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// Copyright (c) 2018-2023, Sylabs Inc. All rights reserved.
// This software is licensed under a 3-clause BSD license. Please consult the
// LICENSE.md file distributed with the sources of this project regarding your
// rights to use or distribute this software.
package oci
import (
"fmt"
"github.com/sylabs/singularity/v4/internal/pkg/util/fs/overlay"
"github.com/sylabs/singularity/v4/pkg/ocibundle/tools"
"github.com/sylabs/singularity/v4/pkg/sylog"
"github.com/sylabs/singularity/v4/pkg/util/singularityconf"
)
// WrapWithWritableTmpFs runs a function wrapped with prep / cleanup steps for a
// tmpfs. This tmpfs is always writable so that the launcher and runtime are
// able to add content to the container. Whether it is writable from inside the
// container is controlled by the runtime config.
func WrapWithWritableTmpFs(f func() error, bundleDir string, allowSetuid bool) error {
overlayDir, err := prepareWritableTmpfs(bundleDir, allowSetuid)
sylog.Debugf("Done with prepareWritableTmpfs; overlayDir is: %q", overlayDir)
if err != nil {
return err
}
err = f()
// Cleanup actions log errors, but don't return - so we get as much cleanup done as possible.
if cleanupErr := cleanupWritableTmpfs(bundleDir, overlayDir); cleanupErr != nil {
sylog.Errorf("While cleaning up writable tmpfs: %v", cleanupErr)
}
// Return any error from the actual container payload - preserve exit code.
return err
}
// WrapWithOverlays runs a function wrapped with prep / cleanup steps for overlays.
func WrapWithOverlays(f func() error, bundleDir string, overlayPaths []string, allowSetuid bool) error {
writableOverlayFound := false
s := overlay.Set{}
for _, p := range overlayPaths {
item, err := overlay.NewItemFromString(p)
if err != nil {
return err
}
item.SetParentDir(bundleDir)
if allowSetuid {
item.SetAllowSetuid(true)
}
if writableOverlayFound && !item.Readonly {
return fmt.Errorf("you can't specify more than one writable overlay; %#v has already been specified as a writable overlay; use '--overlay %s:ro' instead", s.WritableOverlay, item.SourcePath)
}
if !item.Readonly {
writableOverlayFound = true
s.WritableOverlay = item
} else {
s.ReadonlyOverlays = append(s.ReadonlyOverlays, item)
}
}
rootFsDir := tools.RootFs(bundleDir).Path()
err := s.Mount(rootFsDir)
if err != nil {
return err
}
if writableOverlayFound {
err = f()
} else {
err = WrapWithWritableTmpFs(f, bundleDir, allowSetuid)
}
// Cleanup actions log errors, but don't return - so we get as much cleanup done as possible.
if cleanupErr := s.Unmount(rootFsDir); cleanupErr != nil {
sylog.Errorf("While unmounting rootfs overlay: %v", cleanupErr)
}
// Return any error from the actual container payload - preserve exit code.
return err
}
func prepareWritableTmpfs(bundleDir string, allowSetuid bool) (string, error) {
sylog.Debugf("Configuring writable tmpfs overlay for %s", bundleDir)
c := singularityconf.GetCurrentConfig()
if c == nil {
return "", fmt.Errorf("singularity configuration is not initialized")
}
return tools.CreateOverlayTmpfs(bundleDir, int(c.SessiondirMaxSize), allowSetuid)
}
func cleanupWritableTmpfs(bundleDir, overlayDir string) error {
sylog.Debugf("Cleaning up writable tmpfs overlay for %s", bundleDir)
return tools.DeleteOverlayTmpfs(bundleDir, overlayDir)
}
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