[Bug libc/1970] New: getgrnam_r() and groups with more than 1024 bytes

["burnus at gmx dot de" <sourceware-bugzilla@sourceware.org>]

If I have a group with many entries (`/usr/bin/getent group test |wc -c
` > 1024), getgrnam() duely returns the entry whereas getgrnam_r() has some
troubles.

a) sysconf(_SC_GETGR_R_SIZE_MAX);
returns always 1024, which is not large enough, but as there is ENORANGE, it is
not too bad.
SUSv3: "_SC_GETGR_R_SIZE_MAX  Maximum size of getgrgid_r() and getgrnam_r() data
buffers" and "The maximum size needed for this buffer [3rd argument of
getgrnam_r] can be determined with the {_SC_GETGR_R_SIZE_MAX} sysconf() parameter."


b) Using  getgrnam_r() with a big group and a too small buffer =
_SC_GETGR_R_SIZE_MAX == 1024:
(i) group:  files  (in /etc/nsswitch.conf)
returned value: ERANGE, which is ok
(ii) group:  compat (in /etc/nsswitch.conf)
getgrnam_r crashes with a memory access error.
Expected: ERANGE or e.g. EIO.

c) Using  getgrnam_r() with a buffer bigger than 1024
(i) entry < 1024: Ok
(ii) entry > 1024 (independent of group:files vs. group:compat)
Memory access error

-- 
           Summary: getgrnam_r() and groups with more than 1024 bytes
           Product: glibc
           Version: 2.3.5
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: burnus at gmx dot de
                CC: glibc-bugs at sources dot redhat dot com
 GCC build triplet: Compiled on a Linux 2.6.12 system on 2005-09-09.
  GCC host triplet: SUSE Linux 10.0 (i386) with kernel 2.6.14-
                    20051028140608-default
GCC target triplet: Configured for i686-suse-linux.


http://sourceware.org/bugzilla/show_bug.cgi?id=1970

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