wasmperson on How Go detects struct copies with sync.noCopy

Comment on How Go detects struct copies with sync.noCopy parent

(e.g. closing a file), there's generally not much you can do anyway

If closing a file fails then you treat it the same as how you would treat a write failure:

  int err = 1;
  FILE *f = fopen("whatever.txt", "w");
  if(f){
    if(5 == fwrite("Hello", 1, 5, f))
      err = 0;

    if(0 != fclose(f))
      err = 1;
  }
  return err;

Code which writes to files and doesn't check for errors on close is subtly incorrect, although my understanding is that kernel devs bend over backwards to make failure unlikely, probably because everybody does it incorrectly anyway.

tredre3 26d

Not that it matters, but fclose() doesn't happen in the kernel, so the kernel devs can't do anything about it. All libcs have essentially the same implementation:

- is fp NULL or already already closed? return error

- call fflush() and return error if it fails (fflush also happens in userland, it does a seek() then a write() of the userland buffer)

- call close() and return error if it fails

close() follows essentially the same process inside the kernel: check fd is valid, call flush() (this time truly to disk), close it.

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