Move snapshots/devmapper to plugins/snapshots/devmapper

Signed-off-by: Derek McGowan <derek@mcg.dev>

plugins/snapshots/devmapper/config.go

@@ -0,0 +1,126 @@
+//go: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 devmapper
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/docker/go-units"
+	"github.com/pelletier/go-toml/v2"
+)
+
+// Config represents device mapper configuration loaded from file.
+// Size units can be specified in human-readable string format (like "32KIB", "32GB", "32Tb")
+type Config struct {
+	// Device snapshotter root directory for metadata
+	RootPath string `toml:"root_path"`
+
+	// Name for 'thin-pool' device to be used by snapshotter (without /dev/mapper/ prefix)
+	PoolName string `toml:"pool_name"`
+
+	// Defines how much space to allocate when creating base image for container
+	BaseImageSize      string `toml:"base_image_size"`
+	BaseImageSizeBytes uint64 `toml:"-"`
+
+	// Flag to async remove device using Cleanup() callback in snapshots GC
+	AsyncRemove bool `toml:"async_remove"`
+
+	// Whether to discard blocks when removing a thin device.
+	DiscardBlocks bool `toml:"discard_blocks"`
+
+	// Defines file system to use for snapshout device mount. Defaults to "ext4"
+	FileSystemType fsType `toml:"fs_type"`
+
+	// Defines optional file system options passed through config file
+	FsOptions string `toml:"fs_options"`
+}
+
+// LoadConfig reads devmapper configuration file from disk in TOML format
+func LoadConfig(path string) (*Config, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, os.ErrNotExist
+		}
+
+		return nil, err
+
+	}
+	defer f.Close()
+
+	config := Config{}
+	if err := toml.NewDecoder(f).Decode(&config); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal devmapper TOML: %w", err)
+	}
+
+	if err := config.parse(); err != nil {
+		return nil, err
+	}
+
+	if err := config.Validate(); err != nil {
+		return nil, err
+	}
+
+	return &config, nil
+}
+
+func (c *Config) parse() error {
+	baseImageSize, err := units.RAMInBytes(c.BaseImageSize)
+	if err != nil {
+		return fmt.Errorf("failed to parse base image size: '%s': %w", c.BaseImageSize, err)
+	}
+
+	if c.FileSystemType == "" {
+		c.FileSystemType = fsTypeExt4
+	}
+
+	c.BaseImageSizeBytes = uint64(baseImageSize)
+	return nil
+}
+
+// Validate makes sure configuration fields are valid
+func (c *Config) Validate() error {
+	var result []error
+
+	if c.PoolName == "" {
+		result = append(result, fmt.Errorf("pool_name is required"))
+	}
+
+	if c.RootPath == "" {
+		result = append(result, fmt.Errorf("root_path is required"))
+	}
+
+	if c.BaseImageSize == "" {
+		result = append(result, fmt.Errorf("base_image_size is required"))
+	}
+
+	if c.FileSystemType != "" {
+		switch c.FileSystemType {
+		case fsTypeExt4, fsTypeXFS, fsTypeExt2:
+		default:
+			result = append(result, fmt.Errorf("unsupported Filesystem Type: %q", c.FileSystemType))
+		}
+	} else {
+		result = append(result, fmt.Errorf("filesystem type cannot be empty"))
+	}
+
+	return errors.Join(result...)
+}