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FATAL exec warnings lets system() reveal its internal fork/clone #11557

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p5pRT opened this issue Aug 5, 2011 · 7 comments
Open

FATAL exec warnings lets system() reveal its internal fork/clone #11557

p5pRT opened this issue Aug 5, 2011 · 7 comments
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distro-Linux type-core

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@p5pRT
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p5pRT commented Aug 5, 2011

Migrated from rt.perl.org#96332 (status was 'open')

Searchable as RT96332$
@p5pRT
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p5pRT commented Aug 5, 2011

From jens.schmidt35@arcor.de

Created by jens.schmidt35@arcor.de

Consider the following example​:

---- example ----
use warnings qw( FATAL exec );
eval {
  system( "ritzelbimpf" );
};
if ( $@​ ) {
  warn "error​: $@​";
  exit ( 0 );
}
else {
  warn "nonerror";
  exit ( 0 );
}
---- example ----

where the executable "ritzelbimpf" must not exist on your system.

When run, this results in the following output​:

---- output ----
error​: Can't exec "ritzelbimpf"​: No such file or directory at -e line 3.
nonerror at -e line 10.
---- output ----

because the cloned process runs the "if", the main process the "else"
part. I don't think that this is in the spirit of the system() function
which should appear to be synchronous to the caller.

Of course, this way it looks simple. But I use warnings( FATAL all )
in my Perl programs and it took me some time to figure out
why the system() function behaves that strangely.

Perl Info 

Flags:
    category=core
    severity=medium

Site configuration information for perl 5.10.0:

Configured by Debian Project at Thu Jun 30 20:30:13 UTC 2011.

Summary of my perl5 (revision 5 version 10 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.6.32-5-686, archname=i486-linux-gnu-thread-multi
    uname='linux callisto 2.6.32-5-686 #1 smp mon jun 13 04:13:06 utc 2011 i686 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.10.0 -Dsitearch=/usr/local/lib/perl/5.10.0 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.10.0 -Dd_dosuid -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='4.3.2', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib /usr/lib64
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=/lib/libc-2.7.so, so=so, useshrplib=true, libperl=libperl.so.5.10.0
    gnulibc_version='2.7'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib'

Locally applied patches:
    


@INC for perl 5.10.0:
    /etc/perl
    /usr/local/lib/perl/5.10.0
    /usr/local/share/perl/5.10.0
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.10
    /usr/share/perl/5.10
    /usr/local/lib/site_perl
    .


Environment for perl 5.10.0:
    HOME=/home/jschmidt
    LANG=C
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/jschmidt/bin:/home/jschmidt/work/javaenv/bin:/root/bin:/usr/local/bin:/usr/bin:/bin:/usr/games
    PERLENVHOME=/home/jschmidt/work/perl
    PERL_BADLANG (unset)
    SHELL=/bin/bash


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@p5pRT
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p5pRT commented Dec 3, 2012

jens.schmidt35@arcor.de - Status changed from 'new' to 'open'

@p5pRT
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p5pRT commented Dec 3, 2012

jens.schmidt35@arcor.de - Status changed from 'open' to 'new'

@p5pRT
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p5pRT commented Dec 4, 2012

From jens.schmidt35@arcor.de

Still reproduces in Perl 5.16.2.

@p5pRT
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p5pRT commented Dec 4, 2012

jens.schmidt35@arcor.de - Status changed from 'new' to 'open'

@p5pRT
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p5pRT commented Oct 21, 2013

From @jamesrichardsonjr

Hi,

This also reproduces in perl 5.18.1 (Debian GNU/Linux sid) and
perl 5.8.8 (AIX 5 and AIX 6)
--
James

@p5pRT
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p5pRT commented Oct 21, 2013

From [Unknown Contact. See original ticket]

Hi,

This also reproduces in perl 5.18.1 (Debian GNU/Linux sid) and
perl 5.8.8 (AIX 5 and AIX 6)
--
James

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