ash: significant overhaul of redirect saving logic

New code is similar to what hush is doing.
Make CLOSED to -1: same as dash.
popredir() loses "restore" parameter: same as dash.
COPYFD_RESTORE bit is no longer necessary.

This change fixes this interactive bug:

	$ ls -l /proc/$$/fd 10>&-
	ash: can't set tty process group: Bad file descriptor
	ash: can't set tty process group: Bad file descriptor
	[1]+  Done(2)                    ls -l /proc/${\$}/fd 10>&4294967295

function                                             old     new   delta
unwindredir                                           29      27      -2
tryexec                                              154     152      -2
evaltree                                             503     501      -2
evalcommand                                         1369    1367      -2
cmdloop                                              187     185      -2
redirect                                            1029    1018     -11
popredir                                             153     123     -30
need_to_remember                                      36       -     -36
is_hidden_fd                                          68       -     -68
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 0/7 up/down: 0/-155)           Total: -155 bytes
   text    data     bss     dec     hex filename
 914572     485    6848  921905   e1131 busybox_old
 914553     485    6848  921886   e111e busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

5 files changed, 17 insertions, 2 deletions

diff --git a/shell/ash_test/ash-redir/redir_script.tests b/shell/ash_test/ash-redir/redir_script.tests
index ccc497d7b..740daa461 100755
--- a/shell/ash_test/ash-redir/redir_script.tests
+++ b/shell/ash_test/ash-redir/redir_script.tests
@@ -20,10 +20,15 @@ eval "find_fds $fds"
 
 # Shell should not lose that fd. Did it?
 find_fds
-test x"$fds1" = x"$fds" && { echo "Ok: script fd is not closed"; exit 0; }
+test x"$fds1" = x"$fds" \
+&& { echo "Ok: script fd is not closed"; exit 0; }
+
+# One legit way to handle it is to move script fd. For example, if we see that fd 10 moved to fd 11:
+test x"$fds1" = x" 10>&- 3>&-" && \
+test x"$fds"  = x" 11>&- 3>&-" \
+&& { echo "Ok: script fd is not closed"; exit 0; }
 
 echo "Bug: script fd is closed"
 echo "fds1:$fds1"
 echo "fds2:$fds"
 exit 1
-
diff --git a/shell/ash_test/ash-redir/redir_to_bad_fd255.right b/shell/ash_test/ash-redir/redir_to_bad_fd255.right
new file mode 100644
index 000000000..9c5e35b36
--- /dev/null
+++ b/shell/ash_test/ash-redir/redir_to_bad_fd255.right
@@ -0,0 +1,2 @@
+./redir_to_bad_fd255.tests: line 2: 255: Bad file descriptor
+OK
diff --git a/shell/ash_test/ash-redir/redir_to_bad_fd255.tests b/shell/ash_test/ash-redir/redir_to_bad_fd255.tests
new file mode 100755
index 000000000..2266af6da
--- /dev/null
+++ b/shell/ash_test/ash-redir/redir_to_bad_fd255.tests
@@ -0,0 +1,3 @@
+# ash uses fd 10 (usually) for reading the script
+echo LOST >&255
+echo OK
diff --git a/shell/ash_test/ash-redir/redir_to_bad_fd3.right b/shell/ash_test/ash-redir/redir_to_bad_fd3.right
new file mode 100644
index 000000000..895a4a0a6
--- /dev/null
+++ b/shell/ash_test/ash-redir/redir_to_bad_fd3.right
@@ -0,0 +1,2 @@
+./redir_to_bad_fd3.tests: line 2: 3: Bad file descriptor
+OK
diff --git a/shell/ash_test/ash-redir/redir_to_bad_fd3.tests b/shell/ash_test/ash-redir/redir_to_bad_fd3.tests
new file mode 100755
index 000000000..98c54cfc6
--- /dev/null
+++ b/shell/ash_test/ash-redir/redir_to_bad_fd3.tests
@@ -0,0 +1,3 @@
+# ash uses fd 10 (usually) for reading the script
+echo LOST >&3
+echo OK