Re: [Ocaml-lib-devel] IO.really_nread

[Nicolas C. <war...@fr...>]

> Hi all,
> 
> It seems there is no function to read exactly n characters
> into a string (ie. IO.nread just without automatically
> shortening the string if EOF is hit while reading). Since
> at least one person needs it (me :)) I thought I would add
> this:
> 
>    let really_nread i n =
>         if n < 0 then raise (Invalid_argument "IO.really_nread");
>         if n = 0 then
>                 ""
>         else
>         let s = String.create n in
>         let l = ref n in
>         let p = ref 0 in
>         while !l > 0 do
>                 let r = i.in_input s !p !l in
>                 p := !p + r;
>                 l := !l - r;
>         done;
>         s
> 
> which is exactly the same code as IO.nread, except it
> doesn't try to catch the No_more_input exception.
> 
> Any objections to adding this?

This will cause an infinite loop on non-blocking IO (r = 0).
You might want to raise Sys_blocked_io in this case.

Nicolas Cannasse