" **************************************************************************
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.\"
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.TH CURLOPT_XFERINFOFUNCTION 3 "17 Jun 2014" libcurl libcurl
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.SH NAME
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CURLOPT_XFERINFOFUNCTION \- progress meter callback
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.SH SYNOPSIS
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.nf
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#include <curl/curl.h>
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int progress_callback(void *clientp,
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curl_off_t dltotal,
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curl_off_t dlnow,
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curl_off_t ultotal,
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curl_off_t ulnow);
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_XFERINFOFUNCTION,
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progress_callback);
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.fi
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.SH DESCRIPTION
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Pass a pointer to your callback function, which should match the prototype
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shown above.
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This function gets called by libcurl instead of its internal equivalent with a
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frequent interval. While data is being transferred it gets called frequently,
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and during slow periods like when nothing is being transferred it can slow
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down to about one call per second.
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\fIclientp\fP is the pointer set with \fICURLOPT_XFERINFODATA(3)\fP, it is not
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used by libcurl but is only passed along from the application to the callback.
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The callback gets told how much data libcurl is about to transfer and has
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already transferred, in number of bytes. \fIdltotal\fP is the total number of
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bytes libcurl expects to download in this transfer. \fIdlnow\fP is the number
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of bytes downloaded so far. \fIultotal\fP is the total number of bytes libcurl
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expects to upload in this transfer. \fIulnow\fP is the number of bytes
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uploaded so far.
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Unknown/unused argument values passed to the callback are set to zero (like if
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you only download data, the upload size remains 0). Many times the callback is
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called one or more times first, before it knows the data sizes so a program
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must be made to handle that.
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If your callback function returns CURL_PROGRESSFUNC_CONTINUE it makes libcurl
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to continue executing the default progress function.
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Returning any other non-zero value from this callback makes libcurl abort the
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transfer and return \fICURLE_ABORTED_BY_CALLBACK\fP.
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If you transfer data with the multi interface, this function is not called
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during periods of idleness unless you call the appropriate libcurl function
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that performs transfers.
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\fICURLOPT_NOPROGRESS(3)\fP must be set to 0 to make this function actually
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get called.
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.SH DEFAULT
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By default, libcurl has an internal progress meter. That is rarely wanted by
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users.
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.SH PROTOCOLS
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All
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.SH EXAMPLE
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.nf
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struct progress {
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char *private;
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size_t size;
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};
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static size_t progress_callback(void *clientp,
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curl_off_t dltotal,
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curl_off_t dlnow,
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curl_off_t ultotal,
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curl_off_t ulnow)
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{
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struct progress *memory = (struct progress *)clientp;
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/* use the values */
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return 0; /* all is good */
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}
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struct progress data;
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/* pass struct to callback */
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curl_easy_setopt(curl_handle, CURLOPT_XFERINFODATA, &data);
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curl_easy_setopt(curl_handle, CURLOPT_XFERINFOFUNCTION, progress_callback);
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.fi
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.SH AVAILABILITY
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Added in 7.32.0. This callback replaces \fICURLOPT_PROGRESSFUNCTION(3)\fP
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.SH RETURN VALUE
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Returns CURLE_OK.
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.SH "SEE ALSO"
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.BR CURLOPT_NOPROGRESS (3),
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.BR CURLOPT_XFERINFODATA (3)
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