Reroot the exception hierarchy into a toplevel Exception class

As the alternatives are unfortunate for applications trying to catch
all library errors, and it seems deriving from std::runtime_error
causes problems with MSVC DLLs (GH #340)

Effectively reverts 2837e915d82e43

8 files changed, 44 insertions, 33 deletions

diff --git a/src/lib/utils/assert.cpp b/src/lib/utils/assert.cpp
index 978fc12a1..d729a8368 100644
--- a/src/lib/utils/assert.cpp
+++ b/src/lib/utils/assert.cpp
@@ -30,7 +30,7 @@ void assertion_failure(const char* expr_str,
 
    format << "@" << file << ":" << line;
 
-   throw std::runtime_error(format.str());
+   throw Exception(format.str());
    }
 
 }
diff --git a/src/lib/utils/dyn_load/dyn_load.cpp b/src/lib/utils/dyn_load/dyn_load.cpp
index 723d2502e..9b99331d1 100644
--- a/src/lib/utils/dyn_load/dyn_load.cpp
+++ b/src/lib/utils/dyn_load/dyn_load.cpp
@@ -22,7 +22,7 @@ namespace {
 void raise_runtime_loader_exception(const std::string& lib_name,
                                     const char* msg)
    {
-   throw std::runtime_error("Failed to load " + lib_name + ": " +
+   throw Exception("Failed to load " + lib_name + ": " +
                             (msg ? msg : "Unknown error"));
    }
 
@@ -70,7 +70,7 @@ void* Dynamically_Loaded_Library::resolve_symbol(const std::string& symbol)
 #endif
 
    if(!addr)
-      throw std::runtime_error("Failed to resolve symbol " + symbol +
+      throw Exception("Failed to resolve symbol " + symbol +
                                " in " + lib_name);
 
    return addr;
diff --git a/src/lib/utils/exceptn.h b/src/lib/utils/exceptn.h
index eef1b4d43..c9b45f916 100644
--- a/src/lib/utils/exceptn.h
+++ b/src/lib/utils/exceptn.h
@@ -16,8 +16,28 @@
 
 namespace Botan {
 
-typedef std::runtime_error Exception;
-typedef std::invalid_argument Invalid_Argument;
+/**
+* Base class for all exceptions thrown by the library
+*/
+class BOTAN_DLL Exception : public std::exception
+   {
+   public:
+      Exception(const std::string& what) : m_what(what) {}
+      Exception(const char* prefix, const std::string& what) : m_what(std::string(prefix) + " " + what) {}
+      const char* what() const override { return m_what.c_str(); }
+   private:
+      std::string m_what;
+   };
+
+/**
+* An invalid argument which caused
+*/
+class BOTAN_DLL Invalid_Argument : public Exception
+   {
+   public:
+      Invalid_Argument(const std::string& what) :
+         Exception("Invalid argument",  what) {}
+   };
 
 /**
 * Unsupported_Argument Exception
@@ -196,15 +216,6 @@ struct BOTAN_DLL Self_Test_Failure : public Internal_Error
       {}
    };
 
-/**
-* Memory Allocation Exception
-*/
-struct BOTAN_DLL Memory_Exhaustion : public std::bad_alloc
-   {
-   const char* what() const BOTAN_NOEXCEPT override
-      { return "Ran out of memory, allocation failed"; }
-   };
-
 }
 
 #endif
diff --git a/src/lib/utils/http_util/http_util.cpp b/src/lib/utils/http_util/http_util.cpp
index 1a15d6418..c437d0148 100644
--- a/src/lib/utils/http_util/http_util.cpp
+++ b/src/lib/utils/http_util/http_util.cpp
@@ -30,7 +30,7 @@ std::string http_transact_asio(const std::string& hostname,
    tcp.connect(hostname, "http");
 
    if(!tcp)
-      throw std::runtime_error("HTTP connection to " + hostname + " failed");
+      throw Exception("HTTP connection to " + hostname + " failed");
 
    tcp << message;
    tcp.flush();
@@ -45,7 +45,7 @@ std::string http_transact_asio(const std::string& hostname,
 std::string http_transact_fail(const std::string& hostname,
                                const std::string&)
    {
-   throw std::runtime_error("Cannot connect to " + hostname +
+   throw Exception("Cannot connect to " + hostname +
                             ": network code disabled in build");
    }
 
@@ -89,7 +89,7 @@ Response http_sync(http_exch_fn http_transact,
    {
    const auto protocol_host_sep = url.find("://");
    if(protocol_host_sep == std::string::npos)
-      throw std::runtime_error("Invalid URL " + url);
+      throw Exception("Invalid URL " + url);
    const std::string protocol = url.substr(0, protocol_host_sep);
 
    const auto host_loc_sep = url.find('/', protocol_host_sep + 3);
@@ -130,7 +130,7 @@ Response http_sync(http_exch_fn http_transact,
    std::string line1;
    std::getline(io, line1);
    if(!io || line1.empty())
-      throw std::runtime_error("No response");
+      throw Exception("No response");
 
    std::stringstream response_stream(line1);
    std::string http_version;
@@ -142,7 +142,7 @@ Response http_sync(http_exch_fn http_transact,
    std::getline(response_stream, status_message);
 
    if(!response_stream || http_version.substr(0,5) != "HTTP/")
-      throw std::runtime_error("Not an HTTP response");
+      throw Exception("Not an HTTP response");
 
    std::map<std::string, std::string> headers;
    std::string header_line;
@@ -150,7 +150,7 @@ Response http_sync(http_exch_fn http_transact,
       {
       auto sep = header_line.find(": ");
       if(sep == std::string::npos || sep > header_line.size() - 2)
-         throw std::runtime_error("Invalid HTTP header " + header_line);
+         throw Exception("Invalid HTTP header " + header_line);
       const std::string key = header_line.substr(0, sep);
 
       if(sep + 2 < header_line.size() - 1)
@@ -163,7 +163,7 @@ Response http_sync(http_exch_fn http_transact,
    if(status_code == 301 && headers.count("Location"))
       {
       if(allowable_redirects == 0)
-         throw std::runtime_error("HTTP redirection count exceeded");
+         throw Exception("HTTP redirection count exceeded");
       return GET_sync(headers["Location"], allowable_redirects - 1);
       }
 
@@ -180,7 +180,7 @@ Response http_sync(http_exch_fn http_transact,
    if(header_size != "")
       {
       if(resp_body.size() != to_u32bit(header_size))
-         throw std::runtime_error("Content-Length disagreement, header says " +
+         throw Exception("Content-Length disagreement, header says " +
                                   header_size + " got " + std::to_string(resp_body.size()));
       }
 
diff --git a/src/lib/utils/http_util/http_util.h b/src/lib/utils/http_util/http_util.h
index 2acb6c6e4..746b790f1 100644
--- a/src/lib/utils/http_util/http_util.h
+++ b/src/lib/utils/http_util/http_util.h
@@ -43,7 +43,7 @@ struct Response
       void throw_unless_ok()
          {
          if(status_code() != 200)
-            throw std::runtime_error("HTTP error: " + status_message());
+            throw Exception("HTTP error: " + status_message());
          }
 
    private:
diff --git a/src/lib/utils/parsing.cpp b/src/lib/utils/parsing.cpp
index 40eae656a..179e2e546 100644
--- a/src/lib/utils/parsing.cpp
+++ b/src/lib/utils/parsing.cpp
@@ -45,7 +45,7 @@ u32bit to_u32bit(const std::string& str)
       auto message = std::string("Could not read '" + str + "' as decimal string");
       auto exceptionMessage = std::string(e.what());
       if (!exceptionMessage.empty()) message += ": " + exceptionMessage;
-      throw std::runtime_error(message);
+      throw Exception(message);
       }
    }
 
diff --git a/src/lib/utils/read_cfg.cpp b/src/lib/utils/read_cfg.cpp
index 22e725328..0719ee681 100644
--- a/src/lib/utils/read_cfg.cpp
+++ b/src/lib/utils/read_cfg.cpp
@@ -49,7 +49,7 @@ std::map<std::string, std::string> read_cfg(std::istream& is)
       auto eq = s.find("=");
 
       if(eq == std::string::npos || eq == 0 || eq == s.size() - 1)
-         throw std::runtime_error("Bad read_cfg input '" + s + "' on line " + std::to_string(line));
+         throw Exception("Bad read_cfg input '" + s + "' on line " + std::to_string(line));
 
       const std::string key = clean_ws(s.substr(0, eq));
       const std::string val = clean_ws(s.substr(eq + 1, std::string::npos));
diff --git a/src/lib/utils/sqlite3/sqlite3.cpp b/src/lib/utils/sqlite3/sqlite3.cpp
index 267d7530a..fde89b91d 100644
--- a/src/lib/utils/sqlite3/sqlite3.cpp
+++ b/src/lib/utils/sqlite3/sqlite3.cpp
@@ -20,7 +20,7 @@ Sqlite3_Database::Sqlite3_Database(const std::string& db_filename)
       const std::string err_msg = ::sqlite3_errmsg(m_db);
       ::sqlite3_close(m_db);
       m_db = nullptr;
-      throw std::runtime_error("sqlite3_open failed - " + err_msg);
+      throw Exception("sqlite3_open failed - " + err_msg);
       }
    }
 
@@ -43,7 +43,7 @@ size_t Sqlite3_Database::row_count(const std::string& table_name)
    if(stmt->step())
       return stmt->get_size_t(0);
    else
-      throw std::runtime_error("Querying size of table " + table_name + " failed");
+      throw Exception("Querying size of table " + table_name + " failed");
    }
 
 void Sqlite3_Database::create_table(const std::string& table_schema)
@@ -57,7 +57,7 @@ void Sqlite3_Database::create_table(const std::string& table_schema)
       ::sqlite3_free(errmsg);
       ::sqlite3_close(m_db);
       m_db = nullptr;
-      throw std::runtime_error("sqlite3_exec for table failed - " + err_msg);
+      throw Exception("sqlite3_exec for table failed - " + err_msg);
       }
    }
 
@@ -66,7 +66,7 @@ Sqlite3_Database::Sqlite3_Statement::Sqlite3_Statement(sqlite3* db, const std::s
    int rc = ::sqlite3_prepare_v2(db, base_sql.c_str(), -1, &m_stmt, nullptr);
 
    if(rc != SQLITE_OK)
-      throw std::runtime_error("sqlite3_prepare failed " + base_sql +
+      throw Exception("sqlite3_prepare failed " + base_sql +
                                ", code " + std::to_string(rc));
    }
 
@@ -74,16 +74,16 @@ void Sqlite3_Database::Sqlite3_Statement::bind(int column, const std::string& va
    {
    int rc = ::sqlite3_bind_text(m_stmt, column, val.c_str(), -1, SQLITE_TRANSIENT);
    if(rc != SQLITE_OK)
-      throw std::runtime_error("sqlite3_bind_text failed, code " + std::to_string(rc));
+      throw Exception("sqlite3_bind_text failed, code " + std::to_string(rc));
    }
 
 void Sqlite3_Database::Sqlite3_Statement::bind(int column, size_t val)
    {
    if(val != static_cast<size_t>(static_cast<int>(val))) // is this legit?
-      throw std::runtime_error("sqlite3 cannot store " + std::to_string(val) + " without truncation");
+      throw Exception("sqlite3 cannot store " + std::to_string(val) + " without truncation");
    int rc = ::sqlite3_bind_int(m_stmt, column, val);
    if(rc != SQLITE_OK)
-      throw std::runtime_error("sqlite3_bind_int failed, code " + std::to_string(rc));
+      throw Exception("sqlite3_bind_int failed, code " + std::to_string(rc));
    }
 
 void Sqlite3_Database::Sqlite3_Statement::bind(int column, std::chrono::system_clock::time_point time)
@@ -96,7 +96,7 @@ void Sqlite3_Database::Sqlite3_Statement::bind(int column, const std::vector<byt
    {
    int rc = ::sqlite3_bind_blob(m_stmt, column, val.data(), val.size(), SQLITE_TRANSIENT);
    if(rc != SQLITE_OK)
-      throw std::runtime_error("sqlite3_bind_text failed, code " + std::to_string(rc));
+      throw Exception("sqlite3_bind_text failed, code " + std::to_string(rc));
    }
 
 std::pair<const byte*, size_t> Sqlite3_Database::Sqlite3_Statement::get_blob(int column)