PerlDiscuss - Perl Newsgroups and mailing lists <[EMAIL PROTECTED]> writes:
>Hi,
>
>I am using Swig to create a wrapper between C and Perl communication. It
>generates run time error when I try to access file pointer in C opened in
>Perl. The message shown at run time is
>
>"The instruction at "0x77f88216" referenced memory at "0x00000000". The
>memory could not be written".
>
>Below are the corresponding files I am using to attain communication:
>
>1. Interface file cprog.i used in swig to create a wrapper file
>
>%module cprog
>%typemap(perl5,in) FILE * {
>$target = IoIFP(sv_2io($source));\
>}
>int testing(FILE* fp);
perl5.8 and later don't use FILE * for IO by default.
(There may be one under the hood but there may be UTF-8 encoding
or CRLF stuff about too.)
But for XS code it does provide a way to get a FILE * - as another
post has pointed out XS typemaps take this into account.
Note of you force a FILE * then you loose the effect of perl's
IO "layers".
If you are writing the C code specially for perl then using PerlIO *
will allow you to access UTF-8 or other encoded files in same
way perl does.
>
>Swig command I use to create wrapper cprog_wrap.c is
>
>swig -perl -exportall cprog.i
>
>2. C file "cprog.c" to communicate with perl
>
>#include <stdio.h>
>int testing(FILE* fp)
>{
>if(fp)
>fputs("hello", fp);
>else
>return 0;
>}
If you wrote that as
int testing (PerlIO *fp)
{
if (fp)
PerlIO_printf(fp,"hello");
}
It could work even if fp was a
opened by perl as a gziped CRLF file in a Japanese encoding.
>
>3. Perl file "perl1.pl" I use to communicate with C
>
>file "cprog.c"
>use cprog;
>open(OUT, ">-");
>$ret = testing(*OUT);
>print $ret;
>
>Following gives the compilling and linking I use to create the dll
>"cprog.dll"
>
>cl.exe -I "c:\Program Files\Microsoft Visual Studio .NET\Vc7\include"
>-Ic:\Perl\lib\CORE -I "c:\Program Files\Microsoft Visual Studio
>NET\Vc7\PlatformSDK\Include" -c cprog.c cprog_wrap.c -nologo -Gf -W3 -MD
>-Zi -DNDEBUG -O1 -DWIN32 -D_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT
>-DNO_HASH_SEED -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DUSE_PERLIO
>-DPERL_MSVCRT_READFIX
>
>link.exe -dll -nologo -nodefaultlib -opt:ref,icf
>-libpath:"C:\Perl\lib\CORE" -machine:x86 /out:cprog.dll cprog.obj
>cprog_wrap.obj perl58.lib /LIBPATH:"c:\Program Files\Microsoft Visual
>Studio .NET\Vc7\lib" msvcrt.lib kernel32.lib
>
>Actual run time problem occurs when I try to use "fputs()" in C using file
>pointer created in Perl.
>
>Can anyone explain me soon wht's the problem and how should i rectify it?
>
>Regards,
>Karthik.
