Race Condition without Threads?

Question

Let's say I have: sample.c

int main (...) {

  char str*;

  get s through user input

  test(str);

  return 0;

}

void test (str) {

   copy str to new file 

   change file permissions on new file

   close file

}

There's no possibility of a race condition here since I have no threads in my main() method. Is that true?

Answer 1

Another sources of race conditions are interrupts and signals. If you use neither then no race condition will occur (there is single racer)

Answer 2

That's correct. The race condition by definition requires multiple threads and at least one shared resource.

Answer 3

There is the possibility of a race - two users could run your program at the same time.

Answer 4

There is a kind of race condition in that the user can exchange "new file" immediately before you change permissions of "new file". This is (was?) an often used security exploit.

I just see that Neil Butterworth had a related idea.

Answer 5

Any time that you make a system call there is a possibility of a race condition. This is because the kernel links all the threads on the system and allows control interaction between processes. In this case another thread on the system can access the same file as your application.

Answer 6

The boost::filesystem docs have good explanations of filesystem race conditions which are applicable to filesystems in general.