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23 .TH CURLOPT_PROGRESSFUNCTION 3 "February 03, 2016" "libcurl 7.59.0" "curl_easy_setopt options"
26 CURLOPT_PROGRESSFUNCTION \- callback to progress meter function
28 #include <curl/curl.h>
30 int progress_callback(void *clientp,
36 CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROGRESSFUNCTION, progress_callback);
38 Pass a pointer to your callback function, which should match the prototype
41 We encourage users to use the newer \fICURLOPT_XFERINFOFUNCTION(3)\fP instead,
44 This function gets called by libcurl instead of its internal equivalent with a
45 frequent interval. While data is being transferred it will be called very
46 frequently, and during slow periods like when nothing is being transferred it
47 can slow down to about one call per second.
49 \fIclientp\fP is the pointer set with \fICURLOPT_PROGRESSDATA(3)\fP, it is not
50 used by libcurl but is only passed along from the application to the callback.
52 The callback gets told how much data libcurl will transfer and has
53 transferred, in number of bytes. \fIdltotal\fP is the total number of bytes
54 libcurl expects to download in this transfer. \fIdlnow\fP is the number of
55 bytes downloaded so far. \fIultotal\fP is the total number of bytes libcurl
56 expects to upload in this transfer. \fIulnow\fP is the number of bytes
59 Unknown/unused argument values passed to the callback will be set to zero
60 (like if you only download data, the upload size will remain 0). Many times
61 the callback will be called one or more times first, before it knows the data
62 sizes so a program must be made to handle that.
64 Returning a non-zero value from this callback will cause libcurl to abort the
65 transfer and return \fICURLE_ABORTED_BY_CALLBACK\fP.
67 If you transfer data with the multi interface, this function will not be
68 called during periods of idleness unless you call the appropriate libcurl
69 function that performs transfers.
71 \fICURLOPT_NOPROGRESS(3)\fP must be set to 0 to make this function actually
74 By default, libcurl has an internal progress meter. That's rarely wanted by
79 https://curl.haxx.se/libcurl/c/progressfunc.html
85 .BR CURLOPT_VERBOSE "(3), " CURLOPT_NOPROGRESS "(3), "