Fork problems on master branch
Ken Brown
kbrown@cornell.edu
Sat Jun 8 19:44:00 GMT 2019
Earlier today I reported on the cygwin-patches list a fork problem with a
cygwin1.dll built from the master branch of the Cygwin source repo. See
https://cygwin.com/ml/cygwin-patches/2019-q2/msg00155.html. A bisection showed
that commit f03ea8e1 was the first bad commit for the problem being discussed there.
I've just run into a second fork problem for which I think the same commit is
the first bad one. I can't be positive, because the problem is sporadic, so I
might have marked some bad commits as good if I didn't run the test enough times.
The test case for this (attached) is one that I used when testing my new FIFO
code. Normally I run this program in one terminal and type
echo blah > /tmp/myfifo
in a second terminal. For the present purposes, however, you can skip the
second part and simply terminate fifo_fork_test with C-c.
In my testing, I found that running the test program would yield "read: Bad
address" about 1 out of 10 times. Occasionally I would get "read: Communication
error on send" instead. Both error messages indicate a problem with the child
process reading from an fd inherited from the parent.
Ken
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