I open a File with FileMode.Out and I can't read the file from other programs while the file is open. Why is the file sharing set this way? It has been annoying me all the way from my early days of D.

I often open a file at program startup and write log information to it; sometimes the program runs 24 hours a day. What good is a log file if I can never read it?

Please set file sharing to always share read access. It should be 2 simple fixes to stream.d in function parseMode.

Also, there could be a way to extend File to allow specifying file sharing. Since not every environment offers this functionality, it could just be a request, and there could also be another function to call that returns true if sharing is definitely available, or false if it is not or cannot be determined.

A lot of times I just go back to C FILE*s because D's streams just feel icky.


Oh yeah, I forgot, opening for write causes sharing write access. This is really bizarre. It should always share read and should never share write (unless there's a way to change it per File).


I'm going to be pretty mad if this isn't fixed for 1.0 - especially the sharing write.

On Mon, 24 Jul 2006 02:17:07 -0400, Chris Miller <chris@dprogramming.com> wrote:

> I open a File with FileMode.Out and I can't read the file from other programs while the file is open. Why is the file sharing set this way? It has been annoying me all the way from my early days of D.
>
> I often open a file at program startup and write log information to it; sometimes the program runs 24 hours a day. What good is a log file if I can never read it?
>
> Please set file sharing to always share read access. It should be 2 simple fixes to stream.d in function parseMode.
>
> Also, there could be a way to extend File to allow specifying file sharing. Since not every environment offers this functionality, it could just be a request, and there could also be another function to call that returns true if sharing is definitely available, or false if it is not or cannot be determined.
>
> A lot of times I just go back to C FILE*s because D's streams just feel icky.
>
>
> Oh yeah, I forgot, opening for write causes sharing write access. This is really bizarre. It should always share read and should never share write (unless there's a way to change it per File).
>
>
> I'm going to be pretty mad if this isn't fixed for 1.0 - especially the sharing write.


Sorry, forget the last part, it doesn't share write access.

Here's an updated parseMode function to always only give read sharing:


  private void parseMode(int mode,
			 out int access,
			 out int share,
			 out int createMode) {
    version (Win32) {
      share |= FILE_SHARE_READ;
      if (mode & FileMode.In) {
	access |= GENERIC_READ;
	createMode = OPEN_EXISTING;
      }
      if (mode & FileMode.Out) {
	access |= GENERIC_WRITE;
	createMode = OPEN_ALWAYS; // will create if not present
      }
      if ((mode & FileMode.OutNew) == FileMode.OutNew) {
	createMode = CREATE_ALWAYS; // resets file
      }
    }
    version (linux) {
      share = 0444;
      if (mode & FileMode.In) {
	access = O_RDONLY;
      }
      if (mode & FileMode.Out) {
	createMode = O_CREAT; // will create if not present
	access = O_WRONLY;
      }
      if (access == (O_WRONLY | O_RDONLY)) {
	access = O_RDWR;
      }
      if ((mode & FileMode.OutNew) == FileMode.OutNew) {
	access |= O_TRUNC; // resets file
      }
    }
  }


Another concern, when opening for write and not specifying read, should it imply also opening for read?