Re: [mp1]: different output under perlrun and CGI

Philippe M. Chiasson Mon, 02 Aug 2004 12:12:25 -0700

Gunnar Koppel wrote:

Terr!

I got some differencies between using script under CGI and
Apache::PerlRun what i don't understand is that mandatory.

I am not an expert, so i try just to describe my situation.

I have an CGI-script with following sub:

sub PHeader {
$_[0]
? print $q->header(-type=>"text/plain; $char",-cookie=>'')
: print $q->header(-type=>"text/html; $char",-cookie=>'');
}

I call this sub mostly &PHeader and only if i need "Content-type:
text/plain" i add a argument &PHeader(1), for example.

Under CGI it works fine, but under Apache::PerlRun has @_ a value (for
example "Apache::PerlRun=HASH(0x81ea01c) SCALAR(0x821a2bc)", i don't
know where and why it comes) and my PHeader does not understand that i
need a HTML-header. When i call a sub like &PHeader() or PHeader, it
works fine, so main program does not deliver any arguments.


That's very simple ;-)

When running under Apache::PerlRun (or Apache:Registry), your script is
wrapped in a subroutine, that gets a few arguments passed in.

So, from the perlsub manpage:

To call subroutines:

  NAME(LIST);    # & is optional with parentheses.
  NAME LIST;     # Parentheses optional if predeclared/imported.
  &NAME(LIST);   # Circumvent prototypes.
  &NAME;         # Makes current @_ visible to called subroutine.

So, when you are calling &sub; you are propagating the @_ of the current
scope down to that subroutine. As a rule of thumb, you should always calls
subs like sub() unless you _explicitely_ need to propagate @_ down to the
subroutine.

Maybe it is something trivial but i had really confused why i got wrong
headers. When i ran it from command line, i got right header (like under
CGI).

Maybe someone can explain, why under PerlRun i got value for @_?

My system is Debian GNU/Linux Stable, Apache is 1.3.29, mod_perl 1.29,
perl 5.8.3.

example script:
------------
#!/usr/bin/perl -w

use strict;
use CGI qw(:all);
our ($q, $char);
$q = new CGI;
$char = "iso-8859-15";

&PHeader;
# &PHeader() or PHeader works fine;
&PContent;

sub PHeader {
@_
? print $q->header(-type=>"text/plain; $char",-cookie=>'')
: print $q->header(-type=>"text/html; $char",-cookie=>'');
}

sub PContent {
@_
? print "some plain text -> @_"
: print "<b>some HTML-content</b>";
}
------------

Output of `perl -V`
------------
Summary of my perl5 (revision 5.0 version 8 subversion 3) configuration:
   Platform:
     osname=linux, osvers=2.4.25-ti1211, archname=i386-linux-thread-multi
     uname='linux kosh 2.4.25-ti1211 #1 thu feb 19 18:20:12 est 2004
i686 gnulinux '
     config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-Dcccdlflags=-fPIC -Darchname=i386-linux -Dprefix=/usr -Dpriv
lib=/usr/share/perl/5.8 -Darchlib=/usr/lib/perl/5.8 -Dvendorprefix=/usr
-Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/per
l5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.8.3
-Dsitearch=/usr/local/lib/perl/5.8.3 -Dman1dir=/usr/share/man
/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
-Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=
3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Uusenm
-Duseshrplib -Dlibperl=libperl.so.5.8.3 -Dd_dosuid -des'
     hint=recommended, useposix=true, d_sigaction=define
     usethreads=define use5005threads=undef useithreads=define
usemultiplicity=define
     useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
     use64bitint=undef use64bitall=undef uselongdouble=undef
     usemymalloc=n, bincompat5005=undef
   Compiler:
     cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
-DDEBIAN -fno-strict-aliasing -I/usr/local/include -D_LA
RGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
     optimize='-O3',
     cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN
-fno-strict-aliasing -I/usr/local/include'
     ccversion='', gccversion='3.3.3 (Debian 20040314)', gccosandvers=''
     intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
     d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
     ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
     alignbytes=4, prototype=define
   Linker and Libraries:
     ld='cc', ldflags =' -L/usr/local/lib'
     libpth=/usr/local/lib /lib /usr/lib
     libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
     perllibs=-ldl -lm -lpthread -lc -lcrypt
     libc=/lib/libc-2.3.2.so, so=so, useshrplib=true,
libperl=libperl.so.5.8.3
     gnulibc_version='2.3.2'
   Dynamic Linking:
     dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
     cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'


Characteristics of this binary (from libperl):
   Compile-time options: MULTIPLICITY USE_ITHREADS USE_LARGE_FILES
PERL_IMPLICIT_CONTEXT
   Built under linux
   Compiled at Mar 27 2004 16:21:10
   @INC:
     /etc/perl
     /usr/local/lib/perl/5.8.3
     /usr/local/share/perl/5.8.3
     /usr/lib/perl5
     /usr/share/perl5
     /usr/lib/perl/5.8
     /usr/share/perl/5.8
     /usr/local/lib/site_perl
     .
------------


--
--------------------------------------------------------------------------------
Philippe M. Chiasson m/gozer\@(apache|cpan|ectoplasm)\.org/ GPG KeyID : 88C3A5A5
http://gozer.ectoplasm.org/     F9BF E0C2 480E 7680 1AE5 3631 CB32 A107 88C3A5A5

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Re: [mp1]: different output under perlrun and CGI

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