Problem with Sys::Hostname.

[p5pRT]

Migrated from rt.perl.org#892 (status was 'resolved')

Searchable as RT892$

[p5pRT]

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.

Perl Info

``` 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 ```

[p5pRT]

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.

Perl Info

``` 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 ```

[p5pRT]

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.

Perl Info

``` 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 ```

[p5pRT]

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

[p5pRT]

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

[p5pRT]

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

[p5pRT]

From [Unknown Contact. See original ticket]

fixed in perl 5.6.0

[p5pRT]

From The RT System itself

fixed in perl 5.6.0