1 files changed, 37 insertions, 0 deletions
diff --git a/src/malloc/calloc.c b/src/malloc/calloc.c
new file mode 100644
index 00000000..322193ca
--- /dev/null
+++ b/src/malloc/calloc.c
@@ -0,0 +1,37 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+
+static size_t mal0_clear(char *p, size_t n)
+{
+	const size_t pagesz = 4096; /* arbitrary */
+	if (n < pagesz) return n;
+#ifdef __GNUC__
+	typedef uint64_t __attribute__((__may_alias__)) T;
+#else
+	typedef unsigned char T;
+#endif
+	char *pp = p + n;
+	size_t i = (uintptr_t)pp & (pagesz - 1);
+	for (;;) {
+		pp = memset(pp - i, 0, i);
+		if (pp - p < pagesz) return pp - p;
+		for (i = pagesz; i; i -= 2*sizeof(T), pp -= 2*sizeof(T))
+		        if (((T *)pp)[-1] | ((T *)pp)[-2])
+				break;
+	}
+}
+
+void *calloc(size_t m, size_t n)
+{
+	if (n && m > (size_t)-1/n) {
+		errno = ENOMEM;
+		return 0;
+	}
+	n *= m;
+	void *p = malloc(n);
+	if (!p) return p;
+	n = mal0_clear(p, n);
+	return memset(p, 0, n);
+}