Fix process.env and Bun.env object spread

Fixes https://github.com/oven-sh/bun/issues/1512

src/bun.js/bindings/JSEnvironmentVariableMap.cpp

@@ -0,0 +1,71 @@
+#include "root.h"
+#include "ZigGlobalObject.h"
+
+#include "helpers.h"
+
+#include "JavaScriptCore/JSObject.h"
+#include "JavaScriptCore/ObjectConstructor.h"
+
+extern "C" size_t Bun__getEnvNames(JSGlobalObject*, ZigString* names, size_t max);
+extern "C" bool Bun__getEnvValue(JSGlobalObject* globalObject, ZigString* name, ZigString* value);
+
+namespace Bun {
+
+JSC_DEFINE_CUSTOM_GETTER(jsGetterEnvironmentVariable, (JSGlobalObject * globalObject, EncodedJSValue thisValue, PropertyName propertyName))
+{
+    VM& vm = globalObject->vm();
+    auto scope = DECLARE_THROW_SCOPE(vm);
+
+    auto* thisObject = jsDynamicCast<JSObject*>(JSValue::decode(thisValue));
+    if (UNLIKELY(!thisObject))
+        return JSValue::encode(jsUndefined());
+
+    ZigString name = gettoZigString(propertyName.publicName());
+    ZigString value = { nullptr, 0 };
+
+    if (UNLIKELY(name.len == 0))
+        return JSValue::encode(jsUndefined());
+
+    if (!Bun__getEnvValue(globalObject, &name, &value) || value.len == 0) {
+        return JSValue::encode(jsUndefined());
+    }
+
+    JSValue result = jsString(vm, Zig::toStringCopy(value));
+    thisObject->putDirect(vm, propertyName, result, 0);
+    return JSValue::encode(result);
+}
+
+JSC_DEFINE_CUSTOM_SETTER(jsSetterEnvironmentVariable, (JSGlobalObject * globalObject, EncodedJSValue thisValue, EncodedJSValue value, PropertyName propertyName))
+{
+    VM& vm = globalObject->vm();
+    JSC::JSObject* object = JSValue::decode(thisValue).getObject();
+    if (!object)
+        return false;
+
+    object->putDirect(vm, propertyName, JSValue::decode(value), 0);
+    return true;
+}
+
+JSValue createEnvironmentVariablesMap(Zig::GlobalObject* globalObject)
+{
+    VM& vm = globalObject->vm();
+    auto scope = DECLARE_THROW_SCOPE(vm);
+
+    size_t max = 768;
+    ZigString names[max];
+    size_t count = Bun__getEnvNames(globalObject, names, max);
+    JSC::JSObject* object = nullptr;
+    if (count < 63) {
+        object = constructEmptyObject(globalObject, globalObject->objectPrototype(), count);
+    } else {
+        object = constructEmptyObject(globalObject, globalObject->objectPrototype());
+    }
+
+    for (size_t i = 0; i < count; i++) {
+        auto name = Zig::toStringCopy(names[i]);
+        object->putDirectCustomAccessor(vm, Identifier::fromString(vm, name), JSC::CustomGetterSetter::create(vm, jsGetterEnvironmentVariable, jsSetterEnvironmentVariable), JSC::PropertyAttribute::CustomAccessor | 0);
+    }
+
+    return object;
+}
+}