initial commit; mostly documented.

1 files changed, 30 insertions, 0 deletions

diff --git a/reallocarray.c b/reallocarray.c
new file mode 100644
index 0000000..fc492f0
--- /dev/null
+++ b/reallocarray.c
@@ -0,0 +1,30 @@
+#include "malloc.h"
+#include <assert.h>
+#include <string.h>
+
+void*
+__reallocarray_impl(heap_cache_t *cache, void *ptr, size_t nmemb, size_t w)
+{
+    /* Free if w == nmemb == 0*/
+    if(w == 0 || nmemb == 0) {
+        __free_impl(cache, ptr);
+        return NULL;
+    }
+    
+    if(ptr == NULL)
+        return __calloc_impl(cache, nmemb, w);
+
+    size_t allocw = w * nmemb;
+    w = REALW(w);
+    
+    bucket_obj_t *obj = OBJ_FROM_PTR(ptr);
+    assert(OBJ_VALID(obj));
+    size_t oldw = OBJ_WIDTH(obj);
+    if(allocw < oldw) return ptr;
+
+    ptr = __realloc_impl(cache, ptr, allocw);
+    size_t wdiff = allocw - oldw;
+    void *zeroat = (void*)(((uintptr_t)ptr) + oldw);
+    memset(zeroat, 0, wdiff);
+    return ptr;
+}