newlib/winsup/cygwin/DevNotes

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2012-05-02 cgf-000001
<1.7.15>
Fix problem setting parent pid to 1 when process with children execs
itself. Fixes: http://cygwin.com/ml/cygwin/2012-05/msg00009.html
</1.7.15>
Investigating this problem with strace showed that ssh-agent was
checking the parent pid and getting a 1 when it shouldn't have. Other
stuff looked ok so I chose to consider this a smoking gun.
Going back to the version that the OP said did not have the problem, I
worked forward until I found where the problem first occurred -
somewhere around 2012-03-19. And, indeed, the getppid call returned the
correct value in the working version. That means that this stopped
working when I redid the way the process pipe was inherited around
this time period.
It isn't clear why (and I suspect I may have to debug this further at
some poit) this hasn't always been a problem but I made the obvious fix.
We shouldn't have been setting ppid = 1 when we're about to pass off to
an execed process.
As I was writing this, I realized that it was necessary to add some
additional checks. Just checking for "have_execed" isn't enough. If
we've execed a non-cygwin process then it won't know how to deal with
any inherited children. So, always set ppid = 1 if we've execed a
non-cygwin process.