85 lines
3.5 KiB
Groff
85 lines
3.5 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) 1998 - 2014, 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.haxx.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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.\" **************************************************************************
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.\"
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.TH CURLOPT_PROGRESSFUNCTION 3 "17 Jun 2014" "libcurl 7.37.0" "curl_easy_setopt options"
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.SH NAME
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CURLOPT_PROGRESSFUNCTION \- callback to progress meter function
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.SH SYNOPSIS
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#include <curl/curl.h>
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int progress_callback(void *clientp,
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double dltotal,
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double dlnow,
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double ultotal,
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double ulnow);
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROGRESSFUNCTION, progress_callback);
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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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We encourage users to use the newer \fICURLOPT_XFERINFOFUNCTION(3)\fP instead,
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if you can.
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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 will be called very
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frequently, and during slow periods like when nothing is being transferred it
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can slow down to about one call per second.
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\fIclientp\fP is the pointer set with \fICURLOPT_PROGRESSDATA(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 will transfer and has
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transferred, in number of bytes. \fIdltotal\fP is the total number of bytes
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libcurl expects to download in this transfer. \fIdlnow\fP is the number of
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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 will be set to zero
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(like if you only download data, the upload size will remain 0). Many times
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the callback will be called one or more times first, before it knows the data
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sizes so a program must be made to handle that.
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Returning a non-zero value from this callback will cause libcurl to 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 will not be
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called during periods of idleness unless you call the appropriate libcurl
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function 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's 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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https://curl.haxx.se/libcurl/c/progressfunc.html
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.SH AVAILABILITY
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Always
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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_VERBOSE "(3), " CURLOPT_NOPROGRESS "(3), "
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