[mp2] mod_perl closes apache's stdin and/or stdout

[Dmitry Karasik <suppressed>]

Hello,

In mixed environment of mod_perl and cgi, cgi scripts may choose to not use
mod_perl request interface, and read content of POST requests directly from
STDIN.  mod_perl during the initialization process closes file descriptor 0,
and frees it for further reuse in other processes.  Therefore, any cgi script
executing after mod_perl is initialized, and in the same process tree, will
have file descriptor 0 closed. The concrete example where this behavior leads
to impossibility of processing POST requests is reported earlier and is located
at

  http://marc.info/?l=apache-modperl&m=119062450730646&w=2

The proposed patch fixes the issue, however, not being a perl guts expert, I
would urge someone with a deeper knowledge of perl to look at it first. Chances
are that there exists a mechanism in perl that allows non-destructive
duplication and overloading of perl IO handles.

Cheers,
	Dmitry Karasik

--- modperl_io.c.orig	2007-09-25 15:36:02.000000000 +0200
+++ modperl_io.c	2007-09-25 15:35:51.000000000 +0200
@@ -129,6 +129,15 @@
             Perl_croak(aTHX_ "Failed to dup STDIN: %" SVf, get_sv("!", TRUE));
         }
 
+        /* In mixed environment of mod_perl and cgi scripts, cgi scripts may read content of 
+	 * POST requests off STDIN. do_close() calls actual close(0), freeing the descriptor 0
+	 * for reuse, and creating havoc for anyone reading from file descriptor 0.
+	 * This hack changes the IO type to IoTYPE_STD, because do_close() does not call
+	 * underlying close() on IO handles of these types, but does free the associated
+	 * resources. */
+	if ( IoIFP(io) && PerlIO_fileno(IoIFP(io)) == 0)
+           IoTYPE(io) = IoTYPE_STD;
+
         /* similar to PerlIO::scalar, the PerlIO::Apache layer doesn't
          * have file descriptors, so STDIN must be closed before it can
          * be reopened */

2. Used Components and their Configuration:

*** mod_perl version 2.000003

*** using /usr/ports/www/mod_perl2/work/mod_perl-2.0.3/lib/Apache2/BuildConfig.pm

*** Makefile.PL options:
  MP_APR_LIB     => aprext
  MP_APXS        => /usr/local/sbin/apxs
  MP_COMPAT_1X   => 1
  MP_GENERATE_XS => 1
  MP_LIBNAME     => mod_perl
  MP_USE_DSO     => 1


*** The httpd binary was not found


*** (apr|apu)-config linking info

 -L/usr/local/lib -laprutil-1 -lexpat -liconv -L/usr/local/lib
 -L/usr/local/lib -lapr-1 -lcrypt  -lpthread 


*** /usr/local/bin/perl -V
Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
  Platform:
    osname=freebsd, osvers=6.2-release, archname=i386-freebsd-64int
    uname='freebsd freebsd.org 6.2-release freebsd 6.2-release #0: sat oct 14 21:57:31 pdt 2006 suppressed:usrsrcsysmagickernelpath i386 '
    config_args='-sde -Dprefix=/usr/local -Darchlib=/usr/local/lib/perl5/5.8.8/mach -Dprivlib=/usr/local/lib/perl5/5.8.8 -Dman3dir=/usr/local/lib/perl5/5.8.8/perl/man/man3 -Dman1dir=/usr/local/man/man1 -Dsitearch=/usr/local/lib/perl5/site_perl/5.8.8/mach -Dsitelib=/usr/local/lib/perl5/site_perl/5.8.8 -Dscriptdir=/usr/local/bin -Dsiteman3dir=/usr/local/lib/perl5/5.8.8/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Ui_malloc -Ui_iconv -Uinstallusrbinperl -Dcc=cc -Duseshrplib -Dccflags=-DAPPLLIB_EXP="/usr/local/lib/perl5/5.8.8/BSDPAN" -Doptimize=-O2 -fno-strict-aliasing -pipe  -Ud_dosuid -Ui_gdbm -Dusethreads=n -Dusemymalloc=y -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=undef
    usemymalloc=y, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-DAPPLLIB_EXP="/usr/local/lib/perl5/5.8.8/BSDPAN" -DHAS_FPSETMASK -DHAS_FLOATINGPOINT_H -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include',
    optimize='-O2 -fno-strict-aliasing -pipe ',
    cppflags='-DAPPLLIB_EXP="/usr/local/lib/perl5/5.8.8/BSDPAN" -DHAS_FPSETMASK -DHAS_FLOATINGPOINT_H -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include'
    ccversion='', gccversion='3.4.6 [FreeBSD] 20060305', 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='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -Wl,-E -L/usr/local/lib'
    libpth=/usr/lib /usr/local/lib
    libs=-lm -lcrypt -lutil
    perllibs=-lm -lcrypt -lutil
    libc=, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='  -Wl,-R/usr/local/lib/perl5/5.8.8/mach/CORE'
    cccdlflags='-DPIC -fPIC', lddlflags='-shared  -L/usr/local/lib'


Characteristics of this binary (from libperl): 
  Compile-time options: MYMALLOC PERL_MALLOC_WRAP USE_64_BIT_INT
                        USE_LARGE_FILES USE_PERLIO
  Locally applied patches:
	defined-or
  Built under freebsd
  Compiled at Oct 15 2006 05:04:59
  %ENV:
    PERL_LWP_USE_HTTP_10="1"
  @INC:
    /usr/local/lib/perl5/5.8.8/BSDPAN
    /usr/local/lib/perl5/site_perl/5.8.8/mach
    /usr/local/lib/perl5/site_perl/5.8.8
    /usr/local/lib/perl5/site_perl
    /usr/local/lib/perl5/5.8.8/mach
    /usr/local/lib/perl5/5.8.8
    .

*** Packages of interest status:

Apache2            : -
Apache2::Request   : -
CGI                : 3.15
ExtUtils::MakeMaker: 6.30, undef
LWP                : 5.805
mod_perl           : -
mod_perl2          : 2.000003


This report was generated by t/REPORT on Tue Sep 25 13:39:09 2007 GMT.

-------------8<---------- End Bug Report --------------8<----------

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-- 
Sincerely,
	Dmitry Karasik