105 lines
3.5 KiB
Groff
105 lines
3.5 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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.\"
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.TH CURLOPT_IOCTLFUNCTION 3 "16 Jun 2014" libcurl libcurl
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.SH NAME
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CURLOPT_IOCTLFUNCTION \- callback for I/O operations
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.SH SYNOPSIS
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.nf
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#include <curl/curl.h>
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typedef enum {
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CURLIOE_OK, /* I/O operation successful */
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CURLIOE_UNKNOWNCMD, /* command was unknown to callback */
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CURLIOE_FAILRESTART, /* failed to restart the read */
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CURLIOE_LAST /* never use */
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} curlioerr;
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typedef enum {
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CURLIOCMD_NOP, /* no operation */
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CURLIOCMD_RESTARTREAD, /* restart the read stream from start */
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CURLIOCMD_LAST /* never use */
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} curliocmd;
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curlioerr ioctl_callback(CURL *handle, int cmd, void *clientp);
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_IOCTLFUNCTION, ioctl_callback);
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.SH DESCRIPTION
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Pass a pointer to your callback function, which should match the prototype
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shown above.
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This callback function gets called by libcurl when something special
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I/O-related needs to be done that the library cannot do by itself. For now,
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rewinding the read data stream is the only action it can request. The
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rewinding of the read data stream may be necessary when doing an HTTP PUT or
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POST with a multi-pass authentication method.
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The callback MUST return \fICURLIOE_UNKNOWNCMD\fP if the input \fIcmd\fP is
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not \fICURLIOCMD_RESTARTREAD\fP.
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The \fIclientp\fP argument to the callback is set with the
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\fICURLOPT_IOCTLDATA(3)\fP option.
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This option is deprecated! Do not use it. Use \fICURLOPT_SEEKFUNCTION(3)\fP
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instead to provide seeking! If \fICURLOPT_SEEKFUNCTION(3)\fP is set, this
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parameter is ignored when seeking.
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.SH DEFAULT
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By default, this parameter is set to NULL. Not used.
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.SH PROTOCOLS
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Used with HTTP
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.SH EXAMPLE
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.nf
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#include <unistd.h> /* for lseek */
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struct data {
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int fd; /* our file descriptor */
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};
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static curlioerr ioctl_callback(CURL *handle, int cmd, void *clientp)
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{
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struct data *io = (struct data *)clientp;
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if(cmd == CURLIOCMD_RESTARTREAD) {
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lseek(io->fd, 0, SEEK_SET);
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return CURLIOE_OK;
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}
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return CURLIOE_UNKNOWNCMD;
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}
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int main(void)
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{
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struct data ioctl_data;
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CURL *curl = curl_easy_init();
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if(curl) {
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curl_easy_setopt(curl, CURLOPT_IOCTLFUNCTION, ioctl_callback);
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curl_easy_setopt(curl, CURLOPT_IOCTLDATA, &ioctl_data);
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}
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}
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.fi
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.SH AVAILABILITY
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Added in 7.12.3. Deprecated since 7.18.0.
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.SH RETURN VALUE
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Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
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.SH "SEE ALSO"
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.BR CURLOPT_IOCTLDATA (3),
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.BR CURLOPT_SEEKFUNCTION (3)
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