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

p5pRT commented 13 years ago

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

Searchable as RT96332$

p5pRT commented 13 years ago

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 Arcor empfiehlt: Die TOP 1000 Surftipps zu allem, was im Internet interessant und spannend ist - sehen Sie hier: http://www.arcor.de/content/pc_technik/internet/surftipps/surftipps/ ```