lib9p

commit 71591b179b8665ee7e40531f92b5051c47a78297
parent 9dcc186047d9863578b9ec63ef4751eb15882663
Author: Matsuda Kenji <info@mtkn.jp>
Date:   Fri,  3 Nov 2023 16:25:02 +0900

implement semfs

Diffstat:
A
cmd/semfs/fs.go
 | 
160
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
cmd/semfs/main.go
 | 
43
+++++++++++++++++++++++++++++++++++++++++++

2 files changed, 203 insertions(+), 0 deletions(-)
diff --git a/cmd/semfs/fs.go b/cmd/semfs/fs.go
@@ -0,0 +1,160 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"io"
+	"io/fs"
+	"strings"
+	"strconv"
+	"time"
+
+	"git.mtkn.jp/lib9p"
+	"log"
+)
+
+type semFS struct {
+	semfiles []*semFile
+}
+
+func (fsys *semFS) OpenFile(name string, omode lib9p.OpenMode, perm fs.FileMode) (lib9p.File, error) {
+	wnames := strings.Split(name, "/")
+	if len(wnames) != 1 {
+		return nil, errors.New("not found")
+	}
+	switch wnames[0] {
+	case "", ".", "/":
+		return fsys, nil
+	default:
+		for _, f := range fsys.semfiles {
+			if f.name == wnames[0] {
+				return f, nil
+			}
+		}
+		return nil, errors.New("not found")
+	}
+}
+
+func (root *semFS) Stat() (*lib9p.FileInfo, error) {
+	t := uint32(time.Now().Unix())
+	return &lib9p.FileInfo{Stat: lib9p.Stat{
+		Qid:    lib9p.Qid{Type: lib9p.QTDIR, Vers: 0, Path: 0},
+		Mode:   fs.ModeDir | 0777,
+		Atime:  t,
+		Mtime:  t,
+		Length: 0,
+		Name:   ".",
+	}}, nil
+}
+
+func (root *semFS) Close() error { return nil }
+func (root *semFS) Create(name string, uid string, mode lib9p.OpenMode, perm lib9p.FileMode) (lib9p.File, error) {
+	for _, f := range root.semfiles {
+		if f.name == name {
+			return nil, errors.New("file already exists")
+		}
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	newfile := &semFile{
+		name: name,
+		sem: 0,
+		path: uint64(len(root.semfiles)+1),
+		cancel: cancel,
+	}
+	newfile.start(ctx)
+	root.semfiles = append(root.semfiles, newfile)
+	return newfile, nil
+}
+func (root *semFS) Read(p []byte) (n int, err error) {
+	return 0, errors.New("is a directory")
+}
+
+func (root *semFS) ReadDir(n int) ([]*lib9p.DirEntry, error) {
+	de := make([]*lib9p.DirEntry, len(root.semfiles))
+	for i, f := range root.semfiles {
+		fi, err := f.Stat()
+		if err != nil {
+			return nil, err
+		}
+		de[i] = fi
+	}
+	return de, nil
+}
+
+type semFile struct {
+	name string
+	sem  int
+	path uint64
+	offset int
+	rchan chan<- chan struct{}
+	wchan chan<- int
+	queue []chan struct{}
+	cancel context.CancelFunc
+}
+
+func (f *semFile) start(ctx context.Context) {
+	rchan := make(chan chan struct{})
+	wchan := make(chan int)
+	go func(rchan <-chan chan struct{}, wchan <-chan int) {
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case c := <-rchan:
+				if f.sem > 0 {
+					f.sem--
+					close(c)
+				} else {
+					f.queue = append(f.queue, c)
+				}
+			case n := <- wchan:
+				f.sem += n
+				for len(f.queue) > 0 && f.sem > 0 {
+					close(f.queue[0])
+					f.queue = f.queue[1:]
+					f.sem--
+				}
+			}
+		}
+	}(rchan, wchan)
+	f.rchan = rchan
+	f.wchan = wchan
+}
+
+func (f *semFile) Stat() (*lib9p.FileInfo, error) {
+	t := uint32(time.Now().Unix())
+	return &lib9p.FileInfo{Stat: lib9p.Stat{
+		Qid: lib9p.Qid{Type: lib9p.QTFILE, Vers: 0, Path: f.path},
+		Mode: 0666,
+		Atime: t,
+		Mtime: t,
+		Length: int64(f.sem),
+		Name: f.name,
+	}}, nil
+}
+
+func (f *semFile) WStat(stat *lib9p.Stat) error { return nil }
+
+func (f *semFile) Close() error {
+	return nil
+}
+
+func (f *semFile) Read(p []byte) (n int, err error)  {
+	if len(p) > 0 {
+		log.Println("chan")
+		c := make(chan struct{})
+		f.rchan <- c
+		<-c
+		return 0, io.EOF
+	}
+	return 0, nil
+}
+
+func (f *semFile) Write(p []byte) (int, error) {
+	n, err := strconv.Atoi(strings.Split(string(p), "\n")[0])
+	if err != nil {
+		return 0, errors.New("invalid sem")
+	}
+	f.wchan <- n
+	return len(p), nil
+}
diff --git a/cmd/semfs/main.go b/cmd/semfs/main.go
@@ -0,0 +1,43 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"net"
+	"os"
+
+	"git.mtkn.jp/lib9p"
+)
+
+var dFlag = flag.Bool("D", false, "Prints chatty message to the stderr.")
+
+func main() {
+	flag.Parse()
+	if flag.NArg() != 0 {
+		fmt.Fprintf(os.Stderr, "usage: %s [-D]\n", os.Args[0])
+		os.Exit(1)
+	}
+	listener, err := net.Listen("tcp", "127.0.0.1:5640")
+	if err != nil {
+		log.Fatalf("listen tcp: %v", err)
+	}
+	fsys := new(semFS)
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			log.Printf("accept connection: %v", err)
+			continue
+		}
+		go handle(conn, fsys)
+	}
+}
+
+func handle(conn net.Conn, fsys *semFS) {
+	srv := lib9p.NewServer(fsys, 8*1024, conn, conn)
+	if *dFlag {
+		srv.Chatty()
+	}
+	srv.Serve(context.Background())
+}