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file.go
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file.go
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package logging
import (
"fmt"
"io"
"log"
"os"
"syscall"
"github.com/dsh2dsh/zrepl/config"
"github.com/dsh2dsh/zrepl/logger"
)
func parseFileOutlet(in *config.FileLoggingOutlet, formatter EntryFormatter,
) (*FileOutlet, error) {
return newFileOutlet(in.FileName, formatter)
}
func newFileOutlet(filename string, formatter EntryFormatter,
) (*FileOutlet, error) {
outlet := new(FileOutlet).WithFormatter(formatter)
if filename == "" {
return outlet.WithWriter(log.Default().Writer()), nil
}
f, err := newLogFile(filename)
if err != nil {
return nil, err
}
return outlet.WithWriter(f), nil
}
type FileOutlet struct {
formatter EntryFormatter
w io.Writer
}
func (self *FileOutlet) WithFormatter(f EntryFormatter) *FileOutlet {
self.formatter = f
return self
}
func (self *FileOutlet) WithWriter(w io.Writer) *FileOutlet {
self.w = w
return self
}
func (self *FileOutlet) WriteEntry(e logger.Entry) error {
if err := self.formatter.Write(self.w, &e); err != nil {
return fmt.Errorf("write log entry: %w", err)
}
return nil
}
// --------------------------------------------------
func newLogFile(filename string) (f *logFile, err error) {
f = &logFile{filename: filename}
err = f.Open()
return
}
type logFile struct {
file *os.File
filename string
}
func (self *logFile) Write(p []byte) (int, error) {
if err := self.reopenIfNotExists(); err != nil {
return 0, fmt.Errorf("reopen file %q: %w", self.filename, err)
}
n, err := self.file.Write(p)
if err != nil {
return n, fmt.Errorf("write to %q: %w", self.filename, err)
}
return n, nil
}
func (self *logFile) reopenIfNotExists() error {
if ok, err := self.exists(); err != nil {
return err
} else if ok {
return nil
}
return self.reopen()
}
func (self *logFile) exists() (bool, error) {
finfo, err := self.file.Stat()
if err != nil {
return false, fmt.Errorf("stat of %q: %w", self.filename, err)
}
var nlink uint64
if finfo.Sys() != nil {
if stat, ok := finfo.Sys().(*syscall.Stat_t); ok {
nlink = uint64(stat.Nlink)
}
}
return nlink > 0, nil
}
func (self *logFile) reopen() error {
if err := self.file.Close(); err != nil {
return fmt.Errorf("close %q: %w", self.filename, err)
}
return self.Open()
}
func (self *logFile) Open() error {
f, err := os.OpenFile(self.filename,
os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
if err != nil {
return fmt.Errorf("open file: %w", err)
}
self.file = f
return nil
}