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/ulikunitz/xz/internal/hash/rabin_karp.go

@@ -0,0 +1,66 @@
+// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package hash
+
+// A is the default constant for Robin-Karp rolling hash. This is a random
+// prime.
+const A = 0x97b548add41d5da1
+
+// RabinKarp supports the computation of a rolling hash.
+type RabinKarp struct {
+	A uint64
+	// a^n
+	aOldest uint64
+	h       uint64
+	p       []byte
+	i       int
+}
+
+// NewRabinKarp creates a new RabinKarp value. The argument n defines the
+// length of the byte sequence to be hashed. The default constant will will be
+// used.
+func NewRabinKarp(n int) *RabinKarp {
+	return NewRabinKarpConst(n, A)
+}
+
+// NewRabinKarpConst creates a new RabinKarp value. The argument n defines the
+// length of the byte sequence to be hashed. The argument a provides the
+// constant used to compute the hash.
+func NewRabinKarpConst(n int, a uint64) *RabinKarp {
+	if n <= 0 {
+		panic("number of bytes n must be positive")
+	}
+	aOldest := uint64(1)
+	// There are faster methods. For the small n required by the LZMA
+	// compressor O(n) is sufficient.
+	for i := 0; i < n; i++ {
+		aOldest *= a
+	}
+	return &RabinKarp{
+		A: a, aOldest: aOldest,
+		p: make([]byte, 0, n),
+	}
+}
+
+// Len returns the length of the byte sequence.
+func (r *RabinKarp) Len() int {
+	return cap(r.p)
+}
+
+// RollByte computes the hash after x has been added.
+func (r *RabinKarp) RollByte(x byte) uint64 {
+	if len(r.p) < cap(r.p) {
+		r.h += uint64(x)
+		r.h *= r.A
+		r.p = append(r.p, x)
+	} else {
+		r.h -= uint64(r.p[r.i]) * r.aOldest
+		r.h += uint64(x)
+		r.h *= r.A
+		r.p[r.i] = x
+		r.i = (r.i + 1) % cap(r.p)
+	}
+	return r.h
+}