Using set_content_provider with length of 0 makes it infinitely loop

[gtnardy]

Hey, I got an interesting case when trying to send an empty file through set_content_provider,

I have a thing simple as this just to clarify (reduced code):

struct NFile
{
	std::string Data;
	std::uint64_t Size;
};

NFile* File;

// Load file content into File.data string.
// ...

Res.set_content_provider(
	File->Size,
	"application/octet-stream",
	[File](std::size_t Offset, std::size_t Length, httplib::DataSink& Sink)
	{
		Sink.write(&File->Data[Offset], std::min(Length, 1024 * 1024)); // 1 MB Chunks
		return true;
	}
);

But if string is empty (file is empty), the content_provider keeps looping infinitely (triggering the callback), but the request never finishes in fact.

Not sure if this should be something I would need to treat (I'm going to), or if it can enlighten that there's a bug somewhere in the lib internally.

[PixlRainbow]

you can return false in your content provider to cancel the response as a temporary workaround, but zero length is likely also an internal bug with httplib as it checks for < instead of <=

[yhirose]

@gtnardy thanks for the report!