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curl_easy_setopt.3: expand the PROGRESSFUNCTION section 

Explain the callback and its arguments better and with more descriptive
text.
This commit is contained in:
Daniel Stenberg 2013-05-20 10:49:50 +02:00
parent fc4759af9d
commit 7d4d4892d8
1 changed files with 18 additions and 5 deletions
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23
docs/libcurl/curl_easy_setopt.3
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@ -346,11 +346,24 @@ Pass a pointer to a function that matches the following prototype: \fBint
function(void *clientp, double dltotal, double dlnow, double ultotal, double
ulnow); \fP. This function gets called by libcurl instead of its internal
equivalent with a frequent interval during operation (roughly once per second
or sooner) no matter if data is being transferred or not. 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). Returning a non-zero value from
this callback will cause libcurl to abort the transfer and return
\fICURLE_ABORTED_BY_CALLBACK\fP.
or sooner) no matter if data is being transferred or not.
\fIclientp\fP is the pointer set with \fICURLOPT_PROGRESSDATA\fP, it is not
actually 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).
Returning a 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