CURLOPT_PROGRESSFUNCTION(3)curl_easy_setopt optionsCURLOPT_PROGRESSFUNCTION(3)
NAME
CURLOPT_PROGRESSFUNCTION - progress meter callback
SYNOPSIS
#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);
DESCRIPTION
Pass a pointer to your callback function, which should match the proto-
type shown above.
We encourage users to use the newer CURLOPT_XFERINFOFUNCTION(3) in-
stead, 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.
clientp is the pointer set with CURLOPT_PROGRESSDATA(3), it is not used
by libcurl but is only passed along from the application to the call-
back.
The callback gets told how much data libcurl will transfer and has
transferred, in number of bytes. dltotal is the total number of bytes
libcurl expects to download in this transfer. dlnow is the number of
bytes downloaded so far. ultotal is the total number of bytes libcurl
expects to upload in this transfer. ulnow is the number of bytes up-
loaded 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 CURLE_ABORTED_BY_CALLBACK.
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.
CURLOPT_NOPROGRESS(3) must be set to 0 to make this function actually
get called.
DEFAULT
By default, libcurl has an internal progress meter. That is rarely
wanted by users.
PROTOCOLS
All
EXAMPLE
struct progress {
char *private;
size_t size;
};
static size_t progress_callback(void *clientp,
double dltotal,
double dlnow,
double ultotal,
double ulnow)
{
struct memory *progress = (struct progress *)userp;
/* 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);
AVAILABILITY
Always
RETURN VALUE
Returns CURLE_OK.
SEE ALSO
CURLOPT_VERBOSE(3), CURLOPT_NOPROGRESS(3),
libcurl 7.81.0 November 26, 2021 CURLOPT_PROGRESSFUNCTION(3)
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