104 lines
2.5 KiB
Markdown
104 lines
2.5 KiB
Markdown
|
---
|
||
|
|
c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
|
||
|
|
SPDX-License-Identifier: curl
|
||
|
|
Title: CURLOPT_IOCTLFUNCTION
|
||
|
|
Section: 3
|
||
|
|
Source: libcurl
|
||
|
|
See-also:
|
||
|
|
- CURLOPT_IOCTLDATA (3)
|
||
|
|
- CURLOPT_SEEKFUNCTION (3)
|
||
|
|
---
|
||
|
|
|
||
|
|
# NAME
|
||
|
|
|
||
|
|
CURLOPT_IOCTLFUNCTION - callback for I/O operations
|
||
|
|
|
||
|
|
# SYNOPSIS
|
||
|
|
|
||
|
|
~~~c
|
||
|
|
#include <curl/curl.h>
|
||
|
|
|
||
|
|
typedef enum {
|
||
|
|
CURLIOE_OK, /* I/O operation successful */
|
||
|
|
CURLIOE_UNKNOWNCMD, /* command was unknown to callback */
|
||
|
|
CURLIOE_FAILRESTART, /* failed to restart the read */
|
||
|
|
CURLIOE_LAST /* never use */
|
||
|
|
} curlioerr;
|
||
|
|
|
||
|
|
typedef enum {
|
||
|
|
CURLIOCMD_NOP, /* no operation */
|
||
|
|
CURLIOCMD_RESTARTREAD, /* restart the read stream from start */
|
||
|
|
CURLIOCMD_LAST /* never use */
|
||
|
|
} curliocmd;
|
||
|
|
|
||
|
|
curlioerr ioctl_callback(CURL *handle, int cmd, void *clientp);
|
||
|
|
|
||
|
|
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_IOCTLFUNCTION, ioctl_callback);
|
||
|
|
~~~
|
||
|
|
|
||
|
|
# DESCRIPTION
|
||
|
|
|
||
|
|
Pass a pointer to your callback function, which should match the prototype
|
||
|
|
shown above.
|
||
|
|
|
||
|
|
This callback function gets called by libcurl when something special
|
||
|
|
I/O-related needs to be done that the library cannot do by itself. For now,
|
||
|
|
rewinding the read data stream is the only action it can request. The
|
||
|
|
rewinding of the read data stream may be necessary when doing an HTTP PUT or
|
||
|
|
POST with a multi-pass authentication method.
|
||
|
|
|
||
|
|
The callback MUST return *CURLIOE_UNKNOWNCMD* if the input *cmd* is
|
||
|
|
not *CURLIOCMD_RESTARTREAD*.
|
||
|
|
|
||
|
|
The *clientp* argument to the callback is set with the
|
||
|
|
CURLOPT_IOCTLDATA(3) option.
|
||
|
|
|
||
|
|
**This option is deprecated**. Do not use it. Use CURLOPT_SEEKFUNCTION(3)
|
||
|
|
instead to provide seeking! If CURLOPT_SEEKFUNCTION(3) is set, this
|
||
|
|
parameter is ignored when seeking.
|
||
|
|
|
||
|
|
# DEFAULT
|
||
|
|
|
||
|
|
By default, this parameter is set to NULL. Not used.
|
||
|
|
|
||
|
|
# PROTOCOLS
|
||
|
|
|
||
|
|
Used with HTTP
|
||
|
|
|
||
|
|
# EXAMPLE
|
||
|
|
|
||
|
|
~~~c
|
||
|
|
#include <unistd.h> /* for lseek */
|
||
|
|
|
||
|
|
struct data {
|
||
|
|
int fd; /* our file descriptor */
|
||
|
|
};
|
||
|
|
|
||
|
|
static curlioerr ioctl_callback(CURL *handle, int cmd, void *clientp)
|
||
|
|
{
|
||
|
|
struct data *io = (struct data *)clientp;
|
||
|
|
if(cmd == CURLIOCMD_RESTARTREAD) {
|
||
|
|
lseek(io->fd, 0, SEEK_SET);
|
||
|
|
return CURLIOE_OK;
|
||
|
|
}
|
||
|
|
return CURLIOE_UNKNOWNCMD;
|
||
|
|
}
|
||
|
|
int main(void)
|
||
|
|
{
|
||
|
|
struct data ioctl_data;
|
||
|
|
CURL *curl = curl_easy_init();
|
||
|
|
if(curl) {
|
||
|
|
curl_easy_setopt(curl, CURLOPT_IOCTLFUNCTION, ioctl_callback);
|
||
|
|
curl_easy_setopt(curl, CURLOPT_IOCTLDATA, &ioctl_data);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
~~~
|
||
|
|
|
||
|
|
# AVAILABILITY
|
||
|
|
|
||
|
|
Added in 7.12.3. Deprecated since 7.18.0.
|
||
|
|
|
||
|
|
# RETURN VALUE
|
||
|
|
|
||
|
|
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
|