Fix usage of snprintf for MSVC

Fix usage of snprintf for MSVC

Older versions of MSVC don't have a snprintf functions. Some files
were already working around that, but not all of them. Instead of
copying the logic into every file, I centralize it into a new
stdio.h wrapper file and make other files include that.

BUG=
R=mark@chromium.org

Committed: https://chromium.googlesource.com/breakpad/breakpad/+/d5d13e605e161b8374d07ed61b17d75fe6d46381

[labath, 2016-01-18 16:15:05]

labath@google.com changed reviewers:
+ mark@chromium.org

[Mark Mentovai, 2016-01-19 22:06:28]

How old is old? Chrome doesn’t care about MSVC older than 2013. I doubt Breakpad
needs to care about anything much older than that either, maybe it still needs
to care about 2012. The _MSC_VER check for < 1900 says that this is only a
problem pre-2008?

Was this causing a real problem for some build somewhere?

[Ted Mielczarek, 2016-01-20 00:20:24]

On 2016/01/19 22:06:28, Mark Mentovai wrote:
> How old is old? Chrome doesn’t care about MSVC older than 2013. I doubt
Breakpad
> needs to care about anything much older than that either, maybe it still needs
> to care about 2012. The _MSC_VER check for < 1900 says that this is only a
> problem pre-2008?
> 
> Was this causing a real problem for some build somewhere?

snprintf was added in Visual C++ 2015, so the 1900 check should be accurate.

[Mark Mentovai, 2016-01-20 00:40:23]

Oh, 1900 is 2015. OK then, let’s proceed with this.

[Mark Mentovai, 2016-01-20 02:28:09]

LGTM

[Mark Mentovai, 2016-01-20 02:28:48]

Description was changed from

==========
Fix usage of snprintf for MSVC

Older versions of MSVC don't have a snprintf functions. Some files
were already working around that, but not all of them. Instead of
copying the logic into every file, I centralize it into a new
stdio.h wrapper file and make other files include that.

BUG=
==========

to

==========
Fix usage of snprintf for MSVC

Older versions of MSVC don't have a snprintf functions. Some files
were already working around that, but not all of them. Instead of
copying the logic into every file, I centralize it into a new
stdio.h wrapper file and make other files include that.

BUG=
R=mark@chromium.org

Committed:
https://chromium.googlesource.com/breakpad/breakpad/+/d5d13e605e161b8374d07ed...
==========

[Mark Mentovai, 2016-01-20 02:28:49]

Committed patchset #1 (id:1) manually as
d5d13e605e161b8374d07ed61b17d75fe6d46381 (presubmit successful).

[labath, 2016-01-20 10:10:55]

I am using MSVC 2013 to build this. Thank you for committing.

[brucedawson, 2016-01-20 21:29:16]

brucedawson@chromium.org changed reviewers:
+ brucedawson@chromium.org

[brucedawson, 2016-01-20 21:29:16]

https://codereview.chromium.org/1602563003/diff/1/src/common/stdio.h
File src/common/stdio.h (right):

https://codereview.chromium.org/1602563003/diff/1/src/common/stdio.h#newcode38
src/common/stdio.h:38: #define snprintf _snprintf
It's slightly terrifying that we're doing this mapping, since snprintf
guarantees null-termination and _snprintf does not (in the case where the buffer
is too small).

But, this becomes irrelevant to Chromium once we switch to VS 2015 (imminently!)
and the one snprintf usage I saw was safe.

This #define does continue to be a bad idea for breakpad users other than
Chromium who might continue using VS 2013 or earlier. The correct solution is to
write and use an snprintf replacement that guarantees null-termination.

[labath, 2016-01-21 10:37:21]

On 2016/01/20 21:29:16, brucedawson wrote:
> https://codereview.chromium.org/1602563003/diff/1/src/common/stdio.h
> File src/common/stdio.h (right):
> 
> https://codereview.chromium.org/1602563003/diff/1/src/common/stdio.h#newcode38
> src/common/stdio.h:38: #define snprintf _snprintf
> It's slightly terrifying that we're doing this mapping, since snprintf
> guarantees null-termination and _snprintf does not (in the case where the
buffer
> is too small).
> 
> But, this becomes irrelevant to Chromium once we switch to VS 2015
(imminently!)
> and the one snprintf usage I saw was safe.
> 
> This #define does continue to be a bad idea for breakpad users other than
> Chromium who might continue using VS 2013 or earlier. The correct solution is
to
> write and use an snprintf replacement that guarantees null-termination.

I am not sure how breakpad is compiled in chromium, but given how many fixes I
had to apply to get it compiling, it sounds to me like you are not using this
part of code at all (at least not with MSVC 2013?). This code is used for
processing generated minidumps, so I expect it should not end up in the browser.

[Mark Mentovai, 2016-01-21 13:06:42]

Correct. We don’t run any of the processor-side stuff in Chrome or on Windows.

[Ted Mielczarek, 2016-01-21 15:24:11]

On 2016/01/21 13:06:42, Mark Mentovai wrote:
> Correct. We don’t run any of the processor-side stuff in Chrome or on Windows.

Some of it gets built as part of the Windows unit tests, but it's not that big
of a deal.