Posix says about close(2):
"If close() is interrupted by a signal that is to be caught, it shall
return -1 with errno set to [EINTR] and the state of fildes is unspecified."
What means that the file descriptor can be already closed and return
EINTR, making the call try to close it again, while this shouldn't be a real
problem in single-threaded programs (although would return a fake EBADF), it
creates a real problem in multi-threaded programs as you could close other file
descriptors that were open in the mean time. Maybe you could verify with fstat
if is safe to close again (by comparing the ino and dev values or by receveing
EBADF)
