Add ExcServerCopyState()

Add ExcServerCopyState().

ExcServerCopyState() properly sets the new_state and new_state_count
out-parameters for exception handler routines that may deal with
state-carrying exceptions.

This used to exist inline in catch_exception_tool, but that
implementation had a bug caught by the new test.

TEST=crashpad_util_test ExcServerVariants.ExcServerCopyState and others
R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/352160906b96c28289db2235022d872d69a8a370

[Mark Mentovai, 2015-03-30 21:57:53]

mark@chromium.org changed reviewers:
+ rsesek@chromium.org

[Robert Sesek, 2015-03-31 23:03:31]

https://codereview.chromium.org/1049023003/diff/1/util/mach/exc_server_varian...
File util/mach/exc_server_variants.h (right):

https://codereview.chromium.org/1049023003/diff/1/util/mach/exc_server_varian...
util/mach/exc_server_variants.h:234: const natural_t* old_state,
Why use natural_t here instead of thread_state_t ?

https://codereview.chromium.org/1049023003/diff/1/util/mach/exc_server_varian...
File util/mach/exc_server_variants_test.cc (right):

https://codereview.chromium.org/1049023003/diff/1/util/mach/exc_server_varian...
util/mach/exc_server_variants_test.cc:1334: for (size_t i = new_state_count; i <
arraysize(new_state); ++i) {
You use |copy_limit| on line 1318 instead of |new_state_count|.

[Mark Mentovai, 2015-03-31 23:13:24]

Updated.

https://codereview.chromium.org/1049023003/diff/1/util/mach/exc_server_varian...
File util/mach/exc_server_variants.h (right):

https://codereview.chromium.org/1049023003/diff/1/util/mach/exc_server_varian...
util/mach/exc_server_variants.h:234: const natural_t* old_state,
Robert Sesek wrote:
> Why use natural_t here instead of thread_state_t ?

Same as everywhere else this exists as an in-parameter: I want the data to be
const, not the pointer. thread_state_t is defined as natural_t*.

Do you think it’s worth a ConstThreadState typedef defined as const natural_t*?

https://codereview.chromium.org/1049023003/diff/1/util/mach/exc_server_varian...
File util/mach/exc_server_variants_test.cc (right):

https://codereview.chromium.org/1049023003/diff/1/util/mach/exc_server_varian...
util/mach/exc_server_variants_test.cc:1334: for (size_t i = new_state_count; i <
arraysize(new_state); ++i) {
Robert Sesek wrote:
> You use |copy_limit| on line 1318 instead of |new_state_count|.

OK, need to change 1331 too if changing this.

[Robert Sesek, 2015-04-01 16:07:00]

LGTM

https://codereview.chromium.org/1049023003/diff/1/util/mach/exc_server_varian...
File util/mach/exc_server_variants.h (right):

https://codereview.chromium.org/1049023003/diff/1/util/mach/exc_server_varian...
util/mach/exc_server_variants.h:234: const natural_t* old_state,
On 2015/03/31 23:13:23, Mark Mentovai wrote:
> Robert Sesek wrote:
> > Why use natural_t here instead of thread_state_t ?
> 
> Same as everywhere else this exists as an in-parameter: I want the data to be
> const, not the pointer. thread_state_t is defined as natural_t*.
> 
> Do you think it’s worth a ConstThreadState typedef defined as const
natural_t*?

It's a little subtle, but no I think it's fine.

[Mark Mentovai, 2015-04-01 16:16:27]

Committed patchset #2 (id:20001) manually as
352160906b96c28289db2235022d872d69a8a370 (presubmit successful).