yabberyabber
commented
1 year ago Another alternative is to call dup2 twice
- 1: call dup2 to dupe all the fd's that we want to keep
- 2: call bst_close_range to close all the fd's below the __last_fd
- 3: call dup2 again to put those fd's that we opened in step 1 to their original fd
- 4: close the buffer fd's from step 1
That way you don't need to change the FD's which means it doesn't need to be a macro
This solves the same problem as 7fa1d2d (cgroup_helper shan't hold socket for outer_helper process), but goes a bit further by eliminating the entire class of the problem by closing every single file descriptor that isn't actually used by the forked process.
This ensures that long-lived helper processes do not accidentally hold open file descriptors on which parent processes might be waiting for EOF on.