can: module cache, fix fs.readFile

lib/fs.can

@@ -20,8 +20,7 @@ exports.readFile = (filename, callback) {
     onOpen(fd) {
       if (size == 0) {
         fs.close(fd, () {})
-
-        callback(nil, buffer.concat(buffs, total))
+        return callback(nil, buffer.concat(buffs, total))
       }
 
       buff = buffer.new(size)
@@ -47,7 +46,7 @@ exports.readFile = (filename, callback) {
     fs.open(filename, fs.flags.O_RDONLY, 438, (err, fd) {
       if (err) return callback(err)
 
-      onOpen(fd, stat)
+      onOpen(fd)
     })
   })
 }

lib/module.can

@@ -3,12 +3,21 @@ compile = global.compile
 buffer = global._bindings.buffer
 fs = global._natives.fs
 
+cache = clone global._natives
 global.require = (filename) {
-  content = buffer.stringify(fs.readFileSync(filename))
-  content = "return (require) {\n" + content + "\n}"
+  if (cache[filename]) return cache[filename]
 
-  return compile(
+  content = buffer.stringify(fs.readFileSync(filename) ||
+                             fs.readFileSync(filename + '.can'))
+  content = "return (require, module, exports) {\n" + content + "\n}"
+
+  module = {}
+  module.exports = cache[filename] = {}
+
+  compile(
     filename,
     content
-  )()(global.require)
+  )()(global.require, module, module.exports)
+
+  return module.exports
 }

src/bindings/buffer.h

@@ -9,8 +9,8 @@ namespace can {
 
 class Buffer : public candor::CWrapper {
  public:
-  Buffer(ssize_t size) : candor::CWrapper(&magic), size_(size) {
-    data_ = new char[size];
+  Buffer(ssize_t size) : candor::CWrapper(&magic), size_(size > 0 ? size : 0) {
+    data_ = new char[size_];
   }
 
   ~Buffer() {