100 lines
3.7 KiB
Groff
100 lines
3.7 KiB
Groff
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.\" **************************************************************************
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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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.TH curl_multi_info_read 3 "August 22, 2023" "libcurl 8.3.0" "libcurl"
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.SH NAME
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curl_multi_info_read - read multi stack information
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.SH SYNOPSIS
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.nf
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#include <curl/curl.h>
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CURLMsg *curl_multi_info_read(CURLM *multi_handle, int *msgs_in_queue);
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.fi
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.SH DESCRIPTION
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Ask the multi handle if there are any messages from the individual
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transfers. Messages may include information such as an error code from the
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transfer or just the fact that a transfer is completed. More details on these
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should be written down as well.
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Repeated calls to this function returns a new struct each time, until a NULL
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is returned as a signal that there is no more to get at this point. The
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integer pointed to with \fImsgs_in_queue\fP contains the number of remaining
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messages after this function was called.
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When you fetch a message using this function, it is removed from the internal
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queue so calling this function again does not return the same message
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again. It instead returns new messages at each new invoke until the queue is
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emptied.
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\fBWARNING:\fP The data the returned pointer points to does not survive
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calling \fIcurl_multi_cleanup(3)\fP, \fIcurl_multi_remove_handle(3)\fP or
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\fIcurl_easy_cleanup(3)\fP.
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The \fICURLMsg\fP struct is simple and only contains basic information. If
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more involved information is wanted, the particular "easy handle" is present
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in that struct and can be used in subsequent regular
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\fIcurl_easy_getinfo(3)\fP calls (or similar):
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.nf
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struct CURLMsg {
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CURLMSG msg; /* what this message means */
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CURL *easy_handle; /* the handle it concerns */
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union {
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void *whatever; /* message-specific data */
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CURLcode result; /* return code for transfer */
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} data;
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};
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.fi
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When \fBmsg\fP is \fICURLMSG_DONE\fP, the message identifies a transfer that
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is done, and then \fBresult\fP contains the return code for the easy handle
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that just completed.
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At this point, there are no other \fBmsg\fP types defined.
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.SH EXAMPLE
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.nf
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struct CURLMsg *m;
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/* call curl_multi_perform or curl_multi_socket_action first, then loop
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through and check if there are any transfers that have completed */
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do {
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int msgq = 0;
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m = curl_multi_info_read(multi_handle, &msgq);
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if(m && (m->msg == CURLMSG_DONE)) {
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CURL *e = m->easy_handle;
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transfers--;
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curl_multi_remove_handle(multi_handle, e);
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curl_easy_cleanup(e);
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}
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} while(m);
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.fi
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.SH AVAILABILITY
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Added in 7.9.6
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.SH RETURN VALUE
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A pointer to a filled-in struct, or NULL if it failed or ran out of
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structs. It also writes the number of messages left in the queue (after this
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read) in the integer the second argument points to.
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.SH "SEE ALSO"
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.BR curl_multi_cleanup "(3), " curl_multi_init "(3), " curl_multi_perform "(3)"
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