Reentrant runtime systems considered long overdue (sigwinch bug)

Reentrant runtime systems considered long overdue (sigwinch bug)

[Scott Schwartz]

Signals are evil.  

It looks like the sigwinch thing is going wrong because, by the time
rc_read returns in fdgchar, errno has been altered by a system
call---stat in this case.  Hence the check for errno==EINTR never works
out, and bad things happen.  The error "No such file or directory"
isn't something read can return.  That's a clue to the real source of
the error, which is the stat call in rc_access, called inside the
interrupt handler when it tries to run e.g. stty and has to check a
number of entries in your path.  That stat call is (in this instance)
the last time errno gets set before the longjmp out of the read in
rc_read.  Tossing an errno=EINTR after the stat mitigates the problem.

-- Scott