From 613de4db61dd99e7d2049b0a303e167fa711030b Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Sat, 4 Sep 2021 19:34:51 +0200
Subject: new vfs impl pt. 1: implement open()

---
 src/kernel/vfs/backend.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 src/kernel/vfs/backend.c

(limited to 'src/kernel/vfs/backend.c')

diff --git a/src/kernel/vfs/backend.c b/src/kernel/vfs/backend.c
new file mode 100644
index 0000000..cf73ef0
--- /dev/null
+++ b/src/kernel/vfs/backend.c
@@ -0,0 +1,42 @@
+#include <kernel/panic.h>
+#include <kernel/proc.h>
+#include <kernel/vfs/backend.h>
+#include <kernel/vfs/root.h>
+
+// dispatches a VFS operation to the correct process
+_Noreturn void vfs_backend_dispatch(struct vfs_backend *backend, struct vfs_op op) {
+	struct vfs_op_request req = {
+		.op = op,
+		.caller = process_current,
+	};
+	switch (backend->type) {
+		case VFS_BACK_ROOT:
+			int ret = vfs_root_handler(&req);
+			vfs_backend_finish(&req, ret);
+		default:
+			panic();
+	}
+}
+
+// returns from a VFS operation to the calling process
+_Noreturn void vfs_backend_finish(struct vfs_op_request *req, int ret) {
+	if (req->op.type == VFSOP_OPEN && ret >= 0) {
+		// open() calls need special handling
+		// we need to wrap the id returned by the VFS in a handle passed to
+		// the client
+		handle_t handle = process_find_handle(req->caller);
+		if (handle < 0) panic();
+		req->caller->handles[handle] = (struct handle){
+			.type = HANDLE_FILE,
+			.file = {
+				.backend = req->backend,
+				.id = ret,
+			},
+		};
+		ret = handle;
+	} 
+
+	req->caller->state = PS_RUNNING;
+	regs_savereturn(&req->caller->regs, ret);
+	process_switch(req->caller);
+}
-- 
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