Workaround for a bug in unixODBC 2.3.4 (#334)

* Adding a workaround for the error handling issue with unixODBC 2.3.4 when conneciton pooling is enabled

* Adding a check to apply the workaround only to PDO SQLSRV

* Update core_util.cpp

* Unix Conn Pool test

* Modifying the test to use autonomous_setup.php

* Updating path to isPooled.php

source/shared/core_util.cpp

@@ -247,6 +247,17 @@ bool core_sqlsrv_get_odbc_error( sqlsrv_context& ctx, int record_number, sqlsrv_
             r = SQLGetDiagRecW( h_type, h, record_number, wsqlstate, &error->native_code, wnative_message,
                                 SQL_MAX_MESSAGE_LENGTH + 1, &wmessage_len );
             // don't use the CHECK* macros here since it will trigger reentry into the error handling system
+            // Workaround for a bug in unixODBC 2.3.4 when connection pooling is enabled (PDO SQLSRV).
+            // Instead of returning false, we return an empty error message to prevent the driver from throwing an exception.
+            // To reproduce:
+            // Create a connection and close it (return it to the pool)
+            // Create a new connection from the pool. 
+            // Prepare and execute a statement that generates an info message (such as 'USE tempdb;') 
+#ifdef __APPLE__
+            if( r == SQL_NO_DATA && ctx.driver() != NULL /*PDO SQLSRV*/ ) {
+                r = SQL_SUCCESS;
+            }
+#endif // __APPLE__
             if( !SQL_SUCCEEDED( r ) || r == SQL_NO_DATA ) {
                 return false;
             }

test/pdo_sqlsrv/PDO_ConnPool_Unix.phpt

@@ -0,0 +1,34 @@
+--TEST--
+PDO Connection Pooling Test on Unix
+This test assumes odbcinst.ini has not been modified. 
+This test also requires root privileges to modify odbcinst.ini file on Linux.
+--SKIPIF--
+<?php if(PHP_OS === "WINNT") die("Skipped: Test for Linux and Mac");
+--FILE--
+<?php
+$lines_to_add="CPTimeout=5\n[ODBC]\nPooling=Yes\n";
+
+//get odbcinst.ini location
+$lines = explode("\n", shell_exec("odbcinst -j"));
+$odbcinst_ini = explode(" ", $lines[1])[1];
+
+//enable pooling by modifying the odbcinst.ini file
+$current = file_get_contents($odbcinst_ini);
+$current.=$lines_to_add;
+file_put_contents($odbcinst_ini, $current);
+
+//Creating a new php process, because for changes in odbcinst.ini file to affect pooling, drivers must be reloaded.
+print_r(shell_exec("php ./test/pdo_sqlsrv/isPooled.php"));
+
+//disable pooling by modifying the odbcinst.ini file
+$current = file_get_contents($odbcinst_ini);
+$current = str_replace("CPTimeout=5\n[ODBC]\nPooling=Yes\n",'',$current);
+file_put_contents($odbcinst_ini, $current);
+
+print_r(shell_exec("php ./test/pdo_sqlsrv/isPooled.php"));
+?>
+--EXPECT--
+Pooled
+Not Pooled
+
+

test/pdo_sqlsrv/isPooled.php

@@ -0,0 +1,25 @@
+<?php
+include_once 'autonomous_setup.php';
+$conn1 = new PDO("sqlsrv:Server=$serverName", $username, $password);
+$connId1 = ConnectionID($conn1);
+$conn1 = null;
+
+$conn2 = new PDO("sqlsrv:Server=$serverName", $username, $password);
+$connId2 = ConnectionID($conn2);
+
+if ($connId1 === $connId2){
+    echo "Pooled\n";
+}else{
+    echo "Not Pooled\n";
+}
+
+function ConnectionID($conn)
+{
+	$tsql = "SELECT [connection_id] FROM [sys].[dm_exec_connections] where session_id = @@SPID";
+	$stmt = $conn->query($tsql);
+	$connID = $stmt->fetchColumn(0);
+	$stmt->closeCursor();
+	$stmt = null;
+	return ($connID);
+}
+?>