From 267a85f9ef709ccbefe5ae0ccbb306bd21921418 Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Thu, 16 Sep 2021 06:42:07 +0000
Subject: implement output from vfs calls

---
 src/kernel/syscalls.c    | 11 ++++++++++-
 src/kernel/vfs/request.c |  1 -
 src/kernel/vfs/request.h |  8 ++------
 3 files changed, 12 insertions(+), 8 deletions(-)

(limited to 'src/kernel')

diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index d39aed9..a5c6f43 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -236,7 +236,16 @@ int _syscall_fs_respond(char __user *buf, int ret) {
 	struct vfs_request *req = process_current->handled_req;
 	if (!req) return -1;
 
-	// TODO copy buffer
+	if (req->output.len > 0 && ret > 0) {
+		// if this vfsop outputs data and ret is positive, it's the length of the buffer
+		// TODO document
+		if (ret > req->output.len)
+			ret = req->output.len; // i'm not handling this in a special way - the fs server can prevent this on its own
+		if (!virt_cpy(req->caller->pages, req->output.buf,
+					process_current->pages, buf, ret)) {
+			// how should this error even be handled? TODO
+		}
+	}
 
 	process_current->handled_req = NULL;
 	vfs_request_finish(req, ret);
diff --git a/src/kernel/vfs/request.c b/src/kernel/vfs/request.c
index 9a51688..6159bbf 100644
--- a/src/kernel/vfs/request.c
+++ b/src/kernel/vfs/request.c
@@ -96,7 +96,6 @@ int vfs_request_finish(struct vfs_request *req, int ret) {
 	}
 
 	if (req->input.kern)  kfree(req->input.buf_kern);
-	if (req->output.kern) kfree(req->output.buf_kern);
 
 	req->caller->state = PS_RUNNING;
 	regs_savereturn(&req->caller->regs, ret);
diff --git a/src/kernel/vfs/request.h b/src/kernel/vfs/request.h
index aabef4f..0ad50e9 100644
--- a/src/kernel/vfs/request.h
+++ b/src/kernel/vfs/request.h
@@ -18,7 +18,7 @@ struct vfs_backend {
 // describes an in-process vfs call
 struct vfs_request {
 	enum vfs_operation type;
-	struct { // TODO maybe this should be a separate type
+	struct {
 		bool kern; // if false: use .buf ; if true: use .buf_kern
 		union {
 			char __user *buf;
@@ -27,11 +27,7 @@ struct vfs_request {
 		int len;
 	} input;
 	struct {
-		bool kern; // if false: use .buf ; if true: use .buf_kern
-		union {
-			char __user *buf;
-			char *buf_kern;
-		};
+		char __user *buf;
 		int len;
 	} output;
 
-- 
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