kernel: split the kernel/user inputs in VfsReq

I think I've done this refactor in the opposite direction a few years ago.

This is mostly meant to prepare me for setxattr, which requires two inputs -
coincidentally, one is already going to be a kernel input, and the other will
be an user input, so it works out.

I also just didn't like the previous way it worked, this feels cleaner.

1 files changed, 16 insertions, 14 deletions

diff --git a/src/kernel/vfs/request.h b/src/kernel/vfs/request.h
index d6facfd..484fdd7 100644
--- a/src/kernel/vfs/request.h
+++ b/src/kernel/vfs/request.h
@@ -37,20 +37,22 @@ struct VfsBackend {
 /* describes an in-progress vfs call */
 struct VfsReq {
 	enum vfs_op type;
-	struct {
-		bool kern; // if false: use .buf ; if true: use .buf_kern
-		union {
-			char __user *buf;
-			char *buf_kern;
-		};
-		size_t len;
-	} input;
-	struct {
-		char __user *buf;
-		size_t len;
-	} output;
-
-	void __user *id, *id2; // handle.file.id
+
+	/* "kernel" input - an allocation owned by this struct, contains a NUL
+	 * terminated string. the NUL isn't counted in the kinlen (for compat
+	 * with old code). used for the path in open() */
+	char *kin;
+	size_t kinlen;
+
+	/* user inputs and outputs - just point to some buffer in the caller */
+	char __user *uin;
+	size_t uinlen;
+	char __user *out;
+	size_t outlen;
+
+	/* those correspond to handle.file.id
+	 * id2 is used for duplex() */
+	void __user *id, *id2;
 	long offset;
 	int flags;