Experts on embedding Perl in C wanted: Weird problem on RH7.3/Perl 5.6.1

[David F. Skoll]

Hi,

I'm tearing my hair out on this one. I'm trying to embed a Perl
interpreter into a C program. I need to be able to create and destroy
the interpreter periodically, but will never actually have two interpreters
at the same time.

On Red Hat Linux 7.3 with Perl 5.6.1, the attached program segfaults. On
Red Hat 9 with Perl 5.8.0, it works perfectly. Save the program code
as "test-embed-perl.c" and the build script as "buildte". Then run:

sh buildte
./te

to see the behaviour. Enlightenment is appreciated! :-(

A gdb stacktrace shows this:

$ gdb ./te
(gdb) run
Program received signal SIGSEGV, Segmentation fault.
0x080a098b in Perl_sv_upgrade ()
(gdb) where
#0 0x080a098b in Perl_sv_upgrade ()
#1 0x080a4244 in Perl_sv_setpvn ()
#2 0x080a708d in Perl_newSVpvn ()
#3 0x0805abb9 in S_parse_body ()
#4 0x0805a993 in perl_parse ()
#5 0x08059a77 in make_embedded_i nterpreter () at test-embed-perl.c:30
#6 0x08059aa1 in main () at test-embed-perl.c:39
#7 0x400841c4 in __libc_start_ma in () from /lib/libc.so.6

Thanks,

David.

========= buildte =============
#!/bin/sh
echo cc -g `perl -MExtUtils::Embe d -e ccopts` -c -o test-embed-perl.o
test-embed-perl.c
cc -g `perl -MExtUtils::Embe d -e ccopts` -c -o test-embed-perl.o test-embed-perl.c
echo cc -g `perl -MExtUtils::Embe d -e ldopts` -o te test-embed-perl.o -lperl
cc -g `perl -MExtUtils::Embe d -e ldopts` -o te test-embed-perl.o -lperl

======== test-embed-perl.c =========
#include <EXTERN.h>
#include <perl.h>

static PerlInterpreter *my_perl = NULL;

int
make_embedded_i nterpreter()
{
char *argv[5];
int argc;

if (my_perl != NULL) {
perl_destruct(m y_perl);
perl_free(my_pe rl);
my_perl = NULL;
}
my_perl = perl_alloc();
if (!my_perl) {
return -1;
}
PERL_SET_CONTEX T(my_perl);
/* If you leave out the PL_perl_destruc t_level lines, it "works",
but leaks memory like crazy! */
PL_perl_destruc t_level = 1;
perl_construct( my_perl);
PL_perl_destruc t_level = 1;
argv[0] = "";
argv[1] = "-e";
argv[2] = "print(\"foo\\n \");";
argv[3] = NULL;
argc = 3;
perl_parse(my_p erl, NULL, argc, argv, NULL);
perl_run(my_per l);
return 0;
}

int
main()
{
while(1) {
make_embedded_i nterpreter();
}
}

============= Output of perl -V on system where it fails ============
Summary of my perl5 (revision 5.0 version 6 subversion 1) configuration:
Platform:
osname=linux, osvers=2.4.17-0.13smp, archname=i386-linux
uname='linux daffy.perf.redh at.com 2.4.17-0.13smp #1 smp fri feb 1 10:30:48 est 2002 i686 unknown '
config_args='-des -Doptimize=-O2 -march=i386 -mcpu=i686 -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dcccdlflags=-fPIC -Dinstallprefix=/usr -Dprefix=/usr -Darchname=i386-linux -Dvendorprefix=/usr -Dsiteprefix=/usr -Uusethreads -Uuseithreads -Uuselargefiles -Dd_dosuid -Dd_semctl_semun -Di_db -Di_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm'
hint=recommende d, useposix=true, d_sigaction=def ine
usethreads=unde f use5005threads= undef useithreads=und ef usemultiplicity =undef
useperlio=undef d_sfio=undef uselargefiles=u ndef usesocks=undef
use64bitint=und ef use64bitall=und ef uselongdouble=u ndef
Compiler:
cc='gcc', ccflags ='-fno-strict-aliasing -I/usr/local/include',
optimize='-O2 -march=i386 -mcpu=i686',
cppflags='-fno-strict-aliasing -I/usr/local/include'
ccversion='', gccversion='2.9 6 20000731 (Red Hat Linux 7.2 2.96-109)', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=defi ne, longlongsize=8, d_longdbl=defin e, longdblsize=12
ivtype='long', ivsize=4, nvtype='double' , nvsize=8, Off_t='off_t', lseeksize=4
alignbytes=4, usemymalloc=n, prototype=defin e
Linker and Libraries:
ld='gcc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lnsl -ldl -lm -lc -lcrypt -lutil
perllibs=-lnsl -ldl -lm -lc -lcrypt -lutil
libc=/lib/libc-2.2.5.so, so=so, useshrplib=fals e, libperl=libperl .a
Dynamic Linking:
dlsrc=dl_dlopen .xs, dlext=so, d_dlsymun=undef , ccdlflags='-rdynamic'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
Characteristics of this binary (from libperl):
Compile-time options:
Built under linux
Compiled at Apr 1 2002 12:23:22
@INC:
/usr/lib/perl5/5.6.1/i386-linux
/usr/lib/perl5/5.6.1
/usr/lib/perl5/site_perl/5.6.1/i386-linux
/usr/lib/perl5/site_perl/5.6.1
/usr/lib/perl5/site_perl/5.6.0
/usr/lib/perl5/site_perl
/usr/lib/perl5/vendor_perl/5.6.1/i386-linux
/usr/lib/perl5/vendor_perl/5.6.1
/usr/lib/perl5/vendor_perl

[dinser]

Am new to perl but know C alright. Perhaps you
need to allocate some memory to char *argv[]
before you put values into it? Good luck.

Ray

======== test-embed-perl.c =========
#include <EXTERN.h>
#include <perl.h>

static PerlInterpreter *my_perl = NULL;

int
make_embedded_i nterpreter()
{
char *argv[5];
int argc;

if (my_perl != NULL) {
perl_destruct(m y_perl);
perl_free(my_pe rl);
my_perl = NULL;
}
my_perl = perl_alloc();
if (!my_perl) {
return -1;
}
PERL_SET_CONTEX T(my_perl);
/* If you leave out the PL_perl_destruc t_level lines, it "works",
but leaks memory like crazy! */
PL_perl_destruc t_level = 1;
perl_construct( my_perl);
PL_perl_destruc t_level = 1;
argv[0] = "";
argv[1] = "-e";
argv[2] = "print(\"foo\\n \");";
argv[3] = NULL;
argc = 3;
perl_parse(my_p erl, NULL, argc, argv, NULL);
perl_run(my_per l);
return 0;

[David F. Skoll]

dinser wrote:

Am new to perl but know C alright. Perhaps you
need to allocate some memory to char *argv[]
before you put values into it? Good luck.

Nope; that's not it. I guess you're not as familiar with C as you think. :-)

Anyone else?

Regards,

David.

======== test-embed-perl.c =========
#include <EXTERN.h>
#include <perl.h>

static PerlInterpreter *my_perl = NULL;

int
make_embedded_i nterpreter()
{
char *argv[5];
int argc;

if (my_perl != NULL) {
perl_destruct(m y_perl);
perl_free(my_pe rl);
my_perl = NULL;
}
my_perl = perl_alloc();
if (!my_perl) {
return -1;
}
PERL_SET_CONTEX T(my_perl);
/* If you leave out the PL_perl_destruc t_level lines, it "works",
but leaks memory like crazy! */
PL_perl_destruc t_level = 1;
perl_construct( my_perl);
PL_perl_destruc t_level = 1;
argv[0] = "";
argv[1] = "-e";
argv[2] = "print(\"foo\\n \");";
argv[3] = NULL;
argc = 3;
perl_parse(my_p erl, NULL, argc, argv, NULL);
perl_run(my_per l);

[jpulpiano]

Hi,

I am experimenting the same problem on Windows.
I need to do the same and I get the following error:

perl_parse
gdb: kernel event for pid=5488 tid=2148 code=EXCEPTION_ DEBUG_EVENT)
gdb: Target exception EXCEPTION_ACCES S_VIOLATION at 0x28065fbc

Program received signal SIGSEGV, Segmentation fault.
0x28065fbc in perl58!Perl_sv_ setpvn () from c:\Perl\bin\per l58.dll
(gdb) where
#0 0x28065fbc in perl58!Perl_sv_ setpvn () from c:\Perl\bin\per l58.dll
#1 0x28024851 in perl_parse () from c:\Perl\bin\per l58.dll


The only solution I see in my case is to switch on:
Maintaining a persistent interpreter described in
man perlembed or
http://www.linuxonlinehelp.com/man/perlembed.html

Kind regards,

Jean-Philippe