[PATCH 3/3] OvmfPkg/EnrollDefaultKeys: clean up Base64Decode() retval handling

["Laszlo Ersek" <lersek@redhat.com>]

Base64Decode() now guarantees that DestinationSize is larger on output
than it was on input if RETURN_BUFFER_TOO_SMALL is returned. Clean up the
retval handling for the first Base64Decode() call in EnrollDefaultKeys,
which used to work around the ambiguity in the previous Base64Decode()
interface contract.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1891
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c b/OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c
index f45cb799f726..302b80d97720 100644
--- a/OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c
+++ b/OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c
@@ -154,14 +154,8 @@ GetPkKek1 (
   Status = Base64Decode (Base64Cert, Base64CertLen, NULL, &DecodedCertSize);
   switch (Status) {
   case EFI_BUFFER_TOO_SMALL:
-    if (DecodedCertSize > 0) {
-      break;
-    }
-    //
-    // Fall through: the above Base64Decode() call is ill-specified in BaseLib
-    // if Source decodes to zero bytes (for example if it consists of ignored
-    // whitespace only).
-    //
+    ASSERT (DecodedCertSize > 0);
+    break;
   case EFI_SUCCESS:
     AsciiPrint ("error: empty certificate after app prefix %g\n",
       &gOvmfPkKek1AppPrefixGuid);
-- 
2.19.1.3.g30247aa5d201