curl/docs/libcurl/opts/CURLOPT_PROGRESSFUNCTION.3
Patrick Monnerat 6967571bf2
lib: feature deprecation warnings in gcc >= 4.3
Add a deprecated attribute to functions and enum values that should not
be used anymore.
This uses a gcc 4.3 dialect, thus is only available for this version of
gcc and newer. Note that the _Pragma() keyword is introduced by C99, but
is available as part of the gcc dialect even when compiling in C89 mode.

It is still possible to disable deprecation at a calling module compile
time by defining CURL_DISABLE_DEPRECATION.

Gcc type checking macros are made aware of possible deprecations.

Some testing support Perl programs are adapted to the extended
declaration syntax.

Several test and unit test C programs intentionally use deprecated
functions/options and are annotated to not generate a warning.

New test 1222 checks the deprecation status in doc and header files.

Closes #9667
2022-11-15 10:57:29 +01:00

119 lines
4.3 KiB
Groff

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.TH CURLOPT_PROGRESSFUNCTION 3 "17 Jun 2014" "libcurl 7.37.0" "curl_easy_setopt options"
.SH NAME
CURLOPT_PROGRESSFUNCTION \- progress meter callback
.SH SYNOPSIS
.nf
#include <curl/curl.h>
int progress_callback(void *clientp,
double dltotal,
double dlnow,
double ultotal,
double ulnow);
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROGRESSFUNCTION,
progress_callback);
.fi
.SH DESCRIPTION
Pass a pointer to your callback function, which should match the prototype
shown above.
This option is deprecated and we encourage users to use the
newer \fICURLOPT_XFERINFOFUNCTION(3)\fP instead, if you can.
This function gets called by libcurl instead of its internal equivalent with a
frequent interval. While data is being transferred it will be called
frequently, and during slow periods like when nothing is being transferred it
can slow down to about one call per second.
\fIclientp\fP is the pointer set with \fICURLOPT_PROGRESSDATA(3)\fP, it is not
used by libcurl but is only passed along from the application to the callback.
The callback gets told how much data libcurl will transfer and has
transferred, in number of bytes. \fIdltotal\fP is the total number of bytes
libcurl expects to download in this transfer. \fIdlnow\fP is the number of
bytes downloaded so far. \fIultotal\fP is the total number of bytes libcurl
expects to upload in this transfer. \fIulnow\fP is the number of bytes
uploaded so far.
Unknown/unused argument values passed to the callback will be set to zero
(like if you only download data, the upload size will remain 0). Many times
the callback will be called one or more times first, before it knows the data
sizes so a program must be made to handle that.
If your callback function returns CURL_PROGRESSFUNC_CONTINUE it will cause
libcurl to continue executing the default progress function.
Returning any other non-zero value from this callback will cause libcurl to
abort the transfer and return \fICURLE_ABORTED_BY_CALLBACK\fP.
If you transfer data with the multi interface, this function will not be
called during periods of idleness unless you call the appropriate libcurl
function that performs transfers.
\fICURLOPT_NOPROGRESS(3)\fP must be set to 0 to make this function actually
get called.
.SH DEFAULT
By default, libcurl has an internal progress meter. That is rarely wanted by
users.
.SH PROTOCOLS
All
.SH EXAMPLE
.nf
struct progress {
char *private;
size_t size;
};
static size_t progress_callback(void *clientp,
double dltotal,
double dlnow,
double ultotal,
double ulnow)
{
struct progress *memory = (struct progress *)clientp;
/* use the values */
return 0; /* all is good */
}
struct progress data;
/* pass struct to callback */
curl_easy_setopt(curl_handle, CURLOPT_PROGRESSDATA, &data);
curl_easy_setopt(curl_handle, CURLOPT_PROGRESSFUNCTION, progress_callback);
.fi
.SH AVAILABILITY
Deprecated since 7.32.0.
.SH RETURN VALUE
Returns CURLE_OK.
.SH "SEE ALSO"
.BR CURLOPT_VERBOSE "(3), " CURLOPT_NOPROGRESS "(3), "
.BR CURLOPT_XFERINFOFUNCTION "(3)"