tree a575dd9634b47eb6447cbb704971d1c19f6da5b8
parent 1c91b0c43463c27c4930618ffc3700218be12687
author Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> 1654847318 +0200
committer Manuel Pégourié-Gonnard <mpg@elzevir.fr> 1655752349 +0200

Improve contract of mbedtls_pk_ec/rsa()

Trusting the caller to perform the appropriate check is both risky, and
a bit user-unfriendly. Returning NULL on error seems both safer
(dereferencing a NULL pointer is more likely to result in a clean crash,
while mis-casting a pointer might have deeper, less predictable
consequences) and friendlier (the caller can just check the return
value for NULL, which is a common idiom).

Only add that as an additional way of using the function, for the sake
of backwards compatibility. Calls where we know the type of the context
for sure (for example because we just set it up) were legal and safe, so
they should remain legal without checking the result for NULL, which
would be redundant.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>