tal: add tal_resizez for zero-padded expansion.

[ccan] / ccan / tal / tal.c

diff --git a/ccan/tal/tal.c b/ccan/tal/tal.c
index 1934a01318a3f09060614e144d189fff8467469b..1eaa5749476aa3abd23992c16167b031c47175f6 100644 (file)
--- a/ccan/tal/tal.c
+++ b/ccan/tal/tal.c
@@ -670,13 +670,13 @@ tal_t *tal_parent(const tal_t *ctx)
         return from_tal_hdr(ignore_destroying_bit(t->parent_child)->parent);
 }
 
-bool tal_resize_(tal_t **ctxp, size_t size, size_t count)
+bool tal_resize_(tal_t **ctxp, size_t size, size_t count, bool clear)
 {
         struct tal_hdr *old_t, *t;
         struct children *child;
        struct prop_hdr **lenp;
        struct length len;
-       size_t extra = 0;
+       size_t extra = 0, elemsize = size;
 
         old_t = debug_tal(to_tal_hdr(*ctxp));
 
@@ -688,7 +688,8 @@ bool tal_resize_(tal_t **ctxp, size_t size, size_t count)
                /* Copy here, in case we're shrinking! */
                len = *(struct length *)*lenp;
                extra = extra_for_length(size);
-       }
+       } else /* If we don't have an old length, we can't clear! */
+               assert(!clear);
 
         t = resizefn(old_t, sizeof(struct tal_hdr) + size + extra);
        if (!t) {
@@ -700,6 +701,12 @@ bool tal_resize_(tal_t **ctxp, size_t size, size_t count)
        if (lenp) {
                struct length *new_len;
 
+               /* Clear between old end and new end. */
+               if (clear && count > len.count) {
+                       char *old_end = (char *)(t + 1) + len.count * elemsize;
+                       memset(old_end, 0, elemsize * (count - len.count));
+               }
+
                new_len = (struct length *)((char *)(t + 1) + size);
                len.count = count;
                *new_len = len;
@@ -753,7 +760,7 @@ bool tal_expand_(tal_t **ctxp, const void *src, size_t size, size_t count)
        assert(src < *ctxp
               || (char *)src >= (char *)(*ctxp) + (size * old_count));
 
-       if (!tal_resize_(ctxp, size, old_count + count))
+       if (!tal_resize_(ctxp, size, old_count + count, false))
                goto out;
 
        memcpy((char *)*ctxp + size * old_count, src, count * size);
@@ -789,7 +796,7 @@ void *tal_dup_(const tal_t *ctx, const void *p, size_t size,
        if (taken(p)) {
                if (unlikely(!p))
                        return NULL;
-               if (unlikely(!tal_resize_((void **)&p, size, n + extra)))
+               if (unlikely(!tal_resize_((void **)&p, size, n + extra, false)))
                        return tal_free(p);
                if (unlikely(!tal_steal(ctx, p)))
                        return tal_free(p);