diff mupdf-source/thirdparty/curl/docs/libcurl/curl_easy_pause.3 @ 2:b50eed0cc0ef upstream

ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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+.\" **************************************************************************
+.\" *                                  _   _ ____  _
+.\" *  Project                     ___| | | |  _ \| |
+.\" *                             / __| | | | |_) | |
+.\" *                            | (__| |_| |  _ <| |___
+.\" *                             \___|\___/|_| \_\_____|
+.\" *
+.\" * Copyright (C) 1998 - 2016, 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 https://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 curl_easy_pause 3 "17 Dec 2007" "libcurl 7.18.0" "libcurl Manual"
+.SH NAME
+curl_easy_pause - pause and unpause a connection
+.SH SYNOPSIS
+.B #include <curl/curl.h>
+
+.BI "CURLcode curl_easy_pause(CURL *"handle ", int "bitmask " );"
+
+.SH DESCRIPTION
+Using this function, you can explicitly mark a running connection to get
+paused, and you can unpause a connection that was previously paused.
+
+A connection can be paused by using this function or by letting the read or
+the write callbacks return the proper magic return code
+(\fICURL_READFUNC_PAUSE\fP and \fICURL_WRITEFUNC_PAUSE\fP). A write callback
+that returns pause signals to the library that it couldn't take care of any
+data at all, and that data will then be delivered again to the callback when
+the writing is later unpaused.
+
+While it may feel tempting, take care and notice that you cannot call this
+function from another thread. To unpause, you may for example call it from the
+progress callback (\fICURLOPT_PROGRESSFUNCTION(3)\fP), which gets called at
+least once per second, even if the connection is paused.
+
+When this function is called to unpause reading, the chance is high that you
+will get your write callback called before this function returns.
+
+The \fBhandle\fP argument is of course identifying the handle that operates on
+the connection you want to pause or unpause.
+
+The \fBbitmask\fP argument is a set of bits that sets the new state of the
+connection. The following bits can be used:
+.IP CURLPAUSE_RECV
+Pause receiving data. There will be no data received on this connection until
+this function is called again without this bit set. Thus, the write callback
+(\fICURLOPT_WRITEFUNCTION(3)\fP) won't be called.
+.IP CURLPAUSE_SEND
+Pause sending data. There will be no data sent on this connection until this
+function is called again without this bit set. Thus, the read callback
+(\fICURLOPT_READFUNCTION(3)\fP) won't be called.
+.IP CURLPAUSE_ALL
+Convenience define that pauses both directions.
+.IP CURLPAUSE_CONT
+Convenience define that unpauses both directions.
+.SH RETURN VALUE
+CURLE_OK (zero) means that the option was set properly, and a non-zero return
+code means something wrong occurred after the new state was set.  See the
+\fIlibcurl-errors(3)\fP man page for the full list with descriptions.
+.SH LIMITATIONS
+The pausing of transfers does not work with protocols that work without
+network connectivity, like FILE://. Trying to pause such a transfer, in any
+direction, will cause problems in the worst case or an error in the best case.
+.SH AVAILABILITY
+This function was added in libcurl 7.18.0. Before this version, there was no
+explicit support for pausing transfers.
+.SH "USAGE WITH THE MULTI-SOCKET INTERFACE"
+Before libcurl 7.32.0, when a specific handle was unpaused with this function,
+there was no particular forced rechecking or similar of the socket's state,
+which made the continuation of the transfer get delayed until next
+multi-socket call invoke or even longer. Alternatively, the user could
+forcibly call for example \fIcurl_multi_socket_all(3)\fP - with a rather hefty
+performance penalty.
+
+Starting in libcurl 7.32.0, unpausing a transfer will schedule a timeout
+trigger for that handle 1 millisecond into the future, so that a
+curl_multi_socket_action( ... CURL_SOCKET_TIMEOUT) can be used immediately
+afterwards to get the transfer going again as desired.
+.SH "MEMORY USE"
+When pausing a read by returning the magic return code from a write callback,
+the read data is already in libcurl's internal buffers so it'll have to keep
+it in an allocated buffer until the reading is again unpaused using this
+function.
+
+If the downloaded data is compressed and is asked to get uncompressed
+automatically on download, libcurl will continue to uncompress the entire
+downloaded chunk and it will cache the data uncompressed. This has the side-
+effect that if you download something that is compressed a lot, it can result
+in a very large data amount needing to be allocated to save the data during
+the pause. This said, you should probably consider not using paused reading if
+you allow libcurl to uncompress data automatically.
+.SH "SEE ALSO"
+.BR curl_easy_cleanup "(3), " curl_easy_reset "(3)"