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directory.go
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directory.go
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// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) 2022, Unikraft GmbH and The KraftKit Authors.
// Licensed under the BSD-3-Clause License (the "License").
// You may not use this file except in compliance with the License.
package initrd
import (
"context"
"fmt"
"io/fs"
"os"
"path/filepath"
"strings"
"github.com/cavaliergopher/cpio"
"kraftkit.sh/log"
)
type directory struct {
opts InitrdOptions
path string
files []string
}
// NewFromDirectory returns an instantiated Initrd interface which is is able to
// serialize a rootfs from a given directory.
func NewFromDirectory(_ context.Context, path string, opts ...InitrdOption) (Initrd, error) {
rootfs := directory{
opts: InitrdOptions{},
path: path,
}
for _, opt := range opts {
if err := opt(&rootfs.opts); err != nil {
return nil, err
}
}
fi, err := os.Stat(path)
if err != nil && os.IsNotExist(err) {
return nil, fmt.Errorf("file does not exist: %s", path)
} else if err != nil {
return nil, fmt.Errorf("could not check path: %w", err)
} else if !fi.IsDir() {
return nil, fmt.Errorf("supplied path is not a directory: %s", path)
}
return &rootfs, nil
}
// Build implements Initrd.
func (initrd *directory) Build(ctx context.Context) (string, error) {
if initrd.opts.output == "" {
fi, err := os.CreateTemp("", "")
if err != nil {
return "", fmt.Errorf("could not make temporary directory: %w", err)
}
initrd.opts.output = fi.Name()
}
f, err := os.OpenFile(initrd.opts.output, os.O_RDWR|os.O_CREATE, 0o644)
if err != nil {
return "", fmt.Errorf("could not open initramfs file: %w", err)
}
defer f.Close()
writer := cpio.NewWriter(f)
defer writer.Close()
if err := filepath.WalkDir(initrd.path, func(path string, d fs.DirEntry, err error) error {
if err != nil {
return fmt.Errorf("received error before parsing path: %w", err)
}
internal := strings.TrimPrefix(path, filepath.Clean(initrd.path))
if internal == "" {
return nil // Do not archive empty paths
}
info, err := d.Info()
if err != nil {
return fmt.Errorf("could not get directory entry info: %w", err)
}
if d.Type().IsDir() {
if err := writer.WriteHeader(&cpio.Header{
Name: internal,
Mode: cpio.TypeDir,
}); err != nil {
return fmt.Errorf("could not write CPIO header: %w", err)
}
return nil
}
initrd.files = append(initrd.files, internal)
log.G(ctx).
WithField("file", internal).
Trace("archiving")
var data []byte
targetLink := ""
if info.Mode()&os.ModeSymlink != 0 {
targetLink, err = os.Readlink(path)
data = []byte(targetLink)
} else if d.Type().IsRegular() {
data, err = os.ReadFile(path)
} else {
log.G(ctx).Warnf("unsupported file: %s", path)
return nil
}
if err != nil {
return fmt.Errorf("could not read file: %w", err)
}
if err := writer.WriteHeader(&cpio.Header{
Name: internal,
Linkname: targetLink,
Mode: cpio.FileMode(d.Type().Perm()),
Size: info.Size(),
}); err != nil {
return err
}
if _, err := writer.Write(data); err != nil {
return fmt.Errorf("could not write CPIO data: %w", err)
}
return nil
}); err != nil {
return "", fmt.Errorf("could not walk output path: %w", err)
}
return initrd.opts.output, nil
}
// Files implements Initrd.
func (initrd *directory) Files() []string {
return initrd.files
}