1 files changed, 79 insertions, 1 deletions

diff --git a/src/lib/libc/stdlib/malloc.c b/src/lib/libc/stdlib/malloc.c
index af9cf39199..ee4d4c055e 100644
--- a/src/lib/libc/stdlib/malloc.c
+++ b/src/lib/libc/stdlib/malloc.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: malloc.c,v 1.251 2018/11/06 08:01:43 otto Exp $       */
+/*      $OpenBSD: malloc.c,v 1.252 2018/11/18 16:15:18 otto Exp $       */
 /*
  * Copyright (c) 2008, 2010, 2011, 2016 Otto Moerbeek <otto@drijf.net>
  * Copyright (c) 2012 Matthew Dempsky <matthew@openbsd.org>
@@ -1466,6 +1466,84 @@ freezero(void *ptr, size_t sz)
 }
 DEF_WEAK(freezero);
 
+static size_t
+osize(struct dir_info *argpool, void *p)
+{
+        struct dir_info *pool;
+        struct region_info *r;
+        char *saved_function;
+        size_t sz;
+        int i;
+
+        pool = argpool;
+        r = find(pool, p);
+        if (r == NULL) {
+                if (mopts.malloc_mt)  {
+                        for (i = 0; i < _MALLOC_MUTEXES; i++) {
+                                if (i == argpool->mutex)
+                                        continue;
+                                pool->active--;
+                                _MALLOC_UNLOCK(pool->mutex);
+                                pool = mopts.malloc_pool[i];
+                                _MALLOC_LOCK(pool->mutex);
+                                pool->active++;
+                                r = find(pool, p);
+                                if (r != NULL) {
+                                        saved_function = pool->func;
+                                        pool->func = argpool->func;
+                                        break;
+                                }
+                        }
+                }
+                if (r == NULL)
+                        wrterror(argpool, "bogus pointer (double free?) %p", p);
+        }
+
+        REALSIZE(sz, r);
+        if (sz > MALLOC_MAXCHUNK) {
+                if (MALLOC_MOVE_COND(sz))
+                        sz = MALLOC_PAGESIZE - ((char *)p - (char *)r->p);
+                else
+                        sz = PAGEROUND(sz);
+        }
+        if (argpool != pool) {
+                pool->active--;
+                pool->func = saved_function;
+                _MALLOC_UNLOCK(pool->mutex);
+                _MALLOC_LOCK(argpool->mutex);
+                argpool->active++;
+        }
+        return sz;
+}
+
+size_t
+malloc_usable_size(void *ptr)
+{
+        struct dir_info *d;
+        int saved_errno = errno;
+        size_t sz;
+
+        /* This is legal. */
+        if (ptr == NULL)
+                return 0;
+
+        d = getpool();
+        if (d == NULL)
+                wrterror(d, "malloc_usable_size() called before allocation");
+        _MALLOC_LOCK(d->mutex);
+        d->func = "malloc_usable_size";
+        if (d->active++) {
+                malloc_recurse(d);
+                return 0;
+        }
+        sz = osize(d, ptr);
+        d->active--;
+        _MALLOC_UNLOCK(d->mutex);
+        errno = saved_errno;
+        return sz;
+}
+DEF_WEAK(malloc_usable_size);
+
 static void *
 orealloc(struct dir_info *argpool, void *p, size_t newsz, void *f)
 {