libc/CAVEATS - android_bionic - Gitiles

 Bionic is a very small C library because we have decided to *not* implement various features
 of the POSIX standard. we only add functions on a as-needed basis, and there are a few things
 we wish we'll never put in there.

 this file is here to document explicitely what we don't want to support in Bionic:

 - C++ exceptions are not supported. on embedded systems, they lead to extremely larger and
   slower code for no good reason (even when so-called zero-cost exception schemes are
   implemented, they enforce very large numbers of registers spills to the stack, even
   in functions that do not throw an exception themselves).

 - pthread cancellation is *not* supported. this seemingly simple "feature" is the source
   of much bloat and complexity in a C library. Besides, you'd better write correct
   multi-threaded code instead of relying on this stuff.

 - pthread_once() doesn't support C++ exceptions thrown from the init function, or the init
   function doing a fork().

 - locales and wide characters are not supported. we use ICU for all this i18n stuff, which
   is much better than the ill-designed related C libraries functions.

 - at the moment, several user-account-related functions like getpwd are stubbed and return
   the values corresponding to root. this will be fixed when we'll be able to have distinct
   users on the Android filesystem. :-(

   see bionic/stubs.c for the details
	Bionic is a very small C library because we have decided to not implement various features
	of the POSIX standard. we only add functions on a as-needed basis, and there are a few things
	we wish we'll never put in there.

	this file is here to document explicitely what we don't want to support in Bionic:

	- C++ exceptions are not supported. on embedded systems, they lead to extremely larger and
	slower code for no good reason (even when so-called zero-cost exception schemes are
	implemented, they enforce very large numbers of registers spills to the stack, even
	in functions that do not throw an exception themselves).

	- pthread cancellation is not supported. this seemingly simple "feature" is the source
	of much bloat and complexity in a C library. Besides, you'd better write correct
	multi-threaded code instead of relying on this stuff.

	- pthread_once() doesn't support C++ exceptions thrown from the init function, or the init
	function doing a fork().

	- locales and wide characters are not supported. we use ICU for all this i18n stuff, which
	is much better than the ill-designed related C libraries functions.

	- at the moment, several user-account-related functions like getpwd are stubbed and return
	the values corresponding to root. this will be fixed when we'll be able to have distinct
	users on the Android filesystem. :-(

	see bionic/stubs.c for the details