Fix the Linux build on Ubuntu 12.04 LTS

Fix the Linux build on Ubuntu 12.04 LTS

This fixes the build, which fails because the initialization values
for an array of struct sigaction cannot be { 0 }.

+ Get rid of warning related to unused return value for ftruncate()

BUG=492
Committed: https://code.google.com/p/google-breakpad/source/detail?r=1027

[Ted Mielczarek]

LGTM

https://breakpad.appspot.com/447002/diff/1/src/client/linux/handler/exception...
File src/client/linux/handler/exception_handler.cc (right):

https://breakpad.appspot.com/447002/diff/1/src/client/linux/handler/exception...
src/client/linux/handler/exception_handler.cc:120: struct sigaction
old_handlers[kNumHandledSignals];
This is probably okay since we don't actually use the values here before we set
them from calling sigaction. I was just fiddling with this, and you can also get
it to compile by changing this to
 = {{{0}}};
...but that's kind of horrible looking.

[digit]

For some reason, I didn't put Mark as a reviewer on this. Done.

[Mark Mentovai]

Oh. This has already been committed.

In the future, please separate the real I’m-broken fixes out from the
fix-a-stupid-warning fixes.

Anyway, it’s dumb that ftruncate is warn-unused-result, but I think that we can
make an exception to the casting rules and say that it’s OK to just write (void)
when you need to silence that warning. That’s an understood pattern, and
static_cast<void> is ugly and takes up space and isn’t quite as likely to be
immediately understood as the warn-unused-result-avoiding pattern.

http://breakpad.appspot.com/447002/diff/1/src/client/linux/handler/exception_...
File src/client/linux/handler/exception_handler.cc (right):

http://breakpad.appspot.com/447002/diff/1/src/client/linux/handler/exception_...
src/client/linux/handler/exception_handler.cc:120: struct sigaction
old_handlers[kNumHandledSignals];
Ted Mielczarek wrote:
> This is probably okay since we don't actually use the values here before we
set
> them from calling sigaction. I was just fiddling with this, and you can also
get
> it to compile by changing this to
>  = {{{0}}};
> ...but that's kind of horrible looking.

This is static data. It gets zero-initialized by default no matter what you do.

http://breakpad.appspot.com/447002/diff/1/src/client/linux/handler/exception_...
src/client/linux/handler/exception_handler.cc:527:
static_cast<void>(ftruncate(minidump_descriptor_.fd(), 0));
This is ugly.