Move sql error message formatting into Ruby to handle newlines

and handle versions of sqlite3 without sqlite3_error_offset()

Author: flavorjones

ext/sqlite3/exception.c

@@ -105,23 +105,18 @@ rb_sqlite3_raise_with_sql(sqlite3 *db, int status, const char *sql)
         return;
     }
 
-    VALUE error_message = Qnil;
-    const char *sqlite_error_msg = sqlite3_errmsg(db);
-    int error_offset = sqlite3_error_offset(db);
+    const char *error_msg = sqlite3_errmsg(db);
+    int error_offset = -1;
+#ifdef HAVE_SQLITE3_ERROR_OFFSET
+    error_offset = sqlite3_error_offset(db);
+#endif
 
-    // Create a more detailed error message
-    if (error_offset >= 0 && sql) {
-        error_message = rb_sprintf(
-                            "%s:\n%s\n%*s^\n",
-                            sqlite_error_msg, sql, error_offset, ""
-                        );
-    } else {
-        error_message = rb_str_new2(sqlite_error_msg);
-    }
-
-    VALUE exception = rb_exc_new3(klass, error_message);
+    VALUE exception = rb_exc_new2(klass, error_msg);
     rb_iv_set(exception, "@code", INT2FIX(status));
-    rb_iv_set(exception, "@error_offset", INT2FIX(error_offset));
+    if (sql) {
+        rb_iv_set(exception, "@sql", rb_str_new2(sql));
+        rb_iv_set(exception, "@sql_offset", INT2FIX(error_offset));
+    }
 
     rb_exc_raise(exception);
 }

ext/sqlite3/extconf.rb

@@ -132,6 +132,7 @@ def configure_extension
 
         have_func("sqlite3_prepare_v2")
         have_func("sqlite3_db_name", "sqlite3.h") # v3.39.0
+        have_func("sqlite3_error_offset", "sqlite3.h") # v3.38.0
 
         have_type("sqlite3_int64", "sqlite3.h")
         have_type("sqlite3_uint64", "sqlite3.h")

lib/sqlite3/errors.rb

@@ -4,6 +4,33 @@ module SQLite3
   class Exception < ::StandardError
     # A convenience for accessing the error code for this exception.
     attr_reader :code
+
+    # If the error is associated with a SQL query, this is the query
+    attr_reader :sql
+
+    # If the error is associated with a particular offset in a SQL query, this is the integer offset.
+    attr_reader :sql_offset
+
+    def message
+      [super, sql_error].compact.join(":\n")
+    end
+
+    private def sql_error
+      return nil unless @sql
+      return @sql unless @sql_offset.is_a?(Integer)
+
+      offset = @sql_offset
+      sql.lines.flat_map do |line|
+        if offset >= 0 && line.length > offset
+          blanks = " " * offset
+          offset = -1
+          [line.chomp, blanks + "^"]
+        else
+          offset -= line.length if offset
+          line.chomp
+        end
+      end.join("\n")
+    end
   end
 
   class SQLException < Exception; end

test/test_integration.rb

@@ -111,11 +111,18 @@ def test_prepare_exception_shows_error_position
     exception = assert_raise(SQLite3::SQLException) do
       @db.prepare "select from foo"
     end
-    assert_equal(<<~MSG, exception.message)
-      near "from": syntax error:
-      select from foo
-             ^
-    MSG
+    if exception.sql_offset >= 0 # HAVE_SQLITE_ERROR_OFFSET
+      assert_equal(<<~MSG.chomp, exception.message)
+        near "from": syntax error:
+        select from foo
+               ^
+      MSG
+    else
+      assert_equal(<<~MSG.chomp, exception.message)
+        near "from": syntax error:
+        select from foo
+      MSG
+    end
   end
 
   def test_prepare_exception_shows_error_position_newline1
@@ -125,12 +132,20 @@ def test_prepare_exception_shows_error_position_newline1
         from foo
       SQL
     end
-    assert_equal(<<~MSG, exception.message)
-      near "from": syntax error:
-      select
-      from foo
-      ^
-    MSG
+    if exception.sql_offset >= 0 # HAVE_SQLITE_ERROR_OFFSET
+      assert_equal(<<~MSG.chomp, exception.message)
+        near "from": syntax error:
+        select
+        from foo
+        ^
+      MSG
+    else
+      assert_equal(<<~MSG.chomp, exception.message)
+        near "from": syntax error:
+        select
+        from foo
+      MSG
+    end
   end
 
   def test_prepare_exception_shows_error_position_newline2
@@ -140,12 +155,20 @@ def test_prepare_exception_shows_error_position_newline2
         from foo
       SQL
     end
-    assert_equal(<<~MSG, exception.message)
-      no such column: asdf:
-      select asdf
-             ^
-      from foo
-    MSG
+    if exception.sql_offset >= 0 # HAVE_SQLITE_ERROR_OFFSET
+      assert_equal(<<~MSG.chomp, exception.message)
+        no such column: asdf:
+        select asdf
+               ^
+        from foo
+      MSG
+    else
+      assert_equal(<<~MSG.chomp, exception.message)
+        no such column: asdf:
+        select asdf
+        from foo
+      MSG
+    end
   end
 
   def test_prepare_invalid_column