Native wasm32 expand_heap implementation

src/malloc/wasm32/expand_heap.c

@@ -0,0 +1,28 @@
+#include <limits.h>
+#include <stdint.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include "libc.h"
+#include "syscall.h"
+
+#define WASM_PAGE_SIZE 65536
+
+/* Expand the heap in-place use WebAssembly grow_memory operators.
+ * The caller is responsible for locking to prevent concurrent calls. */
+
+void *__expand_heap(size_t *pn)
+{
+	size_t n = *pn;
+	n += -n & WASM_PAGE_SIZE-1;
+	unsigned delta = n / WASM_PAGE_SIZE;
+
+	unsigned res = __builtin_wasm_memory_grow(0, delta);
+	if (res == (unsigned)-1) {
+		errno = ENOMEM;
+		return 0;
+	}
+
+	void *area = (void*)(WASM_PAGE_SIZE * res);
+	*pn = n;
+	return area;
+}