fs: move type checking for fs.ftruncate to js

PR-URL: #17334
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

lib/fs.js

@@ -864,11 +864,11 @@ fs.ftruncate = function(fd, len, callback) {
   } else if (len === undefined) {
     len = 0;
   }
-  if (typeof fd !== 'number')
+  if (!Number.isInteger(fd))
     throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'fd', 'number');
   if (fd < 0 || fd > 0xFFFFFFFF)
     throw new errors.RangeError('ERR_OUT_OF_RANGE', 'fd');
-  if (typeof len !== 'number')
+  if (!Number.isInteger(len))
     throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'len', 'number');
   len = Math.max(0, len);
   const req = new FSReqWrap();
@@ -880,11 +880,11 @@ fs.ftruncateSync = function(fd, len) {
   if (len === undefined) {
     len = 0;
   }
-  if (typeof fd !== 'number')
+  if (!Number.isInteger(fd))
     throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'fd', 'number');
   if (fd < 0 || fd > 0xFFFFFFFF)
     throw new errors.RangeError('ERR_OUT_OF_RANGE', 'fd');
-  if (typeof len !== 'number')
+  if (!Number.isInteger(len))
     throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'len', 'number');
   len = Math.max(0, len);
   return binding.ftruncate(fd, len);

src/node_file.cc

@@ -763,24 +763,11 @@ static void Rename(const FunctionCallbackInfo<Value>& args) {
 static void FTruncate(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
 
-  if (args.Length() < 2)
-    return TYPE_ERROR("fd and length are required");
-  if (!args[0]->IsInt32())
-    return TYPE_ERROR("fd must be a file descriptor");
+  CHECK(args[0]->IsInt32());
+  CHECK(args[1]->IsNumber());
 
   int fd = args[0]->Int32Value();
-
-  // FIXME(bnoordhuis) It's questionable to reject non-ints here but still
-  // allow implicit coercion from null or undefined to zero.  Probably best
-  // handled in lib/fs.js.
-  Local<Value> len_v(args[1]);
-  if (!len_v->IsUndefined() &&
-      !len_v->IsNull() &&
-      !IsInt64(len_v->NumberValue())) {
-    return env->ThrowTypeError("Not an integer");
-  }
-
-  const int64_t len = len_v->IntegerValue();
+  const int64_t len = args[1]->IntegerValue();
 
   if (args[2]->IsObject()) {
     ASYNC_CALL(ftruncate, args[2], UTF8, fd, len)

test/parallel/test-fs-truncate.js

@@ -180,8 +180,69 @@ function testFtruncate(cb) {
   fs.writeFileSync(file5, 'Hi');
   const fd = fs.openSync(file5, 'r+');
   process.on('exit', () => fs.closeSync(fd));
+
+  ['', false, null, {}, []].forEach((i) => {
+    common.expectsError(
+      () => fs.ftruncate(fd, i),
+      {
+        code: 'ERR_INVALID_ARG_TYPE',
+        type: TypeError,
+        message: 'The "len" argument must be of type number'
+      }
+    );
+  });
+
   fs.ftruncate(fd, undefined, common.mustCall(function(err) {
     assert.ifError(err);
     assert(fs.readFileSync(file5).equals(Buffer.from('')));
   }));
 }
+
+{
+  const file6 = path.resolve(tmp, 'truncate-file-6.txt');
+  fs.writeFileSync(file6, 'Hi');
+  const fd = fs.openSync(file6, 'r+');
+  process.on('exit', () => fs.closeSync(fd));
+  fs.ftruncate(fd, -1, common.mustCall(function(err) {
+    assert.ifError(err);
+    assert(fs.readFileSync(file6).equals(Buffer.from('')));
+  }));
+}
+
+['', false, null, undefined, {}, []].forEach((i) => {
+  common.expectsError(
+    () => fs.ftruncate(i),
+    {
+      code: 'ERR_INVALID_ARG_TYPE',
+      type: TypeError,
+      message: 'The "fd" argument must be of type number'
+    }
+  );
+  common.expectsError(
+    () => fs.ftruncateSync(i),
+    {
+      code: 'ERR_INVALID_ARG_TYPE',
+      type: TypeError,
+      message: 'The "fd" argument must be of type number'
+    }
+  );
+});
+
+[-1, 0xFFFFFFFF + 1].forEach((i) => {
+  common.expectsError(
+    () => fs.ftruncate(i),
+    {
+      code: 'ERR_OUT_OF_RANGE',
+      type: RangeError,
+      message: 'The "fd" argument is out of range'
+    }
+  );
+  common.expectsError(
+    () => fs.ftruncateSync(i),
+    {
+      code: 'ERR_OUT_OF_RANGE',
+      type: RangeError,
+      message: 'The "fd" argument is out of range'
+    }
+  );
+});