Raise all SystemCallErrors as Trilogy::Error.

This allows syscall errors to be rescued generically by Trilogy::Error,
or handled individually by consumers using their oriinal Errno classes.

To make this work, we subclass all of the SystemCallErrors and include
the base error module on each of them.

I've also removed the constructors from the existing Errno class subclasses
(Trilogy::TimeoutError, Trilogy::ConnectionClosedError, etc.). We never
set an error_code on syscall errors, so the constructors are not needed.

CHANGELOG.md

@@ -13,6 +13,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 ### Fixed
   - Fix msec values for time columns. #61
 
+### Changed
+  - All SystemCallErrors classified as `Trilogy::Error`.
+
 ## 2.3.0
 
 ### Added

contrib/ruby/ext/trilogy-ruby/cext.c

@@ -20,14 +20,14 @@
 VALUE Trilogy_CastError;
 static VALUE Trilogy_BaseConnectionError, Trilogy_ProtocolError, Trilogy_SSLError, Trilogy_QueryError,
     Trilogy_ConnectionClosedError, Trilogy_ConnectionRefusedError, Trilogy_ConnectionResetError,
-    Trilogy_TimeoutError, Trilogy_Result;
+    Trilogy_TimeoutError, Trilogy_SyscallError, Trilogy_Result;
 
 static ID id_socket, id_host, id_port, id_username, id_password, id_found_rows, id_connect_timeout, id_read_timeout,
     id_write_timeout, id_keepalive_enabled, id_keepalive_idle, id_keepalive_interval, id_keepalive_count,
     id_ivar_affected_rows, id_ivar_fields, id_ivar_last_insert_id, id_ivar_rows, id_ivar_query_time, id_password,
     id_database, id_ssl_ca, id_ssl_capath, id_ssl_cert, id_ssl_cipher, id_ssl_crl, id_ssl_crlpath, id_ssl_key,
     id_ssl_mode, id_tls_ciphersuites, id_tls_min_version, id_tls_max_version, id_multi_statement, id_multi_result,
-    id_from_code, id_connection_options;
+    id_from_code, id_from_errno, id_connection_options;
 
 struct trilogy_ctx {
     trilogy_conn_t conn;
@@ -90,8 +90,8 @@ static void trilogy_syserr_fail_str(int e, VALUE msg)
     } else if (e == ECONNRESET) {
         rb_raise(Trilogy_ConnectionResetError, "%" PRIsVALUE, msg);
     } else {
-        // TODO: All syserr should be wrapped.
-        rb_syserr_fail_str(e, msg);
+        VALUE exc = rb_funcall(Trilogy_SyscallError, id_from_errno, 2, INT2NUM(e), msg);
+        rb_exc_raise(exc);
     }
 }
 
@@ -1088,6 +1088,9 @@ RUBY_FUNC_EXPORTED void Init_cext()
     Trilogy_Result = rb_const_get(Trilogy, rb_intern("Result"));
     rb_global_variable(&Trilogy_Result);
 
+    Trilogy_SyscallError = rb_const_get(Trilogy, rb_intern("SyscallError"));
+    rb_global_variable(&Trilogy_SyscallError);
+
     Trilogy_CastError = rb_const_get(Trilogy, rb_intern("CastError"));
     rb_global_variable(&Trilogy_CastError);
 
@@ -1119,6 +1122,7 @@ RUBY_FUNC_EXPORTED void Init_cext()
     id_multi_statement = rb_intern("multi_statement");
     id_multi_result = rb_intern("multi_result");
     id_from_code = rb_intern("from_code");
+    id_from_errno = rb_intern("from_errno");
     id_ivar_affected_rows = rb_intern("@affected_rows");
     id_ivar_fields = rb_intern("@fields");
     id_ivar_last_insert_id = rb_intern("@last_insert_id");

contrib/ruby/lib/trilogy.rb

@@ -13,6 +13,27 @@ module ConnectionError
     include Error
   end
 
+  # Trilogy may raise various syscall errors, which we treat as Trilogy::Errors.
+  class SyscallError
+    ERRORS = {}
+
+    Errno.constants
+      .map { |c| Errno.const_get(c) }.uniq
+      .select { |c| c.is_a?(Class) && c < SystemCallError }
+      .each do |c|
+        errno_name = c.to_s.split('::').last
+        ERRORS[c::Errno] = const_set(errno_name, Class.new(c) { include Trilogy::Error })
+      end
+
+    ERRORS.freeze
+
+    class << self
+      def from_errno(errno, message)
+        ERRORS[errno].new(message)
+      end
+    end
+  end
+
   class BaseError < StandardError
     include Error
 
@@ -41,29 +62,14 @@ class CastError < ClientError
 
   class TimeoutError < Errno::ETIMEDOUT
     include ConnectionError
-
-    def initialize(error_message = nil, error_code = nil)
-      super
-      @error_code = error_code
-    end
   end
 
   class ConnectionRefusedError < Errno::ECONNREFUSED
     include ConnectionError
-
-    def initialize(error_message = nil, error_code = nil)
-      super
-      @error_code = error_code
-    end
   end
 
   class ConnectionResetError < Errno::ECONNRESET
     include ConnectionError
-
-    def initialize(error_message = nil, error_code = nil)
-      super
-      @error_code = error_code
-    end
   end
 
   # DatabaseError was replaced by ProtocolError, but we'll keep it around as an