mount: (pre-)merge mounting code

coordinator/main.go

@@ -20,6 +20,7 @@ import (
 	"github.com/edgelesssys/contrast/internal/grpc/atlscredentials"
 	"github.com/edgelesssys/contrast/internal/logger"
 	"github.com/edgelesssys/contrast/internal/meshapi"
+	"github.com/edgelesssys/contrast/internal/mount"
 	"github.com/edgelesssys/contrast/internal/userapi"
 	grpcprometheus "github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus"
 	"github.com/prometheus/client_golang/prometheus"
@@ -56,7 +57,7 @@ func run() (retErr error) {
 
 	logger.Info("Coordinator started")
 
-	if err := setupMount(context.Background(), logger); err != nil {
+	if err := mount.SetupMount(context.Background(), logger, "/dev/csi0", "/mnt/state"); err != nil {
 		return fmt.Errorf("setting up mount: %w", err)
 	}
 

internal/mount/mount.go

@@ -0,0 +1,118 @@
+// Copyright 2024 Edgeless Systems GmbH
+// SPDX-License-Identifier: AGPL-3.0-only
+
+package mount
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log/slog"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+)
+
+// SetupMount formats the device to ext4 in case it is not ext4 formatted and mounts it to the provided mount point.
+func SetupMount(ctx context.Context, logger *slog.Logger, devPath, mountPoint string) error {
+	blk, err := blkid(ctx, devPath)
+	if errors.Is(err, errNotIdentified) {
+		logger.Info("device not identified, formatting", "device", devPath)
+		if err := mkfsExt4(ctx, devPath); err != nil {
+			return err
+		}
+	} else if err != nil {
+		return err
+	} else if blk.Type != "ext4" {
+		logger.Info("device is not ext4, formatting", "device", devPath)
+		if err := mkfsExt4(ctx, devPath); err != nil {
+			return err
+		}
+	}
+
+	if err := mount(ctx, devPath, mountPoint); err != nil {
+		return err
+	}
+	logger.Info("device mounted successfully", "dev", devPath, "mountPoint", mountPoint)
+
+	return nil
+}
+
+// blk holds the main attributes of a block device used by blkid system executable command.
+type blk struct {
+	DevName   string
+	UUID      string
+	BlockSize int
+	Type      string
+}
+
+var errNotIdentified = errors.New("blkid did not identify the device")
+
+// blkid creates a blk struct of the device located at the provided devPath.
+func blkid(ctx context.Context, devPath string) (*blk, error) {
+	cmd := exec.CommandContext(ctx, "blkid", "-o", "export", devPath)
+	out, err := cmd.CombinedOutput()
+	var exitErr *exec.ExitError
+	if errors.As(err, &exitErr) && exitErr.ExitCode() == 2 {
+		// See man page, sec EXIT STATUS.
+		return nil, errNotIdentified
+	} else if err != nil {
+		return nil, fmt.Errorf("blkid: %w, output: %q", err, out)
+	}
+	return parseBlkidCommand(out)
+}
+
+// parseBlkidCommand parses the output of the blkid system command to rerpresentative Blkid struct.
+func parseBlkidCommand(out []byte) (*blk, error) {
+	lines := strings.Split(string(out), "\n")
+	b := &blk{}
+
+	for _, line := range lines {
+		if line == "" {
+			continue
+		}
+		key, value, ok := strings.Cut(line, "=")
+		if !ok {
+			return nil, fmt.Errorf("parsing blkid output line %q", line)
+		}
+		switch key {
+		case "DEVNAME":
+			b.DevName = value
+		case "UUID":
+			b.UUID = value
+		case "TYPE":
+			b.Type = value
+		case "BLOCK_SIZE":
+			blockSize, err := strconv.Atoi(value)
+			if err != nil {
+				return nil, fmt.Errorf("parsing BLOCK_SIZE of blkid output %q: %w", value, err)
+			}
+			b.BlockSize = blockSize
+		}
+	}
+	return b, nil
+}
+
+// mkfsExt4 wraps the mkfs.ext4 command and creates an ext4 file system on the device.
+func mkfsExt4(ctx context.Context, devPath string) error {
+	cmd := exec.CommandContext(ctx, "mkfs.ext4", devPath)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("mkfs.ext4: %w, output: %q", err, out)
+	}
+	return nil
+}
+
+// mount wraps the mount command and attaches the device to the specified mountPoint.
+func mount(ctx context.Context, devPath, mountPoint string) error {
+	if err := os.MkdirAll(mountPoint, 0o755); err != nil {
+		return fmt.Errorf("mkdir: %w", err)
+	}
+	cmd := exec.CommandContext(ctx, "mount", devPath, mountPoint)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("mount: %w, output: %q", err, out)
+	}
+	return nil
+}

internal/mount/mount_test.go

@@ -0,0 +1,55 @@
+// Copyright 2024 Edgeless Systems GmbH
+// SPDX-License-Identifier: AGPL-3.0-only
+
+package mount
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseBlkidCommand(t *testing.T) {
+	blk := &blk{
+		DevName:   "/dev/nvme1n1p1",
+		UUID:      "f3e74cbb-4b6c-442b-8cd1-d12e3fc7adcd",
+		BlockSize: 1,
+		Type:      "ntfs",
+	}
+
+	blocks := map[string]struct {
+		outFormatString string
+		expError        bool
+	}{
+		"valid output": {
+			outFormatString: "DEVNAME=%s\nUUID=%s\nBLOCK_SIZE=%d\nTYPE=%s\n",
+			expError:        false,
+		},
+		"no equal sign": {
+			outFormatString: "No-Equal-Sign\n",
+			expError:        true,
+		},
+		"block size is string": {
+			outFormatString: "BLOCK_SIZE=isString\n",
+			expError:        true,
+		},
+	}
+
+	for name, block := range blocks {
+		t.Run(name, func(t *testing.T) {
+			parsedBlock, err := parseBlkidCommand(func(formatString string) []byte {
+				return []byte(fmt.Sprintf(formatString,
+					blk.DevName, blk.UUID, blk.BlockSize, blk.Type))
+			}(block.outFormatString))
+
+			if block.expError {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+				require.Equal(t, blk, parsedBlock)
+
+			}
+		})
+	}
+}