retitle 520744 _SC_GETGR_R_SIZE_MAX returned too small thanks On Fri, Apr 24, 2009 at 09:17:58AM +0200, Guido Günther wrote: > On Thu, Apr 23, 2009 at 11:18:00PM +0200, Aurelien Jarno wrote: > > On Tue, Apr 14, 2009 at 09:32:04AM +0200, Guido Günther wrote: > > > retitle 520744 _SC_GETGR_R_SIZE_MAX returned on amd64 too small > > > user [email protected] > > > usertag 520744 debian-amd64 > > > thanks > > > > > > Hi, > > > attached testcase shows that the buffersize for getgrent_r returned via > > > sysconf(_SC_GETGR_R_SIZE_MAX) is too small on amd64. Using the returned > > > 1024 byetes results in ERANGE. i386 and ppc also use 1024 bytes which > > > works fine. > > > While returning -1 is from sysconf is o.k., a too low value certainly is > > > not. Can this be fixed in a Lenny point release since it might break > > > arbitrary software on this architecture? > > > > What is the example code supposed to do? I have no problem executing it > > here: > > $ ./group > > buffer size from sysconf: 1024 > > gid: 124 > As long as you're not seeing a "Increased buffer to ..." message from > the testcase it's working as expected. When you see the "Increasing > buffer to ..." message the buffer size returned by sysconf is too small > (which is the bug were looking for). > The group that caused the trouble for Andreas had about 70 members (with > a line length in /etc/group of about 515 bytes). No nscd involved.
The title of the bug is actually misleading given that the problem is not specific to amd64 at all. It appears with a smaller line on 64-bit systems than 32-bit systems, due to the fact that pointers to the strings are bigger. That said I don't fully understand POSIX here. What should happen if a line in /etc/group needs more memory than sysconf(_SC_GETGR_R_SIZE_MAX)? The line should be truncated? As far as I understand user can create as many entries as he wants there, so _SC_GETGR_R_SIZE_MAX can only be defined to an arbitrary value. -- Aurelien Jarno GPG: 1024D/F1BCDB73 [email protected] http://www.aurel32.net -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
