Bug 794316: update the 'higher' pointer of the layer right below the new

top of the stack after the old top is popped. r=michal.novotny.
Modified Files:
	pr/src/io/prlayer.c pr/tests/pushtop.c

2 files changed, 15 insertions, 0 deletions

diff --git a/pr/src/io/prlayer.c b/pr/src/io/prlayer.c
index 7519cd9f..faec9095 100644
--- a/pr/src/io/prlayer.c
+++ b/pr/src/io/prlayer.c
@@ -566,6 +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)) {
 			/*
diff --git a/pr/tests/pushtop.c b/pr/tests/pushtop.c
index bd09930f..621a7c72 100644
--- a/pr/tests/pushtop.c
+++ b/pr/tests/pushtop.c
@@ -48,6 +48,17 @@ int main()
 
     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) {