Re: [patches] Patch for OPTION_EGLIBC_NSSWITCH option group.

[Jim Blandy <jimb@xxxxxxxxxxxxxxxx>]

Mark Hatle <mark.hatle@xxxxxxxxxxxxx> writes:
> Jim Blandy wrote:
>> Here's a patch that implements the OPTION_EGLIBC_NSSWITCH option
>> group.  There's one nit I want to clean up (the use of fixed-size
>> arrays for service and database names in nss/nsswitch.h), but this is
>> basically how it would be.
>> 
>> The documentation, copied from option-groups.def:
>> 
>
> ... Thanks!

You're welcome!

>> +       In this arrangement, EGLIBC will not use the 'dlopen' and
>> +       'dlsym' functions to find database access functions.  Instead,
>> +       libc hard-codes references to the service libraries' database
>> +       access functions.  You must explicitly link your program
>> +       against the name service libraries (those whose names start
>> +       with 'libnss_', in the sysroot's '/lib' directory) whose
>> +       functions you intend to use.  This arrangement helps
>> +       system-wide static analysis tools decide which functions a
>> +       system actually uses.
>> +
>> +       Note that some nsswitch service libraries require other option
>> +       groups to be enabled; for example, the OPTION_EGLIBC_INET
>> +       option group must be enabled to use the 'libnss_dns.so.2' or
>> +       'libnss_nis.so.2' service libraries, which use the Domain Name
>> +       System and Network Information Service network protocols to
>> +       answer queries.
>
> Would it work to include the default (compiled in?) name service
> libraries in the libc.so linker script

I think it would.  The gen-fixed-nsswitch program also produces a list of
the service libraries used.

> I'm just trying to think of an automated way to include the libnss
> libraries w/o having to modify the applications.

That should be straightforward.