Most C standard library functions are undefined if passed NULL, even
when the corresponding length is zero. This gives them (and, in turn,
all functions which call them) surprising behavior on empty arrays.
Some compilers will miscompile code due to this rule. See also
https://www.imperialviolet.org/2016/06/26/nonnull.html

Add OPENSSL_memcpy, etc., wrappers which avoid this problem.

BUG=23

Change-Id: I95f42b23e92945af0e681264fffaf578e7f8465e
Reviewed-on: https://boringssl-review.googlesource.com/12928
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>

Android uses MinGW for some host tools on Windows. That toolchain
doesn't support the #pragma tricks we use for thread-local destructors,
but does appear to support pthreads.

This also lets us remove the INIT_ONCE workaround, although that's
removable anyway since Android's MinGW is now new enough.

Change-Id: I8d1573923fdaac880a50d84acbebbf87461c50d2
Reviewed-on: https://boringssl-review.googlesource.com/11125
Reviewed-by: David Benjamin <davidben@google.com>
Reviewed-by: Kenny Root <kroot@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

There's a __pragma expression which allows this. Android builds us Windows with
MinGW for some reason, so we actually do have to tolerate non-MSVC-compatible
Windows compilers. (Clang for Windows is much more sensible than MinGW and
intentionally mimicks MSVC.)

MinGW doesn't understand MSVC's pragmas and warns a lot. #pragma warning is
safe to suppress, so wrap those to shush them. This also lets us do away with a
few ifdefs.

Change-Id: I1f5a8bec4940d4b2d947c4c1cc9341bc15ec4972
Reviewed-on: https://boringssl-review.googlesource.com/8236
Reviewed-by: Adam Langley <agl@google.com>

Now that we no longer support Windows XP, this is available.
Unfortunately, the public header version of CRYPTO_MUTEX means we
still can't easily merge CRYPTO_MUTEX and CRYPTO_STATIC_MUTEX.

BUG=37

Change-Id: If309de3f06e0854c505083b72fd64d1dbb3f4563
Reviewed-on: https://boringssl-review.googlesource.com/8081
Reviewed-by: Adam Langley <agl@google.com>

Windows SRWLOCK requires you call different functions here. Split
them up in preparation for switching Windows from CRITICAL_SECTION.

BUG=37

Change-Id: I7b5c6a98eab9ae5bb0734b805cfa1ff334918f35
Reviewed-on: https://boringssl-review.googlesource.com/8080
Reviewed-by: Adam Langley <agl@google.com>

Now that we no longer support Windows XP, this function is available. In doing
so, remove the odd run_once_arg_t union and pass in a pointer to a function
pointer which is cleaner and still avoids C's silly rule where function
pointers can't be placed in a void*.

BUG=37

Change-Id: I44888bb3779dacdb660706debd33888ca389ebd5
Reviewed-on: https://boringssl-review.googlesource.com/7613
Reviewed-by: David Benjamin <davidben@google.com>

In VS2015's debug runtime, the C runtime has been unloaded by the time
DLL_PROCESS_DETACH is called and things crash. Instead, don't run destructors
at that point.

This means we do *not* free memory associated with any remaining thread-locals
on application shutdown, only shutdown of individual threads. This is actually
desirable since it's consistent with pthreads. If an individual thread calls
pthread_exit, destructors are run. If the entire process exits, they are not.

(It's also consistent with thread_none.c which never bothers to free
anything.)

BUG=chromium:595795

Change-Id: I3e64d46ea03158fefff583c1e3e12dfa0c0e172d
Reviewed-on: https://boringssl-review.googlesource.com/7601
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

The uses of |memcpy| to cast pointer-to-function to pointer-to-data and
back again did not have well-defined semantics. Use a union instead to
avoid the need for such a conversion get well-defined semantics.

Change-Id: I8ee54a83ba75440f7bc78c194eb55e2cf09b05d8
Reviewed-on: https://boringssl-review.googlesource.com/6972
Reviewed-by: David Benjamin <davidben@google.com>

Casting a pointer-to-non-volatile to pointer-to-volatile can be a no-op
as the compiler only requires volatile semantics when the pointed-to
object is a volatile object and there are no pointers-to-non-volatile
involved. This probably doesn't matter unless building with the MSVC
-volatile:iso flag, and maybe not even then, but it is good practice
anyway.

Change-Id: I94900d3dc61de3b8ce2ddecab2811907a9a7adbf
Reviewed-on: https://boringssl-review.googlesource.com/6973
Reviewed-by: David Benjamin <davidben@google.com>

Trusty doesn't have setjmp.h and nor does it have threads.

Change-Id: I005f7a009a13e6632513be9fab2bbe62294519a4
Reviewed-on: https://boringssl-review.googlesource.com/4660
Reviewed-by: Adam Langley <agl@google.com>

This is used with a platform API, so it should use the corresponding
platform type, saving us the size assert. It's ever defined in an
internal header, so we can freely use windows.h and friends.

Change-Id: Idc979309436adcf54524c835ddc2c98c3870d2e2
Reviewed-on: https://boringssl-review.googlesource.com/4680
Reviewed-by: Adam Langley <agl@google.com>

Prior to this, BoringSSL was using OpenSSL's technique of having users
register a callback for locking operation. This change adds native mutex
support.

Since mutexes often need to be in objects that are exposed via public
headers, the non-static mutexes are defined in thread.h. However, on
Windows we don't want to #include windows.h for CRITICAL_SECTION and, on
Linux, pthread.h doesn't define pthread_rwlock_t unless the feature
flags are set correctly—something that we can't control in general
for public header files. Thus, on both platforms, the mutex is defined
as a uint8_t[] of equal or greater size and we depend on static asserts
to ensure that everything works out ok.

Change-Id: Iafec17ae7e3422325e587878a5384107ec6647ab
Reviewed-on: https://boringssl-review.googlesource.com/4321
Reviewed-by: Adam Langley <agl@google.com>

This fixes the Windows build. Otherwise this collides with the symbol in
Chromium's //base. (The 'base' suffix is the name of the library, not some
Windows-ism.)

Change-Id: I65d755f08991978bd2040d53c401082b2fee65fa
Reviewed-on: https://boringssl-review.googlesource.com/4217
Reviewed-by: Adam Langley <agl@google.com>

Historically, OpenSSL has used callbacks for anything thread related,
but we don't actually have that many threading libraries to worry about:
just pthreads and Windows (I hope).

That suggests that it's quite reasonable to handle threading ourselves,
and eliminate the need for users to remember to install the thread
callbacks.

The first user of this would be ERR, which currently simulates
thread-local storage using a lock around a hash table keyed by the TID.
(Although I suspect that change will need some CMake work in order that
libpthread is automatically included with libcrypto when linking tests
etc, but not on Windows and without lots of ifs.)

Change-Id: I4dd088e3794506747f875c1f3e92b9bc6700fad2
Reviewed-on: https://boringssl-review.googlesource.com/4010
Reviewed-by: Adam Langley <agl@google.com>