initial check-in, version 0.5.0 v0.5.0

1 files changed, 47 insertions, 0 deletions

diff --git a/src/malloc/posix_memalign.c b/src/malloc/posix_memalign.c
new file mode 100644
index 00000000..ef86260d
--- /dev/null
+++ b/src/malloc/posix_memalign.c
@@ -0,0 +1,47 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <errno.h>
+
+/* This function should work with most dlmalloc-like chunk bookkeeping
+ * systems, but it's only guaranteed to work with the native implementation
+ * used in this library. */
+
+int posix_memalign(void **res, size_t align, size_t len)
+{
+	unsigned char *mem, *new, *end;
+	size_t header, footer;
+
+	if ((align & -align) != align) return EINVAL;
+	if (len > SIZE_MAX - align) return ENOMEM;
+
+	if (align <= 4*sizeof(size_t)) {
+		if (!(mem = malloc(len)))
+			return errno;
+		*res = mem;
+		return 0;
+	}
+
+	if (!(mem = malloc(len + align-1)))
+		return errno;
+
+	header = ((size_t *)mem)[-1];
+	end = mem + (header & -8);
+	footer = ((size_t *)end)[-2];
+	new = (void *)((uintptr_t)mem + align-1 & -align);
+
+	if (!(header & 7)) {
+		((size_t *)new)[-2] = ((size_t *)mem)[-2] + (new-mem);
+		((size_t *)new)[-1] = ((size_t *)mem)[-1] - (new-mem);
+		*res = new;
+		return 0;
+	}
+
+	((size_t *)mem)[-1] = header&7 | new-mem;
+	((size_t *)new)[-2] = footer&7 | new-mem;
+	((size_t *)new)[-1] = header&7 | end-new;
+	((size_t *)end)[-2] = footer&7 | end-new;
+
+	if (new != mem) free(mem);
+	*res = new;
+	return 0;
+}