cron & Windows 7

["Pierre A. Humblet" <Pierre dot Humblet at ieee dot org>]

I got reports that cron is having problems with Cygwin 1.7.1 on 
Windows 7 - 32 bits.
They occur only with seteuid method 1, not with method 2 nor method 3.

An earlier report http://cygwin.com/ml/cygwin/2009-11/msg00724.html
indicated that there was no problem with 1.7.0. There is no proof that 
the Cygwin update to 1.7.1 caused the problem.

Basically cron starts with a process A that forks a process B, which 
setsid and sleeps until the next minutes. It then forks a process C that runs
the crontabs and forks a process D for every user. Process D calls seteuid
and then execs /bin/sh.

The helpful user was willing to experiment and provided two straces 
of cron, see attachments.

In trace_cron.log we see that, after the seteuid, process D cannot 
load the user32 dll.
winerr 1114, A dynamic link library (DLL) initialization routine failed.
I believe that is occurring while trying to execute GetProcessWindowStation
in fhandler_console::need_invisible, called from spawn_guts.
This call is made while impersonated. I am not sure why it's needed 
there given that a few lines below a brand new invisible WindowStation is
created anyway, at least in this case.

The other log trace_cron+syslog-ng.log was created in another run 
where syslog-ng replaced the Windows application log. I had requested that
test because another unverified report claimed that doing so allowed cron to
run on Windows 7 64 bits.
In this case it didn't help, but the behavior is different (I doubt it's directly due 
to syslog-ng). CreateProcessAsUser succeeds, but its parent never hears from
the child and quits after trying a few times (BTW, the creation of the WindowStation 
is in the retry loop).

Incidentally, I noticed
   get_registry_hive_path: HKLM\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\XXX  not found
That's because there should be a " " between "Windows" and "NT". So USERPROFILE is
never set properly in the environment.

Sorry I don't have access to Windows 7 to investigate more deeply.

Pierre

Attachment: trace_cron+syslog-ng.log
Description: Binary data

Attachment: trace_cron.log
Description: Binary data

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