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Georg Lippitsch brought CURLOPT_SEEKFUNCTION and CURLOPT_SEEKDATA to allow

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libcurl to seek in a given input stream. This is particularly important when
doing upload resumes when there's already a huge part of the file present
remotely. Before, and still if this callback isn't used, libcurl will read
and through away the entire file up to the point to where the resuming
begins (which of course can be a slow opereration depending on file size,
I/O bandwidth and more). This new function will also be preferred to get
used instead of the CURLOPT_IOCTLFUNCTION for seeking back in a stream when
doing multi-stage HTTP auth with POST/PUT.
This commit is contained in:
Daniel Stenberg
2008-01-10 10:30:19 +00:00
parent 0ce484eed9
commit 18faa50940
10 changed files with 172 additions and 54 deletions
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23
docs/libcurl/curl_easy_setopt.3
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@@ -171,11 +171,32 @@ something special I/O-related needs to be done that the library can't 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 a
HTTP PUT or POST with a multi-pass authentication method. (Option added in
7.12.3)
7.12.3).
Use \fICURLOPT_SEEKFUNCTION\fP instead to provide seeking!
.IP CURLOPT_IOCTLDATA
Pass a pointer that will be untouched by libcurl and passed as the 3rd
argument in the ioctl callback set with \fICURLOPT_IOCTLFUNCTION\fP. (Option
added in 7.12.3)
.IP CURLOPT_SEEKFUNCTION
Function pointer that should match the following prototype: \fIint
function(void *instream, curl_off_t offset, int origin);\fP 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 doing a HTTP PUT or POST with a multi-pass authentication
method. The function shall work like "fseek" or "lseek" and accepted SEEK_SET,
SEEK_CUR and SEEK_END as argument for origin, although (in 7.18.0) libcurl
only passes SEEK_SET. The callback must return 0 on success as returning
non-zero will cause the upload operation to fail.
If you forward the input arguments directly to "fseek" or "lseek", note that
the data type for \fIoffset\fP is not the same as defined for curl_off_t on
many systems! (Option added in 7.18.0)
.IP CURLOPT_SEEKDATA
Data pointer to pass to the file read function. If you use the
\fICURLOPT_SEEKFUNCTION\fP option, this is the pointer you'll get as input. If
you don't specify a seek callback, NULL is passed. (Option added in 7.18.0)
.IP CURLOPT_SOCKOPTFUNCTION
Function pointer that should match the \fIcurl_sockopt_callback\fP prototype
found in \fI<curl/curl.h>\fP. This function gets called by libcurl after the