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| .TH CURLOPT_XFERINFOFUNCTION 3 "17 Jun 2014" libcurl libcurl |
| .SH NAME |
| CURLOPT_XFERINFOFUNCTION \- progress meter callback |
| .SH SYNOPSIS |
| .nf |
| #include <curl/curl.h> |
| |
| int progress_callback(void *clientp, |
| curl_off_t dltotal, |
| curl_off_t dlnow, |
| curl_off_t ultotal, |
| curl_off_t ulnow); |
| |
| CURLcode curl_easy_setopt(CURL *handle, CURLOPT_XFERINFOFUNCTION, |
| progress_callback); |
| .fi |
| .SH DESCRIPTION |
| Pass a pointer to your callback function, which should match the prototype |
| shown above. |
| |
| This function gets called by libcurl instead of its internal equivalent with a |
| frequent interval. While data is being transferred it gets 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_XFERINFODATA(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 is about to transfer and has |
| already 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 are set to zero (like if |
| you only download data, the upload size remains 0). Many times the callback is |
| 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 makes libcurl |
| to continue executing the default progress function. |
| |
| Returning any other non-zero value from this callback makes libcurl abort the |
| transfer and return \fICURLE_ABORTED_BY_CALLBACK\fP. |
| |
| If you transfer data with the multi interface, this function is not 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, |
| curl_off_t dltotal, |
| curl_off_t dlnow, |
| curl_off_t ultotal, |
| curl_off_t 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_XFERINFODATA, &data); |
| |
| curl_easy_setopt(curl_handle, CURLOPT_XFERINFOFUNCTION, progress_callback); |
| .fi |
| .SH AVAILABILITY |
| Added in 7.32.0. This callback replaces \fICURLOPT_PROGRESSFUNCTION(3)\fP |
| .SH RETURN VALUE |
| Returns CURLE_OK. |
| .SH "SEE ALSO" |
| .BR CURLOPT_NOPROGRESS (3), |
| .BR CURLOPT_XFERINFODATA (3) |