Make exceptions easier to translate to error codes

Avoid throwing base Botan::Exception type, as it is difficult to
determine what the error is in that case.

Add Exception::error_code and Exception::error_type which allows
(for error code) more information about the error and (for error type)
allows knowing the error type without requiring a sequence of catches.

See GH #1742

9 files changed, 28 insertions, 29 deletions

diff --git a/src/tests/main.cpp b/src/tests/main.cpp
index 6777f85f4..180daf1d4 100644
--- a/src/tests/main.cpp
+++ b/src/tests/main.cpp
@@ -102,7 +102,7 @@ int main(int argc, char* argv[])
 #if defined(BOTAN_HAS_OPENSSL)
       if(opts.provider().empty() || opts.provider() == "openssl")
          {
-         ::ERR_free_strings();
+         ERR_free_strings();
          ::ERR_remove_thread_state(nullptr);
          }
 #endif
diff --git a/src/tests/test_ffi.cpp b/src/tests/test_ffi.cpp
index aca2dbfb9..50c85eff6 100644
--- a/src/tests/test_ffi.cpp
+++ b/src/tests/test_ffi.cpp
@@ -214,12 +214,12 @@ class FFI_Unit_Tests final : public Test
             TEST_FFI_OK(botan_rng_get, (rng, outbuf.data(), outbuf.size()));
             TEST_FFI_OK(botan_rng_reseed, (rng, 256));
 
-            TEST_FFI_RC(-20, botan_rng_reseed_from_rng, (rng, null_rng, 256));
+            TEST_FFI_RC(BOTAN_FFI_ERROR_INVALID_OBJECT_STATE, botan_rng_reseed_from_rng, (rng, null_rng, 256));
             if(rdrand_rng)
                {
                TEST_FFI_OK(botan_rng_reseed_from_rng, (rng, rdrand_rng, 256));
                }
-            TEST_FFI_RC(-20, botan_rng_get, (null_rng, outbuf.data(), outbuf.size()));
+            TEST_FFI_RC(BOTAN_FFI_ERROR_INVALID_OBJECT_STATE, botan_rng_get, (null_rng, outbuf.data(), outbuf.size()));
 
             TEST_FFI_OK(botan_rng_destroy, (rng));
             }
diff --git a/src/tests/test_pkcs11_low_level.cpp b/src/tests/test_pkcs11_low_level.cpp
index ffe9dfc20..6dbd6ac0c 100644
--- a/src/tests/test_pkcs11_low_level.cpp
+++ b/src/tests/test_pkcs11_low_level.cpp
@@ -74,7 +74,7 @@ class RAII_LowLevel
 
          if(slots.empty())
             {
-            throw Exception("No slot with attached token found");
+            throw Test_Error("No slot with attached token found");
             }
 
          return slots;
@@ -100,7 +100,7 @@ class RAII_LowLevel
          {
          if(!m_is_session_open)
             {
-            throw Exception("no open session");
+            throw Test_Error("no open session");
             }
          return m_session_handle;
          }
@@ -109,7 +109,7 @@ class RAII_LowLevel
          {
          if(!m_is_session_open)
             {
-            throw Exception("no open session");
+            throw Test_Error("no open session");
             }
 
          m_low_level.get()->C_CloseSession(m_session_handle);
@@ -120,12 +120,12 @@ class RAII_LowLevel
          {
          if(!m_is_session_open)
             {
-            throw Exception("no open session");
+            throw Test_Error("no open session");
             }
 
          if(m_is_logged_in)
             {
-            throw Exception("Already logged in");
+            throw Test_Error("Already logged in");
             }
 
          m_low_level.get()->C_Login(m_session_handle, user_type, pin);
@@ -136,7 +136,7 @@ class RAII_LowLevel
          {
          if(!m_is_logged_in)
             {
-            throw Exception("Not logged in");
+            throw Test_Error("Not logged in");
             }
 
          m_low_level.get()->C_Logout(m_session_handle);
diff --git a/src/tests/test_rng.cpp b/src/tests/test_rng.cpp
index 0b316335e..a7510b650 100644
--- a/src/tests/test_rng.cpp
+++ b/src/tests/test_rng.cpp
@@ -150,7 +150,7 @@ class Stateful_RNG_Tests : public Test
 
                size_t poll(Botan::RandomNumberGenerator&) override
                   {
-                  throw Botan::Exception("polling not available");
+                  throw Botan::Not_Implemented("polling not available");
                   }
             };
 
diff --git a/src/tests/test_rng.h b/src/tests/test_rng.h
index 822536971..01fe89c92 100644
--- a/src/tests/test_rng.h
+++ b/src/tests/test_rng.h
@@ -122,7 +122,7 @@ class Fixed_Output_Position_RNG final : public Fixed_Output_RNG
 
       void add_entropy(const uint8_t*, size_t) override
          {
-         throw Botan::Exception("add_entropy() not supported by this RNG, test bug?");
+         throw Test_Error("add_entropy() not supported by this RNG, test bug?");
          }
 
       std::string name() const override
@@ -148,7 +148,7 @@ class SeedCapturing_RNG final : public Botan::RandomNumberGenerator
    public:
       void randomize(uint8_t[], size_t) override
          {
-         throw Botan::Exception("SeedCapturing_RNG has no output");
+         throw Test_Error("SeedCapturing_RNG has no output");
          }
 
       bool accepts_input() const override { return true; }
diff --git a/src/tests/test_tests.cpp b/src/tests/test_tests.cpp
index 49a05d6ab..a7324eef8 100644
--- a/src/tests/test_tests.cpp
+++ b/src/tests/test_tests.cpp
@@ -143,7 +143,7 @@ class Test_Tests final : public Test
             {
             Test::Result test_result(testcase_name);
             test_result.test_throws("test_throws", "expected msg",
-                                    []() { throw Botan::Exception("not the message"); });
+                                    []() { throw std::runtime_error("not the message"); });
             verify_failure("test_throws", result, test_result);
             }
 
diff --git a/src/tests/test_tss.cpp b/src/tests/test_tss.cpp
index 714f08df6..139e2087d 100644
--- a/src/tests/test_tss.cpp
+++ b/src/tests/test_tss.cpp
@@ -40,8 +40,8 @@ class TSS_Recovery_Tests final : public Text_Based_Test
                shares.push_back(Botan::RTSS_Share(v.data(), v.size()));
                }
 
-            auto reconstructed_secret = Botan::RTSS_Share::reconstruct(shares);
-            result.test_eq("Reconstructed secret correctly from all shares", reconstructed_secret, input);
+            auto reconstructed_secret_all = Botan::RTSS_Share::reconstruct(shares);
+            result.test_eq("Reconstructed secret correctly from all shares", reconstructed_secret_all, input);
 
             if(header == "Invalid")
                result.test_failure("Invalid shares should not result in recovery");
@@ -127,8 +127,8 @@ class TSS_Generation_Tests final : public Text_Based_Test
             result.test_eq("Expected share", shares[i].data(), expected_shares[i]);
             }
 
-         auto reconstructed_secret = Botan::RTSS_Share::reconstruct(shares);
-         result.test_eq("Reconstructed secret correctly from all shares", reconstructed_secret, input);
+         auto reconstructed_secret_all = Botan::RTSS_Share::reconstruct(shares);
+         result.test_eq("Reconstructed secret correctly from all shares", reconstructed_secret_all, input);
 
          if(N != M)
             {
diff --git a/src/tests/test_x509_path.cpp b/src/tests/test_x509_path.cpp
index 57f2d8602..e86c7b70f 100644
--- a/src/tests/test_x509_path.cpp
+++ b/src/tests/test_x509_path.cpp
@@ -634,19 +634,17 @@ std::vector<Test::Result> BSI_Path_Validation_Tests::run()
       /* Some certificates are rejected when executing the X509_Certificate constructor
        * by throwing a Decoding_Error exception.
        */
-      catch(const Botan::Decoding_Error& d)
+      catch(const Botan::Exception& e)
          {
-         result.test_eq(test_name + " path validation result", d.what(),
-                        expected_result);
-         }
-      catch(const Botan::X509_CRL::X509_CRL_Error& e)
-         {
-         result.test_eq(test_name + " path validation result", e.what(),
-                        expected_result);
-         }
-      catch(const std::exception& e)
-         {
-         result.test_failure(test_name, e.what());
+         if(e.error_type() == Botan::ErrorType::DecodingFailure)
+            {
+            result.test_eq(test_name + " path validation result", e.what(),
+                           expected_result);
+            }
+         else
+            {
+            result.test_failure(test_name, e.what());
+            }
          }
 
       result.end_timer();
diff --git a/src/tests/tests.h b/src/tests/tests.h
index 7a0e4e54e..d21acf6f9 100644
--- a/src/tests/tests.h
+++ b/src/tests/tests.h
@@ -45,6 +45,7 @@ class Test_Error final : public Botan::Exception
    {
    public:
       explicit Test_Error(const std::string& what) : Exception("Test error", what) {}
+      Botan::ErrorType error_type() const noexcept override { return Botan::ErrorType::Unknown; }
    };
 
 class Test_Options