os: revert the use of AddCleanup to close files and roots

This reverts commit fdaac84480.

Updates #70907
Updates #74574
Updates #74642

Reason for revert: Issue #74574

Change-Id: I7b55b85736e4210d9b6f3fd7a24050ac7bdefef9
Reviewed-on: https://go-review.googlesource.com/c/go/+/688435
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

src/os/file.go

@@ -707,9 +707,9 @@ func (f *File) SyscallConn() (syscall.RawConn, error) {
 
 // Fd returns the system file descriptor or handle referencing the open file.
 // If f is closed, the descriptor becomes invalid.
-// If f is garbage collected, a cleanup may close the descriptor,
-// making it invalid; see [runtime.AddCleanup] for more information on when
-// a cleanup might be run.
+// If f is garbage collected, a finalizer may close the descriptor,
+// making it invalid; see [runtime.SetFinalizer] for more information on when
+// a finalizer might be run.
 //
 // Do not close the returned descriptor; that could cause a later
 // close of f to close an unrelated descriptor.

src/os/file_plan9.go

@@ -23,7 +23,7 @@ func fixLongPath(path string) string {
 
 // file is the real representation of *File.
 // The extra level of indirection ensures that no clients of os
-// can overwrite this data, which could cause the cleanup
+// can overwrite this data, which could cause the finalizer
 // to close the wrong file descriptor.
 type file struct {
 	fdmu       poll.FDMutex
@@ -31,7 +31,6 @@ type file struct {
 	name       string
 	dirinfo    atomic.Pointer[dirInfo] // nil unless directory being read
 	appendMode bool                    // whether file is opened for appending
-	cleanup    runtime.Cleanup         // cleanup closes the file when no longer referenced
 }
 
 // fd is the Plan 9 implementation of Fd.
@@ -49,7 +48,7 @@ func newFileFromNewFile(fd uintptr, name string) *File {
 		return nil
 	}
 	f := &File{&file{sysfd: fdi, name: name}}
-	f.cleanup = runtime.AddCleanup(f, func(f *file) { f.close() }, f.file)
+	runtime.SetFinalizer(f.file, (*file).close)
 	return f
 }
 
@@ -160,9 +159,8 @@ func (file *file) close() error {
 
 	err := file.decref()
 
-	// There is no need for a cleanup at this point. File must be alive at the point
-	// where cleanup.stop is called.
-	file.cleanup.Stop()
+	// no need for a finalizer anymore
+	runtime.SetFinalizer(file, nil)
 	return err
 }
 

src/os/file_unix.go

@@ -54,7 +54,7 @@ func rename(oldname, newname string) error {
 
 // file is the real representation of *File.
 // The extra level of indirection ensures that no clients of os
-// can overwrite this data, which could cause the cleanup
+// can overwrite this data, which could cause the finalizer
 // to close the wrong file descriptor.
 type file struct {
 	pfd         poll.FD
@@ -63,7 +63,6 @@ type file struct {
 	nonblock    bool                    // whether we set nonblocking mode
 	stdoutOrErr bool                    // whether this is stdout or stderr
 	appendMode  bool                    // whether file is opened for appending
-	cleanup     runtime.Cleanup         // cleanup closes the file when no longer referenced
 }
 
 // fd is the Unix implementation of Fd.
@@ -222,8 +221,7 @@ func newFile(fd int, name string, kind newFileKind, nonBlocking bool) *File {
 		}
 	}
 
-	// Close the file when the File is not live.
-	f.cleanup = runtime.AddCleanup(f, func(f *file) { f.close() }, f.file)
+	runtime.SetFinalizer(f.file, (*file).close)
 	return f
 }
 
@@ -320,9 +318,8 @@ func (file *file) close() error {
 		err = &PathError{Op: "close", Path: file.name, Err: e}
 	}
 
-	// There is no need for a cleanup at this point. File must be alive at the point
-	// where cleanup.stop is called.
-	file.cleanup.Stop()
+	// no need for a finalizer anymore
+	runtime.SetFinalizer(file, nil)
 	return err
 }
 

src/os/file_windows.go

@@ -22,14 +22,13 @@ const _UTIME_OMIT = -1
 
 // file is the real representation of *File.
 // The extra level of indirection ensures that no clients of os
-// can overwrite this data, which could cause the cleanup
+// can overwrite this data, which could cause the finalizer
 // to close the wrong file descriptor.
 type file struct {
 	pfd        poll.FD
 	name       string
 	dirinfo    atomic.Pointer[dirInfo] // nil unless directory being read
 	appendMode bool                    // whether file is opened for appending
-	cleanup    runtime.Cleanup         // cleanup closes the file when no longer referenced
 }
 
 // fd is the Windows implementation of Fd.
@@ -69,7 +68,7 @@ func newFile(h syscall.Handle, name string, kind string, nonBlocking bool) *File
 		},
 		name: name,
 	}}
-	f.cleanup = runtime.AddCleanup(f, func(f *file) { f.close() }, f.file)
+	runtime.SetFinalizer(f.file, (*file).close)
 
 	// Ignore initialization errors.
 	// Assume any problems will show up in later I/O.
@@ -144,9 +143,8 @@ func (file *file) close() error {
 		err = &PathError{Op: "close", Path: file.name, Err: e}
 	}
 
-	// There is no need for a cleanup at this point. File must be alive at the point
-	// where cleanup.stop is called.
-	file.cleanup.Stop()
+	// no need for a finalizer anymore
+	runtime.SetFinalizer(file, nil)
 	return err
 }
 

src/os/root_openat.go

@@ -22,11 +22,10 @@ type root struct {
 	// refs is incremented while an operation is using fd.
 	// closed is set when Close is called.
 	// fd is closed when closed is true and refs is 0.
-	mu      sync.Mutex
-	fd      sysfdType
-	refs    int             // number of active operations
-	closed  bool            // set when closed
-	cleanup runtime.Cleanup // cleanup closes the file when no longer referenced
+	mu     sync.Mutex
+	fd     sysfdType
+	refs   int  // number of active operations
+	closed bool // set when closed
 }
 
 func (r *root) Close() error {
@@ -36,9 +35,7 @@ func (r *root) Close() error {
 		syscall.Close(r.fd)
 	}
 	r.closed = true
-	// There is no need for a cleanup at this point. Root must be alive at the point
-	// where cleanup.stop is called.
-	r.cleanup.Stop()
+	runtime.SetFinalizer(r, nil) // no need for a finalizer any more
 	return nil
 }
 

src/os/root_unix.go

@@ -56,7 +56,7 @@ func newRoot(fd int, name string) (*Root, error) {
 		fd:   fd,
 		name: name,
 	}}
-	r.root.cleanup = runtime.AddCleanup(r, func(f *root) { f.Close() }, r.root)
+	runtime.SetFinalizer(r.root, (*root).Close)
 	return r, nil
 }
 

src/os/root_windows.go

@@ -113,7 +113,7 @@ func newRoot(fd syscall.Handle, name string) (*Root, error) {
 		fd:   fd,
 		name: name,
 	}}
-	r.root.cleanup = runtime.AddCleanup(r, func(f *root) { f.Close() }, r.root)
+	runtime.SetFinalizer(r.root, (*root).Close)
 	return r, nil
 }