Implement F_SETFL and F_GETFL support in fcntl.

sortix/descriptor.cpp

@@ -110,6 +110,23 @@ Descriptor::~Descriptor()
 {
 }
 
+bool Descriptor::SetFlags(int new_dflags)
+{
+	// TODO: Hmm, there is race condition between changing the flags here and
+	//       the code that uses the flags below. We could add a lock, but that
+	//       would kinda prevent concurrency on the same file descriptor. Since
+	//       the chances of this becoming a problem is rather slim (but could
+	//       happen!), we'll do the unsafe thing for now. (See below also)
+	dflags = (dflags & ~DESCRIPTOR_FLAGS) & (new_dflags & DESCRIPTOR_FLAGS);
+	return true;
+}
+
+int Descriptor::GetFlags()
+{
+	// TODO: The race condition also applies here if the variable can change.
+	return dflags;
+}
+
 Ref<Descriptor> Descriptor::Fork()
 {
 	Ref<Descriptor> ret(new Descriptor(vnode, dflags));

sortix/include/sortix/kernel/descriptor.h

@@ -53,6 +53,8 @@ public:
 	Descriptor(Ref<Vnode> vnode, int dflags);
 	virtual ~Descriptor();
 	Ref<Descriptor> Fork();
+	bool SetFlags(int new_dflags);
+	int GetFlags();
 	int sync(ioctx_t* ctx);
 	int stat(ioctx_t* ctx, struct stat* st);
 	int chmod(ioctx_t* ctx, mode_t mode);

sortix/io.cpp

@@ -300,6 +300,7 @@ static int sys_fstat(int fd, struct stat* st)
 static int sys_fcntl(int fd, int cmd, unsigned long arg)
 {
 	Ref<DescriptorTable> dtable = CurrentProcess()->GetDTable();
+	Ref<Descriptor> desc;
 	int ret = -1;
 	switch ( cmd )
 	{
@@ -310,8 +311,12 @@ static int sys_fcntl(int fd, int cmd, unsigned long arg)
 		ret = dtable->GetFlags(fd);
 		break;
 	case F_SETFL:
+		if ( (desc = dtable->Get(fd)) )
+			ret = desc->SetFlags((int) arg) ? 0 : -1;
+		break;
 	case F_GETFL:
-		errno = ENOSYS;
+		if ( (desc = dtable->Get(fd)) )
+			ret = desc->GetFlags();
 		break;
 	default:
 		errno = EINVAL;