Annotation of embedaddon/curl/docs/libcurl/opts/CURLOPT_PROGRESSFUNCTION.3, revision 1.1.1.1
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23: .TH CURLOPT_PROGRESSFUNCTION 3 "March 23, 2020" "libcurl 7.70.0" "curl_easy_setopt options"
24:
25: .SH NAME
26: CURLOPT_PROGRESSFUNCTION \- callback to progress meter function
27: .SH SYNOPSIS
28: #include <curl/curl.h>
29:
30: int progress_callback(void *clientp,
31: double dltotal,
32: double dlnow,
33: double ultotal,
34: double ulnow);
35:
36: CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROGRESSFUNCTION, progress_callback);
37: .SH DESCRIPTION
38: Pass a pointer to your callback function, which should match the prototype
39: shown above.
40:
41: We encourage users to use the newer \fICURLOPT_XFERINFOFUNCTION(3)\fP instead,
42: if you can.
43:
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.
48:
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.
51:
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
57: uploaded so far.
58:
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.
63:
64: If your callback function returns CURL_PROGRESSFUNC_CONTINUE it will cause
65: libcurl to continue executing the default progress function.
66:
67: Returning any other non-zero value from this callback will cause libcurl to
68: abort the transfer and return \fICURLE_ABORTED_BY_CALLBACK\fP.
69:
70: If you transfer data with the multi interface, this function will not be
71: called during periods of idleness unless you call the appropriate libcurl
72: function that performs transfers.
73:
74: \fICURLOPT_NOPROGRESS(3)\fP must be set to 0 to make this function actually
75: get called.
76: .SH DEFAULT
77: By default, libcurl has an internal progress meter. That's rarely wanted by
78: users.
79: .SH PROTOCOLS
80: All
81: .SH EXAMPLE
82: https://curl.haxx.se/libcurl/c/progressfunc.html
83: .SH AVAILABILITY
84: Always
85: .SH RETURN VALUE
86: Returns CURLE_OK.
87: .SH "SEE ALSO"
88: .BR CURLOPT_VERBOSE "(3), " CURLOPT_NOPROGRESS "(3), "
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