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// Copyright (c) 2022, Sylabs Inc. All rights reserved.
// This software is licensed under a 3-clause BSD license. Please consult the
// LICENSE file distributed with the sources of this project regarding your
// rights to use or distribute this software.
package user
import (
"context"
"errors"
"fmt"
"io"
"os/exec"
"path/filepath"
)
// unmountSquashFS unmounts the filesystem at mountPath.
func unmountSquashFS(ctx context.Context, mountPath string, uo unmountOpts) error {
args := []string{
"-u",
filepath.Clean(mountPath),
}
cmd := exec.CommandContext(ctx, uo.fusermountPath, args...) //nolint:gosec
cmd.Stdout = uo.stdout
cmd.Stderr = uo.stderr
if err := cmd.Run(); err != nil {
return fmt.Errorf("failed to unmount: %w", err)
}
return nil
}
// unmountOpts accumulates unmount options.
type unmountOpts struct {
stdout io.Writer
stderr io.Writer
fusermountPath string
}
// UnmountOpt are used to specify unmount options.
type UnmountOpt func(*unmountOpts) error
// OptUnmountStdout writes standard output to w.
func OptUnmountStdout(w io.Writer) UnmountOpt {
return func(mo *unmountOpts) error {
mo.stdout = w
return nil
}
}
// OptUnmountStderr writes standard error to w.
func OptUnmountStderr(w io.Writer) UnmountOpt {
return func(mo *unmountOpts) error {
mo.stderr = w
return nil
}
}
var errFusermountPathInvalid = errors.New("fusermount path must be relative or absolute")
// OptUnmountFusermountPath sets the path to the fusermount binary.
func OptUnmountFusermountPath(path string) UnmountOpt {
return func(mo *unmountOpts) error {
if filepath.Base(path) == path {
return errFusermountPathInvalid
}
mo.fusermountPath = path
return nil
}
}
// Unmount unmounts the filesystem at mountPath.
//
// Unmount may start one or more underlying processes. By default, stdout and stderr of these
// processes is discarded. To modify this behavior, consider using OptUnmountStdout and/or
// OptUnmountStderr.
//
// By default, Unmount searches for a fusermount binary in the directories named by the PATH
// environment variable. To override this behavior, consider using OptUnmountFusermountPath().
func Unmount(ctx context.Context, mountPath string, opts ...UnmountOpt) error {
uo := unmountOpts{
fusermountPath: "fusermount",
}
for _, opt := range opts {
if err := opt(&uo); err != nil {
return fmt.Errorf("%w", err)
}
}
return unmountSquashFS(ctx, mountPath, uo)
}
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