Re: libc unlink - bug or not?

[Gaius Mulley]

Alexey Ulasevich <alexey.ulasevich@gmail.com> writes:

> Hi,
>
> I tried to use function `unlink` from `libc`, but it's defined may be
> incorrect.
>
> In `libc.def`it's defined like:
>
> PROCEDURE unlink (file: ADDRESS) : [ INTEGER ] ;
>
> I read https://www.nongnu.org/gm2/12/interface_to_c.html and according
> it, the function should be defined like:
>
> PROCEDURE unlink (a: ARRAY OF CHAR) : [ INTEGER ] ;
>
> Or may be I don't understand how to use it be correct way.
>
>
> Thanks.
>
> Aleksey

Hi Aleksey,

it could be defined as:

> PROCEDURE unlink (a: ARRAY OF CHAR) : [ INTEGER ] ;

except the user must ensure that all strings passed to unlink must be
nul terminated.  While "foo" will always be nul terminated, however:

VAR
   buf: ARRAY [0..2] OF CHAR ;
BEGIN
   buf := "foo" ;
   unlink (buf) ;  (* not nul terminated.  *)

won't be nul terminated.  Forcing the user to consider the C string
implementation was part of the reason in choosing file: ADDRESS, also
the close match with man 2 unlink.  Occasionally it might be the case
that an address is more suitable (for example a filename appearing in a
sequence of octets)

regards,
Gaius