writeFile fixes

writeFileSync could exhibit pathological behavior when a buffer could
not be written to the file in a single write() call.

Also, writeFile was not quite as optimized as it could be.

lib/fs.js

@@ -388,17 +388,18 @@ fs.chownSync = function(path, uid, gid) {
   return binding.chown(path, uid, gid);
 };
 
-function writeAll (fd, buffer, callback) {
+function writeAll (fd, buffer, offset, length, callback) {
-  fs.write(fd, buffer, 0, buffer.length, null, function (writeErr, written) {
+  // write(fd, buffer, offset, length, position, callback)
+  fs.write(fd, buffer, offset, length, offset, function (writeErr, written) {
     if (writeErr) {
       fs.close(fd, function () {
         if (callback) callback(writeErr);
       });
     } else {
-      if (written === buffer.length) {
+      if (written === length) {
         fs.close(fd, callback);
       } else {
-        writeAll(fd, buffer.slice(written), callback);
+        writeAll(fd, buffer, offset+written, length-written, callback);
       }
     }
   });
@@ -413,18 +414,21 @@ fs.writeFile = function (path, data, encoding_, callback) {
       if (callback) callback(openErr);
     } else {
       var buffer = Buffer.isBuffer(data) ? data : new Buffer(data, encoding);
-      writeAll(fd, buffer, callback);
+      writeAll(fd, buffer, 0, buffer.length, callback);
     }
   });
 };
 
 fs.writeFileSync = function (path, data, encoding) {
-  encoding = encoding || "utf8"; // default to utf8
   var fd = fs.openSync(path, "w");
+  if (!Buffer.isBuffer(data)) {
+    data = new Buffer(data, encoding || "utf8")
+  }
   var written = 0;
-  while (written < data.length) {
+  var length = data.length;
-    written += fs.writeSync(fd, data, 0, encoding);
+  //writeSync(fd, buffer, offset, length, position)
-    data = data.slice(written);
+  while (written < length) {
+    written += fs.writeSync(fd, data, written, length-written, written);
   }
   fs.closeSync(fd);
 };

test/simple/test-fs-write-file-buffer.js

@@ -0,0 +1,30 @@
+var common = require('../common');
+var join = require('path').join;
+var util = require('util');
+var fs = require('fs');
+
+var data = [
+'/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAUDBAQEAwUEBAQFBQUGBwwIBwcH',
+'Bw8LCwkMEQ8SEhEPERETFhwXExQaFRERGCEYGh0dHx8fExciJCIeJBweHx7/',
+'2wBDAQUFBQcGBw4ICA4eFBEUHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4e',
+'Hh4eHh4eHh4eHh4eHh4eHh4eHh4eHh7/wAARCAAQABADASIAAhEBAxEB/8QA',
+'HwAAAQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUF',
+'BAQAAAF9AQIDAAQRBRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkK',
+'FhcYGRolJicoKSo0NTY3ODk6Q0RFRkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1',
+'dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ipqrKztLW2t7i5usLDxMXG',
+'x8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/8QAHwEAAwEBAQEB',
+'AQEBAQAAAAAAAAECAwQFBgcICQoL/8QAtREAAgECBAQDBAcFBAQAAQJ3AAEC',
+'AxEEBSExBhJBUQdhcRMiMoEIFEKRobHBCSMzUvAVYnLRChYkNOEl8RcYGRom',
+'JygpKjU2Nzg5OkNERUZHSElKU1RVVldYWVpjZGVmZ2hpanN0dXZ3eHl6goOE',
+'hYaHiImKkpOUlZaXmJmaoqOkpaanqKmqsrO0tba3uLm6wsPExcbHyMnK0tPU',
+'1dbX2Nna4uPk5ebn6Onq8vP09fb3+Pn6/9oADAMBAAIRAxEAPwDhfBUFl/wk',
+'OmPqKJJZw3aiZFBw4z93jnkkc9u9dj8XLfSI/EBt7DTo7ea2Ox5YXVo5FC7g',
+'Tjq24nJPXNVtO0KATRvNHCIg3zoWJWQHqp+o4pun+EtJ0zxBq8mnLJa2d1L5',
+'0NvnKRjJBUE5PAx3NYxxUY0pRtvYHSc5Ka2X9d7H/9k='];
+
+data = data.join('\n');
+
+var buf = new Buffer(data, 'base64');
+fs.writeFileSync(join(common.tmpDir, 'test.jpg'), buf);
+
+util.log('Done!');