cp,mv,install: avoid opening non directory destination

commit v9.0-66-ge2daa8f79 introduced an issue, for example
where cp could hang when overwriting a destination fifo,
when it would try to open() the fifo on systems
like Solaris 10 that didn't support the O_DIRECTORY flag.

This is still racy on such systems, but only in the
case where a directory is replaced by a fifo in
the small window between stat() and open().

* src/system.h (target_directory_operand): On systems without
O_DIRECTORY, ensure the file is a directory before attempting to open().
* tests/cp/special-f.sh: Protect cp with timeout(1),
as cp was seen to hang when trying to overwrite an existing fifo.
* NEWS: Mention the bug fix.

1 files changed, 5 insertions, 7 deletions

diff --git a/tests/cp/special-f.sh b/tests/cp/special-f.sh
index a3e7842fa..2c7bf5ea7 100755
--- a/tests/cp/special-f.sh
+++ b/tests/cp/special-f.sh
@@ -24,12 +24,10 @@ mkfifo_or_skip_ fifo
 
 touch e || framework-failure
 
-
-# Without -f, expect it to fail.
-cp -R fifo e || fail=1
-
-# With -f, it must succeed.
-cp -Rf fifo e || fail=1
-test -p fifo || fail=1
+for force in '' '-f'; do
+  # Second time through will need to unlink fifo e
+  timeout 10 cp -R $force fifo e || fail=1
+  test -p fifo || fail=1
+done
 
 Exit $fail