Cipher_Mode API improvements

The Cipher_Mode::update API is more general than needed to just
support ciphers (this is due to it previously being an API of
Transform which before 8b85b780515 was Cipher_Mode's base class)

Define a less general interface `process` which either processes the
blocks in-place, producing exactly as much output as there was input,
or (SIV/CCM case) saves the entire message for processing in `finish`.
These two uses cover all current or anticipated cipher modes.

Leaves `update` for compatability with existing callers; all that is
needed is an inline function forwarding to `process`.

Removes the return type from `start` - in all cipher implementations,
this always returned an empty vector.

Adds BOTAN_ARG_CHECK macro; right now BOTAN_ASSERT is being used
for argument checking in some places, which is not right at all.

2 files changed, 21 insertions, 2 deletions

diff --git a/src/lib/utils/assert.h b/src/lib/utils/assert.h
index f80f9b170..c49ae62ee 100644
--- a/src/lib/utils/assert.h
+++ b/src/lib/utils/assert.h
@@ -35,6 +35,19 @@ BOTAN_NORETURN void BOTAN_DLL assertion_failure(const char* expr_str,
    } while(0)
 
 /**
+* Make an assertion
+*/
+#define BOTAN_ASSERT_NOMSG(expr)                          \
+   do {                                                   \
+      if(!(expr))                                         \
+         Botan::assertion_failure(#expr,                  \
+                                  "",                     \
+                                  BOTAN_CURRENT_FUNCTION, \
+                                  __FILE__,               \
+                                  __LINE__);              \
+   } while(0)
+
+/**
 * Assert that value1 == value2
 */
 #define BOTAN_ASSERT_EQUAL(expr1, expr2, assertion_made)   \
diff --git a/src/lib/utils/exceptn.h b/src/lib/utils/exceptn.h
index 193d78ce9..a3cb11f81 100644
--- a/src/lib/utils/exceptn.h
+++ b/src/lib/utils/exceptn.h
@@ -29,14 +29,20 @@ class BOTAN_DLL Exception : public std::exception
    };
 
 /**
-* An invalid argument which caused
+* An invalid argument
 */
 class BOTAN_DLL Invalid_Argument : public Exception
    {
    public:
       explicit Invalid_Argument(const std::string& msg) :
          Exception("Invalid argument", msg) {}
-   };
+
+      explicit Invalid_Argument(const std::string& msg, const std::string& where) :
+         Exception("Invalid argument", msg + " in " + where) {}
+};
+
+#define BOTAN_ARG_CHECK(expr) \
+   do { if(!(expr)) throw Invalid_Argument(#expr, BOTAN_CURRENT_FUNCTION); } while(0)
 
 /**
 * Unsupported_Argument Exception