When a directory contains read-only files, try to make them writable when recursively deleting on W…

When a directory contains read-only files, try to make them writable when recursively deleting on Windows.

Committed: https://code.google.com/p/dart/source/detail?r=11175

[Bob Nystrom, 2012-08-22 00:22:56]

This fixes an issue I have running the Pub tests on Windows. The tests
frequently do this:

1. Create a temp directory.
2. Create a git repository in it.
3. Run some tests.
4. Delete the directory from step 1.

On Windows, this was failing. The problem is that git marks its object files
(the stuff under .git/objects/...) read-only. When dart:io's directory delete
tried to delete them, it failed.

This is unlike Windows and Mac, where it can delete directories containing git
repoes with read-only files with no problems.

So this patch, I think, gets the Windows behavior closer to those OSes. It's
also closer to Windows Explorer, which seems to let you delete a directory (or
move it to the Recycle Bin) even when it contains read-only files.

What do you think?

[Mads Ager (google), 2012-08-22 07:58:29]

LGTM, I wasn't aware that the DeleteFile API required you to remove the ReadOnly
attribute on the file first. :)

[Søren Gjesse, 2012-08-22 10:38:57]

lgtm

[Bob Nystrom, 2012-08-22 16:47:52]

On 2012/08/22 07:58:29, Mads Ager wrote:
> LGTM, I wasn't aware that the DeleteFile API required you to remove the
ReadOnly
> attribute on the file first. :)

Me either. I guess now we know. :)