use a tagged union for the fdop args

3 files changed, 35 insertions, 12 deletions

diff --git a/src/kernel/fd.c b/src/kernel/fd.c
index c495c8c..77fea05 100644
--- a/src/kernel/fd.c
+++ b/src/kernel/fd.c
@@ -3,34 +3,35 @@
 #include <kernel/panic.h>
 #include <kernel/proc.h>
 
-static int fdop_special_tty(enum fdop fdop, struct fd *fd, user_ptr ptr, size_t len);
+static int fdop_special_tty(struct fdop_args *args);
 
-int fdop_dispatch(enum fdop fdop, struct fd *fd, user_ptr ptr, size_t len) {
-	switch(fd->type) {
+int fdop_dispatch(struct fdop_args args) {
+	switch(args.fd->type) {
 		case FD_EMPTY:
 			return -1;
 		case FD_SPECIAL_TTY:
-			return fdop_special_tty(fdop, fd, ptr, len);
+			return fdop_special_tty(&args);
 		default:
 			panic();
 	}
 }
 
-static int fdop_special_tty(enum fdop fdop, struct fd *fd, user_ptr ptr, size_t len) {
-	switch(fdop) {
+static int fdop_special_tty(struct fdop_args *args) {
+	switch(args->type) {
 		case FDOP_READ:
 			return -1; // input not implemented yet
 
 		case FDOP_WRITE: {
 			 struct virt_iter iter;
-			 virt_iter_new(&iter, ptr, len, process_current->pages, true, false);
+			 virt_iter_new(&iter, args->rw.ptr, args->rw.len,
+					 process_current->pages, true, false);
 			 while (virt_iter_next(&iter))
 				 tty_write(iter.frag, iter.frag_len);
 			 return iter.prior;
 		}
 
 		case FDOP_CLOSE:
-			fd->type = FD_EMPTY;
+			args->fd->type = FD_EMPTY;
 			return 0;
 
 		default: panic();
diff --git a/src/kernel/fd.h b/src/kernel/fd.h
index 90ce717..b35c979 100644
--- a/src/kernel/fd.h
+++ b/src/kernel/fd.h
@@ -22,4 +22,15 @@ enum fdop { // describes the operations which can be done on file descriptors
 	FDOP_CLOSE,
 };
 
-int fdop_dispatch(enum fdop fdop, struct fd *fd, user_ptr ptr, size_t len);
+struct fdop_args {
+	enum fdop type;
+	struct fd *fd;
+	union {
+		struct { // FDOP_READ, FDOP_WRITE
+			user_ptr ptr;
+			size_t len;
+		} rw;
+	};
+};
+
+int fdop_dispatch(struct fdop_args args);
diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index e0fb08b..bf17fd3 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -133,17 +133,28 @@ fail:
 
 int _syscall_fd_read(fd_t fd, user_ptr buf, int len) {
 	if (fd < 0 || fd >= FD_MAX) return -1;
-	return fdop_dispatch(FDOP_READ, &process_current->fds[fd], buf, len);
+	return fdop_dispatch((struct fdop_args){
+			.type = FDOP_READ, 
+			.fd = &process_current->fds[fd], 
+			.rw = {buf, len}
+		});
 }
 
 int _syscall_fd_write(fd_t fd, user_ptr buf, int len) {
 	if (fd < 0 || fd >= FD_MAX) return -1;
-	return fdop_dispatch(FDOP_WRITE, &process_current->fds[fd], buf, len);
+	return fdop_dispatch((struct fdop_args){
+			.type = FDOP_WRITE, 
+			.fd = &process_current->fds[fd], 
+			.rw = {buf, len}
+		});
 }
 
 int _syscall_fd_close(fd_t fd) {
 	if (fd < 0 || fd >= FD_MAX) return -1;
-	return fdop_dispatch(FDOP_CLOSE, &process_current->fds[fd], 0, 0);
+	return fdop_dispatch((struct fdop_args){
+			.type = FDOP_CLOSE, 
+			.fd = &process_current->fds[fd], 
+		});
 }
 
 int syscall_handler(int num, int a, int b, int c) {