mirror of
https://codeberg.org/kiss-community/repo
synced 2024-11-19 21:20:07 -07:00
82 lines
2.8 KiB
Groff
82 lines
2.8 KiB
Groff
.\" generated by cd2nroff 0.1 from CURLOPT_SEEKFUNCTION.md
|
|
.TH CURLOPT_SEEKFUNCTION 3 libcurl
|
|
.SH NAME
|
|
CURLOPT_SEEKFUNCTION \- user callback for seeking in input stream
|
|
.SH SYNOPSIS
|
|
.nf
|
|
#include <curl/curl.h>
|
|
|
|
/* These are the return codes for the seek callbacks */
|
|
#define CURL_SEEKFUNC_OK 0
|
|
#define CURL_SEEKFUNC_FAIL 1 /* fail the entire transfer */
|
|
#define CURL_SEEKFUNC_CANTSEEK 2 /* tell libcurl seeking cannot be done, so
|
|
libcurl might try other means instead */
|
|
|
|
int seek_callback(void *clientp, curl_off_t offset, int origin);
|
|
|
|
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SEEKFUNCTION, seek_callback);
|
|
.fi
|
|
.SH DESCRIPTION
|
|
Pass a pointer to your callback function, which should match the prototype
|
|
shown above.
|
|
|
|
This function gets called by libcurl to seek to a certain position in the
|
|
input stream and can be used to fast forward a file in a resumed upload
|
|
(instead of reading all uploaded bytes with the normal read
|
|
function/callback). It is also called to rewind a stream when data has already
|
|
been sent to the server and needs to be sent again. This may happen when doing
|
|
an HTTP PUT or POST with a multi\-pass authentication method, or when an
|
|
existing HTTP connection is reused too late and the server closes the
|
|
connection. The function shall work like fseek(3) or lseek(3) and it gets
|
|
SEEK_SET, SEEK_CUR or SEEK_END as argument for \fIorigin\fP, although libcurl
|
|
currently only passes SEEK_SET.
|
|
|
|
\fIclientp\fP is the pointer you set with \fICURLOPT_SEEKDATA(3)\fP.
|
|
|
|
The callback function must return \fICURL_SEEKFUNC_OK\fP on success,
|
|
\fICURL_SEEKFUNC_FAIL\fP to cause the upload operation to fail or
|
|
\fICURL_SEEKFUNC_CANTSEEK\fP to indicate that while the seek failed, libcurl
|
|
is free to work around the problem if possible. The latter can sometimes be
|
|
done by instead reading from the input or similar.
|
|
|
|
If you forward the input arguments directly to fseek(3) or lseek(3), note that
|
|
the data type for \fIoffset\fP is not the same as defined for curl_off_t on
|
|
many systems!
|
|
.SH DEFAULT
|
|
By default, this is NULL and unused.
|
|
.SH PROTOCOLS
|
|
All
|
|
.SH EXAMPLE
|
|
.nf
|
|
#include <unistd.h> /* for lseek */
|
|
|
|
struct data {
|
|
int our_fd;
|
|
};
|
|
static int seek_cb(void *clientp, curl_off_t offset, int origin)
|
|
{
|
|
struct data *d = (struct data *)clientp;
|
|
lseek(d->our_fd, offset, origin);
|
|
return CURL_SEEKFUNC_OK;
|
|
}
|
|
|
|
int main(void)
|
|
{
|
|
struct data seek_data;
|
|
CURL *curl = curl_easy_init();
|
|
if(curl) {
|
|
curl_easy_setopt(curl, CURLOPT_SEEKFUNCTION, seek_cb);
|
|
curl_easy_setopt(curl, CURLOPT_SEEKDATA, &seek_data);
|
|
}
|
|
}
|
|
.fi
|
|
.SH AVAILABILITY
|
|
Added in 7.18.0
|
|
.SH RETURN VALUE
|
|
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
|
|
.SH SEE ALSO
|
|
.BR CURLOPT_DEBUGFUNCTION (3),
|
|
.BR CURLOPT_IOCTLFUNCTION (3),
|
|
.BR CURLOPT_SEEKDATA (3),
|
|
.BR CURLOPT_STDERR (3)
|