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port over tar/xz decompressors (#2139)
Signed-off-by: Alex Goodman <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,220 @@ | ||
| package file | ||
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| import ( | ||
| "archive/tar" | ||
| "fmt" | ||
| "io" | ||
| "os" | ||
| "path/filepath" | ||
| "strings" | ||
| "time" | ||
|
|
||
| "github.com/spf13/afero" | ||
| "github.com/xi2/xz" | ||
| ) | ||
|
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| // Note: this is a copy of the TarXzDecompressor from https://github.com/hashicorp/go-getter/blob/v2.2.3/decompress_txz.go | ||
| // with the xz lib swapped out (for performance). A few adjustments were made: | ||
| // - refactored to use afero filesystem abstraction | ||
| // - fixed some linting issues | ||
|
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| // TarXzDecompressor is an implementation of Decompressor that can | ||
| // decompress tar.xz files. | ||
| type tarXzDecompressor struct { | ||
| // FileSizeLimit limits the total size of all | ||
| // decompressed files. | ||
| // | ||
| // The zero value means no limit. | ||
| FileSizeLimit int64 | ||
|
|
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| // FilesLimit limits the number of files that are | ||
| // allowed to be decompressed. | ||
| // | ||
| // The zero value means no limit. | ||
| FilesLimit int | ||
|
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| Fs afero.Fs | ||
| } | ||
|
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| func (d *tarXzDecompressor) Decompress(dst, src string, dir bool, umask os.FileMode) error { | ||
| // If we're going into a directory we should make that first | ||
| mkdir := dst | ||
| if !dir { | ||
| mkdir = filepath.Dir(dst) | ||
| } | ||
| if err := d.Fs.MkdirAll(mkdir, mode(0755, umask)); err != nil { | ||
| return err | ||
| } | ||
|
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| // File first | ||
| f, err := d.Fs.Open(src) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer f.Close() | ||
|
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| // xz compression is second | ||
| txzR, err := xz.NewReader(f, 0) | ||
| if err != nil { | ||
| return fmt.Errorf("error opening an xz reader for %s: %s", src, err) | ||
| } | ||
|
|
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| return untar(d.Fs, txzR, dst, src, dir, umask, d.FileSizeLimit, d.FilesLimit) | ||
| } | ||
|
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| // untar is a shared helper for untarring an archive. The reader should provide | ||
| // an uncompressed view of the tar archive. | ||
| func untar(fs afero.Fs, input io.Reader, dst, src string, dir bool, umask os.FileMode, fileSizeLimit int64, filesLimit int) error { // nolint:funlen,gocognit | ||
| tarR := tar.NewReader(input) | ||
| done := false | ||
| dirHdrs := []*tar.Header{} | ||
| now := time.Now() | ||
|
|
||
| var ( | ||
| fileSize int64 | ||
| filesCount int | ||
| ) | ||
|
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||
| for { | ||
| if filesLimit > 0 { | ||
| filesCount++ | ||
| if filesCount > filesLimit { | ||
| return fmt.Errorf("tar archive contains too many files: %d > %d", filesCount, filesLimit) | ||
| } | ||
| } | ||
|
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| hdr, err := tarR.Next() | ||
| if err == io.EOF { | ||
| if !done { | ||
| // Empty archive | ||
| return fmt.Errorf("empty archive: %s", src) | ||
| } | ||
|
|
||
| break | ||
| } | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
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| switch hdr.Typeflag { | ||
| case tar.TypeSymlink, tar.TypeLink: | ||
| // to prevent any potential indirect traversal attacks | ||
| continue | ||
| case tar.TypeXGlobalHeader, tar.TypeXHeader: | ||
| // don't unpack extended headers as files | ||
| continue | ||
| } | ||
|
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| path := dst | ||
| if dir { | ||
| // Disallow parent traversal | ||
| if containsDotDot(hdr.Name) { | ||
| return fmt.Errorf("entry contains '..': %s", hdr.Name) | ||
| } | ||
|
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| path = filepath.Join(path, hdr.Name) // nolint:gosec // hdr.Name is checked above | ||
| } | ||
|
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| fileInfo := hdr.FileInfo() | ||
|
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| fileSize += fileInfo.Size() | ||
|
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| if fileSizeLimit > 0 && fileSize > fileSizeLimit { | ||
| return fmt.Errorf("tar archive larger than limit: %d", fileSizeLimit) | ||
| } | ||
|
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| if fileInfo.IsDir() { | ||
| if !dir { | ||
| return fmt.Errorf("expected a single file: %s", src) | ||
| } | ||
|
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| // A directory, just make the directory and continue unarchiving... | ||
| if err := fs.MkdirAll(path, mode(0755, umask)); err != nil { | ||
| return err | ||
| } | ||
|
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| // Record the directory information so that we may set its attributes | ||
| // after all files have been extracted | ||
| dirHdrs = append(dirHdrs, hdr) | ||
|
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| continue | ||
| } | ||
| // There is no ordering guarantee that a file in a directory is | ||
| // listed before the directory | ||
| dstPath := filepath.Dir(path) | ||
|
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| // Check that the directory exists, otherwise create it | ||
| if _, err := fs.Stat(dstPath); os.IsNotExist(err) { | ||
| if err := fs.MkdirAll(dstPath, mode(0755, umask)); err != nil { | ||
| return err | ||
| } | ||
| } | ||
|
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| // We have a file. If we already decoded, then it is an error | ||
| if !dir && done { | ||
| return fmt.Errorf("expected a single file, got multiple: %s", src) | ||
| } | ||
|
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| // Mark that we're done so future in single file mode errors | ||
| done = true | ||
|
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| // Size limit is tracked using the returned file info. | ||
| err = copyReader(fs, path, tarR, hdr.FileInfo().Mode(), umask, 0) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
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| // Set the access and modification time if valid, otherwise default to current time | ||
| aTime := now | ||
| mTime := now | ||
| if hdr.AccessTime.Unix() > 0 { | ||
| aTime = hdr.AccessTime | ||
| } | ||
| if hdr.ModTime.Unix() > 0 { | ||
| mTime = hdr.ModTime | ||
| } | ||
| if err := fs.Chtimes(path, aTime, mTime); err != nil { | ||
| return err | ||
| } | ||
| } | ||
|
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| // Perform a final pass over extracted directories to update metadata | ||
| for _, dirHdr := range dirHdrs { | ||
| path := filepath.Join(dst, dirHdr.Name) // nolint:gosec // hdr.Name is checked above | ||
| // Chmod the directory since they might be created before we know the mode flags | ||
| if err := fs.Chmod(path, mode(dirHdr.FileInfo().Mode(), umask)); err != nil { | ||
| return err | ||
| } | ||
| // Set the mtime/atime attributes since they would have been changed during extraction | ||
| aTime := now | ||
| mTime := now | ||
| if dirHdr.AccessTime.Unix() > 0 { | ||
| aTime = dirHdr.AccessTime | ||
| } | ||
| if dirHdr.ModTime.Unix() > 0 { | ||
| mTime = dirHdr.ModTime | ||
| } | ||
| if err := fs.Chtimes(path, aTime, mTime); err != nil { | ||
| return err | ||
| } | ||
| } | ||
|
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| return nil | ||
| } | ||
|
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| // containsDotDot checks if the filepath value v contains a ".." entry. | ||
| // This will check filepath components by splitting along / or \. This | ||
| // function is copied directly from the Go net/http implementation. | ||
| func containsDotDot(v string) bool { | ||
| if !strings.Contains(v, "..") { | ||
| return false | ||
| } | ||
| for _, ent := range strings.FieldsFunc(v, isSlashRune) { | ||
| if ent == ".." { | ||
| return true | ||
| } | ||
| } | ||
| return false | ||
| } | ||
|
|
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| func isSlashRune(r rune) bool { return r == '/' || r == '\\' } |
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