88 lines
2.2 KiB
Go
88 lines
2.2 KiB
Go
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package mount
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import (
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"fmt"
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"os"
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"path/filepath"
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"strings"
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"metis/pkg/util"
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)
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// LoopMount describes a mounted image with boot/root paths.
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type LoopMount struct {
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LoopDevice string // only set when losetup created it
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BootPath string
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RootPath string
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}
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// Setup attaches an image as a loop device with partitions (-P) OR mounts an existing /dev path
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// by assuming p1=boot, p2=root. Intended for Linux hosts only.
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func Setup(path string) (*LoopMount, error) {
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device := path
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loopDevice := ""
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if !strings.HasPrefix(path, "/dev/") {
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var err error
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device, err = createLoop(path)
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if err != nil {
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return nil, err
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}
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loopDevice = device
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}
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bootDir, err := os.MkdirTemp("", "metis-boot-")
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if err != nil {
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return nil, err
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}
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rootDir, err := os.MkdirTemp("", "metis-root-")
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if err != nil {
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return nil, err
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}
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// Assume p1=boot, p2=root (Raspberry Pi style images)
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if err := util.Run("mount", partitionPath(device, 1), bootDir); err != nil {
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_ = Teardown(&LoopMount{LoopDevice: loopDevice, BootPath: bootDir, RootPath: rootDir})
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return nil, fmt.Errorf("mount boot: %w", err)
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}
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if err := util.Run("mount", partitionPath(device, 2), rootDir); err != nil {
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_ = util.Run("umount", bootDir)
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_ = Teardown(&LoopMount{LoopDevice: loopDevice, BootPath: bootDir, RootPath: rootDir})
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return nil, fmt.Errorf("mount root: %w", err)
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}
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return &LoopMount{LoopDevice: loopDevice, BootPath: bootDir, RootPath: rootDir}, nil
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}
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// Teardown unmounts and detaches the loop device.
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func Teardown(m *LoopMount) error {
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if m == nil {
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return nil
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}
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if m.BootPath != "" {
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_ = util.Run("umount", m.BootPath)
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_ = os.RemoveAll(m.BootPath)
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}
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if m.RootPath != "" {
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_ = util.Run("umount", m.RootPath)
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_ = os.RemoveAll(m.RootPath)
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}
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if m.LoopDevice != "" {
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_ = util.Run("losetup", "-d", m.LoopDevice)
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}
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return nil
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}
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func partitionPath(base string, idx int) string {
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p := fmt.Sprintf("%sp%d", base, idx)
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if _, err := os.Stat(p); err == nil {
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return p
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}
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return fmt.Sprintf("%s%d", base, idx)
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}
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func createLoop(imagePath string) (string, error) {
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// losetup -Pf --show <image>
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out, err := util.RunLogged("losetup", "-Pf", "--show", filepath.Clean(imagePath))
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if err != nil {
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return "", err
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}
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return strings.TrimSpace(out), nil
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}
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