This is done to account for platforms, for which we want custom behavior
upon the program termination, hence we call `mbedtls_exit()` instead of
returning from `main()`.
For the sake of consistency, introduces the modifications have been made
to the test and utility examples as well. These, while less likely to be
used in the low level environments, won't suffer from such a change.
Instead of polling the hardware entropy source a single time and
comparing the output with itself, the source is polled at least twice
and make sure that the separate outputs are different.
The self test is a quick way to check at startup whether the entropy
sources are functioning correctly. The self test only polls 8 bytes
from the default entropy source and performs the following checks:
- The bytes are not all 0x00 or 0xFF.
- The hardware does not return an error when polled.
- The entropy does not provide data in a patter. Only check pattern
at byte, word and long word sizes.
Now counts and displays the number of test suites executed, which can vary
depending on build configurations.
All tests are now executed as this is a sample and test program, rather than
exit on first failure.
Exit code now restricted to SUCCESS or FAILURE.
Our Windows implementation based on vsnprintf_s( ..., _TRUNCATE ) sometimes
writes *two* terminating NULLs. Allow for that, but obviously bytes past the
end of the buffer mustn't be touched.
- Added in each tests program to be sure they are run (putting them in a test
suite/function specific to the platform layer would cause them to be skipped
when PLATFORM_C is not defined).
- Platforms have already moved from a standard to a broken snprintf in the
past [1], so make sure to catch that if it ever happens again.
[1]: http://sourceforge.net/p/mingw-w64/mailman/message/31241434/
Things that are not guaranteed by the standard but should be true of all
platforms of interest to us:
- 8-bit chars
- NULL pointers represented by all-bits-zero
