[klibc] [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>
Signed-off-by: maximilian attems <max@stro.at>

3 files changed, 40 insertions, 13 deletions

diff --git a/usr/dash/eval.c b/usr/dash/eval.c
index f73e6e987eedc..3cd2c5f9d90f7 100644
--- a/usr/dash/eval.c
+++ b/usr/dash/eval.c
@@ -219,6 +219,7 @@ evaltree(union node *n, int flags)
 		goto setstatus;
 	case NREDIR:
 		expredir(n->nredir.redirect);
+		pushredir(n->nredir.redirect);
 		status = redirectsafe(n->nredir.redirect, REDIR_PUSH);
 		if (!status) {
 			evaltree(n->nredir.n, flags & EV_TESTED);
@@ -683,6 +684,7 @@ evalcommand(union node *cmd, int flags)
 #endif
 {
 	struct localvar_list *localvar_stop;
+	struct redirtab *redir_stop;
 	struct stackmark smark;
 	union node *argp;
 	struct arglist arglist;
@@ -740,6 +742,7 @@ evalcommand(union node *cmd, int flags)
 
 	preverrout.fd = 2;
 	expredir(cmd->ncmd.redirect);
+	redir_stop = pushredir(cmd->ncmd.redirect);
 	status = redirectsafe(cmd->ncmd.redirect, REDIR_PUSH|REDIR_SAVEFD2);
 
 	path = vpath.text;
@@ -882,6 +885,7 @@ raise:
 out:
 	if (cmd->ncmd.redirect)
 		popredir(execcmd);
+	unwindredir(redir_stop);
 	unwindlocalvars(localvar_stop);
 	if (lastarg)
 		/* dsl: I think this is intended to be used to support
diff --git a/usr/dash/redir.c b/usr/dash/redir.c
index 16decfc968d36..b4e49c0ebcacf 100644
--- a/usr/dash/redir.c
+++ b/usr/dash/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;
+}
diff --git a/usr/dash/redir.h b/usr/dash/redir.h
index ab7ebba0662af..8e56995f04e10 100644
--- a/usr/dash/redir.h
+++ b/usr/dash/redir.h
@@ -41,9 +41,13 @@
 #endif
 #define REDIR_SAVEFD2 03	/* set preverrout */
 
+struct redirtab;
 union node;
 void redirect(union node *, int);
 void popredir(int);
 void clearredir(void);
 int savefd(int, int);
 int redirectsafe(union node *, int);
+void unwindredir(struct redirtab *stop);
+struct redirtab *pushredir(union node *redir);
+