user friendly error handling of zooko names

Fixed it while dead drunk
could not walk in a straight line
had difficulty typing
coded rather slowly, but still wrote
smart code.

Realized that the error handling
has to have exception structures in
scope, but not the constructors in
scope

You can forward the constructors,
but if you forward the structs,
exceptions will crash.  Your exception
constructor inputs can use structs that
are out of scope at the exception handler

src/ILog.h

@@ -10,17 +10,25 @@ void ILogDebug(const char*);
 void queue_error_message(const char*);  //Used for error conditions within a destructor because you cannot throw within a destructor
 void queue_fatal_error(const char*);	//Used for fatal error conditions within a destructor in place of FatalException because you cannot throw within a destructor
 
+struct sqlite3;
+
 class MyException: public std::exception {
 private:
 	std::string err;
+	int err_number;
 public:
 	virtual ~MyException() override = default;
 	MyException() = delete;
-	explicit MyException(const std::string &m) noexcept :err(m){}
-	explicit MyException(const char* sz) noexcept :err(sz) {}
+	explicit MyException(const std::string &m) noexcept :err(m.c_str()),err_number(-1){}
+	explicit MyException(const char* sz) noexcept :err(sz),err_number(-1) {}
+	explicit MyException(const char* sz, int i) noexcept :err(sz), err_number(i) {}
+	explicit MyException(int, sqlite3*) noexcept;
 	virtual const char* what() const override {
 		return err.c_str();
 	}
+	virtual const int what_num() const {
+		return err_number;
+	}
 };
 
 class FatalException : public MyException {
@@ -35,12 +43,6 @@ public:
 	HashReuseException() noexcept;
 };
 
-class SQLexception : public MyException {
-public:
-	using MyException::MyException;
-	SQLexception() noexcept;
-};
-
 class NonUtf8DataInDatabase : public MyException {
 public:
 	using MyException::MyException;

src/ISqlit3Impl.cpp

@@ -52,7 +52,7 @@ public:
 		pdb = nullptr;
 #endif
 		int rc =sqlite3_open_v2(dbName, &pdb, flags, nullptr);
-		if (rc != SQLITE_OK) throw SQLexception(error_message(rc, pdb));
+		if (rc != SQLITE_OK) throw MyException(rc, pdb);
 		assert(pdb != nullptr);
 		//	pdb can never be nullptr, since the sqlite3_open_v2 command always initializes
 		//	it even if open fails
@@ -62,7 +62,7 @@ public:
 		char* zErrMsg = nullptr;
 		int rc = sqlite3_exec(pdb, szsql, callback, nullptr, &zErrMsg);
 		if (rc != SQLITE_OK) {
-			SQLexception e(std::string("SQL Exec Error: ") + zErrMsg);
+			auto e = MyException(zErrMsg, rc);
 			sqlite3_free(zErrMsg);
 			throw e;
 		}
@@ -90,6 +90,11 @@ ISqlite3* Sqlite3_open(const char * db_name) {
 	return new ISqlite3Impl(db_name, SQLITE_OPEN_READWRITE);
 }
 
+MyException::MyException(int i, sqlite3* pdb) noexcept:
+	err_number(i),
+	err(error_message(i, pdb))
+{}
+
 //	Factory method to create database.
 ISqlite3 * Sqlite3_create(const char* db_name) {
 	return new ISqlite3Impl(db_name, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE);
@@ -104,7 +109,7 @@ private:
 	ISqlite3Impl*pdbImplOwn;
 	auto e(int rc) {
 		assert(rc != SQLITE_OK);
-		return SQLexception(error_message(rc, pdbImplOwn->pdb));
+		return MyException(rc, pdbImplOwn->pdb);
 	}
 public:
 	IcompiledImpl_sql() = delete;
@@ -192,7 +197,7 @@ public:
 			//	from n blocks to n+1 blocks when a single transaction updates the root and anciliary data.
 			//	We will build the blockchain hash table in postfix format, with patricia tree nodes that
 			//	have skiplink format stored only in memory and rebuilt each startup so that it grows append only,
-			throw SQLexception("Abnormal busy database");
+			throw MyException("Abnormal busy database", 2^14+2);
 			break;
 		case SQLITE_MISUSE:
 			//ret = MISUSE;

src/db_accessors.h

@@ -114,8 +114,9 @@ namespace ro {
 		result step() {
 			return (*this)->Isqlite3_step();
 		}
+
 		void final_step() {
-			if (step() != result::DONE) throw SQLexception("SQL: Unexpected rows remaining");
+			if (step() != result::DONE) throw MyException("SQL: Unexpected rows remaining", 16384);
 		}
 		void reset() {
 			(*this)->Isqlite3_reset();
@@ -199,6 +200,15 @@ public:
 			csql_into_names.do_one(psz);
 			csql_namekey_into_keys.do_one(pt);
 		}
+		catch (const MyException& e) {
+			csql_rollback.do_one();
+			if (e.what_num() == 19) {
+				throw MyException("Name already in database");
+			}
+			else {
+				throw;
+			}
+		}
 		catch (const std::exception &) {
 			csql_rollback.do_one();
 			throw;

src/localization.cpp

@@ -129,8 +129,6 @@ FatalException::FatalException()		noexcept :
 	MyException(R"|(unspecified fatal exception)|") {};
 HashReuseException::HashReuseException()		noexcept :
 	MyException(R"|(finalized the same hash constructor twice or more)|")	{};
-SQLexception::SQLexception()			noexcept :
-	MyException(R"|(SQL Exception)|")				{};
 BadDataException::BadDataException()	noexcept :
 	MyException(R"|(Bad data exception)|")			{};
 NonUtf8DataInDatabase::NonUtf8DataInDatabase() noexcept :