[PATCH] Apache2::SizeLimit aborts when smaps is not available

[Harry Danilevsky <ha...@gmail.com>]

1. Problem Description:

  Apache2::SizeLimit aborts when smaps facility is unavailable. Here's the
error from the error log:

Linux::Smaps: Cannot open /proc/9700/smaps: No such file or directory
BEGIN failed--compilation aborted at
/data/wre/prereqs/lib/perl5/site_perl/5.10.0/i686-linux/Apache2/SizeLimit.pm
line 98

This installation is part of WebGUI CMS (hence the path, starting with
/data/wre),
but there's nothing specific to WebGUI here - it's just a plain mod_perl
file tree.

The error is not caused by insufficient read permissions - there are
simply no smaps files in /proc/xxx.
Apache2::SizeLimit documentation mentions two possible solutions:

   1. Installing an OS patch with smaps support (which may or may not be an
option)

   2. Setting $Apache2::SizeLimit::USE_SMAPS to 0 before the first check.
This doesn't
      help in this particular case, because the error is generated within
the BEGIN block;
      besides, the chunk of code which produces this error, pays no
attention to $USE_SMAPS


I believe the error is caused simply by placing the wrong (or rather
insufficient) statement inside eval() :

        if ( eval { require Linux::Smaps } and Linux::Smaps->new($$) ) {
             ...
        }

Linux::Smaps module is present, and obviously returns 1, but
Linux::Smaps->new throws an error
which is not being caught by eval.

I propose the following trivial patch:


--------------------------8<--------------------

*** ./SizeLimit.pm      2009-11-30 09:13:16.000000000 -0600
--- /tmp/SizeLimit.pm.orig      2009-11-30 09:24:04.000000000 -0600
***************
*** 58,64 ****

      }
      elsif (LINUX) {
!         if ( eval { require Linux::Smaps and Linux::Smaps->new($$) } ) {
              $HOW_BIG_IS_IT = \&linux_smaps_size_check_first_time;
          }
          else {
--- 58,64 ----

      }
      elsif (LINUX) {
!         if ( eval { require Linux::Smaps } and Linux::Smaps->new($$) ) {
              $HOW_BIG_IS_IT = \&linux_smaps_size_check_first_time;
          }
          else {

--------------------------8<--------------------


-- Harry Danilevsky

harry.danilevsky@gmail.com


2. Used Components and their Configuration:

*** mod_perl version 2.000004

*** using
/data/wre/prereqs/lib/perl5/site_perl/5.10.0/i686-linux/Apache2/BuildConfig.pm

*** Makefile.PL options:
  MP_APR_LIB     => aprext
  MP_APXS        => /data/wre/prereqs/bin/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/data/wre/prereqs/lib -laprutil-1  -lexpat
 -L/data/wre/prereqs/lib -lapr-1 -lrt -lcrypt  -lpthread -ldl



*** /data/wre/prereqs/bin/perl -V
Summary of my perl5 (revision 5 version 10 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.4.21-51.el, archname=i686-linux
    uname='linux centos3 2.4.21-51.el #1 thu aug 16 17:03:59 edt 2007 i686
i686 i386 gnulinux '
    config_args='-Dprefix=/data/wre/prereqs -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-fno-strict-aliasing -pipe -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='3.2.3 20030502 (Red Hat Linux 3.2.3-59)',
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=-lnsl -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 -O2 -L/usr/local/lib'


Characteristics of this binary (from libperl):
  Compile-time options: PERL_DONT_CREATE_GVSV PERL_MALLOC_WRAP
                        USE_LARGE_FILES USE_PERLIO
  Built under linux
  Compiled at May 27 2009 20:31:04
  %ENV:
    PERL_LWP_USE_HTTP_10="1"
  @INC:
    /data/wre/prereqs/lib/perl5/5.10.0/i686-linux
    /data/wre/prereqs/lib/perl5/5.10.0
    /data/wre/prereqs/lib/perl5/site_perl/5.10.0/i686-linux
    /data/wre/prereqs/lib/perl5/site_perl/5.10.0
    .

*** Packages of interest status:

Apache2            : -
Apache2::Request   : 2.08
CGI                : 3.42
ExtUtils::MakeMaker: 6.48
LWP                : 5.824
mod_perl           : -
mod_perl2          : 2.000004


3. This is the core dump trace: (if you get a core dump):



This report was generated by bin/mp2bug on Mon Nov 30 17:25:35 2009 GMT.