No code within BoringSSL or Google (grep for EVP_PKEY_CTX_(ctrl|get|set)) is
sensitive to the various failure cases. Normalize it all to 0/1 for simplicity.
This does carry a slight risk: any new ctrl hooks we import from upstream that,
like EVP_PKEY_CTX_get_rsa_oaep_md, return something other than success/failure
cannot be called directly via EVP_PKEY_CTX_ctrl. They instead need to
internally be routed through a struct like CBS and only called through the
wrappers. To that end, unexport EVP_PKEY_CTX_ctrl and require that callers use
the wrappers. No code in Google uses it directly and, if need be, switching to
the wrapper would be an incredibly upstreamable patch.
Change-Id: I3fd4e5a1a0f3d4d1c4122c52d4c74a5105b99cd5
Reviewed-on: https://boringssl-review.googlesource.com/3874
Reviewed-by: Adam Langley <agl@google.com>
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