openSync/writeSync/closeSync produces empty file

[gracjan]

Code:

var fd = fs.openSync("abc.txt", "w");
var buf = Buffer.from("Was here.\n");
fs.writeSync(fd, buf);
fs.closeSync(fd);

produces empty file. Expected is that it writes whole buffer. Note that fs.writeSync(fd, "Was here.\n"); writes whole string.

• Version:
  v6.2.2
• Platform:
  Darwin MacBook-Pro-3.local 14.5.0 Darwin Kernel Version 14.5.0: Thu Apr 21 20:40:54 PDT 2016; root:xnu-2782.50.3~1/RELEASE_X86_64 x86_64
• Subsystem:
  fs(?)

[saghul]

The writeSync call returns 0, which means no data was written. Didn't have time to investigate further.

[addaleax]

fs.writeSync(fd, buf, 0, buf.length); should work; right now, fs.writeSync always uses the length argument, even when it’s undefined. I doubt that’s intentional, though.

[papandreou]

Sounds like you've run into the same problem for writeSync as I did with write a few days ago: #7856

[gracjan]

@papandreou: looks alike. Will the fix there also fix my issue?

[papandreou]

I don't think it will in its current state, no. I'm on holiday for the next week, but will make sure to pick it up if noone else has landed a fix in the mean time. It's weird, seems like this bug has been there since at least 0.6. It really is the most basic form of fs.write(Sync) -- and now the two of us both discover it within half a week :)

[gracjan]

@papandreou, alternatevly you could change this here

node/src/node_file.cc

Line 1001 in c86c1ee

// Wrapper for write(2).

so that WriteBuffer accepts the following spec:

// Wrapper for write(2).
//
// bytesWritten = write(fd, buffer, offset, length, position, callback)
// 0 fd        integer. file descriptor
// 1 buffer    the data to write
// 2 offset    where in the buffer to start from if integer, 0 if undefined or null
// 3 length    how much to write if integer, buffer length minus offset if undefined or null
// 4 position  if integer, position to write at in the file.
//             if null or undefined, write from the current position

As I understand WriteBuffer is common meeting point for all write and writeSync functions. Thos functions could be simplified after WriteBuffer gets new functionality.

[papandreou]

Fixed by #7856 (released in 7.2.0). This issue can be closed now.