add curl 7.16.0 to in tree libs

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@3744 d0543943-73ff-0310-b7d9-9358b9ac24b2

libs/curl/docs/libcurl/curl_multi_socket.3

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+.\" $Id: curl_multi_socket.3,v 1.7 2006-08-01 08:57:32 bagder Exp $
+.\"
+.TH curl_multi_socket 3 "9 Jul 2006" "libcurl 7.16.0" "libcurl Manual"
+.SH NAME
+curl_multi_socket \- reads/writes available data
+.SH SYNOPSIS
+#include <curl/curl.h>
+
+CURLMcode curl_multi_socket(CURLM * multi_handle, curl_socket_t sockfd,
+                            int *running_handles);
+
+CURLMcode curl_multi_socket_all(CURLM *multi_handle,
+                                int *running_handles);
+.SH DESCRIPTION
+Alternative versions of \fIcurl_multi_perform(3)\fP that allows the
+application to pass in one of the file descriptors/sockets that have been
+detected to have \&"action" on them and let libcurl perform. This allows
+libcurl to not have to scan through all possible file descriptors to check for
+action. When the application has detected action on a socket handled by
+libcurl, it should call \fIcurl_multi_socket(3)\fP with the \fBsockfd\fP
+argument set to the socket with the action.
+
+At return, the int \fBrunning_handles\fP points to will contain the number of
+still running easy handles within the multi handle. When this number reaches
+zero, all transfers are complete/done. Note that when you call
+\fIcurl_multi_socket(3)\fP on a specific socket and the counter decreases by
+one, it DOES NOT necessarily mean that this exact socket/transfer is the one
+that completed. Use \fIcurl_multi_info_read(3)\fP to figure out which easy
+handle that completed.
+
+The curl_multi_socket functions inform the application about updates in the
+socket (file descriptor) status by doing none, one or multiple calls to the
+socket callback function set with the CURLMOPT_SOCKETFUNCTION option to
+\fIcurl_multi_setopt(3)\fP. They update the status with changes since the
+previous time this function was called.
+
+To force libcurl to (re-)check all its internal sockets and transfers instead
+of just a single one, you call \fBcurl_multi_socket_all(3)\fP. This is
+typically done as the first function call before the application has any
+knowledge about what sockets libcurl uses.
+
+Applications should call \fBcurl_multi_timeout(3)\fP to figure out how long to
+wait for socket actions \- at most \- before doing the timeout action: call
+the \fBcurl_multi_socket(3)\fP function with the \fBsockfd\fP argument set to
+CURL_SOCKET_TIMEOUT.
+
+.SH "CALLBACK DETAILS"
+
+The socket \fBcallback\fP function uses a prototype like this
+.nf
+
+  int curl_socket_callback(CURL *easy,      /* easy handle */
+                           curl_socket_t s, /* socket */
+                           int action,      /* see values below */
+                           void *userp,    /* private callback pointer */
+                           void *socketp); /* private socket pointer */
+
+.fi
+The callback MUST return 0.
+
+The \fIeasy\fP argument is a pointer to the easy handle that deals with this
+particular socket. Note that a single handle may work with several sockets
+simultaneously.
+
+The \fIs\fP argument is the actual socket value as you use it within your
+system.
+
+The \fIaction\fP argument to the callback has one of five values:
+.RS
+.IP "CURL_POLL_NONE (0)"
+register, not interested in readiness (yet)
+.IP "CURL_POLL_IN (1)"
+register, interested in read readiness
+.IP "CURL_POLL_OUT (2)"
+register, interested in write readiness
+.IP "CURL_POLL_INOUT (3)"
+register, interested in both read and write readiness
+.IP "CURL_POLL_REMOVE (4)"
+deregister
+.RE
+
+The \fIsocketp\fP argument is a private pointer you have previously set with
+\fIcurl_multi_assign(3)\fP to be associated with the \fIs\fP socket. If no
+pointer has been set, socketp will be NULL. This argument is of course a
+service to applications that want to keep certain data or structs that are
+strictly associated to the given socket.
+
+The \fIuserp\fP argument is a private pointer you have previously set with
+\fIcurl_multi_setopt(3)\fP and the CURLMOPT_SOCKETDATA option.
+.SH "RETURN VALUE"
+CURLMcode type, general libcurl multi interface error code.
+
+If you receive \fICURLM_CALL_MULTI_PERFORM\fP, this basically means that you
+should call \fIcurl_multi_perform\fP again, before you wait for more actions
+on libcurl's sockets. You don't have to do it immediately, but the return code
+means that libcurl may have more data available to return or that there may be
+more data to send off before it is "satisfied".
+
+NOTE that this only returns errors etc regarding the whole multi stack. There
+might still have occurred problems on individual transfers even when this
+function returns OK.
+.SH "TYPICAL USAGE"
+1. Create a multi handle
+
+2. Set the socket callback with CURLMOPT_SOCKETFUNCTION
+
+3. Add easy handles
+
+4. Call curl_multi_socket_all() first once
+
+5. Setup a "collection" of sockets to supervise when your socket
+callback is called.
+
+6. Use curl_multi_timeout() to figure out how long to wait for action
+
+7. Wait for action on any of libcurl's sockets
+
+8, When action happens, call curl_multi_socket() for the socket(s) that got
+action.
+
+9. Go back to step 6.
+.SH AVAILABILITY
+This function was added in libcurl 7.15.4, although not deemed stable yet.
+.SH "SEE ALSO"
+.BR curl_multi_cleanup "(3), " curl_multi_init "(3), "
+.BR curl_multi_fdset "(3), " curl_multi_info_read "(3)"