vendor: update buildkit to v0.17.0-rc2

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/containerd/continuity/testutil/loopback/loopback_linux.go

@@ -0,0 +1,118 @@
+//go:build linux
+// +build linux
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package loopback
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+
+	"github.com/containerd/log"
+)
+
+// New creates a loopback device
+func New(size int64) (*Loopback, error) {
+	// create temporary file for the disk image
+	file, err := os.CreateTemp("", "containerd-test-loopback")
+	if err != nil {
+		return nil, fmt.Errorf("could not create temporary file for loopback: %w", err)
+	}
+
+	if err := file.Truncate(size); err != nil {
+		file.Close()
+		os.Remove(file.Name())
+		return nil, fmt.Errorf("failed to resize temp file: %w", err)
+	}
+	file.Close()
+
+	// create device
+	losetup := exec.Command("losetup", "--find", "--show", file.Name())
+	var stdout, stderr bytes.Buffer
+	losetup.Stdout = &stdout
+	losetup.Stderr = &stderr
+	if err := losetup.Run(); err != nil {
+		os.Remove(file.Name())
+		return nil, fmt.Errorf("loopback setup failed (%v): stdout=%q, stderr=%q: %w", losetup.Args, stdout.String(), stderr.String(), err)
+	}
+
+	deviceName := strings.TrimSpace(stdout.String())
+	log.L.Debugf("Created loop device %s (using %s)", deviceName, file.Name())
+
+	cleanup := func() error {
+		// detach device
+		log.L.Debugf("Removing loop device %s", deviceName)
+		losetup := exec.Command("losetup", "--detach", deviceName)
+		if out, err := losetup.CombinedOutput(); err != nil {
+			return fmt.Errorf("Could not remove loop device %s (%v): %q: %w", deviceName, losetup.Args, string(out), err)
+		}
+
+		// remove file
+		log.L.Debugf("Removing temporary file %s", file.Name())
+		return os.Remove(file.Name())
+	}
+
+	l := Loopback{
+		File:   file.Name(),
+		Device: deviceName,
+		close:  cleanup,
+	}
+	return &l, nil
+}
+
+// Loopback device
+type Loopback struct {
+	// File is the underlying sparse file
+	File string
+	// Device is /dev/loopX
+	Device string
+	close  func() error
+}
+
+// SoftSize returns st_size
+func (l *Loopback) SoftSize() (int64, error) {
+	st, err := os.Stat(l.File)
+	if err != nil {
+		return 0, err
+	}
+	return st.Size(), nil
+}
+
+// HardSize returns st_blocks * 512; see stat(2)
+func (l *Loopback) HardSize() (int64, error) {
+	st, err := os.Stat(l.File)
+	if err != nil {
+		return 0, err
+	}
+	st2, ok := st.Sys().(*syscall.Stat_t)
+	if !ok {
+		return 0, errors.New("st.Sys() is not a *syscall.Stat_t")
+	}
+	// NOTE: st_blocks has nothing to do with st_blksize; see stat(2)
+	return st2.Blocks * 512, nil
+}
+
+// Close detaches the device and removes the underlying file
+func (l *Loopback) Close() error {
+	return l.close()
+}