[RFC]: make IcedTea-web to be compatible with RHEL5 libraries

[Jiri Vanek]

On 08/23/2011 01:33 PM, Jiri Vanek wrote:
> On 08/22/2011 10:55 PM, Deepak Bhole wrote:
>> * Jiri Vanek<jvanek at redhat.com> [2011-08-22 09:21]:
>>> On 07/21/2011 03:21 PM, Dr Andrew John Hughes wrote:
>>>> On 12:08 Thu 21 Jul , Jiri Vanek wrote:
>>>>>
>>>>> Hi!
>>>>>
>>>>> This patch is another attempt o make icedtea-web buildable on rhel 5 with older libraries. Before build of plugin itself is started, then testing c++ program is tried to be linked with same options. If this compilation fails, then original IcedTeaNPPlugin.cc is backuped, glibBuildable.patch is applied to IcedTeaNPPlugin.cc and then plugin is linked.
>>>>> During clean-plugin original IcedTeaNPPlugin.cc is restored from backup (and when test application is compiled, then this binary is deleted, also backup is delete)
>>>>>
>>>>> Please, when you will ask me to include this "solution" more to configure (or autotools or anywhere) then I will need a little bit of help.
>>>>>
>>>>
>>>> I suggest taking a look at the autoconf manual and function detection:
>>>>
>>>> http://www.gnu.org/software/autoconf/manual/autoconf.html#Library-Functions
>>>>
>>>> Then, rather than patching, I'd add a header file with #ifdefs to handle both cases.
>>>>
>>>
>>> 2011-08-22 Jiri Vanek<jvanek at redhat.com>
>>> Added functionality to allow icedtea web to be buildable with
>>> rhel5 libraries
>>> * testGlibs.cc: testing file. If not compiled, then Rhel5Compatible
>>> macro is defined for compiling IcedTeaNPPlugin.cc.
>>> * plugin/icedteanp/IcedTeaNPPlugin.cc: added replacements for incompatible
>>> functions, added #define sections for use this function instead of glib ones
>>> *Makefile.am: (stamps/patch-for-glib): new target, compiling testGlibs.cc
>>> ($(PLUGIN_DIR)/%.o): now depends on stamps/patch-for-glib and define
>>> Rhel5Compatible if testGlibs.cc was compiled successfully
>>> ($(PLUGIN_DIR)/IcedTeaPlugin.so): same as ^
>>> (clean-IcedTeaPlugin): removes compiled testGlibs if exists
>>>
>>
>> Is this RHEL 5 specific or glib version specific? It looks to be the
>> latter. In which case no test program should be needed -- just a check
>> for glib version and conditional compilation accordingly.
>
> Very well then :)
> I will add this to acinclude.m4
>
>
> AC_DEFUN_ONCE([IT_GET_GLIBCVERSION],
> [
> AC_MSG_CHECKING([for glibc version >= 2.12])
> basicVersion=`ldd --version | grep "@<:@0123456789@:>@\.@<:@0123456789@:>@" | sed "s/ldd (GNU libc) //"`;
> echo "- $basicVersion -"
> versions=(`echo $basicVersion | sed "s/\./ /g"`);
> if test ${versions@<:@0@:>@} -lt 2 ; then
> GLIBCVERSION="no"
> else
> if test ${versions@<:@0@:>@} -gt 2 ; then
> GLIBCVERSION="yes"
> else
> #maybe
> if test ${versions@<:@1@:>@} -ge 12 ; then
> GLIBCVERSION="yes"
> else
> GLIBCVERSION="no"
> fi;
> fi;
> fi;
> AC_MSG_RESULT([${GLIBCVERSION}])
> AC_SUBST(GLIBCVERSION)
> ])
>
>
>
> this will add make variable GLIBCVERSION for conditional compilation in makefile.
> The docmentation says "since 2.16" but it can not be true, as rhel5 have 2.5 and have missing those functions, and rhel 6 have 2.12.5 and my F13 have 2.12 and both HAVE those functions .... :-/ But it is not firs time glibc documentation was wrong.
>
> I still think compilation is much more bulet-proof, but if you are ok with this then I will post updated patch.
>
> Regards J.
>
> (maybe useless) ps: @<:@ is replaced by [ and @:>@ by ] during configure generation... no other way here...long live the Autotools :(
> pps: I'm happy autotools-lame, please feel free to correct me in above script as much as possible.
>
>
>>
>> Cheers,
>> Deepak
>>
>>>
>>> Regards J.
>>

Following Omair's advice, instead of version checking I have used AC_TRY_LINK:

2011-08-25 Jiri Vanek<jvanek at redhat.com>
	Added functionality to allow icedtea web to be buildable with
	 rhel5 libraries
	*acinclude.m4: added block to test version of glibc instaled by linking
	 program using glibc functions used in icedtea plugin.
	* plugin/icedteanp/IcedTeaNPPlugin.cc: added replacements for incompatible
	functions, added #define sections for use this function instead of glib ones
	*Makefile.am: ($(PLUGIN_DIR)/%.o): using GLIBCVERSION setted by configure
	 is setting  define Rhel5Compatible
	($(PLUGIN_DIR)/IcedTeaPlugin.so): same as ^
	*configure.ac: added IT_GET_GLIBCVERSION
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