[Gm2] Re: How do I declare a character pointer returned from a "C" function?

[Gaius Mulley]

> Okay -- my question was too generic.  Specifically, it seems that the
> TermFile tests fail on Solaris 10 because TermFile.mod tries to open /
> dev/tty and this does not work in Solaris 10.  The recommended method
> is to retrieve the name of the current terminal via ttyname() or
> ttyname_r(), preferably the latter.  In both cases, pointers to the
> string containing the name are returned.
>
> I wish to replace the Assign('/dev/tty', a) statement in
> TermFile.getname() with a call to ttyname_r() but I do not know how
> to define the latter in libc.def.  If I define it as you suggest,
> then it is unclear to me how to copy the contents of the string into
> a (locus citato).


Hi John,

I hope you don't mind me CC:ing the list as this technique maybe
useful to others interfacing to C based libraries.

I understand the question better now I think and would use
the module DynamicStrings to create a String and CopyOut the
result.  So 


PROCEDURE getname (d: DeviceTablePtr;
                   VAR a: ARRAY OF CHAR) ;
BEGIN
   Assign('/dev/tty', a)
END getname ;

could be replaced with the following code:

IMPORT DynamicStrings ;

  ...

PROCEDURE getname (d: DeviceTablePtr;
                   VAR a: ARRAY OF CHAR) ;
VAR
   s: DynamicStrings.String ;
BEGIN
   s := DynamicStrings.InitStringCharStar(ttyname_r()) ;
   DynamicStrings.CopyOut(a, s) ;
   s := DynamicStrings.KillString(s)
END getname ;



regards,
Gaius