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|
package pkg
import (
"archive/tar"
"errors"
"fmt"
"io"
"io/fs"
"os"
"path/filepath"
)
// A tarArtifact is an [Artifact] unpacking a tarball backed by a [FileArtifact].
type tarArtifact struct {
// Caller-supplied backing tarball.
f Artifact
}
var _ CuresExempt = new(tarArtifact)
// tarArtifactNamed embeds tarArtifact for a [fmt.Stringer] tarball.
type tarArtifactNamed struct {
tarArtifact
// Copied from tarArtifact.f.
name string
}
var _ fmt.Stringer = new(tarArtifactNamed)
// String returns the name of the underlying [Artifact] prefixed with unpack.
func (a *tarArtifactNamed) String() string { return "unpack-" + a.name }
// NewTar returns a new [Artifact] unpacking the tar stream produced by the
// backing [Artifact]. The source [Artifact] must be a [FileArtifact].
func NewTar(a Artifact) Artifact {
ta := tarArtifact{a}
if s, ok := a.(fmt.Stringer); ok {
if name := s.String(); name != "" {
return &tarArtifactNamed{ta, name}
}
}
return &ta
}
// Kind returns the hardcoded [Kind] constant.
func (a *tarArtifact) Kind() Kind { return KindTar }
// Params is a noop.
func (a *tarArtifact) Params(*IContext) {}
func init() {
register(KindTar, func(r *IRReader) Artifact {
a := NewTar(r.Next())
if _, ok := r.Finalise(); ok {
panic(ErrUnexpectedChecksum)
}
return a
})
}
// Inputs returns a slice containing the backing file.
func (a *tarArtifact) Inputs() []Artifact {
return []Artifact{a.f}
}
// IsExclusive returns false: decompressor and tar reader are fully sequential.
func (a *tarArtifact) IsExclusive() bool { return false }
// 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(t *TContext) (err error) {
var r io.ReadCloser
if r, err = t.Open(a.f); err != nil {
return
}
defer func() {
closeErr := r.Close()
if err == nil {
err = closeErr
}
}()
type dirTargetPerm struct {
path string
mode fs.FileMode
}
var madeDirectories []dirTargetPerm
if err = os.MkdirAll(t.GetTempDir().String(), 0700); err != nil {
return
}
var root *os.Root
if root, err = os.OpenRoot(t.GetTempDir().String()); err != nil {
return
}
defer func() {
closeErr := root.Close()
if err == nil {
err = closeErr
}
}()
var header *tar.Header
tr := tar.NewReader(r)
for header, err = tr.Next(); err == nil; header, err = tr.Next() {
typeflag := header.Typeflag
if typeflag == 0 {
if len(header.Name) > 0 && header.Name[len(header.Name)-1] == '/' {
typeflag = tar.TypeDir
} else {
typeflag = tar.TypeReg
}
}
if typeflag >= '0' && typeflag <= '9' && typeflag != tar.TypeDir {
if err = root.MkdirAll(filepath.Dir(header.Name), 0700); err != nil {
return
}
}
switch typeflag {
case tar.TypeReg:
var f *os.File
if f, err = root.OpenFile(
header.Name,
os.O_CREATE|os.O_EXCL|os.O_WRONLY,
header.FileInfo().Mode()&0500,
); err != nil {
return
}
if _, err = io.Copy(f, tr); err != nil {
_ = f.Close()
return
} else if err = f.Close(); err != nil {
return
}
break
case tar.TypeLink:
if err = root.Link(
header.Linkname,
header.Name,
); err != nil {
return
}
break
case tar.TypeSymlink:
if err = root.Symlink(
header.Linkname,
header.Name,
); err != nil {
return
}
break
case tar.TypeDir:
madeDirectories = append(madeDirectories, dirTargetPerm{
path: header.Name,
mode: header.FileInfo().Mode(),
})
if err = root.MkdirAll(header.Name, 0700); err != nil {
return
}
break
case tar.TypeXGlobalHeader:
continue // ignore
default:
return DisallowedTypeflagError(typeflag)
}
}
if errors.Is(err, io.EOF) {
err = nil
}
if err == nil {
for _, e := range madeDirectories {
if err = root.Chmod(e.path, e.mode&0500); err != nil {
return
}
}
} else {
return
}
temp := t.GetTempDir()
if err = os.Chmod(temp.String(), 0700); err != nil {
return
}
var entries []os.DirEntry
if entries, err = os.ReadDir(temp.String()); err != nil {
return
}
if len(entries) == 1 && entries[0].IsDir() {
p := temp.Append(entries[0].Name())
if err = os.Chmod(p.String(), 0700); err != nil {
return
}
err = os.Rename(p.String(), t.GetWorkDir().String())
} else {
err = os.Rename(temp.String(), t.GetWorkDir().String())
}
return
}
// CuresExempt exempts the cheap [KindTar] implementation often at the end of a
// [FileArtifact] pipeline.
func (*tarArtifact) CuresExempt() {}
|
