1 files changed, 246 insertions, 0 deletions
diff --git a/modules/util/rotatingfilewriter/writer.go b/modules/util/rotatingfilewriter/writer.go
new file mode 100644
index 0000000..c595f49
--- /dev/null
+++ b/modules/util/rotatingfilewriter/writer.go
@@ -0,0 +1,246 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package rotatingfilewriter
+
+import (
+	"bufio"
+	"compress/gzip"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+
+	"code.gitea.io/gitea/modules/graceful/releasereopen"
+	"code.gitea.io/gitea/modules/util"
+)
+
+type Options struct {
+	Rotate           bool
+	MaximumSize      int64
+	RotateDaily      bool
+	KeepDays         int
+	Compress         bool
+	CompressionLevel int
+}
+
+type RotatingFileWriter struct {
+	mu sync.Mutex
+	fd *os.File
+
+	currentSize int64
+	openDate    int
+
+	options Options
+
+	cancelReleaseReopen func()
+}
+
+var ErrorPrintf func(format string, args ...any)
+
+// errorf tries to print error messages. Since this writer could be used by a logger system, this is the last chance to show the error in some cases
+func errorf(format string, args ...any) {
+	if ErrorPrintf != nil {
+		ErrorPrintf("rotatingfilewriter: "+format+"\n", args...)
+	}
+}
+
+// Open creates a new rotating file writer.
+// Notice: if a file is opened by two rotators, there will be conflicts when rotating.
+// In the future, there should be "rotating file manager"
+func Open(filename string, options *Options) (*RotatingFileWriter, error) {
+	if options == nil {
+		options = &Options{}
+	}
+
+	rfw := &RotatingFileWriter{
+		options: *options,
+	}
+
+	if err := rfw.open(filename); err != nil {
+		return nil, err
+	}
+
+	rfw.cancelReleaseReopen = releasereopen.GetManager().Register(rfw)
+	return rfw, nil
+}
+
+func (rfw *RotatingFileWriter) Write(b []byte) (int, error) {
+	if rfw.options.Rotate && ((rfw.options.MaximumSize > 0 && rfw.currentSize >= rfw.options.MaximumSize) || (rfw.options.RotateDaily && time.Now().Day() != rfw.openDate)) {
+		if err := rfw.DoRotate(); err != nil {
+			// if this writer is used by a logger system, it's the logger system's responsibility to handle/show the error
+			return 0, err
+		}
+	}
+
+	n, err := rfw.fd.Write(b)
+	if err == nil {
+		rfw.currentSize += int64(n)
+	}
+	return n, err
+}
+
+func (rfw *RotatingFileWriter) Flush() error {
+	return rfw.fd.Sync()
+}
+
+func (rfw *RotatingFileWriter) Close() error {
+	rfw.mu.Lock()
+	if rfw.cancelReleaseReopen != nil {
+		rfw.cancelReleaseReopen()
+		rfw.cancelReleaseReopen = nil
+	}
+	rfw.mu.Unlock()
+	return rfw.fd.Close()
+}
+
+func (rfw *RotatingFileWriter) open(filename string) error {
+	fd, err := os.OpenFile(filename, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0o660)
+	if err != nil {
+		return err
+	}
+
+	rfw.fd = fd
+
+	finfo, err := fd.Stat()
+	if err != nil {
+		return err
+	}
+	rfw.currentSize = finfo.Size()
+	rfw.openDate = finfo.ModTime().Day()
+
+	return nil
+}
+
+func (rfw *RotatingFileWriter) ReleaseReopen() error {
+	return errors.Join(
+		rfw.fd.Close(),
+		rfw.open(rfw.fd.Name()),
+	)
+}
+
+// DoRotate the log file creating a backup like xx.2013-01-01.2
+func (rfw *RotatingFileWriter) DoRotate() error {
+	if !rfw.options.Rotate {
+		return nil
+	}
+
+	rfw.mu.Lock()
+	defer rfw.mu.Unlock()
+
+	prefix := fmt.Sprintf("%s.%s.", rfw.fd.Name(), time.Now().Format("2006-01-02"))
+
+	var err error
+	fname := ""
+	for i := 1; err == nil && i <= 999; i++ {
+		fname = prefix + fmt.Sprintf("%03d", i)
+		_, err = os.Lstat(fname)
+		if rfw.options.Compress && err != nil {
+			_, err = os.Lstat(fname + ".gz")
+		}
+	}
+	// return error if the last file checked still existed
+	if err == nil {
+		return fmt.Errorf("cannot find free file to rename %s", rfw.fd.Name())
+	}
+
+	fd := rfw.fd
+	if err := fd.Close(); err != nil { // close file before rename
+		return err
+	}
+
+	if err := util.Rename(fd.Name(), fname); err != nil {
+		return err
+	}
+
+	if rfw.options.Compress {
+		go func() {
+			err := compressOldFile(fname, rfw.options.CompressionLevel)
+			if err != nil {
+				errorf("DoRotate: %v", err)
+			}
+		}()
+	}
+
+	if err := rfw.open(fd.Name()); err != nil {
+		return err
+	}
+
+	go deleteOldFiles(
+		filepath.Dir(fd.Name()),
+		filepath.Base(fd.Name()),
+		time.Now().AddDate(0, 0, -rfw.options.KeepDays),
+	)
+
+	return nil
+}
+
+func compressOldFile(fname string, compressionLevel int) error {
+	reader, err := os.Open(fname)
+	if err != nil {
+		return fmt.Errorf("compressOldFile: failed to open existing file %s: %w", fname, err)
+	}
+	defer reader.Close()
+
+	buffer := bufio.NewReader(reader)
+	fnameGz := fname + ".gz"
+	fw, err := os.OpenFile(fnameGz, os.O_WRONLY|os.O_CREATE, 0o660)
+	if err != nil {
+		return fmt.Errorf("compressOldFile: failed to open new file %s: %w", fnameGz, err)
+	}
+	defer fw.Close()
+
+	zw, err := gzip.NewWriterLevel(fw, compressionLevel)
+	if err != nil {
+		return fmt.Errorf("compressOldFile: failed to create gzip writer: %w", err)
+	}
+	defer zw.Close()
+
+	_, err = buffer.WriteTo(zw)
+	if err != nil {
+		_ = zw.Close()
+		_ = fw.Close()
+		_ = util.Remove(fname + ".gz")
+		return fmt.Errorf("compressOldFile: failed to write to gz file: %w", err)
+	}
+	_ = reader.Close()
+
+	err = util.Remove(fname)
+	if err != nil {
+		return fmt.Errorf("compressOldFile: failed to delete old file: %w", err)
+	}
+	return nil
+}
+
+func deleteOldFiles(dir, prefix string, removeBefore time.Time) {
+	err := filepath.WalkDir(dir, func(path string, d os.DirEntry, err error) (returnErr error) {
+		defer func() {
+			if r := recover(); r != nil {
+				returnErr = fmt.Errorf("unable to delete old file '%s', error: %+v", path, r)
+			}
+		}()
+
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			return nil
+		}
+		info, err := d.Info()
+		if err != nil {
+			return err
+		}
+		if info.ModTime().Before(removeBefore) {
+			if strings.HasPrefix(filepath.Base(path), prefix) {
+				return util.Remove(path)
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		errorf("deleteOldFiles: failed to delete old file: %v", err)
+	}
+}