1 files changed, 28 insertions, 0 deletions
diff --git a/lib/array/array_resz.c b/lib/array/array_resz.c
new file mode 100644
index 0000000..d28a7a0
--- /dev/null
+++ b/lib/array/array_resz.c
@@ -0,0 +1,28 @@
+#include <stdckdint.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "array.h"
+#include "alloc.h"
+
+void *
+(array_resz)(void *ptr, ptrdiff_t ncap, ptrdiff_t elemsz, ptrdiff_t align)
+{
+	ptrdiff_t newsz, pad = -sizeof(_mlib_arr_hdr_t) & (align - 1);
+	_mlib_arr_hdr_t *hdr = _mlib_array_hdr(ptr, align);
+	/* Overflow; just call the allocator with the maximum size to force
+	   proper error handling */
+	if (ckd_mul(&newsz, ncap, elemsz)
+	 || ckd_add(&newsz, newsz, pad)
+	 || ckd_add(&newsz, newsz, sizeof(_mlib_arr_hdr_t)))
+	{
+		hdr->mem.alloc(hdr->mem, ALLOC_NEW, nullptr, 0,
+			PTRDIFF_MAX, PTRDIFF_MAX, PTRDIFF_MAX);
+		unreachable();
+	}
+
+	ptrdiff_t oldsz = sizeof(_mlib_arr_hdr_t) + pad + hdr->cap*elemsz;
+	hdr = (_mlib_arr_hdr_t *)resz(hdr->mem, (uint8_t *)hdr, oldsz, newsz);
+	hdr->cap = ncap;
+	return (uint8_t *)hdr + sizeof(*hdr) + pad;
+}