MinGW32: define STRUNCATE

MinGW32: define STRUNCATE and change strncpy_s implementation to follow specification.

This fixes the debug build for MinGW32

Patch by Bert Belder.

Committed: http://code.google.com/p/v8/source/detail?r=8552

[piscisaureus, 2011-07-05 13:31:54]

Add a defined constant that mingw's headers don't have.

[Vyacheslav Egorov (Chromium), 2011-07-05 13:46:51]

http://codereview.chromium.org/7308007/diff/1/src/platform-win32.cc
File src/platform-win32.cc (right):

http://codereview.chromium.org/7308007/diff/1/src/platform-win32.cc#newcode154
src/platform-win32.cc:154: strncpy(strDest, strSource, count);
This implementation is not safe and is not following strncpy_s semantics.

It should ensure that \0 is always copied to the destination.

It should check for the case when count == _TRUNCATE, and handle it
appropriately (truncate the string if needed and return STRUNCATE). 

Please make it behave like described in
http://msdn.microsoft.com/en-us/library/5dae5d43(v=vs.80).aspx

[piscisaureus, 2011-07-05 13:51:42]

So you're saying that this can't land unless I also fix *another* issue with the
code?

But yeah - valid point.

[piscisaureus, 2011-07-05 16:16:41]

Addressed your comment. I didn't run the test suite yet - the gcc/msvc toolchain
issue is back when I add sample=shell to the scons command. I'll get you know
when I figure this out.

[piscisaureus, 2011-07-05 22:25:00]

Path set 3 is the real thing. 

I've tried to follow the strncpy_s specifications on msdn, with this remark that
when msvcrt would invoke the error handler this implementation just crashes by
failing a CHECK.

It passes all tests on MinGW.(except for cctest/test-strtod, but this is not a
regression).

[Vyacheslav Egorov (Chromium), 2011-07-06 12:10:33]

Thanks. 

I'll with nit and land.

http://codereview.chromium.org/7308007/diff/5001/src/platform-win32.cc
File src/platform-win32.cc (right):

http://codereview.chromium.org/7308007/diff/5001/src/platform-win32.cc#newcod...
src/platform-win32.cc:162: while (dest_size && *source != 0) {
Google Style Guide disallows implicit int to boolean conversions.

http://codereview.chromium.org/7308007/diff/5001/src/platform-win32.cc#newcod...
src/platform-win32.cc:174: while (dest_size && count && *source != 0) {
Ditto.

[Vyacheslav Egorov (Chromium), 2011-07-06 12:25:56]

Landed.