I think you are right, the call should be make_blocks(5, [Bin]). Checking in a
fix now.
-Damien
On Jun 15, 2010, at 9:10 AM, Andrey Somov wrote:
> Hi,
> while reading the CouchDB source I found a question in couch_file.erl,
> I am not sure whether it is a bug or not.
>
> Lines 297-311:
>
> handle_call({write_header, Bin}, _From, #file{fd=Fd, eof=Pos}=File) ->
> BinSize = size(Bin),
> case Pos rem ?SIZE_BLOCK of
> 0 ->
> Padding = <<>>;
> BlockOffset ->
> Padding = <<0:(8*(?SIZE_BLOCK-BlockOffset))>>
> end,
> FinalBin = [Padding, <<1, BinSize:32/integer>> | make_blocks(1, [Bin])],
> case file:write(Fd, FinalBin) of
> ok ->
> {reply, ok, File#file{eof=Pos+iolist_size(FinalBin)}};
> Error ->
> {reply, Error, File}
> end;
>
>
> Because <<1, BinSize:32/integer>> occupies 5 bytes make_blocks() shall
> use offset=5, but the offset is only 1.
> (it should be make_blocks(5, [Bin]))
>
> Since the header is smaller then 4k there is no difference and it
> works (the tests succeed with both 1 and 5). But it makes it more
> difficult to understand the code for those who study the source to
> understand how it works.
>
> -
> Thank you,
> Andrey
