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[perl #23656] Safe reval bleeds local variable values



# New Ticket Created by  guy@albertelli.com 
# Please include the string:  [perl #23656]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt2/Ticket/Display.html?id=23656 >



This is a bug report for perl from guy@albertelli.com,
generated with the help of perlbug 1.34 running under perl v5.8.1.


-----------------------------------------------------------------
[Please enter your report here]

The reval method of a Safe object bleeds the local variables into
the expression being evaled.

Example:
----
#!/usr/bin/perl
use Safe;
$safe=new Safe;
print("Test 1 is ".$safe->reval('return $expr;')."\n");
print("Test 2 is" .$safe->reval('return $expe;')."\n");
----

Incorrectly prints:
Test 1 is return $expr;
Test 2 is

Rather than the correct:
Test 1 is
Test 2 is


This occurs for all of the local variables in reval.



I suggest modifying the reval Subroutine to be:

sub reval {
    $Safe::evalsub;
    {
	my ($obj, $expr, $strict) = @_;
	my $root = $obj->{Root};

	# Create anon sub ref in root of compartment.
	# Uses a closure (on $expr) to pass in the code to be executed.
	# (eval on one line to keep line numbers as expected by caller)
	my $evalcode = sprintf('package %s; sub { @_ = (); eval $expr; }', $obj->{Root});
	
	if ($strict) { use strict; $Safe::evalsub = eval $evalcode; }
	else         {  no strict; $Safe::evalsub = eval $evalcode; }
    }
    return Opcode::_safe_call_sv($_[0]->{Root}, $_[0]->{Mask}, $Safe::evalsub);
}



[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=library
    severity=low
---
Site configuration information for perl v5.8.1:

Configured by bhcompile at Wed Aug 20 09:13:59 EDT 2003.

Summary of my perl5 (revision 5.0 version 8 subversion 1) configuration:
  Platform:
    osname=linux, osvers=2.4.21-1.1931.2.393.entsmp, archname=i386-linux-thread-multi
    uname='linux daffy.perf.redhat.com 2.4.21-1.1931.2.393.entsmp #1 smp wed aug 13 21:51:41 edt 2003 i686 i686 i386 gnulinux '
    config_args='-des -Doptimize=-O2 -g -pipe -march=i386 -mcpu=i686 -Dversion=5.8.1 -Dmyhostname=localhost -Dperladmin=root@localhost -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dinstallprefix=/usr -Dprefix=/usr -Darchname=i386-linux -Dvendorprefix=/usr -Dsiteprefix=/usr -Dotherlibdirs=/usr/lib/perl5/5.8.1 -Duseshrplib -Dusethreads -Duseithreads -Duselargefiles -Dd_dosuid -Dd_semctl_semun -Di_db -Ui_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio -Dinstallusrbinperl -Ubincompat5005 -Uversiononly -Dpager=/usr/bin/less -isr'
    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 -DTHREADS_HAVE_PIDS -DDEBUGGING -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
    optimize='-O2 -g -pipe -march=i386 -mcpu=i686',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBUGGING -fno-strict-aliasing -I/usr/local/include -I/usr/include/gdbm'
    ccversion='', gccversion='3.3.1 20030811 (Red Hat Linux 3.3.1-1)', 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=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
    perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
    libc=/lib/libc-2.3.2.so, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version='2.3.2'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic -Wl,-rpath,/usr/lib/perl5/5.8.1/i386-linux-thread-multi/CORE'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    RC4

---
@INC for perl v5.8.1:
    /usr/lib/perl5/5.8.1/i386-linux-thread-multi
    /usr/lib/perl5/5.8.1
    /usr/lib/perl5/site_perl/5.8.1/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.1
    /usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.0
    /usr/lib/perl5/site_perl
    /usr/lib/perl5/vendor_perl/5.8.1/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.1
    /usr/lib/perl5/vendor_perl/5.8.0/i386-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.0
    /usr/lib/perl5/vendor_perl
    /usr/lib/perl5/5.8.1/i386-linux-thread-multi
    /usr/lib/perl5/5.8.1
    .

---
Environment for perl v5.8.1:
    HOME=/home/albertel
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/kerberos/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/home/albertel/bin
    PERL_BADLANG (unset)
    SHELL=/bin/bash


Follow-Ups from:
Benjamin Goldberg <ben.goldberg@hotpop.com>
Benjamin Goldberg <ben.goldberg@hotpop.com>

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