From b46ac7dbb45a94f36d1cbd9b791df91b1d1af4ac Mon Sep 17 00:00:00 2001
From: Nathan Bird <nathan@acceleration.net>
Date: Tue, 19 Jan 2010 13:59:52 -0500
Subject: [PATCH] Mysql shouldn't segfault in database-query when running a
 command with no resultset. From docs at
 http://dev.mysql.com/doc/refman/5.0/en/mysql-real-query.html and
 http://dev.mysql.com/doc/refman/5.0/en/mysql-field-count.html after
 performing the query and attempting to get a result set, the RS ptr should be
 checked for null and if it is check mysql_errno to see if there actually was
 an error, or just no result.

This patch makes database-query return NIL if there was no resultset.
---
 db-mysql/mysql-sql.lisp | 85 ++++++++++++++++++++++-------------------
 1 file changed, 45 insertions(+), 40 deletions(-)

diff --git a/db-mysql/mysql-sql.lisp b/db-mysql/mysql-sql.lisp
index 849fb39..8ea7f4f 100644
--- a/db-mysql/mysql-sql.lisp
+++ b/db-mysql/mysql-sql.lisp
@@ -180,50 +180,55 @@
 
 
 (defmethod database-query (query-expression (database mysql-database)
-                           result-types field-names)
+			   result-types field-names)
   (declare (optimize (speed 3) (safety 0) (debug 0) (space 0)))
   (let ((mysql-ptr (database-mysql-ptr database)))
     (uffi:with-cstring (query-native query-expression)
       (if (zerop (mysql-real-query mysql-ptr query-native
-                                   (expression-length query-expression)))
-          (let ((res-ptr (mysql-use-result mysql-ptr)))
-            (if res-ptr
-                (unwind-protect
-                     (let ((num-fields (mysql-num-fields res-ptr)))
-                       (declare (fixnum num-fields))
-                       (setq result-types (canonicalize-types
-                                    result-types res-ptr))
-                       (values
-                        (loop for row = (mysql-fetch-row res-ptr)
-                              for lengths = (mysql-fetch-lengths res-ptr)
-                              until (uffi:null-pointer-p row)
-                              collect
-                              (do* ((rlist (make-list num-fields))
-                                    (i 0 (1+ i))
-                                    (pos rlist (cdr pos)))
-                                   ((= i num-fields) rlist)
-                                (declare (fixnum i))
-                                (setf (car pos)
-                                      (convert-raw-field
-                                       (uffi:deref-array row '(:array
-                                                               (* :unsigned-char))
-                                                         i)
-                                       result-types i
-                                       (uffi:deref-array lengths '(:array :unsigned-long)
-                                                         i)))))
-                        (when field-names
-                          (result-field-names res-ptr))))
-                  (mysql-free-result res-ptr))
-                (error 'sql-database-data-error
-                       :database database
-                       :expression query-expression
-                       :error-id (mysql-errno mysql-ptr)
-                       :message (mysql-error-string mysql-ptr))))
-          (error 'sql-database-data-error
-                 :database database
-                 :expression query-expression
-                 :error-id (mysql-errno mysql-ptr)
-                 :message (mysql-error-string mysql-ptr))))))
+				   (expression-length query-expression)))
+	  (let ((res-ptr (mysql-use-result mysql-ptr)))
+	    (if (and res-ptr (not (uffi:null-pointer-p res-ptr)))
+		(unwind-protect
+		     (let ((num-fields (mysql-num-fields res-ptr)))
+		       (declare (fixnum num-fields))
+		       (setq result-types (canonicalize-types
+					   result-types res-ptr))
+		       (values
+			 (loop for row = (mysql-fetch-row res-ptr)
+			       for lengths = (mysql-fetch-lengths res-ptr)
+			       until (uffi:null-pointer-p row)
+			       collect
+			    (do* ((rlist (make-list num-fields))
+				  (i 0 (1+ i))
+				  (pos rlist (cdr pos)))
+				((= i num-fields) rlist)
+			      (declare (fixnum i))
+			      (setf (car pos)
+				    (convert-raw-field
+				     (uffi:deref-array row '(:array
+							     (* :unsigned-char))
+						       i)
+				     result-types i
+				     (uffi:deref-array lengths '(:array :unsigned-long)
+						       i)))))
+			 (when field-names
+			   (result-field-names res-ptr))))
+		  (mysql-free-result res-ptr))
+		(unless (zerop (mysql-errno mysql-ptr))
+		  ;;from http://dev.mysql.com/doc/refman/5.0/en/mysql-field-count.html
+		  ;; if mysql_use_result or mysql_store_result return a null ptr,
+		  ;; we use a mysql_errno check to see if it had a problem or just
+		  ;; was a query without a result. If no error, just return nil.
+		  (error 'sql-database-data-error
+			 :database database
+			 :expression query-expression
+			 :error-id (mysql-errno mysql-ptr)
+			 :message (mysql-error-string mysql-ptr)))))
+	  (error 'sql-database-data-error
+		 :database database
+		 :expression query-expression
+		 :error-id (mysql-errno mysql-ptr)
+		 :message (mysql-error-string mysql-ptr))))))
 
 (defmethod database-execute-command (sql-expression (database mysql-database))
   (uffi:with-cstring (sql-native sql-expression)
-- 
2.34.1