Annotation of embedaddon/curl/docs/libcurl/opts/CURLOPT_XFERINFOFUNCTION.3, revision 1.1.1.1
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23: .TH CURLOPT_XFERINFOFUNCTION 3 "March 23, 2020" "libcurl 7.70.0" "curl_easy_setopt options"
24:
25: .SH NAME
26: CURLOPT_XFERINFOFUNCTION \- callback to progress meter function
27: .SH SYNOPSIS
28: #include <curl/curl.h>
29:
30: int progress_callback(void *clientp,
31: curl_off_t dltotal,
32: curl_off_t dlnow,
33: curl_off_t ultotal,
34: curl_off_t ulnow);
35:
36: CURLcode curl_easy_setopt(CURL *handle, CURLOPT_XFERINFOFUNCTION, progress_callback);
37: .SH DESCRIPTION
38: Pass a pointer to your callback function, which should match the prototype
39: shown above.
40:
41: This function gets called by libcurl instead of its internal equivalent with a
42: frequent interval. While data is being transferred it will be called very
43: frequently, and during slow periods like when nothing is being transferred it
44: can slow down to about one call per second.
45:
46: \fIclientp\fP is the pointer set with \fICURLOPT_XFERINFODATA(3)\fP, it is not
47: used by libcurl but is only passed along from the application to the callback.
48:
49: The callback gets told how much data libcurl will transfer and has
50: transferred, in number of bytes. \fIdltotal\fP is the total number of bytes
51: libcurl expects to download in this transfer. \fIdlnow\fP is the number of
52: bytes downloaded so far. \fIultotal\fP is the total number of bytes libcurl
53: expects to upload in this transfer. \fIulnow\fP is the number of bytes
54: uploaded so far.
55:
56: Unknown/unused argument values passed to the callback will be set to zero
57: (like if you only download data, the upload size will remain 0). Many times
58: the callback will be called one or more times first, before it knows the data
59: sizes so a program must be made to handle that.
60:
61: If your callback function returns CURL_PROGRESSFUNC_CONTINUE it will cause
62: libcurl to continue executing the default progress function.
63:
64: Returning any other non-zero value from this callback will cause libcurl to
65: abort the transfer and return \fICURLE_ABORTED_BY_CALLBACK\fP.
66:
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.
70:
71: \fICURLOPT_NOPROGRESS(3)\fP must be set to 0 to make this function actually
72: get called.
73: .SH DEFAULT
74: By default, libcurl has an internal progress meter. That's rarely wanted by
75: users.
76: .SH PROTOCOLS
77: All
78: .SH EXAMPLE
79: https://curl.haxx.se/libcurl/c/progressfunc.html
80: .SH AVAILABILITY
81: Added in 7.32.0. This callback replaces \fICURLOPT_PROGRESSFUNCTION(3)\fP
82: .SH RETURN VALUE
83: Returns CURLE_OK.
84: .SH "SEE ALSO"
85: .BR CURLOPT_XFERINFODATA "(3), " CURLOPT_NOPROGRESS "(3), "
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