Add the child_port Mach subsystem

Add the child_port Mach subsystem.

R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/e9482a704d131827ce84f09f7df2f42978018160

[Mark Mentovai, 2014-11-24 20:06:51]

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

[Robert Sesek, 2014-11-24 20:33:04]

https://codereview.chromium.org/752243002/diff/1/util/mach/child_port.defs
File util/mach/child_port.defs (right):

https://codereview.chromium.org/752243002/diff/1/util/mach/child_port.defs#ne...
util/mach/child_port.defs:36: import "util/mach/child_port_types.h";
Do you need to define the Mach types above if you include this header?

[Mark Mentovai, 2014-11-24 20:42:28]

https://codereview.chromium.org/752243002/diff/1/util/mach/child_port.defs
File util/mach/child_port.defs (right):

https://codereview.chromium.org/752243002/diff/1/util/mach/child_port.defs#ne...
util/mach/child_port.defs:36: import "util/mach/child_port_types.h";
Robert Sesek wrote:
> Do you need to define the Mach types above if you include this header?

Yup. MIG reads the types above, but doesn’t generate C typedefs for them.
child_port_types.h is necessary to provide equivalent typedefs for C/C++ code.
It’s silly, because MIG could write typedefs, it just doesn’t.

This “import” line just tells MIG to output an #include for this file. It
doesn’t actually open child_port_types.h itself or understand how to parse the C
code in there to read the typedefs.

[Robert Sesek, 2014-11-24 20:45:12]

LGTM

https://codereview.chromium.org/752243002/diff/1/util/mach/child_port.defs
File util/mach/child_port.defs (right):

https://codereview.chromium.org/752243002/diff/1/util/mach/child_port.defs#ne...
util/mach/child_port.defs:36: import "util/mach/child_port_types.h";
On 2014/11/24 20:42:28, Mark Mentovai wrote:
> Robert Sesek wrote:
> > Do you need to define the Mach types above if you include this header?
> 
> Yup. MIG reads the types above, but doesn’t generate C typedefs for them.
> child_port_types.h is necessary to provide equivalent typedefs for C/C++ code.
> It’s silly, because MIG could write typedefs, it just doesn’t.
> 
> This “import” line just tells MIG to output an #include for this file. It
> doesn’t actually open child_port_types.h itself or understand how to parse the
C
> code in there to read the typedefs.

MIG is weird. You'd expect it to either generate typedefs or to process a C
header with the types.

[Mark Mentovai, 2014-11-24 20:47:55]

More MIG annoyances: in an earlier version of this change, the token was a
uint64_t[4], so the C interfaces used child_port_token_t*. Naturally, I wanted
it to point to const data. There was no way to convince MIG to make it const. It
accepted a “const” qualifier for the argument, but it didn’t do anything with it
at all.

[Mark Mentovai, 2014-11-24 20:48:14]

Committed patchset #1 (id:1) manually as
e9482a704d131827ce84f09f7df2f42978018160 (presubmit successful).