From @muir

Created by @muir

David,

Do you still maintain Sys​::Hostname? If so, I would like to bring
a problem to your attention.

On FreeBSD, the following hangs forever with an infinate loop in sh.

  perl -MSys​::Hostname -e '$SIG{"CHLD"} = "IGNORE"; hostname();'

The fix is pretty simple​: make $SIG{CHLD} local.

retrieving revision 1.1.1.1
diff -c -r1.1.1.1 Hostname.pm
*** Hostname.pm 1998/09/09 06​:59​:55 1.1.1.1
--- Hostname.pm 1999/06/20 22​:59​:51
***************
*** 94,99 ****
--- 94,100 ----
  # method 3 - trusty old hostname command
  || eval {
  local $SIG{__DIE__};
+ local $SIG{CHLD};
  $host = `(hostname) 2>/dev/null`; # bsdish
  }
 

This is a bug report for perl from muir@​idiom.com,
generated with the help of perlbug 1.26 running under perl 5.00502.

Site configuration information for perl 5.00502:

Configured by markm at $Date: 1999/01/17 09:53:34 $.

Summary of my perl5 (5.0 patchlevel 5 subversion 2) configuration:
  Platform:
    osname=freebsd, osvers=3.0-current, archname=i386-freebsd
    uname='freebsd 3.0-current #0: '
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef useperlio=undef d_sfio=undef
  Compiler:
    cc='cc', optimize='undef', gccversion=2.7.2.1
    cppflags=''
    ccflags =''
    stdchar='char', d_stdstdio=undef, usevfork=true
    intsize=4, longsize=4, ptrsize=4, doublesize=8
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    alignbytes=4, usemymalloc=n, prototype=define
  Linker and Libraries:
    ld='ld', ldflags ='-Wl,-E '
    libpth=/usr/lib
    libs=-lm -lc -lcrypt
    libc=undef, so=so, useshrplib=true, libperl=libperl.so.3
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
    cccdlflags='-DPIC -fpic', lddlflags='-shared '

Locally applied patches:
    


@INC for perl 5.00502:
    /usr/libdata/perl/5.00502/mach
    /usr/libdata/perl/5.00502
    /usr/local/lib/perl5/site_perl/5.005/i386-freebsd
    /usr/local/lib/perl5/site_perl/5.005
    .


Environment for perl 5.00502:
    HOME=/home/muir
    LANG (unset)
    LD_LIBRARY_PATH=.:/usr/lib:/usr/local/lib
    LOGDIR (unset)
    PATH=.:/home/muir/bin/idiom:/home/muir/bin:/home/muir/bin/share:/bin:/usr/bin:/sbin:/usr/sbin:/usr/local/shbin:/usr/local/sbin:/usr/local/bin:/usr/local/ptybin:/usr/X11R6/bin:/usr/bin/X11:/usr/local/tex/bin:/usr/ucb:/usr/bin:/bin:/etc:/usr/etc:/usr/games:/lib:/usr/lib:/usr/local/java/bin:/usr/lib/uucp:/usr/openwin/bin:/usr/openwin/bin/xview:/usr/openwin/demo:/usr/adm:/home/muir/tmp
    PERL_BADLANG (unset)
    SHELL=/bin/tcsh

From @muir

Created by @muir

David,

Do you still maintain Sys​::Hostname? If so, I would like to bring
a problem to your attention.

On FreeBSD, the following hangs forever with an infinate loop in sh.

  perl -MSys​::Hostname -e '$SIG{"CHLD"} = "IGNORE"; hostname();'

The fix is pretty simple​: make $SIG{CHLD} local.

retrieving revision 1.1.1.1
diff -c -r1.1.1.1 Hostname.pm
*** Hostname.pm 1998/09/09 06​:59​:55 1.1.1.1
--- Hostname.pm 1999/06/20 22​:59​:51
***************
*** 94,99 ****
--- 94,100 ----
  # method 3 - trusty old hostname command
  || eval {
  local $SIG{__DIE__};
+ local $SIG{CHLD};
  $host = `(hostname) 2>/dev/null`; # bsdish
  }
 

This is a bug report for perl from muir@​idiom.com,
generated with the help of perlbug 1.26 running under perl 5.00502.

Site configuration information for perl 5.00502:

Configured by markm at $Date: 1999/01/17 09:53:34 $.

Summary of my perl5 (5.0 patchlevel 5 subversion 2) configuration:
  Platform:
    osname=freebsd, osvers=3.0-current, archname=i386-freebsd
    uname='freebsd 3.0-current #0: '
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef useperlio=undef d_sfio=undef
  Compiler:
    cc='cc', optimize='undef', gccversion=2.7.2.1
    cppflags=''
    ccflags =''
    stdchar='char', d_stdstdio=undef, usevfork=true
    intsize=4, longsize=4, ptrsize=4, doublesize=8
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    alignbytes=4, usemymalloc=n, prototype=define
  Linker and Libraries:
    ld='ld', ldflags ='-Wl,-E '
    libpth=/usr/lib
    libs=-lm -lc -lcrypt
    libc=undef, so=so, useshrplib=true, libperl=libperl.so.3
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
    cccdlflags='-DPIC -fpic', lddlflags='-shared '

Locally applied patches:
    


@INC for perl 5.00502:
    /usr/libdata/perl/5.00502/mach
    /usr/libdata/perl/5.00502
    /usr/local/lib/perl5/site_perl/5.005/i386-freebsd
    /usr/local/lib/perl5/site_perl/5.005
    .


Environment for perl 5.00502:
    HOME=/home/muir
    LANG (unset)
    LD_LIBRARY_PATH=.:/usr/lib:/usr/local/lib
    LOGDIR (unset)
    PATH=.:/home/muir/bin/idiom:/home/muir/bin:/home/muir/bin/share:/bin:/usr/bin:/sbin:/usr/sbin:/usr/local/shbin:/usr/local/sbin:/usr/local/bin:/usr/local/ptybin:/usr/X11R6/bin:/usr/bin/X11:/usr/local/tex/bin:/usr/ucb:/usr/bin:/bin:/etc:/usr/etc:/usr/games:/lib:/usr/lib:/usr/local/java/bin:/usr/lib/uucp:/usr/openwin/bin:/usr/openwin/bin/xview:/usr/openwin/demo:/usr/adm:/home/muir/tmp
    PERL_BADLANG (unset)
    SHELL=/bin/tcsh

From [Unknown Contact. See original ticket]

Isn't this illustrative of a more general problem of mixing zombies,
sig kids, explicit reapers, and backticks? (And maybe pipe opens).
I don't think we've ever enumerated precisely what is safe to do in a
module with respect to process management to avoid interfering with
Perl internals, the main program, or other modules. A list of "dos
and don'ts", would be great to have, perhaps even something checkable
semi-automatically for CPAN and Core modules.

--tom

From @muir

* Isn't this illustrative of a more general problem of mixing zombies,
* sig kids, explicit reapers, and backticks? (And maybe pipe opens).
* I don't think we've ever enumerated precisely what is safe to do in a
* module with respect to process management to avoid interfering with
* Perl internals, the main program, or other modules. A list of "dos
* and don'ts", would be great to have, perhaps even something checkable
* semi-automatically for CPAN and Core modules.

Is that backwards? I would tend to think that the CPAN and Core
modules should insulate themselves from things that other programmers
rather than trying to document gotchas like​:

  Don't change $SIG{CHLD} if you use Sys​::Hostname or anything
  that uses Sys​::Hostname like ...

Much better IMHO to fix Sys​::Hostname so that it always works.

That said, there are things that module writers should not need
to worry about. I was going to say "like changing $[," but that
was fixed by making it file-scoped.

-Dave

From [Unknown Contact. See original ticket]

Is that backwards? I would tend to think that the CPAN and Core
modules should insulate themselves from things that other programmers
rather than trying to document gotchas like​:

Don't change $SIG{CHLD} if you use Sys​::Hostname or anything
that uses Sys​::Hostname like ...

Much better IMHO to fix Sys​::Hostname so that it always works.

That's what I meant for us to go look for.

--tom

From [Unknown Contact. See original ticket]

fixed in perl 5.6.0

From The RT System itself

fixed in perl 5.6.0