perl5db.pl does not set new filehandles into ReadLine after pager command

[p5pRT]

Migrated from rt.perl.org#121456 (status was 'resolved')

Searchable as RT121456$

[p5pRT]

From hiroo.hayashi@computer.org

Created by hiroo.hayashi@computer.org

perl5db.pl does not set new file-handles into ReadLine after pager
command. This cause a segmentation fault when used with
Term​::ReadLine​::Gnu.
See https://rt.cpan.org/Public/Bug/Display.html?id=83040 for more details.

When the pager command (| or ||) is used in perldb, it overwrites the OUT
file
handle. perldb.pl has a function, reset_IN_OUT(), for such case, but
it is not called after the pager command.

From http​://search.cpan.org/~rjbs/perl-5.18.2/lib/perl5db.pl#reset_IN_OUT
-----------------------
reset_IN_OUT
This routine handles restoring the debugger's input and output
file-handles after we've tried and failed to move them elsewhere. In
addition, it assigns the debugger's output file-handle to $LINEINFO if
it was already open there.
-----------------------

In reset_IN_OUT() Term​::ReadLine​:newTTY() is called.

The perl implementations of Term​::ReadLine (Term​::ReadLine​::Stub or
Term​::ReadLine​::Perl, etc.) are not affected by this bug, because the OUT
file
handle is in the global scope. But for XS implementation needs newTTY() to
be called.

Attached are the patches for
  perldb5 version 1.43 in perl 5.19.9 (latest development release)
  perldb5 version 1.39_10 in perl 5.18.2 (latest stable)
  perldb5 version 1.37 in perl 5.16.3 (previous stable)

Perl Info

Flags:
    category=utilities
    severity=medium

Site configuration information for perl 5.16.3:

Configured by Red Hat, Inc. at Mon Nov 11 12:49:48 UTC 2013.

Summary of my perl5 (revision 5 version 16 subversion 3) configuration:

  Platform:
    osname=linux, osvers=3.10.9-200.fc19.x86_64,
archname=x86_64-linux-thread-multi
    uname='linux buildvm-04.phx2.fedoraproject.org 3.10.9-200.fc19.x86_64
#1 smp wed aug 21 19:27:58 utc 2013 x86_64 x86_64 x86_64 gnulinux '
    config_args='-des -Doptimize=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2
-fexceptions -fstack-protector --param=ssp-buffer-size=4  -m64
-mtune=generic -Dccdlflags=-Wl,--enable-new-dtags -Dlddlflags=-shared -O2
-g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector
--param=ssp-buffer-size=4  -m64 -mtune=generic -Wl,-z,relro  -DDEBUGGING=-g
-Dversion=5.16.3 -Dmyhostname=localhost -Dperladmin=root@localhost -Dcc=gcc
-Dcf_by=Red Hat, Inc. -Dprefix=/usr -Dvendorprefix=/usr
-Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl5
-Dsitearch=/usr/local/lib64/perl5 -Dprivlib=/usr/share/perl5
-Dvendorlib=/usr/share/perl5/vendor_perl -Darchlib=/usr/lib64/perl5
-Dvendorarch=/usr/lib64/perl5/vendor_perl
-Darchname=x86_64-linux-thread-multi -Dlibpth=/usr/local/lib64 /lib64
/usr/lib64 -Duseshrplib -Dusethreads -Duseithreads
-Dusedtrace=/usr/bin/dtrace -Duselargefiles -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 -Dscriptdir=/usr/bin -Dusesitecustomize'
    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='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing
-pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions
-fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe
-fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.7.2 20121109 (Red Hat 4.7.2-8)',
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='gcc', ldflags =' -fstack-protector'
    libpth=/usr/local/lib64 /lib64 /usr/lib64
    libs=-lresolv -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
-lgdbm_compat
    perllibs=-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
    libc=, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version='2.16'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef,
ccdlflags='-Wl,--enable-new-dtags -Wl,-rpath,/usr/lib64/perl5/CORE'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -pipe -Wall
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector
--param=ssp-buffer-size=4 -m64 -mtune=generic -Wl,-z,relro '

Locally applied patches:



@INC for perl 5.16.3:
    /home/hiroo/perl5/lib/perl5/x86_64-linux-thread-multi
    /home/hiroo/perl5/lib/perl5
    /home/hiroo/perl5/lib/perl5/x86_64-linux-thread-multi
    /home/hiroo/perl5/lib/perl5
    /usr/local/lib64/perl5
    /usr/local/share/perl5
    /usr/lib64/perl5/vendor_perl
    /usr/share/perl5/vendor_perl
    /usr/lib64/perl5
    /usr/share/perl5
    .


Environment for perl 5.16.3:
    HOME=/home/hiroo
    LANG=en_US.utf8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)

PATH=/home/hiroo/perl5/bin:/home/hiroo/perl5/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/home/hiroo/.local/bin:/home/hiroo/bin
    PERL5LIB=/home/hiroo/perl5/lib/perl5:/home/hiroo/perl5/lib/perl5:
    PERL_BADLANG (unset)
    PERL_LOCAL_LIB_ROOT=:/home/hiroo/perl5:/home/hiroo/perl5
    PERL_MB_OPT=--install_base /home/hiroo/perl5
    PERL_MM_OPT=INSTALL_BASE=/home/hiroo/perl5
    SHELL=/bin/bash


-- 
Hiroo Hayashi

[p5pRT]

From hiroo.hayashi@computer.org

perl5db-1.37_in5.16.3.diff

*** perl5db.pl.org	Mon Mar 17 22:17:34 2014
--- perl5db.pl	Tue Mar 18 01:01:22 2014
***************
*** 3316,3321 ****
--- 3316,3324 ----
                      open( OUT, ">&SAVEOUT" ) || &warn("Can't restore DB::OUT");
                  }
  
+ 		# Let Readline know the new filehandles.
+ 		reset_IN_OUT( \*IN, \*OUT );
+ 
                  # Close filehandle pager was using, restore the normal one
                  # if necessary,
                  close(SAVEOUT);

[p5pRT]

From hiroo.hayashi@computer.org

perl5db-1.39_10_in5.18.2.diff

*** perl5db.pl.org	Mon Mar 17 22:13:16 2014
--- perl5db.pl	Tue Mar 18 01:03:05 2014
***************
*** 2418,2423 ****
--- 2418,2426 ----
              open( OUT, ">&SAVEOUT" ) || _db_warn("Can't restore DB::OUT");
          }
  
+ 	# Let Readline know the new filehandles.
+ 	reset_IN_OUT( \*IN, \*OUT );
+ 
          # Close filehandle pager was using, restore the normal one
          # if necessary,
          close(SAVEOUT);

[p5pRT]

From hiroo.hayashi@computer.org

perl5db-1.43_in5.19.9.diff

*** perl5db.pl.org	Mon Mar 17 22:12:56 2014
--- perl5db.pl	Tue Mar 18 01:04:53 2014
***************
*** 2419,2424 ****
--- 2419,2427 ----
              open( OUT, ">&SAVEOUT" ) || _db_warn("Can't restore DB::OUT");
          }
  
+ 	# Let Readline know the new filehandles.
+ 	reset_IN_OUT( \*IN, \*OUT );
+ 
          # Close filehandle pager was using, restore the normal one
          # if necessary,
          close(SAVEOUT);

[p5pRT]

From @shlomif

Hi all,

On Mon Mar 17 10​:02​:01 2014, hiroo.hayashi@​computer.org wrote​:

This is a bug report for perl from hiroo.hayashi@​computer.org,
generated with the help of perlbug 1.39 running under perl 5.16.3.

-----------------------------------------------------------------
[Please describe your issue here]

perl5db.pl does not set new file-handles into ReadLine after pager
command. This cause a segmentation fault when used with
Term​::ReadLine​::Gnu.
See https://rt.cpan.org/Public/Bug/Display.html?id=83040 for more
details.

When the pager command (| or ||) is used in perldb, it overwrites the
OUT
file
handle. perldb.pl has a function, reset_IN_OUT(), for such case, but
it is not called after the pager command.

From http​://search.cpan.org/~rjbs/perl-
5.18.2/lib/perl5db.pl#reset_IN_OUT
-----------------------
reset_IN_OUT
This routine handles restoring the debugger's input and output
file-handles after we've tried and failed to move them elsewhere. In
addition, it assigns the debugger's output file-handle to $LINEINFO if
it was already open there.
-----------------------

In reset_IN_OUT() Term​::ReadLine​:newTTY() is called.

The perl implementations of Term​::ReadLine (Term​::ReadLine​::Stub or
Term​::ReadLine​::Perl, etc.) are not affected by this bug, because the
OUT
file
handle is in the global scope. But for XS implementation needs
newTTY() to
be called.

Attached are the patches for
perldb5 version 1.43 in perl 5.19.9 (latest development release)
perldb5 version 1.39_10 in perl 5.18.2 (latest stable)
perldb5 version 1.37 in perl 5.16.3 (previous stable)

Thanks for the investigation and the fix. I tested it in bleadperl and it indeed fixed the problem (which also bothered me, but I lacked the tuits to fix it). That put aside, I have reworked the bleadperl patch a little to​:

1. Fix the grammar in the comment a little.

2. Fix the indentation from tabs-based to be consistently space-based.

That patch is attached here and I'm planning to also work on similar patches for maintperl-5.18.x and maintperl-5.16.x.

Note that the cmp_version.t core test fails with it - perhaps the $VERSION in perl5db.pl needs to be updated.

Regards,

-- Shlomi Fish

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags​:
category=utilities
severity=medium
---
Site configuration information for perl 5.16.3​:

Configured by Red Hat, Inc. at Mon Nov 11 12​:49​:48 UTC 2013.

Summary of my perl5 (revision 5 version 16 subversion 3)
configuration​:

Platform​:
osname=linux, osvers=3.10.9-200.fc19.x86_64,
archname=x86_64-linux-thread-multi
uname='linux buildvm-04.phx2.fedoraproject.org 3.10.9-
200.fc19.x86_64
#1 smp wed aug 21 19​:27​:58 utc 2013 x86_64 x86_64 x86_64 gnulinux '
config_args='-des -Doptimize=-O2 -g -pipe -Wall -Wp,-
D_FORTIFY_SOURCE=2
-fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64
-mtune=generic -Dccdlflags=-Wl,--enable-new-dtags -Dlddlflags=-shared
-O2
-g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector
--param=ssp-buffer-size=4 -m64 -mtune=generic -Wl,-z,relro
-DDEBUGGING=-g
-Dversion=5.16.3 -Dmyhostname=localhost -Dperladmin=root@​localhost
-Dcc=gcc
-Dcf_by=Red Hat, Inc. -Dprefix=/usr -Dvendorprefix=/usr
-Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl5
-Dsitearch=/usr/local/lib64/perl5 -Dprivlib=/usr/share/perl5
-Dvendorlib=/usr/share/perl5/vendor_perl -Darchlib=/usr/lib64/perl5
-Dvendorarch=/usr/lib64/perl5/vendor_perl
-Darchname=x86_64-linux-thread-multi -Dlibpth=/usr/local/lib64 /lib64
/usr/lib64 -Duseshrplib -Dusethreads -Duseithreads
-Dusedtrace=/usr/bin/dtrace -Duselargefiles -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 -Dscriptdir=/usr/bin -Dusesitecustomize'
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='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing
-pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64',
optimize='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions
-fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic',
cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe
-fstack-protector -I/usr/local/include'
ccversion='', gccversion='4.7.2 20121109 (Red Hat 4.7.2-8)',
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='gcc', ldflags =' -fstack-protector'
libpth=/usr/local/lib64 /lib64 /usr/lib64
libs=-lresolv -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread
-lc
-lgdbm_compat
perllibs=-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
libc=, so=so, useshrplib=true, libperl=libperl.so
gnulibc_version='2.16'
Dynamic Linking​:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef,
ccdlflags='-Wl,--enable-new-dtags -Wl,-rpath,/usr/lib64/perl5/CORE'
cccdlflags='-fPIC', lddlflags='-shared -O2 -g -pipe -Wall
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector
--param=ssp-buffer-size=4 -m64 -mtune=generic -Wl,-z,relro '

Locally applied patches​:

---
@​INC for perl 5.16.3​:
/home/hiroo/perl5/lib/perl5/x86_64-linux-thread-multi
/home/hiroo/perl5/lib/perl5
/home/hiroo/perl5/lib/perl5/x86_64-linux-thread-multi
/home/hiroo/perl5/lib/perl5
/usr/local/lib64/perl5
/usr/local/share/perl5
/usr/lib64/perl5/vendor_perl
/usr/share/perl5/vendor_perl
/usr/lib64/perl5
/usr/share/perl5
.

---
Environment for perl 5.16.3​:
HOME=/home/hiroo
LANG=en_US.utf8
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)

PATH=/home/hiroo/perl5/bin​:/home/hiroo/perl5/bin​:/usr/local/bin​:/usr/bin​:/bin​:/usr/local/sbin​:/usr/sbin​:/home/hiroo/.local/bin​:/home/hiroo/bin
PERL5LIB=/home/hiroo/perl5/lib/perl5​:/home/hiroo/perl5/lib/perl5​:
PERL_BADLANG (unset)
PERL_LOCAL_LIB_ROOT=​:/home/hiroo/perl5​:/home/hiroo/perl5
PERL_MB_OPT=--install_base /home/hiroo/perl5
PERL_MM_OPT=INSTALL_BASE=/home/hiroo/perl5
SHELL=/bin/bash

[p5pRT]

From @shlomif

perl5db-bleadperl-Term-RL-Gnu-pager-crash.patch

diff --git a/lib/perl5db.pl b/lib/perl5db.pl
index c1d6752..ae04a9a 100644
--- a/lib/perl5db.pl
+++ b/lib/perl5db.pl
@@ -2419,6 +2419,9 @@ sub _DB__at_end_of_every_command {
             open( OUT, ">&SAVEOUT" ) || _db_warn("Can't restore DB::OUT");
         }
 
+        # Let Readline know about the new filehandles.
+        reset_IN_OUT( \*IN, \*OUT );
+
         # Close filehandle pager was using, restore the normal one
         # if necessary,
         close(SAVEOUT);

[p5pRT]

The RT System itself - Status changed from 'new' to 'open'

[p5pRT]

From @shlomif

Hi,

replying to myself, I'm attaching the corresponding patches for maint5.18 and maint5.16 (which I tested to see that the bug is fixed). Please also credit Hiroo Hayashi as an originator of these patch.

Regards,

-- Shlomi Fish

[p5pRT]

From @shlomif

perl5db-maint5.16-Term-RL-Gnu-pager-crash.patch

diff --git a/lib/perl5db.pl b/lib/perl5db.pl
index 889f305..29bf740 100644
--- a/lib/perl5db.pl
+++ b/lib/perl5db.pl
@@ -3316,6 +3316,9 @@ our standard filehandles for input and output.
                     open( OUT, ">&SAVEOUT" ) || &warn("Can't restore DB::OUT");
                 }
 
+                # Let Readline know about the new filehandles.
+                reset_IN_OUT( \*IN, \*OUT );
+
                 # Close filehandle pager was using, restore the normal one
                 # if necessary,
                 close(SAVEOUT);

[p5pRT]

From @shlomif

perl5db-maint5.18-Term-RL-Gnu-pager-crash.patch

diff --git a/lib/perl5db.pl b/lib/perl5db.pl
index da532fb..c2921d7 100644
--- a/lib/perl5db.pl
+++ b/lib/perl5db.pl
@@ -2418,6 +2418,9 @@ sub _DB__at_end_of_every_command {
             open( OUT, ">&SAVEOUT" ) || _db_warn("Can't restore DB::OUT");
         }
 
+        # Let Readline know about the new filehandles.
+        reset_IN_OUT( \*IN, \*OUT );
+
         # Close filehandle pager was using, restore the normal one
         # if necessary,
         close(SAVEOUT);

[p5pRT]

From @rjbs

This has been applied to 5.19, and I've marked it as blocking the 5.16 and 5.18 maint branches' next releases.

--
rjbs

[p5pRT]

From @tonycoz

On Mon Apr 07 07​:59​:57 2014, rjbs wrote​:

This has been applied to 5.19, and I've marked it as blocking the 5.16
and 5.18 maint branches' next releases.

+1 for maint 5.18 and 5.16.

Tony

[p5pRT]

From @khwilliamson

On 04/15/2014 09​:24 PM, Tony Cook via RT wrote​:

On Mon Apr 07 07​:59​:57 2014, rjbs wrote​:

This has been applied to 5.19, and I've marked it as blocking the 5.16
and 5.18 maint branches' next releases.

+1 for maint 5.18 and 5.16.

Tony

---
via perlbug​: queue​: perl5 status​: open
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=121456

+1 to both

[p5pRT]

From @mauke

On Tue Apr 15 21​:08​:24 2014, public@​khwilliamson.com wrote​:

On 04/15/2014 09​:24 PM, Tony Cook via RT wrote​:

On Mon Apr 07 07​:59​:57 2014, rjbs wrote​:

This has been applied to 5.19, and I've marked it as blocking the 5.16
and 5.18 maint branches' next releases.

+1 for maint 5.18 and 5.16.

Tony

---
via perlbug​: queue​: perl5 status​: open
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=121456

+1 to both

This ticket is open and listed as blocking 5.18.5. But it is listed as fixed in perl5184delta, so I think the blocking part can be removed (right?).

Is there anything else left to do or can this whole ticket be closed?

[p5pRT]

From @jkeenan

On Fri Feb 26 10​:00​:33 2016, mauke- wrote​:

On Tue Apr 15 21​:08​:24 2014, public@​khwilliamson.com wrote​:

On 04/15/2014 09​:24 PM, Tony Cook via RT wrote​:

On Mon Apr 07 07​:59​:57 2014, rjbs wrote​:

This has been applied to 5.19, and I've marked it as blocking the
5.16
and 5.18 maint branches' next releases.

+1 for maint 5.18 and 5.16.

Tony

---
via perlbug​: queue​: perl5 status​: open
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=121456

+1 to both

This ticket is open and listed as blocking 5.18.5. But it is listed as
fixed in perl5184delta, so I think the blocking part can be removed
(right?).

Is there anything else left to do or can this whole ticket be closed?

Let's close the ticket. The changes were applied to 5.16.3 and 5.18.4. I don't think there's anything left to be done.

Thank you very much.
--
James E Keenan (jkeenan@​cpan.org)