One of the aspects of CloudABI is that it aims to help you write code
that is thread-safe out of the box. This is very important if you want
to write libraries that are easy to reuse. For CloudABI we decided to
not provide the thread-unsafe functions. So far this is working out
pretty well, as thread-unsafety issues are detected really early on.
The following patch adds a knob to libc++,
_LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS, that can be set to disable
thread-unsafe functions that can easily be avoided in practice. The
following functions are not thread-safe:
- <clocale>: locale handles should be preferred over setlocale().
- <cstdlib>: mbrlen(), mbrtowc() and wcrtomb() should be preferred over
their non-restartable counterparts.
- <ctime>: asctime(), ctime(), gmtime() and localtime() are not
thread-safe. The first two are also deprecated by POSIX.
Differential Revision: http://reviews.llvm.org/D8703
Reviewed by: marshall
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@240527 91177308-0d34-0410-b5e6-96231b3b80d8
The idea behind Nuxi CloudABI is that it is targeted at (but not limited to)
running networked services in a sandboxed environment. The model behind stdin,
stdout and stderr is strongly focused on interactive tools in a command shell.
CloudABI does not support the notion of stdin and stdout, as 'standard
input/output' does not apply to services. The concept of stderr does makes
sense though, as services do need some mechanism to log error messages in a
uniform way.
This patch extends libc++ in such a way that std::cin and std::cout and the
associated <cstdio>/<cwchar> functions can be disabled through the flags
_LIBCPP_HAS_NO_STDIN and _LIBCPP_HAS_NO_STDOUT, respectively. At the same time
it attempts to clean up src/iostream.cpp a bit. Instead of using a single array
of mbstate_t objects and hardcoding the array indices, it creates separate
objects that declared next to the iostream objects and their buffers. The code
is also restructured by interleaving the construction and setup of c* and wc*
objects. That way it is more obvious that this is done identically.
The c* and wc* objects already have separate unit tests. Make use of this fact
by adding XFAILs in case libcpp-has-no-std* is set. That way the tests work in
both directions. If stdin or stdout is disabled, these tests will therefore
test for the absence of c* and wc*.
Differential Revision: http://reviews.llvm.org/D8340
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@233275 91177308-0d34-0410-b5e6-96231b3b80d8
