internal: add wasip1 support

For #58141

Co-authored-by: Richard Musiol <neelance@gmail.com>
Co-authored-by: Achille Roussel <achille.roussel@gmail.com>
Co-authored-by: Julien Fabre <ju.pryz@gmail.com>
Co-authored-by: Evan Phoenix <evan@phx.io>
Change-Id: I1488726e5b43cd21c5f83900476afd2fb63d70c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/479622
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>

src/cmd/dist/test.go

@@ -1476,6 +1476,9 @@ func (t *tester) hasSwig() bool {
 	return true
 }
 
+// hasParallelism is a copy of the function
+// internal/testenv.HasParallelism, which can't be used here
+// because cmd/dist can not import internal packages during bootstrap.
 func (t *tester) hasParallelism() bool {
 	switch goos {
 	case "js", "wasip1":

src/internal/poll/fcntl_wasm.go

@@ -2,13 +2,13 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build js && wasm
+//go:build (js && wasm) || wasip1
 
 package poll
 
 import "syscall"
 
-// fcntl not supported on js/wasm
+// fcntl not supported on js/wasm or wasip1/wasm.
 func fcntl(fd int, cmd int, arg int) (int, error) {
 	return 0, syscall.ENOSYS
 }

src/internal/poll/fd_fsync_posix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build aix || dragonfly || freebsd || (js && wasm) || linux || netbsd || openbsd || solaris
+//go:build aix || dragonfly || freebsd || (js && wasm) || linux || netbsd || openbsd || solaris || wasip1
 
 package poll
 

src/internal/poll/fd_poll_wasm.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build js && wasm
+//go:build (js && wasm) || wasip1
 
 package poll
 
@@ -42,7 +42,7 @@ func (pd *pollDesc) wait(mode int, isFile bool) error {
 	if pd.closing {
 		return errClosing(isFile)
 	}
-	if isFile { // TODO(neelance): wasm: Use callbacks from JS to block until the read/write finished.
+	if isFile { // TODO(neelance): js/wasm: Use callbacks from JS to block until the read/write finished.
 		return nil
 	}
 	return ErrDeadlineExceeded

src/internal/poll/fd_posix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build unix || (js && wasm) || windows
+//go:build unix || (js && wasm) || wasip1 || windows
 
 package poll
 

src/internal/poll/fd_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build unix || (js && wasm)
+//go:build unix || (js && wasm) || wasip1
 
 package poll
 
@@ -22,12 +22,12 @@ type FD struct {
 	// System file descriptor. Immutable until Close.
 	Sysfd int
 
+	// Platform dependent state of the file descriptor.
+	SysFile
+
 	// I/O poller.
 	pd pollDesc
 
-	// Writev cache.
-	iovecs *[]syscall.Iovec
-
 	// Semaphore signaled when file is closed.
 	csema uint32
 
@@ -625,38 +625,6 @@ func (fd *FD) Accept() (int, syscall.Sockaddr, string, error) {
 	}
 }
 
-// Seek wraps syscall.Seek.
-func (fd *FD) Seek(offset int64, whence int) (int64, error) {
-	if err := fd.incref(); err != nil {
-		return 0, err
-	}
-	defer fd.decref()
-	return syscall.Seek(fd.Sysfd, offset, whence)
-}
-
-// ReadDirent wraps syscall.ReadDirent.
-// We treat this like an ordinary system call rather than a call
-// that tries to fill the buffer.
-func (fd *FD) ReadDirent(buf []byte) (int, error) {
-	if err := fd.incref(); err != nil {
-		return 0, err
-	}
-	defer fd.decref()
-	for {
-		n, err := ignoringEINTRIO(syscall.ReadDirent, fd.Sysfd, buf)
-		if err != nil {
-			n = 0
-			if err == syscall.EAGAIN && fd.pd.pollable() {
-				if err = fd.pd.waitRead(fd.isFile); err == nil {
-					continue
-				}
-			}
-		}
-		// Do not call eofError; caller does not expect to see io.EOF.
-		return n, err
-	}
-}
-
 // Fchmod wraps syscall.Fchmod.
 func (fd *FD) Fchmod(mode uint32) error {
 	if err := fd.incref(); err != nil {
@@ -668,15 +636,6 @@ func (fd *FD) Fchmod(mode uint32) error {
 	})
 }
 
-// Fchdir wraps syscall.Fchdir.
-func (fd *FD) Fchdir() error {
-	if err := fd.incref(); err != nil {
-		return err
-	}
-	defer fd.decref()
-	return syscall.Fchdir(fd.Sysfd)
-}
-
 // Fstat wraps syscall.Fstat
 func (fd *FD) Fstat(s *syscall.Stat_t) error {
 	if err := fd.incref(); err != nil {
@@ -711,19 +670,6 @@ func DupCloseOnExec(fd int) (int, string, error) {
 	return dupCloseOnExecOld(fd)
 }
 
-// dupCloseOnExecOld is the traditional way to dup an fd and
-// set its O_CLOEXEC bit, using two system calls.
-func dupCloseOnExecOld(fd int) (int, string, error) {
-	syscall.ForkLock.RLock()
-	defer syscall.ForkLock.RUnlock()
-	newfd, err := syscall.Dup(fd)
-	if err != nil {
-		return -1, "dup", err
-	}
-	syscall.CloseOnExec(newfd)
-	return newfd, "", nil
-}
-
 // Dup duplicates the file descriptor.
 func (fd *FD) Dup() (int, string, error) {
 	if err := fd.incref(); err != nil {

src/internal/poll/fd_unixjs.go

@@ -0,0 +1,68 @@
+// Copyright 2023 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 unix || (js && wasm)
+
+package poll
+
+import "syscall"
+
+type SysFile struct {
+	// Writev cache.
+	iovecs *[]syscall.Iovec
+}
+
+// dupCloseOnExecOld is the traditional way to dup an fd and
+// set its O_CLOEXEC bit, using two system calls.
+func dupCloseOnExecOld(fd int) (int, string, error) {
+	syscall.ForkLock.RLock()
+	defer syscall.ForkLock.RUnlock()
+	newfd, err := syscall.Dup(fd)
+	if err != nil {
+		return -1, "dup", err
+	}
+	syscall.CloseOnExec(newfd)
+	return newfd, "", nil
+}
+
+// Fchdir wraps syscall.Fchdir.
+func (fd *FD) Fchdir() error {
+	if err := fd.incref(); err != nil {
+		return err
+	}
+	defer fd.decref()
+	return syscall.Fchdir(fd.Sysfd)
+}
+
+// ReadDirent wraps syscall.ReadDirent.
+// We treat this like an ordinary system call rather than a call
+// that tries to fill the buffer.
+func (fd *FD) ReadDirent(buf []byte) (int, error) {
+	if err := fd.incref(); err != nil {
+		return 0, err
+	}
+	defer fd.decref()
+	for {
+		n, err := ignoringEINTRIO(syscall.ReadDirent, fd.Sysfd, buf)
+		if err != nil {
+			n = 0
+			if err == syscall.EAGAIN && fd.pd.pollable() {
+				if err = fd.pd.waitRead(fd.isFile); err == nil {
+					continue
+				}
+			}
+		}
+		// Do not call eofError; caller does not expect to see io.EOF.
+		return n, err
+	}
+}
+
+// Seek wraps syscall.Seek.
+func (fd *FD) Seek(offset int64, whence int) (int64, error) {
+	if err := fd.incref(); err != nil {
+		return 0, err
+	}
+	defer fd.decref()
+	return syscall.Seek(fd.Sysfd, offset, whence)
+}

src/internal/poll/fd_wasip1.go

@@ -0,0 +1,186 @@
+// Copyright 2023 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.
+
+package poll
+
+import (
+	"sync/atomic"
+	"syscall"
+	"unsafe"
+)
+
+type SysFile struct {
+	// Cache for the file type, lazily initialized when Seek is called.
+	Filetype uint32
+
+	// If the file represents a directory, this field contains the current
+	// readdir position. It is reset to zero if the program calls Seek(0, 0).
+	Dircookie uint64
+
+	// Absolute path of the file, as returned by syscall.PathOpen;
+	// this is used by Fchdir to emulate setting the current directory
+	// to an open file descriptor.
+	Path string
+
+	// TODO(achille): it could be meaningful to move isFile from FD to a method
+	// on this struct type, and expose it as `IsFile() bool` which derives the
+	// result from the Filetype field. We would need to ensure that Filetype is
+	// always set instead of being lazily initialized.
+}
+
+// dupCloseOnExecOld always errors on wasip1 because there is no mechanism to
+// duplicate file descriptors.
+func dupCloseOnExecOld(fd int) (int, string, error) {
+	return -1, "dup", syscall.ENOSYS
+}
+
+// Fchdir wraps syscall.Fchdir.
+func (fd *FD) Fchdir() error {
+	if err := fd.incref(); err != nil {
+		return err
+	}
+	defer fd.decref()
+	return syscall.Chdir(fd.Path)
+}
+
+// ReadDir wraps syscall.ReadDir.
+// We treat this like an ordinary system call rather than a call
+// that tries to fill the buffer.
+func (fd *FD) ReadDir(buf []byte, cookie syscall.Dircookie) (int, error) {
+	if err := fd.incref(); err != nil {
+		return 0, err
+	}
+	defer fd.decref()
+	for {
+		n, err := syscall.ReadDir(fd.Sysfd, buf, cookie)
+		if err != nil {
+			n = 0
+			if err == syscall.EAGAIN && fd.pd.pollable() {
+				if err = fd.pd.waitRead(fd.isFile); err == nil {
+					continue
+				}
+			}
+		}
+		// Do not call eofError; caller does not expect to see io.EOF.
+		return n, err
+	}
+}
+
+func (fd *FD) ReadDirent(buf []byte) (int, error) {
+	n, err := fd.ReadDir(buf, fd.Dircookie)
+	if err != nil {
+		return 0, err
+	}
+	if n <= 0 {
+		return n, nil // EOF
+	}
+
+	// We assume that the caller of ReadDirent will consume the entire buffer
+	// up to the last full entry, so we scan through the buffer looking for the
+	// value of the last next cookie.
+	b := buf[:n]
+
+	for len(b) > 0 {
+		next, ok := direntNext(b)
+		if !ok {
+			break
+		}
+		size, ok := direntReclen(b)
+		if !ok {
+			break
+		}
+		if size > uint64(len(b)) {
+			break
+		}
+		fd.Dircookie = syscall.Dircookie(next)
+		b = b[size:]
+	}
+
+	// Trim a potentially incomplete trailing entry; this is necessary because
+	// the code in src/os/dir_unix.go does not deal well with partial values in
+	// calls to direntReclen, etc... and ends up causing an early EOF before all
+	// directory entries were consumed. ReadDirent is called with a large enough
+	// buffer (8 KiB) that at least one entry should always fit, tho this seems
+	// a bit brittle but cannot be addressed without a large change of the
+	// algorithm in the os.(*File).readdir method.
+	return n - len(b), nil
+}
+
+// Seek wraps syscall.Seek.
+func (fd *FD) Seek(offset int64, whence int) (int64, error) {
+	if err := fd.incref(); err != nil {
+		return 0, err
+	}
+	defer fd.decref()
+	// syscall.Filetype is a uint8 but we store it as a uint32 in SysFile in
+	// order to use atomic load/store on the field, which is why we have to
+	// perform this type conversion.
+	fileType := syscall.Filetype(atomic.LoadUint32(&fd.Filetype))
+
+	if fileType == syscall.FILETYPE_UNKNOWN {
+		var stat syscall.Stat_t
+		if err := fd.Fstat(&stat); err != nil {
+			return 0, err
+		}
+		fileType = stat.Filetype
+		atomic.StoreUint32(&fd.Filetype, uint32(fileType))
+	}
+
+	if fileType == syscall.FILETYPE_DIRECTORY {
+		// If the file descriptor is opened on a directory, we reset the readdir
+		// cookie when seeking back to the beginning to allow reusing the file
+		// descriptor to scan the directory again.
+		if offset == 0 && whence == 0 {
+			fd.Dircookie = 0
+			return 0, nil
+		} else {
+			return 0, syscall.EINVAL
+		}
+	}
+
+	return syscall.Seek(fd.Sysfd, offset, whence)
+}
+
+// https://github.com/WebAssembly/WASI/blob/main/legacy/preview1/docs.md#-dirent-record
+const sizeOfDirent = 24
+
+func direntReclen(buf []byte) (uint64, bool) {
+	namelen, ok := direntNamlen(buf)
+	return sizeOfDirent + namelen, ok
+}
+
+func direntNamlen(buf []byte) (uint64, bool) {
+	return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Namlen), unsafe.Sizeof(syscall.Dirent{}.Namlen))
+}
+
+func direntNext(buf []byte) (uint64, bool) {
+	return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Next), unsafe.Sizeof(syscall.Dirent{}.Next))
+}
+
+// readInt returns the size-bytes unsigned integer in native byte order at offset off.
+func readInt(b []byte, off, size uintptr) (u uint64, ok bool) {
+	if len(b) < int(off+size) {
+		return 0, false
+	}
+	return readIntLE(b[off:], size), true
+}
+
+func readIntLE(b []byte, size uintptr) uint64 {
+	switch size {
+	case 1:
+		return uint64(b[0])
+	case 2:
+		_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
+		return uint64(b[0]) | uint64(b[1])<<8
+	case 4:
+		_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
+		return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24
+	case 8:
+		_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
+		return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+			uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+	default:
+		panic("internal/poll: readInt with unsupported size")
+	}
+}

src/internal/poll/hook_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build unix || (js && wasm)
+//go:build unix || (js && wasm) || wasip1
 
 package poll
 

src/internal/poll/sys_cloexec.go

@@ -5,7 +5,7 @@
 // This file implements accept for platforms that do not provide a fast path for
 // setting SetNonblock and CloseOnExec.
 
-//go:build aix || darwin || (js && wasm)
+//go:build aix || darwin || (js && wasm) || wasip1
 
 package poll
 

src/internal/syscall/unix/net_wasip1.go

@@ -0,0 +1,44 @@
+// Copyright 2023 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 wasip1
+
+package unix
+
+import (
+	"syscall"
+	_ "unsafe"
+)
+
+func RecvfromInet4(fd int, p []byte, flags int, from *syscall.SockaddrInet4) (int, error) {
+	return 0, syscall.ENOSYS
+}
+
+func RecvfromInet6(fd int, p []byte, flags int, from *syscall.SockaddrInet6) (n int, err error) {
+	return 0, syscall.ENOSYS
+}
+
+func SendtoInet4(fd int, p []byte, flags int, to *syscall.SockaddrInet4) (err error) {
+	return syscall.ENOSYS
+}
+
+func SendtoInet6(fd int, p []byte, flags int, to *syscall.SockaddrInet6) (err error) {
+	return syscall.ENOSYS
+}
+
+func SendmsgNInet4(fd int, p, oob []byte, to *syscall.SockaddrInet4, flags int) (n int, err error) {
+	return 0, syscall.ENOSYS
+}
+
+func SendmsgNInet6(fd int, p, oob []byte, to *syscall.SockaddrInet6, flags int) (n int, err error) {
+	return 0, syscall.ENOSYS
+}
+
+func RecvmsgInet4(fd int, p, oob []byte, flags int, from *syscall.SockaddrInet4) (n, oobn int, recvflags int, err error) {
+	return 0, 0, 0, syscall.ENOSYS
+}
+
+func RecvmsgInet6(fd int, p, oob []byte, flags int, from *syscall.SockaddrInet6) (n, oobn int, recvflags int, err error) {
+	return 0, 0, 0, syscall.ENOSYS
+}

src/internal/syscall/unix/nonblocking_wasip1.go

@@ -0,0 +1,11 @@
+// Copyright 2023 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 wasip1
+
+package unix
+
+func IsNonblock(fd int) (nonblocking bool, err error) {
+	return false, nil
+}

src/internal/testenv/exec.go

@@ -20,7 +20,7 @@ import (
 // using os.StartProcess or (more commonly) exec.Command.
 func HasExec() bool {
 	switch runtime.GOOS {
-	case "js", "ios":
+	case "wasip1", "js", "ios":
 		return false
 	}
 	return true

src/internal/testenv/testenv.go

@@ -46,7 +46,7 @@ func HasGoBuild() bool {
 		return false
 	}
 	switch runtime.GOOS {
-	case "android", "js", "ios":
+	case "android", "js", "ios", "wasip1":
 		return false
 	}
 	return true
@@ -80,6 +80,7 @@ func MustHaveGoRun(t testing.TB) {
 
 // HasParallelism reports whether the current system can execute multiple
 // threads in parallel.
+// There is a copy of this function in cmd/dist/test.go.
 func HasParallelism() bool {
 	switch runtime.GOOS {
 	case "js", "wasip1":
@@ -257,14 +258,14 @@ func HasSrc() bool {
 // HasExternalNetwork reports whether the current system can use
 // external (non-localhost) networks.
 func HasExternalNetwork() bool {
-	return !testing.Short() && runtime.GOOS != "js"
+	return !testing.Short() && runtime.GOOS != "js" && runtime.GOOS != "wasip1"
 }
 
 // MustHaveExternalNetwork checks that the current system can use
 // external (non-localhost) networks.
 // If not, MustHaveExternalNetwork calls t.Skip with an explanation.
 func MustHaveExternalNetwork(t testing.TB) {
-	if runtime.GOOS == "js" {
+	if runtime.GOOS == "js" || runtime.GOOS == "wasip1" {
 		t.Skipf("skipping test: no external network on %s", runtime.GOOS)
 	}
 	if testing.Short() {
@@ -372,7 +373,7 @@ func SkipFlakyNet(t testing.TB) {
 // CPUIsSlow reports whether the CPU running the test is suspected to be slow.
 func CPUIsSlow() bool {
 	switch runtime.GOARCH {
-	case "arm", "mips", "mipsle", "mips64", "mips64le":
+	case "arm", "mips", "mipsle", "mips64", "mips64le", "wasm":
 		return true
 	}
 	return false

src/internal/testenv/testenv_notunix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build windows || plan9 || (js && wasm)
+//go:build windows || plan9 || (js && wasm) || wasip1
 
 package testenv
 

src/syscall/syscall_wasip1.go

@@ -7,6 +7,7 @@
 package syscall
 
 import (
+	"errors"
 	"internal/itoa"
 	"internal/oserror"
 	"unsafe"
@@ -81,6 +82,8 @@ func (e Errno) Is(target error) bool {
 		return e == EEXIST || e == ENOTEMPTY
 	case oserror.ErrNotExist:
 		return e == ENOENT
+	case errors.ErrUnsupported:
+		return e == ENOSYS
 	}
 	return false
 }