3 files changed, 34 insertions, 2 deletions

diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index 0b557fb..fcd3c1e 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -200,6 +200,27 @@ fail:
 	return -1;
 }
 
+int _syscall_fs_wait(handle_t back, user_ptr info) {
+	struct handle *back_handle;
+
+	if (back < 0 || back >= HANDLE_MAX) return -1;
+	back_handle = &process_current->handles[back];
+	if (back_handle->type != HANDLE_FS_BACK)
+		return -1;
+
+	process_current->state = PS_WAITS4REQUEST;
+	back_handle->fs.backend->handler = process_current;
+
+	if (back_handle->fs.backend->queue) {
+		// handle queued requests
+		struct process *queued = back_handle->fs.backend->queue;
+		back_handle->fs.backend->queue = NULL; // TODO get the next queued proc
+		vfs_request_pass2handler(queued->pending_req);
+	} else {
+		process_switch_any();
+	}
+}
+
 int syscall_handler(int num, int a, int b, int c) {
 	switch (num) {
 		case _SYSCALL_EXIT:
@@ -220,6 +241,8 @@ int syscall_handler(int num, int a, int b, int c) {
 			return _syscall_close(a);
 		case _SYSCALL_FS_CREATE:
 			return _syscall_fs_create(a);
+		case _SYSCALL_FS_WAIT:
+			return _syscall_fs_wait(a, b);
 		default:
 			tty_const("unknown syscall ");
 			panic();
diff --git a/src/kernel/vfs/backend.c b/src/kernel/vfs/backend.c
index 7e53e51..4b22104 100644
--- a/src/kernel/vfs/backend.c
+++ b/src/kernel/vfs/backend.c
@@ -27,14 +27,22 @@ _Noreturn void vfs_backend_dispatch(struct vfs_backend *backend, struct vfs_op o
 				process_current->pending_req = req;
 				process_switch_any();
 			} else {
-				assert(backend->handler->state == PS_WAITS4REQUEST);
-				panic(); // TODO
+				vfs_request_pass2handler(req);
 			}
 		default:
 			panic();
 	}
 }
 
+_Noreturn void vfs_request_pass2handler(struct vfs_op_request *req) {
+	assert(req->backend->handler);
+	assert(req->backend->handler->state == PS_WAITS4REQUEST);
+
+	req->backend->handler->state = PS_RUNNING;
+	// TODO pass the request to the process
+	process_switch(req->backend->handler);
+}
+
 // returns from a VFS operation to the calling process
 _Noreturn void vfs_backend_finish(struct vfs_op_request *req, int ret) {
 	struct process *caller = req->caller;
diff --git a/src/kernel/vfs/backend.h b/src/kernel/vfs/backend.h
index bf16ee7..bc0dc45 100644
--- a/src/kernel/vfs/backend.h
+++ b/src/kernel/vfs/backend.h
@@ -25,4 +25,5 @@ struct vfs_op_request {
 
 // these can switch processes
 _Noreturn void vfs_backend_dispatch(struct vfs_backend *backend, struct vfs_op op);
+_Noreturn void vfs_request_pass2handler(struct vfs_op_request *);
 _Noreturn void vfs_backend_finish(struct vfs_op_request *, int ret);