[M3devel] Problem interfacing C lib

[Mika Nystrom]

char_star is, at least in my installation

UNTRACED REF [-16_7f-1 .. 16_7f]

But it's a good point that it's not actually an UNTRACED REF ARRAY OF CHAR

However 

ADR(chars[0]) 

ought to be more or less precisely of the type char_star

... so I doubt that is the problem.

I'm curious about whether the assembly code for the call changes without
the <*EXTERNAL*> pragma... it shouldn't should it?  In which case, where
is chars passed, in pure Modula-3 code?  I don't know enough about the
standard ABI of amd64 to know what the code should look like I'm afraid.

   Mika

"Daniel Alejandro Benavides D." writes:
>Hi all:
>I think the unchecked error lays down to:
>Unsafe Operations section 2.7 (cf. Green Book SPWM3, p- 61):
>it's allowed to have " ... a value of type ADDRESS to be assigned to a vari=
>able of type UNTRACED REF T. It is an unchecked runtime error if the value =
>does not address a variable of type T."
>
>which could be reads conversely as:
>
>a value of type UNTRACED REF T to be assigned to a variable of type ADDRESS=
>. It is a checked runtime error if the variable does not address      a var=
>iable of type .T=20
>=20
>And because because char_star is a subrange [-128 .. 127] OF INTEGER (and n=
>ot ADDRESS)  and chars is UNTRACED REF ARRAY OF CHAR erro is cf. the specif=
>ication.
>So maybe you need to change your char_star
>
>Thanks in advance
>
>
>--- El mar, 20/3/12, Dragi=C5=A1a Duri=C4=87 <dragisha at m3w.org> escribi=C3=
>=B3:
>
>> De: Dragi=C5=A1a Duri=C4=87 <dragisha at m3w.org>
>> Asunto: Re: [M3devel] Problem interfacing C lib
>> Para: "Mika Nystrom" <mika at async.caltech.edu>
>> CC: m3devel at elegosoft.com
>> Fecha: martes, 20 de marzo, 2012 01:04
>> Errorr is SIGSEGV.
>>=20
>> chars is UNTRACED REF ARRAY OF CHAR but it is lesser
>> problem, I think. It looks like  formal 'what' is not
>> sent at all!? It's place is taken by next argument - INTEGER
>> len (equal 0x7 in this example).
>>=20
>> One common problem I meet often (as I bind C often :) is
>> this - address of open array argument is ot what it looks
>> like. To be sure you are getting address of various UNTRACED
>> REF..ARRAY.. and open array procedure arguments - use=20
>>=20
>> ADR(chars[0])
>>=20
>> and do not use:
>>=20
>> LOOPHOLE(chars, ADDRESS)
>>=20
>> Of course, I tried ADR(chars[0]) :) - Same thing happened.
>> Right now II downgraded my code to use strstr(3), but this
>> argument passing still bugs me.
>>=20
>> dd
>>=20
>>=20
>> On Mar 20, 2012, at 1:26 AM, Mika Nystrom wrote:
>>=20
>> > What are the declarations of all the variables involved
>> in the call?
>> >=20
>> > And what is the actual error?  Is it a SIGBUS,
>> SIGSEGV?
>> >=20
>> > =3D?utf-8?Q?Dragi=3DC5=3DA1a_Duri=3DC4=3D87?=3D writes:
>> >> I had some error before I LOOPHOLEd it.
>> >>=20
>> >> On Mar 19, 2012, at 7:27 PM, Daniel Alejandro
>> Benavides D. wrote:
>> >>=20
>> >>> Hi all:
>> >>> if chars is ADDRESS type why are you
>> LOOPHOLE'ing it?=3D20
>> >>> Thanks in advance
>> >>> =3D20
>> >>> --- El lun, 19/3/12, Dragi=3DC5=3DA1a Duri=3DC4=3D87
>> <dragisha at m3w.org>
>> =3D
>> >> escribi=3DC3=3DB3:
>> >>> =3D20
>> >>>> De: Dragi=3DC5=3DA1a Duri=3DC4=3D87 <dragisha at m3w.org>
>> >>>> Asunto: [M3devel] Problem interfacing C
>> lib
>> >>>> Para: "m3devel" <m3devel at elegosoft.com>
>> >>>> Fecha: lunes, 19 de marzo, 2012 12:13
>> >>>> #1  0x00000035bd8172a0 in
>> >>>> evbuffer_search_range (buffer=3D3D0x694090,
>> what=3D3D0x7 <Address
>> >>>> 0x7 out of bounds>, len=3D3D0,
>> start=3D3D0x0,
>> >>>> end=3D3D0x7fffffffdbb0)
>> >>>>   at buffer.c:2441
>> >>>> #2  0x0000000000404a0c in
>> Buffer__Search (t=3D3D<error
>> >>>> reading variable>, pattern=3D3D<error
>> reading
>> >>>> variable>, from=3D3D<error reading
>> variable>,=3D20
>> >>>>   to=3D3D<error reading
>> variable>) at
>> >>>> ../src/Buffer.m3:150
>> >>>> =3D20
>> >>>> Buffer.m3:150
>> >>>>       pos :=3D3D
>> >>>> evbuffer.search_range(t.b, LOOPHOLE(chars,
>> ADDRESS), len,
>> >>>> NIL, NIL);
>> >>>> =3D20
>> >>>> t.b is a pointer, so is chars=3DE2=3D80=3DA6 len
>> is Utypes.size_t and
>> >>>> it's value is 7.
>> >>>> =3D20
>> >>>> <* EXTERNAL evbuffer_search_range *>
>> >>>> PROCEDURE search_range(buf: t; what:
>> char_star; len: size_t;
>> >>>> start, end: UNTRACED REF ptr): ptr;
>> >>>> =3D20
>> >>>> t is an ADDRESS, and so on=3DE2=3D80=3DA6
>> >>>> =3D20
>> >>>> Critical Mass Modula-3 version d5.9.0
>> >>>> last updated: 2010-07-21
>> >>>> compiled: 2010-10-04 07:24:16
>> >>>> configuration: /etc/cm3.cfg
>> >>>> host: AMD64_LINUX
>> >>>> target: AMD64_LINUX
>> >>>> =3D20
>> >>>> =3D20
>> >>>> Any ideas? TIA,
>> >>>> dd
>> >>>> =3D20
>> >>>> =3D20
>>=20
>>