[btsync and folder permissions]

I suspect the problem is a bug in the function below (in pseudocode from disassembly). It seems to take a file permission set as an argument and return a specific permission set based on that. The return value is then used as part of a call to chmod.

I'm not certain what the intended logic is, but it seems that an input that is user writable:

input & 0x80 != 0

and group executable:

input & 0x8 != 0

results in a return value of 774, which is suspicious since the bug we see is a missing the other executable bit. A return of 775 would make more sense.

function sub_4c013a {
  input = rdi;
  result = 0x0;
  if ((input & 0x80) != 0x0) {
    result = 0x1b4;
  }
  else {
    if ((input & 0x1) != 0x0) {
      result = 0x124;
    }
  }
  if ((input & 0x8) != 0x0) {
    result = result | 0x48;
  }
  return result;
}

I suspect this:

result | 0x48 # 0110

should be this:

result | 0x49 # 0111