open >&= works on RDONLY filehandle?

[p5pRT]

Migrated from rt.perl.org#1960 (status was 'resolved')

Searchable as RT1960$

[p5pRT]

From joseph@cscaper.com

use POSIX;
$fd = POSIX​::open("foo", O_RDONLY, 0644) or die $!;
open FH, ">&=$fd" or die $!;
print FH "here's something\n" or die $!;

Does it make sense that this yields no errors?

Perl Info

Site configuration information for perl 5.00502:

Configured by root at Thu Dec 31 02:40:42 MST 1998.

Summary of my perl5 (5.0 patchlevel 5 subversion 2) configuration:
  Platform:
    osname=solaris, osvers=2.7, archname=sun4-solaris
    uname='sunos rom 5.7 generic sun4u sparc sunw,ultrasparc-iii-engine '
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef useperlio=undef d_sfio=undef
  Compiler:
    cc='gcc -B/usr/ccs/bin/', optimize='-O', gccversion=egcs-2.91.60 19981201 (egcs-1.1.1 release)
    cppflags='-I/usr/local/include'
    ccflags ='-I/usr/local/include'
    stdchar='char', d_stdstdio=define, usevfork=false
    intsize=4, longsize=4, ptrsize=4, doublesize=8
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    alignbytes=8, usemymalloc=y, prototype=define
  Linker and Libraries:
    ld='gcc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lsocket -lnsl -lgdbm -ldl -lm -lc -lcrypt
    libc=/lib/libc.so, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
    cccdlflags='-fPIC', lddlflags='-G -L/usr/local/lib'

Locally applied patches:
    


@INC for perl 5.00502:
    /usr/local/lib/perl5/5.00502/sun4-solaris
    /usr/local/lib/perl5/5.00502
    /usr/local/lib/perl5/site_perl/5.005/sun4-solaris
    /usr/local/lib/perl5/site_perl/5.005
    .


Environment for perl 5.00502:
    HOME=/home/joseph
    LANG (unset)
    LD_LIBRARY_PATH=/usr/lang/SC1.0.1:/usr/openwin/lib
    LOGDIR (unset)
    PATH=.:/usr/local/bin:/usr/ucb:/bin:/usr/bin:/usr/5bin:/etc:/usr/etc:/usr/lang:/usr/local/postgres95/bin:/usr/ccs/bin:/usr/sbin:/usr/X11/bin:/usr/openwin/bin:/usr/local/framemaker/bin:/usr/local/pbmplus/bin:/usr/local/games/bin
    PERL_BADLANG (unset)
    SHELL=/bin/tcsh

[p5pRT]

From @gsar

On 30 Dec 1999 23​:16​:23 GMT, joseph@​cscaper.com wrote​:

use POSIX;
$fd = POSIX​::open("foo", O_RDONLY, 0644) or die $!;
open FH, ">&=$fd" or die $!;
print FH "here's something\n" or die $!;

Does it make sense that this yields no errors?

This looks Solaris-specific. The fdopen() fails properly on Linux 2.0.36
with glibc.

Sarathy
gsar@​ActiveState.com

Site configuration information for perl 5.00502​:

Configured by root at Thu Dec 31 02​:40​:42 MST 1998.

Summary of my perl5 (5.0 patchlevel 5 subversion 2) configuration​:
Platform​:
osname=solaris, osvers=2.7, archname=sun4-solaris
uname='sunos rom 5.7 generic sun4u sparc sunw,ultrasparc-iii-engine '

[p5pRT]

From @ysth

In article <200001021725.JAA05334@​activestate.com>,
Gurusamy Sarathy <gsar@​ActiveState.com> wrote​:

On 30 Dec 1999 23​:16​:23 GMT, joseph@​cscaper.com wrote​:

use POSIX;
$fd = POSIX​::open("foo", O_RDONLY, 0644) or die $!;
open FH, ">&=$fd" or die $!;
print FH "here's something\n" or die $!;

Does it make sense that this yields no errors?

This looks Solaris-specific. The fdopen() fails properly on Linux 2.0.36
with glibc.

Under os2 it also doesn't give an error. However, adding a close FH
does get an EACCES error. Changing the print to​:

print FH 'x' x 10000 or die $!;

also gets an error.

It is not clear to me that the standards require fdopen to check this.
Perhaps it is simply left as undefined behaviour.