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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build js && wasm
package syscall
import (
"errors"
"sync"
"syscall/js"
)
// Provided by package runtime.
func now() (sec int64, nsec int32)
var jsProcess = js.Global().Get("process")
var jsFS = js.Global().Get("fs")
var constants = jsFS.Get("constants")
var uint8Array = js.Global().Get("Uint8Array")
var (
nodeWRONLY = constants.Get("O_WRONLY").Int()
nodeRDWR = constants.Get("O_RDWR").Int()
nodeCREATE = constants.Get("O_CREAT").Int()
nodeTRUNC = constants.Get("O_TRUNC").Int()
nodeAPPEND = constants.Get("O_APPEND").Int()
nodeEXCL = constants.Get("O_EXCL").Int()
)
type jsFile struct {
path string
entries []string
dirIdx int // entries[:dirIdx] have already been returned in ReadDirent
pos int64
seeked bool
}
var filesMu sync.Mutex
var files = map[int]*jsFile{
0: {},
1: {},
2: {},
}
func fdToFile(fd int) (*jsFile, error) {
filesMu.Lock()
f, ok := files[fd]
filesMu.Unlock()
if !ok {
return nil, EBADF
}
return f, nil
}
func Open(path string, openmode int, perm uint32) (int, error) {
if err := checkPath(path); err != nil {
return 0, err
}
flags := 0
if openmode&O_WRONLY != 0 {
flags |= nodeWRONLY
}
if openmode&O_RDWR != 0 {
flags |= nodeRDWR
}
if openmode&O_CREATE != 0 {
flags |= nodeCREATE
}
if openmode&O_TRUNC != 0 {
flags |= nodeTRUNC
}
if openmode&O_APPEND != 0 {
flags |= nodeAPPEND
}
if openmode&O_EXCL != 0 {
flags |= nodeEXCL
}
if openmode&O_SYNC != 0 {
return 0, errors.New("syscall.Open: O_SYNC is not supported by js/wasm")
}
jsFD, err := fsCall("open", path, flags, perm)
if err != nil {
return 0, err
}
fd := jsFD.Int()
var entries []string
if stat, err := fsCall("fstat", fd); err == nil && stat.Call("isDirectory").Bool() {
dir, err := fsCall("readdir", path)
if err != nil {
return 0, err
}
entries = make([]string, dir.Length())
for i := range entries {
entries[i] = dir.Index(i).String()
}
}
if path[0] != '/' {
cwd := jsProcess.Call("cwd").String()
path = cwd + "/" + path
}
f := &jsFile{
path: path,
entries: entries,
}
filesMu.Lock()
files[fd] = f
filesMu.Unlock()
return fd, nil
}
func Close(fd int) error {
filesMu.Lock()
delete(files, fd)
filesMu.Unlock()
_, err := fsCall("close", fd)
return err
}
func CloseOnExec(fd int) {
// nothing to do - no exec
}
func Mkdir(path string, perm uint32) error {
if err := checkPath(path); err != nil {
return err
}
_, err := fsCall("mkdir", path, perm)
return err
}
func ReadDirent(fd int, buf []byte) (int, error) {
f, err := fdToFile(fd)
if err != nil {
return 0, err
}
if f.entries == nil {
return 0, EINVAL
}
n := 0
for f.dirIdx < len(f.entries) {
entry := f.entries[f.dirIdx]
l := 2 + len(entry)
if l > len(buf) {
break
}
buf[0] = byte(l)
buf[1] = byte(l >> 8)
copy(buf[2:], entry)
buf = buf[l:]
n += l
f.dirIdx++
}
return n, nil
}
func setStat(st *Stat_t, jsSt js.Value) {
st.Dev = int64(jsSt.Get("dev").Int())
st.Ino = uint64(jsSt.Get("ino").Int())
st.Mode = uint32(jsSt.Get("mode").Int())
st.Nlink = uint32(jsSt.Get("nlink").Int())
st.Uid = uint32(jsSt.Get("uid").Int())
st.Gid = uint32(jsSt.Get("gid").Int())
st.Rdev = int64(jsSt.Get("rdev").Int())
st.Size = int64(jsSt.Get("size").Int())
st.Blksize = int32(jsSt.Get("blksize").Int())
st.Blocks = int32(jsSt.Get("blocks").Int())
atime := int64(jsSt.Get("atimeMs").Int())
st.Atime = atime / 1000
st.AtimeNsec = (atime % 1000) * 1000000
mtime := int64(jsSt.Get("mtimeMs").Int())
st.Mtime = mtime / 1000
st.MtimeNsec = (mtime % 1000) * 1000000
ctime := int64(jsSt.Get("ctimeMs").Int())
st.Ctime = ctime / 1000
st.CtimeNsec = (ctime % 1000) * 1000000
}
func Stat(path string, st *Stat_t) error {
if err := checkPath(path); err != nil {
return err
}
jsSt, err := fsCall("stat", path)
if err != nil {
return err
}
setStat(st, jsSt)
return nil
}
func Lstat(path string, st *Stat_t) error {
if err := checkPath(path); err != nil {
return err
}
jsSt, err := fsCall("lstat", path)
if err != nil {
return err
}
setStat(st, jsSt)
return nil
}
func Fstat(fd int, st *Stat_t) error {
jsSt, err := fsCall("fstat", fd)
if err != nil {
return err
}
setStat(st, jsSt)
return nil
}
func Unlink(path string) error {
if err := checkPath(path); err != nil {
return err
}
_, err := fsCall("unlink", path)
return err
}
func Rmdir(path string) error {
if err := checkPath(path); err != nil {
return err
}
_, err := fsCall("rmdir", path)
return err
}
func Chmod(path string, mode uint32) error {
if err := checkPath(path); err != nil {
return err
}
_, err := fsCall("chmod", path, mode)
return err
}
func Fchmod(fd int, mode uint32) error {
_, err := fsCall("fchmod", fd, mode)
return err
}
func Chown(path string, uid, gid int) error {
if err := checkPath(path); err != nil {
return err
}
_, err := fsCall("chown", path, uint32(uid), uint32(gid))
return err
}
func Fchown(fd int, uid, gid int) error {
_, err := fsCall("fchown", fd, uint32(uid), uint32(gid))
return err
}
func Lchown(path string, uid, gid int) error {
if err := checkPath(path); err != nil {
return err
}
if jsFS.Get("lchown").IsUndefined() {
// fs.lchown is unavailable on Linux until Node.js 10.6.0
// TODO(neelance): remove when we require at least this Node.js version
return ENOSYS
}
_, err := fsCall("lchown", path, uint32(uid), uint32(gid))
return err
}
func UtimesNano(path string, ts []Timespec) error {
if err := checkPath(path); err != nil {
return err
}
if len(ts) != 2 {
return EINVAL
}
atime := ts[0].Sec
mtime := ts[1].Sec
_, err := fsCall("utimes", path, atime, mtime)
return err
}
func Rename(from, to string) error {
if err := checkPath(from); err != nil {
return err
}
if err := checkPath(to); err != nil {
return err
}
_, err := fsCall("rename", from, to)
return err
}
func Truncate(path string, length int64) error {
if err := checkPath(path); err != nil {
return err
}
_, err := fsCall("truncate", path, length)
return err
}
func Ftruncate(fd int, length int64) error {
_, err := fsCall("ftruncate", fd, length)
return err
}
func Getcwd(buf []byte) (n int, err error) {
defer recoverErr(&err)
cwd := jsProcess.Call("cwd").String()
n = copy(buf, cwd)
return
}
func Chdir(path string) (err error) {
if err := checkPath(path); err != nil {
return err
}
defer recoverErr(&err)
jsProcess.Call("chdir", path)
return
}
func Fchdir(fd int) error {
f, err := fdToFile(fd)
if err != nil {
return err
}
return Chdir(f.path)
}
func Readlink(path string, buf []byte) (n int, err error) {
if err := checkPath(path); err != nil {
return 0, err
}
dst, err := fsCall("readlink", path)
if err != nil {
return 0, err
}
n = copy(buf, dst.String())
return n, nil
}
func Link(path, link string) error {
if err := checkPath(path); err != nil {
return err
}
if err := checkPath(link); err != nil {
return err
}
_, err := fsCall("link", path, link)
return err
}
func Symlink(path, link string) error {
if err := checkPath(path); err != nil {
return err
}
if err := checkPath(link); err != nil {
return err
}
_, err := fsCall("symlink", path, link)
return err
}
func Fsync(fd int) error {
_, err := fsCall("fsync", fd)
return err
}
func Read(fd int, b []byte) (int, error) {
f, err := fdToFile(fd)
if err != nil {
return 0, err
}
if f.seeked {
n, err := Pread(fd, b, f.pos)
f.pos += int64(n)
return n, err
}
buf := uint8Array.New(len(b))
n, err := fsCall("read", fd, buf, 0, len(b), nil)
if err != nil {
return 0, err
}
js.CopyBytesToGo(b, buf)
n2 := n.Int()
f.pos += int64(n2)
return n2, err
}
func Write(fd int, b []byte) (int, error) {
f, err := fdToFile(fd)
if err != nil {
return 0, err
}
if f.seeked {
n, err := Pwrite(fd, b, f.pos)
f.pos += int64(n)
return n, err
}
if faketime && (fd == 1 || fd == 2) {
n := faketimeWrite(fd, b)
if n < 0 {
return 0, errnoErr(Errno(-n))
}
return n, nil
}
buf := uint8Array.New(len(b))
js.CopyBytesToJS(buf, b)
n, err := fsCall("write", fd, buf, 0, len(b), nil)
if err != nil {
return 0, err
}
n2 := n.Int()
f.pos += int64(n2)
return n2, err
}
func Pread(fd int, b []byte, offset int64) (int, error) {
buf := uint8Array.New(len(b))
n, err := fsCall("read", fd, buf, 0, len(b), offset)
if err != nil {
return 0, err
}
js.CopyBytesToGo(b, buf)
return n.Int(), nil
}
func Pwrite(fd int, b []byte, offset int64) (int, error) {
buf := uint8Array.New(len(b))
js.CopyBytesToJS(buf, b)
n, err := fsCall("write", fd, buf, 0, len(b), offset)
if err != nil {
return 0, err
}
return n.Int(), nil
}
func Seek(fd int, offset int64, whence int) (int64, error) {
f, err := fdToFile(fd)
if err != nil {
return 0, err
}
var newPos int64
switch whence {
case 0:
newPos = offset
case 1:
newPos = f.pos + offset
case 2:
var st Stat_t
if err := Fstat(fd, &st); err != nil {
return 0, err
}
newPos = st.Size + offset
default:
return 0, errnoErr(EINVAL)
}
if newPos < 0 {
return 0, errnoErr(EINVAL)
}
f.seeked = true
f.dirIdx = 0 // Reset directory read position. See issue 35767.
f.pos = newPos
return newPos, nil
}
func Dup(fd int) (int, error) {
return 0, ENOSYS
}
func Dup2(fd, newfd int) error {
return ENOSYS
}
func Pipe(fd []int) error {
return ENOSYS
}
func fsCall(name string, args ...any) (js.Value, error) {
type callResult struct {
val js.Value
err error
}
c := make(chan callResult, 1)
f := js.FuncOf(func(this js.Value, args []js.Value) any {
var res callResult
if len(args) >= 1 { // on Node.js 8, fs.utimes calls the callback without any arguments
if jsErr := args[0]; !jsErr.IsNull() {
res.err = mapJSError(jsErr)
}
}
res.val = js.Undefined()
if len(args) >= 2 {
res.val = args[1]
}
c <- res
return nil
})
defer f.Release()
jsFS.Call(name, append(args, f)...)
res := <-c
return res.val, res.err
}
// checkPath checks that the path is not empty and that it contains no null characters.
func checkPath(path string) error {
if path == "" {
return EINVAL
}
for i := 0; i < len(path); i++ {
if path[i] == '\x00' {
return EINVAL
}
}
return nil
}
func recoverErr(errPtr *error) {
if err := recover(); err != nil {
jsErr, ok := err.(js.Error)
if !ok {
panic(err)
}
*errPtr = mapJSError(jsErr.Value)
}
}
// mapJSError maps an error given by Node.js to the appropriate Go error
func mapJSError(jsErr js.Value) error {
errno, ok := errnoByCode[jsErr.Get("code").String()]
if !ok {
panic(jsErr)
}
return errnoErr(Errno(errno))
}