--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/curl/docs/libcurl/opts/CURLOPT_SOCKOPTFUNCTION.3	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,124 @@
+.\" **************************************************************************
+.\" *                                  _   _ ____  _
+.\" *  Project                     ___| | | |  _ \| |
+.\" *                             / __| | | | |_) | |
+.\" *                            | (__| |_| |  _ <| |___
+.\" *                             \___|\___/|_| \_\_____|
+.\" *
+.\" * Copyright (C) 1998 - 2017, 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 CURLOPT_SOCKOPTFUNCTION 3 "16 Jun 2014" "libcurl 7.37.0" "curl_easy_setopt options"
+.SH NAME
+CURLOPT_SOCKOPTFUNCTION \- set callback for setting socket options
+.SH SYNOPSIS
+.nf
+#include <curl/curl.h>
+
+typedef enum  {
+  CURLSOCKTYPE_IPCXN,  /* socket created for a specific IP connection */
+  CURLSOCKTYPE_ACCEPT, /* socket created by accept() call */
+  CURLSOCKTYPE_LAST    /* never use */
+} curlsocktype;
+
+#define CURL_SOCKOPT_OK 0
+#define CURL_SOCKOPT_ERROR 1 /* causes libcurl to abort and return
+                                CURLE_ABORTED_BY_CALLBACK */
+#define CURL_SOCKOPT_ALREADY_CONNECTED 2
+
+int sockopt_callback(void *clientp,
+                     curl_socket_t curlfd,
+                     curlsocktype purpose);
+
+CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);
+.SH DESCRIPTION
+Pass a pointer to your callback function, which should match the prototype
+shown above.
+
+When set, this callback function gets called by libcurl when the socket has
+been created, but before the connect call to allow applications to change
+specific socket options. The callback's \fIpurpose\fP argument identifies the
+exact purpose for this particular socket:
+
+\fICURLSOCKTYPE_IPCXN\fP for actively created connections or since 7.28.0
+\fICURLSOCKTYPE_ACCEPT\fP for FTP when the connection was setup with PORT/EPSV
+(in earlier versions these sockets weren't passed to this callback).
+
+Future versions of libcurl may support more purposes. libcurl passes the newly
+created socket descriptor to the callback in the \fIcurlfd\fP parameter so
+additional setsockopt() calls can be done at the user's discretion.
+
+The \fIclientp\fP pointer contains whatever user-defined value set using the
+\fICURLOPT_SOCKOPTDATA(3)\fP function.
+
+Return \fICURL_SOCKOPT_OK\fP from the callback on success. Return
+\fICURL_SOCKOPT_ERROR\fP from the callback function to signal an unrecoverable
+error to the library and it will close the socket and return
+\fICURLE_COULDNT_CONNECT\fP.
+Alternatively, the callback function can return
+\fICURL_SOCKOPT_ALREADY_CONNECTED\fP, to tell libcurl that the socket is
+already connected and then libcurl will not attempt to connect it. This allows
+an application to pass in an already connected socket with
+\fICURLOPT_OPENSOCKETFUNCTION(3)\fP and then have this function make libcurl
+not attempt to connect (again).
+.SH DEFAULT
+By default, this callback is NULL and unused.
+.SH PROTOCOLS
+All
+.SH EXAMPLE
+.nf
+/* make libcurl use the already established socket 'sockfd' */
+
+static curl_socket_t opensocket(void *clientp,
+                                curlsocktype purpose,
+                                struct curl_sockaddr *address)
+{
+  curl_socket_t sockfd;
+  sockfd = *(curl_socket_t *)clientp;
+  /* the actual externally set socket is passed in via the OPENSOCKETDATA
+     option */
+  return sockfd;
+}
+
+static int sockopt_callback(void *clientp, curl_socket_t curlfd,
+                            curlsocktype purpose)
+{
+  /* This return code was added in libcurl 7.21.5 */
+  return CURL_SOCKOPT_ALREADY_CONNECTED;
+}
+
+curl = curl_easy_init();
+if(curl) {
+  /* libcurl will internally think that you connect to the host
+   * and port that you specify in the URL option. */
+  curl_easy_setopt(curl, CURLOPT_URL, "http://99.99.99.99:9999");
+  /* call this function to get a socket */
+  curl_easy_setopt(curl, CURLOPT_OPENSOCKETFUNCTION, opensocket);
+  curl_easy_setopt(curl, CURLOPT_OPENSOCKETDATA, &sockfd);
+
+  /* call this function to set options for the socket */
+  curl_easy_setopt(curl, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);
+
+  res = curl_easy_perform(curl);
+
+  curl_easy_cleanup(curl);
+.fi
+.SH AVAILABILITY
+Added in 7.16.0. The \fICURL_SOCKOPT_ALREADY_CONNECTED\fP return code was
+added in 7.21.5.
+.SH RETURN VALUE
+Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
+.SH "SEE ALSO"
+.BR CURLOPT_SOCKOPTDATA "(3), " CURLOPT_OPENSOCKETFUNCTION "(3), "