Re: NUL-terminating APIs, was Serious problem with lua GetSelText function in Scite 5.1.5

Hi Neil,
I can confirm that the two patches completely solve the problem, at least 
for scite.
The behaviour of GetSelText is even more consequent than before:
local sel, selb = editor:GetSelText()  issued on the word "end" now returns 
"end", 3 in scite515.
In scite514 the returned strings were "end", 4, whereas #end was equal  to 
3.
Thank you very much!!

Paolo


Neil Hodgson schrieb am Mittwoch, 10. November 2021 um 07:07:02 UTC+1:

> Paolo Gotti:
>
> > I'm sorry to bother you, but the behaviour of lua GetSelText function 
> has changed.
> > The returned string now always include the terminating 0.
>
> In previous versions of SciTE, string results from Scintilla API calls 
> that included NUL bytes were truncated early at the NUL. A change was made 
> to pass the whole string including any NUL bytes.
>
> There have been some inconsistencies in the way that string returning APIs 
> were handled by Scintilla, particularly SCI_GETTEXT, SCI_GETSELTEXT, and 
> SCI_GETCURLINE. Most APIs return the length of the string excluding any NUL 
> byte terminator but the mentioned APIs returned one more, including the NUL.
>
> It is likely best to change these 3 APIs to be consistent with others. 
> However, this could break applications that will no longer allocate enough 
> memory to include the NUL terminator. Downstream projects should check 
> their use of these APIs.
>
> The normal technique is to call the Scintilla API with NULL as the string 
> argument which returns the length. Then allocate a string of length+1 bytes 
> (the +1 may be set to NUL). Then call the API with this allocated string. 
> Use the resulting string in a way that ignores the trailing NUL. If using 
> the C++ std::string type, an extra NUL byte is automatically allocated at 
> the end which is not counted in std::string::length() so works without 
> problems.
>
> The attached LengthFix.patch changes Scintilla to return the string length 
> for the 3 above mentioned APIs.
>
> The attached LengthFixSciTE.patch changes the Lua Scintilla interface to 
> return an empty string instead of nil when the API returns an empty string. 
> This was previously hidden by the +1 on the length.
>
> > As a consequence, even no selection at all gets length=1.
> > Many scripts of mine are broken, but I have already reverted to the 
> previous version.
> > Nonetheless, somebody could get strange results.
>
> The above changes modify behaviour too much to be pushed in a quick 
> update, so users should either strip terminating NULs off API results or 
> return to the previous SciTE release for now.
>
> Neil
>

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