github/containerd
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases 2 Wiki Activity

go-winio: Prevent Data Race when accessing closing

Browse Source 
The race usually happens when `closeHandle()` and `prepareIo()` are called
concurrently; the former tries to set `closing` to `true` the latter tries
to read its value.

In order to avoid this issue, we added a lock around the variable.

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>
This commit is contained in:
Kenfe-Mickael Laventure 2017-07-19 16:08:57 +02:00
parent db1b0a2a5a
commit 7f786cf075
No known key found for this signature in database
GPG Key ID: 40CF16616B361216
1 changed files with 15 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
vendor/github.com/Microsoft/go-winio/file.go generated vendored
View File

@ -69,6 +69,7 @@ func initIo() {
// win32File implements Reader, Writer, and Closer on a Win32 handle without blocking in a syscall. // win32File implements Reader, Writer, and Closer on a Win32 handle without blocking in a syscall.
// It takes ownership of this handle and will close it if it is garbage collected. // It takes ownership of this handle and will close it if it is garbage collected.
type win32File struct { type win32File struct {
sync.Mutex
handle syscall.Handle handle syscall.Handle
wg sync.WaitGroup wg sync.WaitGroup
closing bool closing bool
@ -105,17 +106,28 @@ func MakeOpenFile(h syscall.Handle) (io.ReadWriteCloser, error) {
return makeWin32File(h) return makeWin32File(h)
} }
func (f *win32File) isClosing() bool {
f.Lock()
closing := f.closing
f.Unlock()
return closing
}
// closeHandle closes the resources associated with a Win32 handle // closeHandle closes the resources associated with a Win32 handle
func (f *win32File) closeHandle() { func (f *win32File) closeHandle() {
f.Lock()
if !f.closing { if !f.closing {
// cancel all IO and wait for it to complete // cancel all IO and wait for it to complete
f.closing = true f.closing = true
f.Unlock()
cancelIoEx(f.handle, nil) cancelIoEx(f.handle, nil)
f.wg.Wait() f.wg.Wait()
// at this point, no new IO can start // at this point, no new IO can start
syscall.Close(f.handle) syscall.Close(f.handle)
f.handle = 0 f.handle = 0
return
} }
f.Unlock()
} }
// Close closes a win32File. // Close closes a win32File.
@ -128,7 +140,7 @@ func (f *win32File) Close() error {
// The caller must call f.wg.Done() when the IO is finished, prior to Close() returning. // The caller must call f.wg.Done() when the IO is finished, prior to Close() returning.
func (f *win32File) prepareIo() (*ioOperation, error) { func (f *win32File) prepareIo() (*ioOperation, error) {
f.wg.Add(1) f.wg.Add(1)
if f.closing { if f.isClosing() {
return nil, ErrFileClosed return nil, ErrFileClosed
} }
c := &ioOperation{} c := &ioOperation{}
@ -159,7 +171,7 @@ func (f *win32File) asyncIo(c *ioOperation, d *deadlineHandler, bytes uint32, er
return int(bytes), err return int(bytes), err
} }
if f.closing { if f.isClosing() {
cancelIoEx(f.handle, &c.o) cancelIoEx(f.handle, &c.o)
} }
@ -175,7 +187,7 @@ func (f *win32File) asyncIo(c *ioOperation, d *deadlineHandler, bytes uint32, er
case r = <-c.ch: case r = <-c.ch:
err = r.err err = r.err
if err == syscall.ERROR_OPERATION_ABORTED { if err == syscall.ERROR_OPERATION_ABORTED {
if f.closing { if f.isClosing() {
err = ErrFileClosed err = ErrFileClosed
} }
} }