Notes:
* Make _libssh2_random return code consistent
Previously, _libssh2_random was advertized in HACKING.CRYPTO as
returning `void` (and was implemented that way in os400qc3.c), but that
was in other crypto backends a lie; _libssh2_random is (a macro
expanding) to an int-value expression or function.
Moreover, that returned code was:
— 0 or success, -1 on error for the MbedTLS & WinCNG crypto backends
But also:
— 1 on success, -1 or 0 on error for the OpenSSL backend!
– 1 on success, error cannot happen for libgcrypt!
This commit makes explicit that _libssh2_random can fail (because most of
the underlying crypto functions can indeed fail!), and it makes its result
code consistent: 0 on success, -1 on error.
This is related to issue #519https://github.com/libssh2/libssh2/issues/519
It fixes the first half of it.
* Don't silent errors of _libssh2_random
Make sure to check the returned code of _libssh2_random(), and
propagates any failure.
A new LIBSSH_ERROR_RANDGEN constant is added to libssh2.h
None of the existing error constants seemed fit.
This commit is related to d74285b68450c0e9ea6d5f8070450837fb1e74a7
and to https://github.com/libssh2/libssh2/issues/519 (see the issue
for more info.) It closes#519.
Credit:
Paul Capron
b3a8a6d27c