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Patch to stop t/op/fork.t relying on rand #9299

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p5pRT opened this issue Apr 23, 2008 · 4 comments
Closed

Patch to stop t/op/fork.t relying on rand #9299

p5pRT opened this issue Apr 23, 2008 · 4 comments

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@p5pRT
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p5pRT commented Apr 23, 2008

Migrated from rt.perl.org#53238 (status was 'resolved')

Searchable as RT53238$

@p5pRT
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p5pRT commented Apr 23, 2008

From ddick@aapt.net.au

Created by ddick@aapt.net.au

t/op/fork.t depends on rand behaving in a non-random fashion. After
forking it generates a random number without seeding with srand and
depends on the resu
lts of the two rands being different. Sometimes they are the same,
causing incorrect failures. This patch fixes this issue by sending a
known string from
the child and testing the value in the parent.

Perl Info

Flags:
    category=core
    severity=low

This perlbug was built using Perl v5.8.8 in the Red Hat build system.
It is being executed now by Perl v5.8.8 - Thu Mar 20 04:50:10 EDT 2008.

Site configuration information for perl v5.8.8:

Configured by Red Hat, Inc. at Thu Mar 20 04:50:10 EDT 2008.

Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
  Platform:
    osname=linux, osvers=2.6.18-53.1.6.el5xen, 
archname=i386-linux-thread-multi
    uname='linux xenbuilder4.fedora.phx.redhat.com 2.6.18-53.1.6.el5xen 
#1 smp wed jan 16 04:10:44 est 2008 i686 i686 i386 gnulinux '
    config_args='-des -Doptimize=-O2 -g -pipe -Wall 
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector 
--param=ssp-buffer-size=4 -m32 -march=i386 -mtune=generic 
-fasynchronous-unwind-tables -Dversion=5.8.8 -Dmyhostname=localhost 
-Dperladmin=root@localhost -Dcc=gcc -Dcf_by=Red Hat, Inc. 
-Dinstallprefix=/usr -Dprefix=/usr -Darchname=i386-linux 
-Dvendorprefix=/usr -Dsiteprefix=/usr -Duseshrplib -Dusethreads 
-Duseithreads -Duselargefiles -Dd_dosuid -Dd_semctl_semun -Di_db 
-Ui_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio 
-Dinstallusrbinperl=n -Ubincompat5005 -Uversiononly 
-Dpager=/usr/bin/less -isr -Dd_gethostent_r_proto -Ud_endhostent_r_proto 
-Ud_sethostent_r_proto -Ud_endprotoent_r_proto -Ud_setprotoent_r_proto 
-Ud_endservent_r_proto -Ud_setservent_r_proto -Dinc_version_list=5.8.7 
5.8.6 5.8.5 -Dscriptdir=/usr/bin'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=define use5005threads=undef 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='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing 
-pipe -Wdeclaration-after-statement -I/usr/local/include 
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
    optimize='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions 
-fstack-protector --param=ssp-buffer-size=4 -m32 -march=i386 
-mtune=generic -fasynchronous-unwind-tables',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe 
-Wdeclaration-after-statement -I/usr/local/include -I/usr/include/gdbm'
    ccversion='', gccversion='4.1.2 20070925 (Red Hat 4.1.2-33)', 
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='gcc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lresolv -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
    perllibs=-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
    libc=/lib/libc-2.7.so, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version='2.7'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E 
-Wl,-rpath,/usr/lib/perl5/5.8.8/i386-linux-thread-multi/CORE'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -pipe -Wall 
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector 
--param=ssp-buffer-size=4 -m32 -march=i386 -mtune=generic 
-fasynchronous-unwind-tables -L/usr/local/lib'

Locally applied patches:



@INC for perl v5.8.8:
    /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.7/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.6/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.5/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.8
    /usr/lib/perl5/site_perl/5.8.7
    /usr/lib/perl5/site_perl/5.8.6
    /usr/lib/perl5/site_perl/5.8.5
    /usr/lib/perl5/site_perl
    /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.7/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.6/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.5/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.8
    /usr/lib/perl5/vendor_perl/5.8.7
    /usr/lib/perl5/vendor_perl/5.8.6
    /usr/lib/perl5/vendor_perl/5.8.5
    /usr/lib/perl5/vendor_perl
    /usr/lib/perl5/5.8.8/i386-linux-thread-multi
    /usr/lib/perl5/5.8.8
    .


Environment for perl v5.8.8:
    HOME=/home/dave
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    
PATH=/usr/kerberos/bin:/usr/lib/ccache:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/home/dave/bin
    PERL_BADLANG (unset)
    SHELL=/bin/bash

@p5pRT
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p5pRT commented Apr 23, 2008

From ddick@aapt.net.au

perl.patch
diff -Naur old/t/op/fork.t new/t/op/fork.t
--- old/t/op/fork.t     2003-10-03 04:35:14.000000000 +1000
+++ new/t/op/fork.t     2008-02-26 16:31:42.043818960 +1100
@@ -431,16 +431,14 @@
 my $pid = fork;
 die "fork: $!" if !defined $pid;
 if ($pid == 0) {
-    my $rand_child = rand;
     close RDR;
-    print WTR $rand_child, "\n";
+    print WTR "STRING_FROM_CHILD\n";
     close WTR;
 } else {
-    my $rand_parent = rand;
     close WTR;
-    chomp(my $rand_child  = <RDR>);
+    chomp(my $string_from_child  = <RDR>);
     close RDR;
-    print $rand_child ne $rand_parent, "\n";
+    print $string_from_child eq "STRING_FROM_CHILD", "\n";
 }
 EXPECT
 1

@p5pRT
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p5pRT commented Apr 26, 2008

@rgs - Status changed from 'new' to 'resolved'

@p5pRT p5pRT closed this as completed Apr 26, 2008
@p5pRT
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p5pRT commented Apr 26, 2008

From @rgs

2008/4/23 via RT David Dick <perlbug-followup@​perl.org>​:

t/op/fork.t depends on rand behaving in a non-random fashion. After
forking it generates a random number without seeding with srand and
depends on the resu
lts of the two rands being different. Sometimes they are the same,
causing incorrect failures. This patch fixes this issue by sending a
known string from
the child and testing the value in the parent.

Thanks, applied.

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