os, internal/poll: loop on EINTR for all file syscalls

When using a FUSE file system, any system call that touches the file
system can return EINTR.

Fixes #40846

Change-Id: I25d32da22cec08dea81ab297291a85ad72db2df7
Reviewed-on: https://go-review.googlesource.com/c/go/+/249178
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

src/internal/poll/fd_fsync_posix.go

@@ -14,5 +14,7 @@ func (fd *FD) Fsync() error {
 		return err
 	}
 	defer fd.decref()
-	return syscall.Fsync(fd.Sysfd)
+	return ignoringEINTR(func() error {
+		return syscall.Fsync(fd.Sysfd)
+	})
 }

src/internal/poll/fd_opendir_darwin.go

@@ -19,7 +19,13 @@ func (fd *FD) OpenDir() (uintptr, string, error) {
 	if err != nil {
 		return 0, call, err
 	}
-	dir, err := fdopendir(fd2)
+	var dir uintptr
+	for {
+		dir, err = fdopendir(fd2)
+		if err != syscall.EINTR {
+			break
+		}
+	}
 	if err != nil {
 		syscall.Close(fd2)
 		return 0, "fdopendir", err

src/internal/poll/fd_posix.go

@@ -35,7 +35,9 @@ func (fd *FD) Fchmod(mode uint32) error {
 		return err
 	}
 	defer fd.decref()
-	return syscall.Fchmod(fd.Sysfd, mode)
+	return ignoringEINTR(func() error {
+		return syscall.Fchmod(fd.Sysfd, mode)
+	})
 }
 
 // Fchown wraps syscall.Fchown.
@@ -44,7 +46,9 @@ func (fd *FD) Fchown(uid, gid int) error {
 		return err
 	}
 	defer fd.decref()
-	return syscall.Fchown(fd.Sysfd, uid, gid)
+	return ignoringEINTR(func() error {
+		return syscall.Fchown(fd.Sysfd, uid, gid)
+	})
 }
 
 // Ftruncate wraps syscall.Ftruncate.
@@ -53,7 +57,9 @@ func (fd *FD) Ftruncate(size int64) error {
 		return err
 	}
 	defer fd.decref()
-	return syscall.Ftruncate(fd.Sysfd, size)
+	return ignoringEINTR(func() error {
+		return syscall.Ftruncate(fd.Sysfd, size)
+	})
 }
 
 // RawControl invokes the user-defined function f for a non-IO
@@ -66,3 +72,19 @@ func (fd *FD) RawControl(f func(uintptr)) error {
 	f(uintptr(fd.Sysfd))
 	return nil
 }
+
+// ignoringEINTR makes a function call and repeats it if it returns
+// an EINTR error. This appears to be required even though we install all
+// signal handlers with SA_RESTART: see #22838, #38033, #38836, #40846.
+// Also #20400 and #36644 are issues in which a signal handler is
+// installed without setting SA_RESTART. None of these are the common case,
+// but there are enough of them that it seems that we can't avoid
+// an EINTR loop.
+func ignoringEINTR(fn func() error) error {
+	for {
+		err := fn()
+		if err != syscall.EINTR {
+			return err
+		}
+	}
+}

src/internal/poll/fd_unix.go

@@ -152,7 +152,7 @@ func (fd *FD) Read(p []byte) (int, error) {
 		p = p[:maxRW]
 	}
 	for {
-		n, err := ignoringEINTR(syscall.Read, fd.Sysfd, p)
+		n, err := ignoringEINTRIO(syscall.Read, fd.Sysfd, p)
 		if err != nil {
 			n = 0
 			if err == syscall.EAGAIN && fd.pd.pollable() {
@@ -264,7 +264,7 @@ func (fd *FD) Write(p []byte) (int, error) {
 		if fd.IsStream && max-nn > maxRW {
 			max = nn + maxRW
 		}
-		n, err := ignoringEINTR(syscall.Write, fd.Sysfd, p[nn:max])
+		n, err := ignoringEINTRIO(syscall.Write, fd.Sysfd, p[nn:max])
 		if n > 0 {
 			nn += n
 		}
@@ -423,7 +423,7 @@ func (fd *FD) ReadDirent(buf []byte) (int, error) {
 	}
 	defer fd.decref()
 	for {
-		n, err := ignoringEINTR(syscall.ReadDirent, fd.Sysfd, buf)
+		n, err := ignoringEINTRIO(syscall.ReadDirent, fd.Sysfd, buf)
 		if err != nil {
 			n = 0
 			if err == syscall.EAGAIN && fd.pd.pollable() {
@@ -452,7 +452,9 @@ func (fd *FD) Fstat(s *syscall.Stat_t) error {
 		return err
 	}
 	defer fd.decref()
-	return syscall.Fstat(fd.Sysfd, s)
+	return ignoringEINTR(func() error {
+		return syscall.Fstat(fd.Sysfd, s)
+	})
 }
 
 // tryDupCloexec indicates whether F_DUPFD_CLOEXEC should be used.
@@ -514,7 +516,7 @@ func (fd *FD) WriteOnce(p []byte) (int, error) {
 		return 0, err
 	}
 	defer fd.writeUnlock()
-	return ignoringEINTR(syscall.Write, fd.Sysfd, p)
+	return ignoringEINTRIO(syscall.Write, fd.Sysfd, p)
 }
 
 // RawRead invokes the user-defined function f for a read operation.
@@ -555,14 +557,8 @@ func (fd *FD) RawWrite(f func(uintptr) bool) error {
 	}
 }
 
-// ignoringEINTR makes a function call and repeats it if it returns
-// an EINTR error. This appears to be required even though we install
-// all signal handlers with SA_RESTART: see #22838, #38033, #38836.
-// Also #20400 and #36644 are issues in which a signal handler is
-// installed without setting SA_RESTART. None of these are the common case,
-// but there are enough of them that it seems that we can't avoid
-// an EINTR loop.
-func ignoringEINTR(fn func(fd int, p []byte) (int, error), fd int, p []byte) (int, error) {
+// ignoringEINTRIO is like ignoringEINTR, but just for IO calls.
+func ignoringEINTRIO(fn func(fd int, p []byte) (int, error), fd int, p []byte) (int, error) {
 	for {
 		n, err := fn(fd, p)
 		if err != syscall.EINTR {

src/os/dir_darwin.go

@@ -47,6 +47,9 @@ func (f *File) readdirnames(n int) (names []string, err error) {
 	var entptr *syscall.Dirent
 	for len(names) < size || n == -1 {
 		if res := readdir_r(d.dir, &dirent, &entptr); res != 0 {
+			if syscall.Errno(res) == syscall.EINTR {
+				continue
+			}
 			return names, wrapSyscallError("readdir", syscall.Errno(res))
 		}
 		if entptr == nil { // EOF

src/os/file.go

@@ -255,7 +255,10 @@ func Mkdir(name string, perm FileMode) error {
 	if runtime.GOOS == "windows" && isWindowsNulName(name) {
 		return &PathError{"mkdir", name, syscall.ENOTDIR}
 	}
-	e := syscall.Mkdir(fixLongPath(name), syscallMode(perm))
+	longName := fixLongPath(name)
+	e := ignoringEINTR(func() error {
+		return syscall.Mkdir(longName, syscallMode(perm))
+	})
 
 	if e != nil {
 		return &PathError{"mkdir", name, e}

src/os/file_plan9.go

@@ -558,3 +558,7 @@ func (c *rawConn) Write(f func(uintptr) bool) error {
 func newRawConn(file *File) (*rawConn, error) {
 	return nil, syscall.EPLAN9
 }
+
+func ignoringEINTR(fn func() error) error {
+	return fn()
+}

src/os/file_posix.go

@@ -76,7 +76,11 @@ func syscallMode(i FileMode) (o uint32) {
 
 // See docs in file.go:Chmod.
 func chmod(name string, mode FileMode) error {
-	if e := syscall.Chmod(fixLongPath(name), syscallMode(mode)); e != nil {
+	longName := fixLongPath(name)
+	e := ignoringEINTR(func() error {
+		return syscall.Chmod(longName, syscallMode(mode))
+	})
+	if e != nil {
 		return &PathError{"chmod", name, e}
 	}
 	return nil
@@ -101,7 +105,10 @@ func (f *File) chmod(mode FileMode) error {
 // On Windows or Plan 9, Chown always returns the syscall.EWINDOWS or
 // EPLAN9 error, wrapped in *PathError.
 func Chown(name string, uid, gid int) error {
-	if e := syscall.Chown(name, uid, gid); e != nil {
+	e := ignoringEINTR(func() error {
+		return syscall.Chown(name, uid, gid)
+	})
+	if e != nil {
 		return &PathError{"chown", name, e}
 	}
 	return nil
@@ -114,7 +121,10 @@ func Chown(name string, uid, gid int) error {
 // On Windows, it always returns the syscall.EWINDOWS error, wrapped
 // in *PathError.
 func Lchown(name string, uid, gid int) error {
-	if e := syscall.Lchown(name, uid, gid); e != nil {
+	e := ignoringEINTR(func() error {
+		return syscall.Lchown(name, uid, gid)
+	})
+	if e != nil {
 		return &PathError{"lchown", name, e}
 	}
 	return nil
@@ -222,3 +232,19 @@ func (f *File) checkValid(op string) error {
 	}
 	return nil
 }
+
+// ignoringEINTR makes a function call and repeats it if it returns an
+// EINTR error. This appears to be required even though we install all
+// signal handlers with SA_RESTART: see #22838, #38033, #38836, #40846.
+// Also #20400 and #36644 are issues in which a signal handler is
+// installed without setting SA_RESTART. None of these are the common case,
+// but there are enough of them that it seems that we can't avoid
+// an EINTR loop.
+func ignoringEINTR(fn func() error) error {
+	for {
+		err := fn()
+		if err != syscall.EINTR {
+			return err
+		}
+	}
+}

src/os/file_unix.go

@@ -39,7 +39,9 @@ func rename(oldname, newname string) error {
 			return &LinkError{"rename", oldname, newname, syscall.EEXIST}
 		}
 	}
-	err = syscall.Rename(oldname, newname)
+	err = ignoringEINTR(func() error {
+		return syscall.Rename(oldname, newname)
+	})
 	if err != nil {
 		return &LinkError{"rename", oldname, newname, err}
 	}
@@ -129,7 +131,9 @@ func newFile(fd uintptr, name string, kind newFileKind) *File {
 		switch runtime.GOOS {
 		case "darwin", "dragonfly", "freebsd", "netbsd", "openbsd":
 			var st syscall.Stat_t
-			err := syscall.Fstat(fdi, &st)
+			err := ignoringEINTR(func() error {
+				return syscall.Fstat(fdi, &st)
+			})
 			typ := st.Mode & syscall.S_IFMT
 			// Don't try to use kqueue with regular files on *BSDs.
 			// On FreeBSD a regular file is always
@@ -264,7 +268,10 @@ func (f *File) seek(offset int64, whence int) (ret int64, err error) {
 // If the file is a symbolic link, it changes the size of the link's target.
 // If there is an error, it will be of type *PathError.
 func Truncate(name string, size int64) error {
-	if e := syscall.Truncate(name, size); e != nil {
+	e := ignoringEINTR(func() error {
+		return syscall.Truncate(name, size)
+	})
+	if e != nil {
 		return &PathError{"truncate", name, e}
 	}
 	return nil
@@ -277,11 +284,15 @@ func Remove(name string) error {
 	// whether name is a file or directory.
 	// Try both: it is cheaper on average than
 	// doing a Stat plus the right one.
-	e := syscall.Unlink(name)
+	e := ignoringEINTR(func() error {
+		return syscall.Unlink(name)
+	})
 	if e == nil {
 		return nil
 	}
-	e1 := syscall.Rmdir(name)
+	e1 := ignoringEINTR(func() error {
+		return syscall.Rmdir(name)
+	})
 	if e1 == nil {
 		return nil
 	}
@@ -316,7 +327,9 @@ func tempDir() string {
 // Link creates newname as a hard link to the oldname file.
 // If there is an error, it will be of type *LinkError.
 func Link(oldname, newname string) error {
-	e := syscall.Link(oldname, newname)
+	e := ignoringEINTR(func() error {
+		return syscall.Link(oldname, newname)
+	})
 	if e != nil {
 		return &LinkError{"link", oldname, newname, e}
 	}
@@ -326,7 +339,9 @@ func Link(oldname, newname string) error {
 // Symlink creates newname as a symbolic link to oldname.
 // If there is an error, it will be of type *LinkError.
 func Symlink(oldname, newname string) error {
-	e := syscall.Symlink(oldname, newname)
+	e := ignoringEINTR(func() error {
+		return syscall.Symlink(oldname, newname)
+	})
 	if e != nil {
 		return &LinkError{"symlink", oldname, newname, e}
 	}
@@ -365,7 +380,16 @@ func (f *File) readdir(n int) (fi []FileInfo, err error) {
 func Readlink(name string) (string, error) {
 	for len := 128; ; len *= 2 {
 		b := make([]byte, len)
-		n, e := fixCount(syscall.Readlink(name, b))
+		var (
+			n int
+			e error
+		)
+		for {
+			n, e = fixCount(syscall.Readlink(name, b))
+			if e != syscall.EINTR {
+				break
+			}
+		}
 		// buffer too small
 		if runtime.GOOS == "aix" && e == syscall.ERANGE {
 			continue

src/os/getwd.go

@@ -45,7 +45,16 @@ func Getwd() (dir string, err error) {
 	// If the operating system provides a Getwd call, use it.
 	// Otherwise, we're trying to find our way back to ".".
 	if syscall.ImplementsGetwd {
-		s, e := syscall.Getwd()
+		var (
+			s string
+			e error
+		)
+		for {
+			s, e = syscall.Getwd()
+			if e != syscall.EINTR {
+				break
+			}
+		}
 		if useSyscallwd(e) {
 			return s, NewSyscallError("getwd", e)
 		}

src/os/stat_unix.go

@@ -28,7 +28,9 @@ func (f *File) Stat() (FileInfo, error) {
 // statNolog stats a file with no test logging.
 func statNolog(name string) (FileInfo, error) {
 	var fs fileStat
-	err := syscall.Stat(name, &fs.sys)
+	err := ignoringEINTR(func() error {
+		return syscall.Stat(name, &fs.sys)
+	})
 	if err != nil {
 		return nil, &PathError{"stat", name, err}
 	}
@@ -39,7 +41,9 @@ func statNolog(name string) (FileInfo, error) {
 // lstatNolog lstats a file with no test logging.
 func lstatNolog(name string) (FileInfo, error) {
 	var fs fileStat
-	err := syscall.Lstat(name, &fs.sys)
+	err := ignoringEINTR(func() error {
+		return syscall.Lstat(name, &fs.sys)
+	})
 	if err != nil {
 		return nil, &PathError{"lstat", name, err}
 	}

src/runtime/trace/trace_stack_test.go

@@ -252,7 +252,7 @@ func TestTraceSymbolize(t *testing.T) {
 			{trace.EvGoSysCall, []frame{
 				{"syscall.read", 0},
 				{"syscall.Read", 0},
-				{"internal/poll.ignoringEINTR", 0},
+				{"internal/poll.ignoringEINTRIO", 0},
 				{"internal/poll.(*FD).Read", 0},
 				{"os.(*File).read", 0},
 				{"os.(*File).Read", 0},