win: Use signed int as the integer representation of HANDLEs

win: Use signed int as the integer representation of HANDLEs

HandleToInt() and IntToHandle() use int, a signed type, for the 32-bit
integer representation of HANDLE values. For opaque values, an unsigned
type would normally be used, but in this case, signed was chosen for
sign extension to work correctly. INVALID_HANDLE_VALUE is defined as
((HANDLE)(LONG_PTR)-1), and this needs to round-trip through the chosen
integer representation back to the same HANDLE value. Sign extension is
also recommended by
https://msdn.microsoft.com/en-us/library/windows/desktop/aa384203.

As suggested in
https://codereview.chromium.org/1422503015/diff/1/util/win/handle.cc#newcode24

R=scottmg@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/b666bcbe98c67256a64418313755a40fea2992d6

[Mark Mentovai, 2015-11-06 16:06:20]

Description was changed from

==========
win: Use signed int as the integer representation of HANDLEs.

HandleToInt() and IntToHandle() use int, a signed type, for the 32-bit
integer representation of HANDLE values. For opaque values, an unsigned
type would normally be used, but in this case, signed was chosen for
sign extension to work correctly. INVALID_HANDLE_VALUE is defined as
((HANDLE)(LONG_PTR)-1), and this needs to round-trip through the chosen
integer representation back to the same HANDLE value. Sign extension is
also recommended by
https://msdn.microsoft.com/en-us/library/windows/desktop/aa384203.

As suggested in
https://codereview.chromium.org/1422503015/diff/1/util/win/handle.cc#newcode24
==========

to

==========
win: Use signed int as the integer representation of HANDLEs

HandleToInt() and IntToHandle() use int, a signed type, for the 32-bit
integer representation of HANDLE values. For opaque values, an unsigned
type would normally be used, but in this case, signed was chosen for
sign extension to work correctly. INVALID_HANDLE_VALUE is defined as
((HANDLE)(LONG_PTR)-1), and this needs to round-trip through the chosen
integer representation back to the same HANDLE value. Sign extension is
also recommended by
https://msdn.microsoft.com/en-us/library/windows/desktop/aa384203.

As suggested in
https://codereview.chromium.org/1422503015/diff/1/util/win/handle.cc#newcode24
==========

[Mark Mentovai, 2015-11-06 16:06:33]

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

[scottmg, 2015-11-06 18:33:22]

lgtm

https://codereview.chromium.org/1422023010/diff/20001/util/win/handle.h
File util/win/handle.h (right):

https://codereview.chromium.org/1422023010/diff/20001/util/win/handle.h#newco...
util/win/handle.h:25: //! pointers to anything. Only 32 bits of kernel `HANDLE`s
are significant, even
Ah, I meant to mention "shareable" in the last change, good stuff.

https://codereview.chromium.org/1422023010/diff/20001/util/win/registration_p...
File util/win/registration_protocol_win.h (left):

https://codereview.chromium.org/1422023010/diff/20001/util/win/registration_p...
util/win/registration_protocol_win.h:109: //!     clients should convert the
value to `HANDLEEE` using sign-extension.
EEEE!

[Mark Mentovai, 2015-11-06 18:36:27]

https://codereview.chromium.org/1422023010/diff/20001/util/win/handle.h
File util/win/handle.h (right):

https://codereview.chromium.org/1422023010/diff/20001/util/win/handle.h#newco...
util/win/handle.h:25: //! pointers to anything. Only 32 bits of kernel `HANDLE`s
are significant, even
scottmg wrote:
> Ah, I meant to mention "shareable" in the last change, good stuff.

Yeah, yesterday, I was kind of struggling with the best way to express this
while making it clear that it didn’t apply to things like HMODULE. Then it hit
me this morning!

[Mark Mentovai, 2015-11-06 20:03:21]

Committed patchset #2 (id:20001) manually as
b666bcbe98c67256a64418313755a40fea2992d6 (presubmit successful).