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| .TH CURLOPT_XFERINFOFUNCTION 3 "November 04, 2020" "libcurl 7.78.0" "curl_easy_setopt options" |
| |
| .SH NAME |
| CURLOPT_XFERINFOFUNCTION \- callback to progress meter function |
| .SH SYNOPSIS |
| #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); |
| .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 will be called very |
| 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 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's rarely wanted by |
| users. |
| .SH PROTOCOLS |
| All |
| .SH EXAMPLE |
| https://curl.se/libcurl/c/progressfunc.html |
| .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_XFERINFODATA "(3), " CURLOPT_NOPROGRESS "(3), " |
