Dump: add output format tar and output to stdout (#10376)

* Dump: Use mholt/archive/v3 to support tar including many compressions

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: Allow dump output to stdout

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: Fixed bug present since #6677 where SessionConfig.Provider is never "file"

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: never pack RepoRootPath, LFS.ContentPath and LogRootPath when they are below AppDataPath

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: also dump LFS (fixes #10058)

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: never dump CustomPath if CustomPath is a subdir of or equal to AppDataPath (fixes #10365)

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Use log.Info instead of fmt.Fprintf

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* import ordering

* make fmt

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: Matti R <matti@mdranta.net>

vendor/github.com/mholt/archiver/v3/gz.go

@@ -0,0 +1,76 @@
+package archiver
+
+import (
+	"compress/gzip"
+	"fmt"
+	"io"
+	"path/filepath"
+
+	pgzip "github.com/klauspost/pgzip"
+)
+
+// Gz facilitates gzip compression.
+type Gz struct {
+	CompressionLevel int
+	SingleThreaded   bool
+}
+
+// Compress reads in, compresses it, and writes it to out.
+func (gz *Gz) Compress(in io.Reader, out io.Writer) error {
+	var w io.WriteCloser
+	var err error
+	if gz.SingleThreaded {
+		w, err = gzip.NewWriterLevel(out, gz.CompressionLevel)
+	} else {
+		w, err = pgzip.NewWriterLevel(out, gz.CompressionLevel)
+	}
+	if err != nil {
+		return err
+	}
+	defer w.Close()
+	_, err = io.Copy(w, in)
+	return err
+}
+
+// Decompress reads in, decompresses it, and writes it to out.
+func (gz *Gz) Decompress(in io.Reader, out io.Writer) error {
+	var r io.ReadCloser
+	var err error
+	if gz.SingleThreaded {
+		r, err = gzip.NewReader(in)
+	} else {
+		r, err = pgzip.NewReader(in)
+	}
+	if err != nil {
+		return err
+	}
+	defer r.Close()
+	_, err = io.Copy(out, r)
+	return err
+}
+
+// CheckExt ensures the file extension matches the format.
+func (gz *Gz) CheckExt(filename string) error {
+	if filepath.Ext(filename) != ".gz" {
+		return fmt.Errorf("filename must have a .gz extension")
+	}
+	return nil
+}
+
+func (gz *Gz) String() string { return "gz" }
+
+// NewGz returns a new, default instance ready to be customized and used.
+func NewGz() *Gz {
+	return &Gz{
+		CompressionLevel: gzip.DefaultCompression,
+	}
+}
+
+// Compile-time checks to ensure type implements desired interfaces.
+var (
+	_ = Compressor(new(Gz))
+	_ = Decompressor(new(Gz))
+)
+
+// DefaultGz is a default instance that is conveniently ready to use.
+var DefaultGz = NewGz()