Add alloc_size(): every allocator has to be able to answer this, since

[ccan] / ccan / alloc / alloc.c

diff --git a/ccan/alloc/alloc.c b/ccan/alloc/alloc.c
index f7a05e2d9f273d64f98aa36d977b80121094f057..c70b7fa7817a40da51f15cddedb7ddfb6db6aa18 100644 (file)
--- a/ccan/alloc/alloc.c
+++ b/ccan/alloc/alloc.c
@@ -822,6 +822,53 @@ void alloc_free(void *pool, unsigned long poolsize, void *free)
        }
 }
 
+unsigned long alloc_size(void *pool, unsigned long poolsize, void *p)
+{
+       unsigned long len, pagenum;
+       struct metaheader *mh;
+
+       assert(poolsize >= MIN_SIZE);
+
+       mh = first_mheader(pool, poolsize);
+       assert((char *)p >= (char *)(mh + 1));
+       assert((char *)pool + poolsize > (char *)p);
+
+       pagenum = pool_offset(pool, p) / getpagesize();
+
+       if (get_page_state(pool, pagenum) == SPECIAL) {
+               unsigned long off = (unsigned long)p % getpagesize();
+               uint8_t *metadata = get_page_metadata(pool, pagenum);
+               enum sub_metadata_type type = get_bit_pair(metadata, 0);
+
+               assert(off < SUBPAGE_METAOFF);
+
+               switch (type) {
+               case BITMAP:
+                       assert(off % BITMAP_GRANULARITY == 0);
+                       off /= BITMAP_GRANULARITY;
+
+                       /* Offset by one because first bit used for header. */
+                       off++;
+                       len = BITMAP_GRANULARITY;
+                       while (++off < SUBPAGE_METAOFF / BITMAP_GRANULARITY
+                              && get_bit_pair(metadata, off) == TAKEN)
+                               len += BITMAP_GRANULARITY;
+                       break;
+               case UNIFORM:
+                       len = decode_usize(metadata);
+                       break;
+               default:
+                       assert(0);
+               }
+       } else {
+               len = getpagesize();
+               while (get_page_state(pool, ++pagenum) == TAKEN)
+                       len += getpagesize();
+       }
+
+       return len;
+}
+
 static bool is_metadata_page(void *pool, unsigned long poolsize,
                             unsigned long page)
 {