syscall: add support for proc thread attribute lists

This will allow us to pass additional attributes when starting
processes.

Updates #44011.

Change-Id: I4af365c5544a6d421830f247593ec970200e5e03
Reviewed-on: https://go-review.googlesource.com/c/go/+/288296
Trust: Jason A. Donenfeld <[email protected]>
Trust: Alex Brainman <[email protected]>
Reviewed-by: Alex Brainman <[email protected]>

Author: zx2c4

src/syscall/syscall_windows.go

@@ -284,6 +284,9 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 // This function returns 1 byte BOOLEAN rather than the 4 byte BOOL.
 //sys	CreateSymbolicLink(symlinkfilename *uint16, targetfilename *uint16, flags uint32) (err error) [failretval&0xff==0] = CreateSymbolicLinkW
 //sys	CreateHardLink(filename *uint16, existingfilename *uint16, reserved uintptr) (err error) [failretval&0xff==0] = CreateHardLinkW
+//sys	initializeProcThreadAttributeList(attrlist *_PROC_THREAD_ATTRIBUTE_LIST, attrcount uint32, flags uint32, size *uintptr) (err error) = InitializeProcThreadAttributeList
+//sys	deleteProcThreadAttributeList(attrlist *_PROC_THREAD_ATTRIBUTE_LIST) = DeleteProcThreadAttributeList
+//sys	updateProcThreadAttribute(attrlist *_PROC_THREAD_ATTRIBUTE_LIST, flags uint32, attr uintptr, value uintptr, size uintptr, prevvalue uintptr, returnedsize *uintptr) (err error) = UpdateProcThreadAttribute
 
 // syscall interface implementation for other packages
 
@@ -1240,3 +1243,23 @@ func GetQueuedCompletionStatus(cphandle Handle, qty *uint32, key *uint32, overla
 func PostQueuedCompletionStatus(cphandle Handle, qty uint32, key uint32, overlapped *Overlapped) error {
 	return postQueuedCompletionStatus(cphandle, qty, uintptr(key), overlapped)
 }
+
+// newProcThreadAttributeList allocates new PROC_THREAD_ATTRIBUTE_LIST, with
+// the requested maximum number of attributes, which must be cleaned up by
+// deleteProcThreadAttributeList.
+func newProcThreadAttributeList(maxAttrCount uint32) (*_PROC_THREAD_ATTRIBUTE_LIST, error) {
+	var size uintptr
+	err := initializeProcThreadAttributeList(nil, maxAttrCount, 0, &size)
+	if err != ERROR_INSUFFICIENT_BUFFER {
+		if err == nil {
+			return nil, errorspkg.New("unable to query buffer size from InitializeProcThreadAttributeList")
+		}
+		return nil, err
+	}
+	al := (*_PROC_THREAD_ATTRIBUTE_LIST)(unsafe.Pointer(&make([]byte, size)[0]))
+	err = initializeProcThreadAttributeList(al, maxAttrCount, 0, &size)
+	if err != nil {
+		return nil, err
+	}
+	return al, nil
+}

src/syscall/types_windows.go

@@ -490,6 +490,22 @@ type StartupInfo struct {
 	StdErr        Handle
 }
 
+type _PROC_THREAD_ATTRIBUTE_LIST struct {
+	_ [1]byte
+}
+
+const (
+	_PROC_THREAD_ATTRIBUTE_PARENT_PROCESS = 0x00020000
+	_PROC_THREAD_ATTRIBUTE_HANDLE_LIST    = 0x00020002
+)
+
+type _STARTUPINFOEXW struct {
+	StartupInfo
+	ProcThreadAttributeList *_PROC_THREAD_ATTRIBUTE_LIST
+}
+
+const _EXTENDED_STARTUPINFO_PRESENT = 0x00080000
+
 type ProcessInformation struct {
 	Process   Handle
 	Thread    Handle