Patchset to add asynchronous open/close to master

[Stefan (metze) Metzmacher]

Hi Jeremy,

>> What I'm planning is to write some test code that
>> checks if on modern glibc systems that setreuid()
>> only changes the euid/egid of the specific thread
>> it is called from, and if so we're already good
>> for the aio open code.
>>
>> If (as appears possible now I've looked at the
>> glibc code) they have changed this to cause
>> setreuid() to do the SETXID signalling (which
>> is what glibc uses internally to request individual
>> threads change their own uid/gids) then we will
>> need to change source3/lib/util_sec.c to use
>> the raw system setreuid() system call directly
>> instead of going through the glibc wrapper, in
>> order to keep the same functionalty we are
>> already depending on in Linux.
>>
>> I'll report back once I've tested things more.
> 
> Ok, attached is some test code (run as root :-).
> 
> Looks like glibc has changed setreuid to use
> the SETXID call.
> 
> Using setreuid:
> 
> # ./a.out 
> MAIN THREAD 1: uid = 0, gid = 0
> CHILD THREAD 1: uid = 0, gid = 0
> MAIN THREAD 2: uid = 300, gid = 300
> CHILD THREAD 2: uid = 300, gid = 300
> 
> Using syscall(SYS_setreuid,...)
> 
> # ./a.out 
> MAIN THREAD 1: uid = 0, gid = 0
> CHILD THREAD 1: uid = 0, gid = 0
> MAIN THREAD 2: uid = 300, gid = 300
> CHILD THREAD 2: uid = 0, gid = 0
> 
> So looks like we need to change to using
> syscall(SYS_setreuid,...) in Samba on Linux
> instead of calling setreuid() directly, as
> the current glibc breaks the assumptions
> of we're using inside the aio code.
> 
> I'll prepare a patch for master/3.6.x
> to fix this issue.

I think you need to test with the full unix token,
not only uid and gid.

metze

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