[REDIR] Fix popredir on abnormal exit from built-in

Just like the poplocalvar problem recently fixed, redirections
can also be leaked in case of an abnormal exit.  This patch fixes
it using the same method as poplocalvar, by storing the previous
redirection state and restoring to that point.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 32 insertions, 13 deletions

diff --git a/src/redir.c b/src/redir.c
index 16decfc..b4e49c0 100644
--- a/src/redir.c
+++ b/src/redir.c
@@ -111,20 +111,12 @@ redirect(union node *redir, int flags)
 		memory[i] = 0;
 	memory[1] = flags & REDIR_BACKQ;
 #endif
-	if (!redir) {
+	if (!redir)
 		return;
-	}
 	sv = NULL;
 	INTOFF;
-	if (likely(flags & REDIR_PUSH)) {
-		struct redirtab *q;
-		q = ckmalloc(sizeof (struct redirtab));
-		q->next = redirlist;
-		redirlist = q;
-		for (i = 0 ; i < 10 ; i++)
-			q->renamed[i] = EMPTY;
-		sv = q;
-	}
+	if (likely(flags & REDIR_PUSH))
+		sv = redirlist;
 	n = redir;
 	do {
 		newfd = openredirect(n);
@@ -373,8 +365,7 @@ RESET {
 	/*
 	 * Discard all saved file descriptors.
 	 */
-	while (redirlist)
-		popredir(0);
+	unwindredir(0);
 }
 
 #endif
@@ -485,3 +476,31 @@ redirectsafe(union node *redir, int flags)
 	RESTOREINT(saveint);
 	return err;
 }
+
+
+void unwindredir(struct redirtab *stop)
+{
+	while (redirlist != stop)
+		popredir(0);
+}
+
+
+struct redirtab *pushredir(union node *redir)
+{
+	struct redirtab *sv;
+	struct redirtab *q;
+	int i;
+
+	q = redirlist;
+	if (!redir)
+		goto out;
+
+	sv = ckmalloc(sizeof (struct redirtab));
+	sv->next = q;
+	redirlist = sv;
+	for (i = 0; i < 10; i++)
+		sv->renamed[i] = EMPTY;
+
+out:
+	return q;
+}