Add a function to detect patches that can't be safely applied.

Add a function to detect patches that can't be safely applied.

It tries to err on the safe side.

BUG=
TEST=

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=70087

[M-A Ruel, 2010-12-22 21:06:11]

This is important before enabling the commit queue since I don't want it to
commit incorrectly patches; and a fair number of patches can't be committed
correctly right now. I tried to err on the safe side even if the patch parsing
code is quite ugly. Will change if necessary.

Dependent on http://codereview.chromium.org/6031003

[Dirk Pranke, 2010-12-22 23:25:11]

The code looks plausible to me but I don't know enough about the types of errors
that svn apply can fail with. I can LGTM this but it's more of a rubber stamp.
Maybe someone else should have a look as well?

[M-A Ruel, 2010-12-23 17:36:15]

On 2010/12/22 23:25:11, dpranke wrote:
> The code looks plausible to me but I don't know enough about the types of
errors
> that svn apply can fail with. I can LGTM this but it's more of a rubber stamp.
> Maybe someone else should have a look as well?

I'm sure I'll need to change it as I find other edge cases. Right now it's just
there to make sure it doesn't commit known broken patches. That's why I added
the unit test.

It's possible that I use a full blown class to handle the patches especially the
svn specific stuff, a few off the shelf classes already exist, but for now I'll
keep it simple.

[M-A Ruel, 2010-12-23 20:38:24]

On 2010/12/23 17:36:15, Marc-Antoine Ruel wrote:
> On 2010/12/22 23:25:11, dpranke wrote:
> > The code looks plausible to me but I don't know enough about the types of
> errors
> > that svn apply can fail with. I can LGTM this but it's more of a rubber
stamp.
> > Maybe someone else should have a look as well?
> 
> I'm sure I'll need to change it as I find other edge cases. Right now it's
just
> there to make sure it doesn't commit known broken patches. That's why I added
> the unit test.
> 
> It's possible that I use a full blown class to handle the patches especially
the
> svn specific stuff, a few off the shelf classes already exist, but for now
I'll
> keep it simple.

Actually I found an issue in a following change but I won't modify this one
since it wasn't too bad and it's not worth rewriting the history. I'll commit
since I'm finalizing the tests.

Note that it's git that is applying the patch here, no svn. svn can't apply
patches *at all*.