log: add "filename:line" prefix by ourself (go-sql-driver#1589)

go-sql-driver#1563 broke the filename:lineno prefix in the log
message by introducing a helper function.
This commit adds the "filename:line" prefix in the helper function
instead of log.Lshortfile option to show correct filename:lineno.

connection.go

@@ -13,8 +13,10 @@ import (
  "database/sql"
  "database/sql/driver"
  "encoding/json"
+ "fmt"
  "io"
  "net"
+ "runtime"
  "strconv"
  "strings"
  "sync/atomic"
@@ -47,6 +49,16 @@ type mysqlConn struct {
 
 // Helper function to call per-connection logger.
 func (mc *mysqlConn) log(v ...any) {
+ _, filename, lineno, ok := runtime.Caller(1)
+ if ok {
+ pos := strings.LastIndexByte(filename, '/')
+ if pos != -1 {
+ filename = filename[pos+1:]
+ }
+ prefix := fmt.Sprintf("%s:%d ", filename, lineno)
+ v = append([]any{prefix}, v...)
+ }
+
  mc.cfg.Logger.Print(v...)
 }
 

errors.go

@@ -37,7 +37,7 @@ var (
  errBadConnNoWrite = errors.New("bad connection")
 )
 
-var defaultLogger = Logger(log.New(os.Stderr, "[mysql] ", log.Ldate|log.Ltime|log.Lshortfile))
+var defaultLogger = Logger(log.New(os.Stderr, "[mysql] ", log.Ldate|log.Ltime))
 
 // Logger is used to log critical error messages.
 type Logger interface {