Annotation of embedaddon/curl/docs/libcurl/opts/CURLOPT_XFERINFOFUNCTION.3, revision 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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