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|
package pkg
import (
"archive/tar"
"bytes"
"compress/gzip"
"context"
"encoding/binary"
"errors"
"io"
"io/fs"
"net/http"
"os"
"hakurei.app/container/check"
)
const (
// TarUncompressed denotes an uncompressed tarball.
TarUncompressed = iota
// TarGzip denotes a tarball compressed via [gzip].
TarGzip
)
// A tarArtifact is an [Artifact] unpacking a tarball backed by a [File].
type tarArtifact struct {
// Caller-supplied backing tarball.
f File
// Compression on top of the tarball.
compression uint64
}
// NewTar returns a new [Artifact] backed by the supplied [File] and
// compression method.
func NewTar(f File, compression uint64) Artifact {
return &tarArtifact{f: f, compression: compression}
}
// NewHTTPGetTar is abbreviation for NewHTTPGet passed to NewTar.
func NewHTTPGetTar(
ctx context.Context,
hc *http.Client,
url string,
checksum Checksum,
compression uint64,
) Artifact {
return NewTar(NewHTTPGet(ctx, hc, url, checksum), compression)
}
// Kind returns the hardcoded [Kind] constant.
func (a *tarArtifact) Kind() Kind { return KindTar }
// Params returns compression encoded in little endian.
func (a *tarArtifact) Params() []byte {
return binary.LittleEndian.AppendUint64(nil, a.compression)
}
// Dependencies returns a slice containing the backing file.
func (a *tarArtifact) Dependencies() []Artifact {
return []Artifact{a.f}
}
// A DisallowedTypeflagError describes a disallowed typeflag encountered while
// unpacking a tarball.
type DisallowedTypeflagError byte
func (e DisallowedTypeflagError) Error() string {
return "disallowed typeflag '" + string(e) + "'"
}
// Cure cures the [Artifact], producing a directory located at work.
func (a *tarArtifact) Cure(work *check.Absolute, loadData CacheDataFunc) (err error) {
var tr io.ReadCloser
{
var data []byte
data, err = loadData(a.f)
if err != nil {
return
}
tr = io.NopCloser(bytes.NewReader(data))
}
defer func() {
closeErr := tr.Close()
if err == nil {
err = closeErr
}
}()
switch a.compression {
case TarUncompressed:
break
case TarGzip:
if tr, err = gzip.NewReader(tr); err != nil {
return
}
break
default:
return os.ErrInvalid
}
type dirTargetPerm struct {
path *check.Absolute
mode fs.FileMode
}
var madeDirectories []dirTargetPerm
var header *tar.Header
r := tar.NewReader(tr)
for header, err = r.Next(); err == nil; header, err = r.Next() {
typeflag := header.Typeflag
for {
switch typeflag {
case 0:
if len(header.Name) > 0 && header.Name[len(header.Name)-1] == '/' {
typeflag = tar.TypeDir
} else {
typeflag = tar.TypeReg
}
continue
case tar.TypeReg:
var f *os.File
if f, err = os.OpenFile(
work.Append(header.Name).String(),
os.O_CREATE|os.O_EXCL|os.O_WRONLY,
header.FileInfo().Mode()&0400,
); err != nil {
return
}
if _, err = io.Copy(f, r); err != nil {
_ = f.Close()
return
} else if err = f.Close(); err != nil {
return
}
break
case tar.TypeLink:
if err = os.Link(
header.Linkname,
work.Append(header.Name).String(),
); err != nil {
return
}
break
case tar.TypeSymlink:
if err = os.Symlink(
header.Linkname,
work.Append(header.Name).String(),
); err != nil {
return
}
break
case tar.TypeDir:
pathname := work.Append(header.Name)
madeDirectories = append(madeDirectories, dirTargetPerm{
path: pathname,
mode: header.FileInfo().Mode(),
})
if err = os.MkdirAll(
pathname.String(),
0700,
); err != nil {
return
}
break
case tar.TypeXGlobalHeader:
// ignore
break
default:
return DisallowedTypeflagError(typeflag)
}
break
}
}
if errors.Is(err, io.EOF) {
err = nil
}
if err == nil {
for _, e := range madeDirectories {
if err = os.Chmod(e.path.String(), e.mode&0500); err != nil {
return
}
}
err = os.Chmod(work.String(), 0500)
}
return
}
|
