Mail Archives: cygwin/2003/08/04/20:59:01
On Tue, Aug 05, 2003 at 01:45:48AM +0200, Pavel Tsekov wrote:
>Hello,
Hi Pavel, nice to see a message from you.
>On rxvt startup two utmp entries are created - the first one is created by
>Cygwin and the second one is created by rxvt itself:
>
>$ who
>Administ tty1 Aug 5 01:26 (MORDOR)
>Administ tty2 Aug 5 01:26 (:0)
>
>After rxvt shutdown:
>
>$ who
>Administ tty2 Aug 5 01:26 (:0)
>
>The cause for this seems to be that rxvt assumes that the return value
>of getutid () is usable in a call to pututline (), which doesn't seem
>to hold true on Cygwin. It turns out that Cygwin uses the same static
>variable to return utmp entries to the caller and also for its own
>internal purposes i.e. searching for the right utmp entry. I don't
>know if Cygwin is right or not in this case, and there doesn't seem to
>be a lot of documentation on this topic. The linux man pages tells
>that the return value of getutid(), getutline() and getutent() is a
>static memory but doesn't say anything about what could possibly happen
>if one uses it back in a call to pututline(). So I guess the behaviour
>is pretty much undefined. On the other hand there is a comment in the
>Cygwin source of logout() which indicates that the author of putline ()
>was aware of this behaviour so I draw the conclusion that it is not a
>bug in Cygwin:
>
> /* We can't use ut further since it's a pointer to the static utmp_data
> area (see below) and would get overwritten in pututline(). So we
> copy it back to the local ut_buf. */
>
>I've created a simple testcase (attached) which when ran on Linux
>produces the results that rxvt expects. Unfortunately currently I do
>not have access to any other unices on which I can run the testcase.
A simple test case. Sob. A simple test case. Oh, how I've missed you.
Given the good problem description and the simple test case, this shouldn't
be hard to fix. I'll see what I can do. The behavior that you've described
has bugged me for a while. I'm glad that you tracked down what was going on.
cgf
--
Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
Problem reports: http://cygwin.com/problems.html
Documentation: http://cygwin.com/docs.html
FAQ: http://cygwin.com/faq/
- Raw text -