InputStream from process loses trailing data

[DartBot]

This issue was originally filed by rchandia@google.com

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What steps will reproduce the problem?

1. Run this (LostInfo.dart) with the vm:

void main() {
  int BUF_LEN = 13;
  List<int> out = new List<int>();
  List<int> err = new List<int>();
  
  Process p = new Process('/bin/bash', ['-c', 'seq -s: 1 10']);
  p.setExitHandler((int status) {
      print('exit($status)');
      print('OUT: -------------');
      print(new String.fromCharCodes(out));
      print('ERR: -------------');
      print(new String.fromCharCodes(err));
      p.close();
    });
  
  p.start();
  read(false, new List(BUF_LEN), p.stdoutStream, out);
  read(false, new List(BUF_LEN), p.stderrStream, err);
}

void processBuf(List<int> l, List<int> data) {
  data.addAll(l);
}

void read(bool fromCallback, List<int> buf, InputStream i, List<int> data) {
  if (fromCallback) {
    data.addAll(buf);
  }
  while(i.read(buf, 0, buf.length, () => read(true, buf, i, data))) {
    data.addAll(buf);
  }
}

What is the expected output? What do you see instead?
$ dart LostInfo.dart
exit(0)
OUT: -------------
1:2:3:4:5:6:7:8:9:10

ERR: -------------

$

Instead I see:
$ dart LostInfo.dart
exit(0)
OUT: -------------
1:2:3:4:5:6:7
ERR: -------------

$

[sgjesse]

The problem is that the InputStream.read callback is only called if the number of characters requested in actually read. As the process generated 21 characters of output (including trailing '\n'). Setting BUF_LEN to 1, 3, 7 or 21 will print all 21 characters.

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Set owner to @sgjesse.
Added Accepted label.

[sgjesse]

This has been fixed as part of the InputStream refactoring.

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Added Fixed label.