[btr] Fix merge_input_pool().

This function contained the following bug: wbr, buf1 and sz1 could
be used without being initialized. This was sometimes hitting the
assertion (buf1 && buf2).

Fix this by initializing these variables at the top.

diff --git a/buffer_tree.c b/buffer_tree.c
index dfecf10a24906f2e165ed9368f69c23e99f6e291..40079c2ff9984f5207ad5f1cb0aeaaf78bf9dedc 100644 (file)
--- a/buffer_tree.c
+++ b/buffer_tree.c
@@ -582,18 +582,20 @@ static bool need_buffer_pool_merge(struct btr_node *btrn)
 
 static void merge_input_pool(struct btr_node *btrn, size_t dest_size)
 {
-       struct btr_buffer_reference *br, *wbr;
+       struct btr_buffer_reference *br, *wbr = NULL;
        int num_refs; /* including wrap buffer */
-       char *buf, *buf1, *buf2 = NULL;
-       size_t sz, sz1, sz2 = 0, wsz;
+       char *buf, *buf1 = NULL, *buf2 = NULL;
+       size_t sz, sz1 = 0, sz2 = 0, wsz;
 
-       if (list_empty(&btrn->input_queue))
+       br = get_first_input_br(btrn);
+       if (!br || br_available_bytes(br) >= dest_size)
                return;
-
        num_refs = 0;
        FOR_EACH_BUFFER_REF(br, btrn) {
                num_refs++;
                sz = btr_get_buffer_by_reference(br, &buf);
+               if (sz == 0)
+                       break;
                if (br->wrap_count != 0) {
                        assert(!wbr);
                        assert(num_refs == 1);
@@ -622,15 +624,15 @@ next:
                if (sz1 + sz2 >= dest_size)
                        break;
        }
+       if (!buf2) /* nothing to do */
+               return;
+       assert(buf1 && sz2 > 0);
        /*
         * If the second buffer is large, we only take the first part of it to
         * avoid having to memcpy() huge buffers.
         */
        sz2 = PARA_MIN(sz2, (size_t)(64 * 1024));
        if (!wbr) {
-               assert(buf1);
-               if (!buf2) /* nothing to do */
-                       return;
                /* Make a new wrap buffer combining buf1 and buf2. */
                sz = sz1 + sz2;
                buf = para_malloc(sz);
@@ -647,6 +649,7 @@ next:
                para_list_add(&br->node, &btrn->input_queue);
                return;
        }
+       PARA_DEBUG_LOG("increasing wrap buffer, sz1: %zu, sz2: %zu\n", sz1, sz2);
        /*
         * We already have a wrap buffer, but it is too small. It might be
         * partially used.
@@ -654,10 +657,8 @@ next:
        wsz = br_available_bytes(wbr);
        if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
                return;
-       assert(buf1 && buf2);
        sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */
        wbr->btrb->size += sz;
-       PARA_DEBUG_LOG("increasing wrap buffer to %zu\n", wbr->btrb->size);
        wbr->btrb->buf = para_realloc(wbr->btrb->buf, wbr->btrb->size);
        /* copy the new data to the end of the reallocated buffer */
        assert(sz2 >= sz);