Bug 794316 - PR_PushIOLayer doesn't push layer on the top correctly, …

…r=wtc

nsprpub/pr/src/io/prlayer.c

@@ -523,6 +523,11 @@ PR_IMPLEMENT(PRStatus) PR_PushIOLayer(
 		*stack = *fd;
 		*fd = copy;
 		fd->higher = stack;
+		if (fd->lower)
+		{
+			PR_ASSERT(fd->lower->higher == stack);
+			fd->lower->higher = fd;
+		}
 		stack->lower = fd;
 		stack->higher = NULL;
 	} else {
@@ -561,6 +566,10 @@ PR_IMPLEMENT(PRFileDesc*) PR_PopIOLayer(PRFileDesc *stack, PRDescIdentity id)
         *stack = *extract;
         *extract = copy;
         stack->higher = NULL;
+        if (stack->lower) {
+            PR_ASSERT(stack->lower->higher == extract);
+            stack->lower->higher = stack;
+        }
 	} else if ((PR_IO_LAYER_HEAD == stack->identity) &&
 					(extract == stack->lower) && (extract->lower == NULL)) {
 			/*

nsprpub/pr/tests/Makefile.in

@@ -114,6 +114,7 @@ CSRCS =             \
 	provider.c		\
 	prpoll.c		\
 	prpollml.c		\
+	pushtop.c		\
 	ranfile.c       \
 	randseed.c      \
 	reinit.c        \

nsprpub/pr/tests/pushtop.c

@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A regression test for bug 794316 */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "prio.h"
+
+static PRIOMethods dummyMethods;
+
+int main()
+{
+    PRDescIdentity topId, middleId, bottomId;
+    PRFileDesc *top, *middle, *bottom;
+    PRFileDesc *fd;
+
+    topId = PR_GetUniqueIdentity("top");
+    middleId = PR_GetUniqueIdentity("middle");
+    bottomId = PR_GetUniqueIdentity("bottom");
+
+    top = PR_CreateIOLayerStub(topId, &dummyMethods);
+    middle = PR_CreateIOLayerStub(middleId, &dummyMethods);
+    bottom = PR_CreateIOLayerStub(bottomId, &dummyMethods);
+
+    fd = bottom;
+    PR_PushIOLayer(fd, PR_TOP_IO_LAYER, middle);
+    PR_PushIOLayer(fd, PR_TOP_IO_LAYER, top);
+
+    top = fd;
+    middle = top->lower;
+    bottom = middle->lower;
+
+    /* Verify that the higher pointers are correct. */
+    if (middle->higher != top) {
+        fprintf(stderr, "middle->higher is wrong\n");
+        fprintf(stderr, "FAILED\n");
+        exit(1);
+    }
+    if (bottom->higher != middle) {
+        fprintf(stderr, "bottom->higher is wrong\n");
+        fprintf(stderr, "FAILED\n");
+        exit(1);
+    }
+
+    top = PR_PopIOLayer(fd, topId);
+    top->dtor(top);
+
+    middle = fd;
+    bottom = middle->lower;
+
+    /* Verify that the higher pointer is correct. */
+    if (bottom->higher != middle) {
+        fprintf(stderr, "bottom->higher is wrong\n");
+        fprintf(stderr, "FAILED\n");
+        exit(1);
+    }
+
+    middle = PR_PopIOLayer(fd, middleId);
+    middle->dtor(middle);
+    if (fd->identity != bottomId) {
+        fprintf(stderr, "The bottom layer has the wrong identity\n");
+        fprintf(stderr, "FAILED\n");
+        exit(1);
+    }
+    fd->dtor(fd);
+
+    printf("PASS\n");
+    return 0;
+}

nsprpub/pr/tests/runtests.pl

@@ -313,6 +313,7 @@ sub win_test_prog {
 "primblok",
 "provider",
 "prpollml",
+"pushtop",
 "ranfile",
 "randseed",
 "reinit",

nsprpub/pr/tests/runtests.sh

@@ -143,6 +143,7 @@ prftest
 primblok
 provider
 prpollml
+pushtop
 ranfile
 randseed
 reinit