PERL Miscellaneous - question about "requiring" linux/stat.ph

Author

question about "requiring" linux/stat.ph

szr

2008-02-14, 4:25 am

Hello. I am wrapping up a rather large server migration job I was tasked
with. Everything is running wonderfully.

One thing I noticed in a few legacy Perl scripts that had <code>require
"linux/stat.ph";</code> near the top and making use of functions like
S_ISLNK, resulting in this sort of error, which can be easily
reproduced:

$ perl -e 'require "linux/stat.ph"; &S_ISLNK'
Undefined subroutine &main::S_ISLNK called at -e line 1.

It seems the problem is coming from line 7 in
/usr/local/perl5.8.8/lib/site_perl/5.8.8/i686-linux-64int-ld/linux/stat.ph

if(defined( &__KERNEL__) || !defined( &__GLIBC__) ||
((defined(&__GLIBC__) ? &__GLIBC__ : 0) < 2)) {

Here is what the values for those defines are:

$ perl -e 'require
"/usr/local/perl5.8.8/lib/site_perl/5.8.8/i686-linux-64int-ld/linux/stat.ph";
print "[", &__KERNEL__, "]"'
Undefined subroutine &main::__KERNEL__ called at -e line 1.

$ perl -e 'require
"/usr/local/perl5.8.8/lib/site_perl/5.8.8/i686-linux-64int-ld/linux/stat.ph";
print "[", &__GLIBC__, "]"'
[2]

&__KERNEL__ is not defined and &__GLIBC__ is 2

If I comment out line 7 (and it's closing brace) then all the &S_ subs
(ie, S_ISLNK) are found properly, but I don't want to use such a hack, I
would like to fix the problem itself.

Thanks for any help.

-------------------------------
Perl Info Below
-------------------------------

$ perl -v

This is perl, v5.8.8 built for i686-linux-64int-ld
[...]

$ perl -V
Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
Platform:
osname=linux, osvers=2.4.20-8, archname=i686-linux-64int-ld
uname='linux srlinux 2.4.20-8 #1 thu mar 13 17:54:28 est 2003 i686
i686 i386 gnulinux '
config_args='-Dprefix=/usr/local/perl5.8.8 -Duse64bitint'
hint=recommended, useposix=true, d_sigaction=define
usethreads=undef use5005threads=undef useithreads=undef
usemultiplicity=undef
useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=define use64bitall=undef uselongdouble=define
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags
='-fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64
-I/usr/include/gdbm',
optimize='-O2',
cppflags='-fno-strict-aliasing -pipe -I/usr/local/include -I/usr/include/gdbm'
ccversion='', gccversion='3.2.2 20030222 (Red Hat Linux 3.2.2-5)',
gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long long', ivsize=8, nvtype='long double', nvsize=12,
Off_t='off_t', ls

size=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
libc=/lib/libc-2.3.2.so, so=so, useshrplib=false, libperl=libperl.a
gnulibc_version='2.3.2'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Characteristics of this binary (from libperl):
Compile-time options: PERL_MALLOC_WRAP USE_64_BIT_INT USE_LARGE_FILES
USE_LONG_DOUBLE USE_PERLIO
Built under linux
Compiled at Feb 11 2008 01:12:44
%ENV:
PERL5LIB="/home/SR/perllib:"
@INC:
/home/SR/perllib
/usr/local/perl5.8.8/lib/5.8.8/i686-linux-64int-ld
/usr/local/perl5.8.8/lib/5.8.8
/usr/local/perl5.8.8/lib/site_perl/5.8.8/i686-linux-64int-ld
/usr/local/perl5.8.8/lib/site_perl/5.8.8
/usr/local/perl5.8.8/lib/site_perl

John W. Krahn

2008-02-14, 7:08 pm

szr wrote:
> Hello. I am wrapping up a rather large server migration job I was tasked
> with. Everything is running wonderfully.
>
> One thing I noticed in a few legacy Perl scripts that had <code>require
> "linux/stat.ph";</code> near the top and making use of functions like
> S_ISLNK, resulting in this sort of error, which can be easily
> reproduced:
>
> $ perl -e 'require "linux/stat.ph"; &S_ISLNK'
> Undefined subroutine &main::S_ISLNK called at -e line 1.

Change:

require "linux/stat.ph";

To:

use Fcntl;

perldoc -f stat
[ SNIP ]
You can import symbolic mode constants ("S_IF*") and functions
("S_IS*") from the Fcntl module:

John
--
Perl isn't a toolbox, but a small machine shop where you
can special-order certain sorts of tools at low cost and
in short order. -- Larry Wall

szr

2008-02-14, 7:08 pm

John W. Krahn wrote:
> szr wrote:
>
> Change:
>
> require "linux/stat.ph";
>
> To:
>
> use Fcntl;
>
>
> perldoc -f stat
> [ SNIP ]
> You can import symbolic mode constants ("S_IF*") and functions
> ("S_IS*") from the Fcntl module:
>

Thanks.

use Fcntl ':mode';

did the trick :)

--
szr

Ben Morrow

2008-02-14, 7:08 pm

Quoth "szr" <szrRE@szromanMO.comVE>:
> Hello. I am wrapping up a rather large server migration job I was tasked
> with. Everything is running wonderfully.
>
> One thing I noticed in a few legacy Perl scripts that had <code>require
> "linux/stat.ph";</code> near the top and making use of functions like
> S_ISLNK, resulting in this sort of error, which can be easily
> reproduced:
>
> $ perl -e 'require "linux/stat.ph"; &S_ISLNK'
> Undefined subroutine &main::S_ISLNK called at -e line 1.

You should be importing these constants from Fcntl with non-ancient
versions of Perl. h2ph can't always cope with the complicated
conditional definitions in Linux' system headers, so sometimes the
generated .ph files are not useable.

perl -MFcntl=:mode -le'print S_ISLNK(S_IFLNK)'

Generally speaking you can just use -l instead, though.

Ben

szr

2008-02-29, 7:10 pm

Ben Morrow wrote:
> Quoth "szr" <szrRE@szromanMO.comVE>:
>
> You should be importing these constants from Fcntl with non-ancient
> versions of Perl. h2ph can't always cope with the complicated
> conditional definitions in Linux' system headers, so sometimes the
> generated .ph files are not useable.
>
> perl -MFcntl=:mode -le'print S_ISLNK(S_IFLNK)'
>
> Generally speaking you can just use -l instead, though.
>
> Ben

Thank you for the information.

-szr

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