Add posix.truncate()

doc/api.txt

@@ -653,6 +653,11 @@ sys.puts("stats: " + JSON.stringify(stats));
   - on success: no parameters.
   - on error: no parameters.
 
++posix.truncate(fd, len)+ ::
+  See ftruncate(2).
+  - on success: no parameters.
+  - on error: no parameters.
+
 
 +posix.stat(path)+ ::
 See stat(2).

src/node.js

@@ -571,6 +571,16 @@ var posixModule = createInternalModule("posix", function (exports) {
     return process.fs.rename(oldPath, newPath);
   };
 
+  exports.truncate = function (fd, len) {
+    var promise = new events.Promise();
+    process.fs.truncate(fd, len, callback(promise));
+    return promise;
+  };
+
+  exports.truncateSync = function (fd, len) {
+    return process.fs.truncate(fd, len);
+  };
+
   exports.rmdir = function (path) {
     var promise = new events.Promise();
     process.fs.rmdir(path, callback(promise));

src/node_file.cc

@@ -53,6 +53,7 @@ static int After(eio_req *req) {
       case EIO_UNLINK:
       case EIO_RMDIR:
       case EIO_MKDIR:
+      case EIO_FTRUNCATE:
         argc = 0;
         break;
 
@@ -202,6 +203,25 @@ static Handle<Value> Rename(const Arguments& args) {
   }
 }
 
+static Handle<Value> Truncate(const Arguments& args) {
+  HandleScope scope;
+
+  if (args.Length() < 2 || !args[0]->IsInt32()) {
+    return THROW_BAD_ARGS;
+  }
+
+  int fd = args[0]->Int32Value();
+  off_t len = args[1]->Uint32Value();
+
+  if (args[2]->IsFunction()) {
+    ASYNC_CALL(ftruncate, args[2], fd, len)
+  } else {
+    int ret = ftruncate(fd, len);
+    if (ret != 0) return ThrowException(errno_exception(errno));
+    return Undefined();
+  }
+}
+
 static Handle<Value> Unlink(const Arguments& args) {
   HandleScope scope;
 
@@ -412,6 +432,7 @@ void File::Initialize(Handle<Object> target) {
   NODE_SET_METHOD(target, "open", Open);
   NODE_SET_METHOD(target, "read", Read);
   NODE_SET_METHOD(target, "rename", Rename);
+  NODE_SET_METHOD(target, "truncate", Truncate);
   NODE_SET_METHOD(target, "rmdir", RMDir);
   NODE_SET_METHOD(target, "mkdir", MKDir);
   NODE_SET_METHOD(target, "sendfile", SendFile);