From d44969769f05a1ffb6df9782b2058c5e9b4477aa Mon Sep 17 00:00:00 2001
From: Meghan Denny <meghan@bun.sh>
Date: Wed, 7 Aug 2024 02:31:45 -0700
Subject: [PATCH] darwin: implement node:os.freemem() (#12870)

---
 src/bun.js/bindings/OsBinding.cpp | 25 +++++++++++++++++++++++++
 src/darwin_c.zig                  |  3 +--
 test/js/node/os/os.test.js        |  4 ++--
 3 files changed, 28 insertions(+), 4 deletions(-)
 create mode 100644 src/bun.js/bindings/OsBinding.cpp

diff --git a/src/bun.js/bindings/OsBinding.cpp b/src/bun.js/bindings/OsBinding.cpp
new file mode 100644
index 00000000000000..c994fe8d9866d2
--- /dev/null
+++ b/src/bun.js/bindings/OsBinding.cpp
@@ -0,0 +1,25 @@
+#include "root.h"
+
+#if OS(DARWIN)
+#include <mach/vm_types.h>
+#include <mach/mach_host.h>
+#include <mach/mach_init.h>
+#include <mach/message.h>
+#include <mach/vm_statistics.h>
+#include <unistd.h>
+
+// Adapted from libuv darwin uv_get_free_memory, MIT
+extern "C" uint64_t Bun__Os__getFreeMemory(void)
+{
+    vm_statistics_data_t info;
+    mach_msg_type_number_t count = sizeof(info) / sizeof(integer_t);
+
+    if (host_statistics(mach_host_self(), HOST_VM_INFO,
+            (host_info_t)&info, &count)
+        != KERN_SUCCESS) {
+        return 0;
+    }
+
+    return (uint64_t)info.free_count * sysconf(_SC_PAGESIZE);
+}
+#endif
diff --git a/src/darwin_c.zig b/src/darwin_c.zig
index bdf1c9767470b6..dabd819a1dc2bd 100644
--- a/src/darwin_c.zig
+++ b/src/darwin_c.zig
@@ -553,8 +553,7 @@ pub const kFSEventStreamEventFlagUnmount: c_int = 128;
 pub const kFSEventStreamEventFlagUserDropped: c_int = 2;
 
 pub fn getFreeMemory() u64 {
-    // NOT IMPLEMENTED YET
-    return 1024 * 1024;
+    return @extern(*const fn () callconv(.C) u64, .{ .name = "Bun__Os__getFreeMemory" })();
 }
 
 pub fn getTotalMemory() u64 {
diff --git a/test/js/node/os/os.test.js b/test/js/node/os/os.test.js
index f676a4040ed768..2e1655b43f6db2 100644
--- a/test/js/node/os/os.test.js
+++ b/test/js/node/os/os.test.js
@@ -12,11 +12,11 @@ it("endianness", () => {
 });
 
 it("freemem", () => {
-  expect(os.freemem() > 0).toBe(true);
+  expect(os.freemem()).toBeGreaterThan(1024 * 1024);
 });
 
 it("totalmem", () => {
-  expect(os.totalmem() > 0).toBe(true);
+  expect(os.totalmem()).toBeGreaterThan(1024 * 1024);
 });
 
 it("getPriority", () => {