feat: Add archiver with filename-embedded headers

cmd/stfs-uvf-with-header/main.go

@@ -0,0 +1,160 @@
+package main
+
+//go:generate sh -c "mkdir -p ../../pkg/api/proto/v1 && protoc --go_out=paths=source_relative,plugins=grpc:../../pkg/api/proto/v1 -I=../../api/proto/v1 ../../api/proto/v1/*.proto"
+
+import (
+	"archive/tar"
+	"encoding/base64"
+	"flag"
+	"io"
+	"io/fs"
+	"log"
+	"os"
+	"path/filepath"
+	"syscall"
+	"time"
+	"unsafe"
+
+	api "github.com/pojntfx/stfs/pkg/api/proto/v1"
+	"golang.org/x/sys/unix"
+	"google.golang.org/protobuf/proto"
+)
+
+// See https://github.com/benmcclelland/mtio
+const (
+	MTIOCTOP = 0x40086d01 // Do magnetic tape operation
+	MTEOM    = 12         // Goto end of recorded media (for appending files)
+
+	STFSVersion = 1
+)
+
+// Operation is struct for MTIOCTOP
+type Operation struct {
+	Op    int16 // Operation ID
+	Pad   int16 // Padding to match C structures
+	Count int32 // Operation count
+}
+
+func main() {
+	file := flag.String("file", "/dev/nst0", "File (tape drive or tar file) to open")
+	dir := flag.String("dir", ".", "Directory to add to the file")
+
+	flag.Parse()
+
+	isRegular := true
+	stat, err := os.Stat(*file)
+	if err == nil {
+		isRegular = stat.Mode().IsRegular()
+	} else {
+		if os.IsNotExist(err) {
+			isRegular = true
+		} else {
+			panic(err)
+		}
+	}
+
+	var f *os.File
+	if isRegular {
+		f, err = os.OpenFile(*file, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)
+		if err != nil {
+			panic(err)
+		}
+
+		// No need to go to end manually due to `os.O_APPEND`
+	} else {
+		// Go to end of file
+		syscall.Syscall(
+			syscall.SYS_IOCTL,
+			f.Fd(),
+			MTIOCTOP,
+			uintptr(unsafe.Pointer(
+				&Operation{
+					Op: MTEOM,
+				},
+			)),
+		)
+
+		f, err = os.OpenFile(*file, os.O_APPEND|os.O_WRONLY, os.ModeCharDevice)
+		if err != nil {
+			panic(err)
+		}
+	}
+	defer f.Close()
+
+	tw := tar.NewWriter(f) // We are not closing the tar writer to prevent writing the trailer
+
+	if err := filepath.Walk(*dir, func(path string, info fs.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		link := ""
+		if info.Mode()&os.ModeSymlink == os.ModeSymlink {
+			if link, err = os.Readlink(path); err != nil {
+				return err
+			}
+		}
+
+		hdr, err := tar.FileInfoHeader(info, link)
+		if err != nil {
+			return err
+		}
+
+		hdr.Format = tar.FormatGNU // Required for AccessTime, ChangeTime etc.
+
+		var unixStat syscall.Stat_t
+		if err := syscall.Stat(path, &unixStat); err != nil {
+			return err
+		}
+
+		mtimesec, mtimensec := unixStat.Mtim.Unix()
+		atimesec, atimensec := unixStat.Atim.Unix()
+		ctimesec, ctimensec := unixStat.Ctim.Unix()
+
+		hdr.ModTime = time.Unix(mtimesec, mtimensec)
+		hdr.AccessTime = time.Unix(atimesec, atimensec)
+		hdr.ChangeTime = time.Unix(ctimesec, ctimensec)
+
+		hdr.Devmajor = int64(unix.Major(unixStat.Dev))
+		hdr.Devminor = int64(unix.Minor(unixStat.Dev))
+
+		wrapper := &api.Wrapper{
+			Version: STFSVersion,
+			Header: &api.Header{
+				Action: api.Action_CREATE,
+				Name:   path,
+			},
+		}
+
+		encodedName, err := proto.Marshal(wrapper)
+		if err != nil {
+			return err
+		}
+
+		hdr.Name = base64.StdEncoding.EncodeToString(encodedName)
+
+		log.Println(hdr)
+
+		if err := tw.WriteHeader(hdr); err != nil {
+			return err
+		}
+
+		if !info.Mode().IsRegular() {
+			return nil
+		}
+
+		file, err := os.Open(path)
+		if err != nil {
+			return err
+		}
+		defer file.Close()
+
+		if _, err := io.Copy(tw, file); err != nil {
+			return err
+		}
+
+		return nil
+	}); err != nil {
+		panic(err)
+	}
+}