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[perl #114678] Can not catch die exception thrown in tie handler

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From:
Jim Avera
Date:
August 30, 2012 21:45
Subject:
[perl #114678] Can not catch die exception thrown in tie handler
Message ID:
rt-3.6.HEAD-11172-1346388337-1676.114678-75-0@perl.org
# New Ticket Created by  Jim Avera 
# Please include the string:  [perl #114678]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=114678 >



-----------------------------------------------------------------
An exception thrown from a tied variable handler can not be caught.  
The application is unconditionally terminated.
At least so it seems!

If true, it is a severe limitation on the possible robustness 
of applications which use tied variables to access something
which might encounter an error or timeout.

#!/usr/bin/perl
use strict; use warnings; 

package Tie::MyTie;
sub TIESCALAR { my $class=shift; return bless [], $class; }
sub FETCH { die "FETCH throwing an error" }

package main;

our $x;
tie $x, 'Tie::MyTie', 42;

# This eval should catch the exception, no?
my $val = eval '$x';  # dies here (really dead)
warn "caught exception:$@" if $@;

warn "Expecting to get here\n";
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl 5.14.2:

Configured by Debian Project at Fri Aug 10 21:43:06 UTC 2012.

Summary of my perl5 (revision 5 version 14 subversion 2) configuration:
   
  Platform:
    osname=linux, osvers=2.6.42-26-generic, archname=x86_64-linux-gnu-thread-multi
    uname='linux allspice 2.6.42-26-generic #41-ubuntu smp thu jun 14 17:49:24 utc 2012 x86_64 x86_64 x86_64 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.14 -Darchlib=/usr/lib/perl/5.14 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.14.2 -Dsitearch=/usr/local/lib/perl/5.14.2 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Duse64bitint -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -Ui_libutil -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.14.2 -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -fstack-protector -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 -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.6.3', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /usr/lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=, so=so, useshrplib=true, libperl=libperl.so.5.14.2
    gnulibc_version='2.15'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib -fstack-protector'

Locally applied patches:
    

---
@INC for perl 5.14.2:
    /home/jima/local/lib/perl/5.14.2
    /home/jima/local/lib/perl
    /home/jima/local/share/perl/5.14.2
    /home/jima/local/share/perl
    /home/jima/lib/perl
    /etc/perl
    /usr/local/lib/perl/5.14.2
    /usr/local/share/perl/5.14.2
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.14
    /usr/share/perl/5.14
    /usr/local/lib/site_perl
    .

---
Environment for perl 5.14.2:
    HOME=/home/jima
    LANG=en_US.UTF-8
    LANGUAGE=
    LD_LIBRARY_PATH=/home/jima/local/lib
    LOGDIR (unset)
    PATH=/home/jima/bin:/home/jima/local/bin:/home/jima/jima_tools/bin:/opt/libreoffice3.6/program:/usr/bin:/bin:/usr/sbin:/sbin:/usr/bin/X11:/usr/local/bin:/usr/local/sbin:/usr/games:.
    PERL5LIB=/home/jima/local/lib/perl:/home/jima/local/share/perl:/home/jima/lib/perl
    PERL_BADLANG (unset)
    SHELL=/bin/bash


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