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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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22 .TH curl_multi_socket 3 "9 Jul 2006" "libcurl 7.16.0" "libcurl Manual"
23 .SH NAME
24 curl_multi_socket \- reads/writes available data
25 .SH SYNOPSIS
26 .nf
27 #include <curl/curl.h>
28 CURLMcode curl_multi_socket(CURLM * multi_handle, curl_socket_t sockfd,
29 int *running_handles);
30
31 CURLMcode curl_multi_socket_all(CURLM *multi_handle,
32 int *running_handles);
33 .fi
34 .SH DESCRIPTION
35 These functions are deprecated. Do not use! See
36 \fIcurl_multi_socket_action(3)\fP instead!
37
38 At return, the integer \fBrunning_handles\fP points to will contain the number
39 of still running easy handles within the multi handle. When this number
40 reaches zero, all transfers are complete/done. Note that when you call
41 \fIcurl_multi_socket_action(3)\fP on a specific socket and the counter
42 decreases by one, it DOES NOT necessarily mean that this exact socket/transfer
43 is the one that completed. Use \fIcurl_multi_info_read(3)\fP to figure out
44 which easy handle that completed.
45
46 The \fIcurl_multi_socket_action(3)\fP functions inform the application about
47 updates in the socket (file descriptor) status by doing none, one, or multiple
48 calls to the socket callback function set with the
49 \fICURLMOPT_SOCKETFUNCTION(3)\fP option to \fIcurl_multi_setopt(3)\fP. They
50 update the status with changes since the previous time the callback was
51 called.
52
53 Get the timeout time by setting the \fICURLMOPT_TIMERFUNCTION(3)\fP option
54 with \fIcurl_multi_setopt(3)\fP. Your application will then get called with
55 information on how long to wait for socket actions at most before doing the
56 timeout action: call the \fIcurl_multi_socket_action(3)\fP function with the
57 \fBsockfd\fP argument set to CURL_SOCKET_TIMEOUT. You can also use the
58 \fIcurl_multi_timeout(3)\fP function to poll the value at any given time, but
59 for an event-based system using the callback is far better than relying on
60 polling the timeout value.
61
62 Usage of \fIcurl_multi_socket(3)\fP is deprecated, whereas the function is
63 equivalent to \fIcurl_multi_socket_action(3)\fP with \fBev_bitmask\fP set to
64 0.
65
66 Force libcurl to (re-)check all its internal sockets and transfers instead of
67 just a single one by calling \fIcurl_multi_socket_all(3)\fP. Note that there
68 should not be any reason to use this function!
69 .SH "CALLBACK DETAILS"
70
71 The socket \fBcallback\fP function uses a prototype like this
72 .nf
73
74 int curl_socket_callback(CURL *easy, /* easy handle */
75 curl_socket_t s, /* socket */
76 int action, /* see values below */
77 void *userp, /* private callback pointer */
78 void *socketp); /* private socket pointer */
79
80 .fi
81 The callback MUST return 0.
82
83 The \fIeasy\fP argument is a pointer to the easy handle that deals with this
84 particular socket. Note that a single handle may work with several sockets
85 simultaneously.
86
87 The \fIs\fP argument is the actual socket value as you use it within your
88 system.
89
90 The \fIaction\fP argument to the callback has one of five values:
91 .RS
92 .IP "CURL_POLL_NONE (0)"
93 register, not interested in readiness (yet)
94 .IP "CURL_POLL_IN (1)"
95 register, interested in read readiness
96 .IP "CURL_POLL_OUT (2)"
97 register, interested in write readiness
98 .IP "CURL_POLL_INOUT (3)"
99 register, interested in both read and write readiness
100 .IP "CURL_POLL_REMOVE (4)"
101 unregister
102 .RE
103
104 The \fIsocketp\fP argument is a private pointer you have previously set with
105 \fIcurl_multi_assign(3)\fP to be associated with the \fIs\fP socket. If no
106 pointer has been set, socketp will be NULL. This argument is of course a
107 service to applications that want to keep certain data or structs that are
108 strictly associated to the given socket.
109
110 The \fIuserp\fP argument is a private pointer you have previously set with
111 \fIcurl_multi_setopt(3)\fP and the \fICURLMOPT_SOCKETDATA(3)\fP option.
112 .SH "RETURN VALUE"
113 CURLMcode type, general libcurl multi interface error code.
114
115 Legacy: If you receive \fICURLM_CALL_MULTI_PERFORM\fP, this basically means
116 that you should call \fIcurl_multi_socket(3)\fP again, before you wait for
117 more actions on libcurl's sockets. You don't have to do it immediately, but
118 the return code means that libcurl may have more data available to return or
119 that there may be more data to send off before it is "satisfied".
120
121 In modern libcurls, \fICURLM_CALL_MULTI_PERFORM\fP or
122 \fICURLM_CALL_MULTI_SOCKET\fP should not be returned and no application needs
123 to care about them.
124
125 NOTE that the return code is for the whole multi stack. Problems still might have
126 occurred on individual transfers even when one of these functions
127 return OK.
128 .SH "TYPICAL USAGE"
129 1. Create a multi handle
130
131 2. Set the socket callback with \fICURLMOPT_SOCKETFUNCTION(3)\fP
132
133 3. Set the timeout callback with \fICURLMOPT_TIMERFUNCTION(3)\fP, to get to
134 know what timeout value to use when waiting for socket activities.
135
136 4. Add easy handles with curl_multi_add_handle()
137
138 5. Provide some means to manage the sockets libcurl is using, so you can check
139 them for activity. This can be done through your application code, or by way
140 of an external library such as libevent or glib.
141
142 6. Wait for activity on any of libcurl's sockets, use the timeout value your
143 callback has been told
144
145 7, When activity is detected, call curl_multi_socket_action() for the
146 socket(s) that got action. If no activity is detected and the timeout expires,
147 call \fIcurl_multi_socket_action(3)\fP with \fICURL_SOCKET_TIMEOUT\fP
148
149 8. Go back to step 6.
150 .SH AVAILABILITY
151 This function was added in libcurl 7.15.4, and is deemed stable since
152 7.16.0.
153
154 \fIcurl_multi_socket(3)\fP is deprecated, use
155 \fIcurl_multi_socket_action(3)\fP instead!
156 .SH "SEE ALSO"
157 .BR curl_multi_cleanup "(3), " curl_multi_init "(3), "
158 .BR curl_multi_fdset "(3), " curl_multi_info_read "(3), "
159 .BR "the hiperfifo.c example"