fs: support util.promisify for fs.read/fs.write

PR-URL: https://github.com/nodejs/node/pull/12442
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: William Kapke <william.kapke@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/fs.js b/lib/fs.js
index ac1f90109a..b62bc67920 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -656,6 +656,9 @@ fs.read = function(fd, buffer, offset, length, position, callback) {
   binding.read(fd, buffer, offset, length, position, req);
 };
 
+Object.defineProperty(fs.read, internalUtil.customPromisifyArgs,
+                      { value: ['bytesRead', 'buffer'], enumerable: false });
+
 fs.readSync = function(fd, buffer, offset, length, position) {
   if (length === 0) {
     return 0;
@@ -706,6 +709,9 @@ fs.write = function(fd, buffer, offset, length, position, callback) {
   return binding.writeString(fd, buffer, offset, length, req);
 };
 
+Object.defineProperty(fs.write, internalUtil.customPromisifyArgs,
+                      { value: ['bytesWritten', 'buffer'], enumerable: false });
+
 // usage:
 //  fs.writeSync(fd, buffer[, offset[, length[, position]]]);
 // OR