ape: fix thread race with close() and select()

in ape close(), do the real filedescriptor _CLOSE() *after* we cleared
the _fdinfo[] slot because once closed, we dont own the slot anymore and
another process doing open() can trash the slot. make sure open() retuns
fd < OPEN_MAX.

double check in _startbuf() holding mux->lock if the fd is already buffered
preveting running double copyprocs on a fd.

dont zero the mux->rwant/ewant bitmaps at the end of select() as we do not
hold the mix->lock.

in _closebuf() kill copyproc while holding the mux->lock to make sure the
copyproc isnt holding it at the time it is killed. run kill() multiple times
to make sure the proc is gone.

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/src/ape/lib/ap/plan9/read.c b/sys/src/ape/lib/ap/plan9/read.c
index 471ab7e33..435a6d7f2 100644
--- a/sys/src/ape/lib/ap/plan9/read.c
+++ b/sys/src/ape/lib/ap/plan9/read.c
@@ -38,7 +38,7 @@ read(int d, void *buf, size_t nbytes)
 		}
 		n = _readbuf(d, buf, nbytes, noblock);
 	}else{
-		n = _READ(d,  buf, nbytes);
+		n = _READ(d, buf, nbytes);
 		if(n < 0)
 			_syserrno();
 	}