ash: fix bug where redirection of closed fd was leaving it open afterwards.

redirect                                             983    1024     +41
bb_echo                                              276     301     +25
popredir                                             118     132     +14
evalcommand                                         1163    1176     +13
bbunpack                                             358     366      +8
echocmd                                               13       5      -8
echo_main                                             13       5      -8
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 5/2 up/down: 101/-16)            Total: 85 bytes
   text    data     bss     dec     hex filename
 774999     962    9236  785197   bfb2d busybox_old
 775084     962    9236  785282   bfb82 busybox_unstripped

3 files changed, 29 insertions, 13 deletions

diff --git a/shell/ash.c b/shell/ash.c
index bb930f55f..4113ce8e2 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -4567,6 +4567,7 @@ stoppedjobs(void)
  */
 
 #define EMPTY -2                /* marks an unused slot in redirtab */
+#define CLOSED -3               /* marks a slot of previously-closed fd */
 #ifndef PIPE_BUF
 # define PIPESIZE 4096          /* amount of buffering in a pipe */
 #else
@@ -4791,7 +4792,7 @@ redirect(union node *redir, int flags)
         int i;
         int fd;
         int newfd;
-        int *p;
+
         nullredirs++;
         if (!redir) {
                 return;
@@ -4799,15 +4800,13 @@ redirect(union node *redir, int flags)
         sv = NULL;
         INT_OFF;
         if (flags & REDIR_PUSH) {
-                struct redirtab *q;
-                q = ckmalloc(sizeof(struct redirtab));
-                q->next = redirlist;
-                redirlist = q;
-                q->nullredirs = nullredirs - 1;
+                sv = ckmalloc(sizeof(*sv));
+                sv->next = redirlist;
+                redirlist = sv;
+                sv->nullredirs = nullredirs - 1;
                 for (i = 0; i < 10; i++)
-                        q->renamed[i] = EMPTY;
+                        sv->renamed[i] = EMPTY;
                 nullredirs = 0;
-                sv = q;
         }
         n = redir;
         do {
@@ -4817,9 +4816,14 @@ redirect(union node *redir, int flags)
                         continue; /* redirect from/to same file descriptor */
 
                 newfd = openredirect(n);
-                if (fd == newfd)
+                if (fd == newfd) {
+                        /* Descriptor wasn't open before redirect.
+                         * Mark it for close in the future */
+                        if (sv && sv->renamed[fd] == EMPTY)
+                                sv->renamed[fd] = CLOSED;
                         continue;
-                if (sv && *(p = &sv->renamed[fd]) == EMPTY) {
+                }
+                if (sv && sv->renamed[fd] == EMPTY) {
                         i = fcntl(fd, F_DUPFD, 10);
 
                         if (i == -1) {
@@ -4831,7 +4835,7 @@ redirect(union node *redir, int flags)
                                         /* NOTREACHED */
                                 }
                         } else {
-                                *p = i;
+                                sv->renamed[fd] = i;
                                 close(fd);
                         }
                 } else {
@@ -4840,7 +4844,7 @@ redirect(union node *redir, int flags)
                 dupredirect(n, newfd);
         } while ((n = n->nfile.next));
         INT_ON;
-        if (flags & REDIR_SAVEFD2 && sv && sv->renamed[2] >= 0)
+        if ((flags & REDIR_SAVEFD2) && sv && sv->renamed[2] >= 0)
                 preverrout_fd = sv->renamed[2];
 }
 
@@ -4858,6 +4862,11 @@ popredir(int drop)
         INT_OFF;
         rp = redirlist;
         for (i = 0; i < 10; i++) {
+                if (rp->renamed[i] == CLOSED) {
+                        if (!drop)
+                                close(i);
+                        continue;
+                }
                 if (rp->renamed[i] != EMPTY) {
                         if (!drop) {
                                 close(i);
@@ -10994,7 +11003,7 @@ exitcmd(int argc, char **argv)
 static int
 echocmd(int argc, char **argv)
 {
-        return bb_echo(argv);
+        return bb_echo(argc, argv);
 }
 #endif
 
diff --git a/shell/ash_test/ash-redir/redir.right b/shell/ash_test/ash-redir/redir.right
new file mode 100644
index 000000000..2a02d41ce
--- /dev/null
+++ b/shell/ash_test/ash-redir/redir.right
@@ -0,0 +1 @@
+TEST
diff --git a/shell/ash_test/ash-redir/redir.tests b/shell/ash_test/ash-redir/redir.tests
new file mode 100644
index 000000000..7a1a66806
--- /dev/null
+++ b/shell/ash_test/ash-redir/redir.tests
@@ -0,0 +1,6 @@
+# test: closed fds should stay closed
+exec 1>&-
+echo TEST >TEST
+echo JUNK # lost: stdout is closed
+cat TEST >&2
+rm TEST