Win64: Fix a pointer truncation bug in nspr.

Win64: Fix a pointer truncation bug in nspr.

Found by this clang warning:

..\..\third_party\nss\nspr\pr\src\threads\combined\pruthr.c(82,23) :  warning(clang): cast to 'char *' from smaller integer type 'long' [-Wint-to-pointer-cast]
    stack->stackTop = (char*) ((((long)&type + _pr_pageSize - 1)
                      ^
..\..\third_party\nss\nspr\pr\src\threads\combined\pruthr.c(182,25) :  warning(clang): cast to 'char *' from smaller integer type 'long' [-Wint-to-pointer-cast]
        ts->allocBase = (char*) ((((long)&ts + _pr_pageSize - 1)
                        ^
2 warnings generated.

I don't know if this code path is hit in practice.

BUG=82385
R=scottmg@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=293130

[Nico, 2014-11-26 18:26:33]

thakis@chromium.org changed reviewers:
+ scottmg@chromium.org, wtc@chromium.org

[scottmg, 2014-11-26 18:41:51]

lgtm

[Nico, 2014-11-26 19:09:28]

Committed patchset #1 (id:1) manually as r293130 (presubmit successful).

[wtc, 2014-12-01 18:34:02]

Patch set 1 LGTM.

This will be fixed in NSPR 4.10.8. Thanks.

https://codereview.chromium.org/757333003/diff/1/nspr/pr/src/threads/combined...
File nspr/pr/src/threads/combined/pruthr.c (right):

https://codereview.chromium.org/757333003/diff/1/nspr/pr/src/threads/combined...
nspr/pr/src/threads/combined/pruthr.c:76: stack->stackTop = (char*)
((((intptr_t)&type) >> _pr_pageShift)
In the NSPR upstream, I changed intptr_t to PRWord, which is a (poorly named)
NSPR type commonly used for this purpose. In Chromium it is fine to just use
intptr_t.

PRWord and intptr_t are both defined as __int64 in WIN64. Here is Visual C++
2010's definition of intptr_t:

#ifndef _INTPTR_T_DEFINED
 #define _INTPTR_T_DEFINED
 #ifdef _WIN64
typedef __int64 intptr_t;
 #else /* _WIN64 */
typedef _W64 int intptr_t;
 #endif /* _WIN64 */
#endif /* _INTPTR_T_DEFINED */