From a451b4506bb86ba267e9ccae4dd017500a1f8e74 Mon Sep 17 00:00:00 2001
From: pjht <pterpstra@pterpstra.com>
Date: Mon, 30 Sep 2024 13:31:40 -0500
Subject: [PATCH] Implement seeking

---
 Cargo.lock  |  4 ++++
 src/main.rs | 53 +++++++++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 319e764..553b41a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -69,6 +69,9 @@ name = "bitflags"
 version = "2.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b048fb63fd8b5923fc5aa7b340d8e156aec7ec02f0c78fa8a6ddc2613f6f71de"
+dependencies = [
+ "serde",
+]
 
 [[package]]
 name = "byteorder"
@@ -214,6 +217,7 @@ checksum = "ef1a6892d9eef45c8fa6b9e0086428a2cca8491aca8f787c534a3d6d0bcb3ced"
 name = "file_rpc"
 version = "0.1.0"
 dependencies = [
+ "bitflags",
  "parking_lot",
  "postcard",
  "serde",
diff --git a/src/main.rs b/src/main.rs
index e807315..e08286e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -36,7 +36,7 @@ use std::{
 
 use hba::Hba;
 use itertools::Itertools;
-use parking_lot::Mutex;
+use parking_lot::{Mutex, RwLock};
 use port::DeviceEnum;
 use x86_64::structures::paging::PageTableFlags;
 
@@ -44,29 +44,35 @@ use x86_64::structures::paging::PageTableFlags;
 struct AhciState {
     hba: Arc<Mutex<Hba>>,
     dev_port_map: Arc<HashMap<PathBuf, usize>>,
+    files: Arc<RwLock<Vec<(usize, u64)>>>,
 }
 
 impl dev_driver_rpc::Server for AhciState {
     fn open(&self, path: &Path) -> Result<u64, ()> {
-        Ok(*self.dev_port_map.get(path).ok_or(())? as u64)
+        let port = *self.dev_port_map.get(path).ok_or(())?;
+        let mut files = self.files.write();
+        files.push((port, 0));
+        Ok((files.len() - 1) as u64)
     }
 }
 
 impl file_rpc::Server for AhciState {
     #[allow(clippy::significant_drop_tightening)]
-    fn read(&self, fd: u64, pos: u64, len: usize) -> Result<std::borrow::Cow<'_, [u8]>, ()> {
+    fn read(&self, fd: u64, len: usize) -> Result<std::borrow::Cow<'_, [u8]>, ()> {
         let hba = self.hba.lock();
-        let port = hba.ports().get(fd as usize).ok_or(())?;
+        let (port_no, pos) = self.files.read()[fd as usize];
+        let port = hba.ports().get(port_no).ok_or(())?;
         let device = port.get_device().map_err(|_| ())?.ok_or(())?;
         let DeviceEnum::Ata(device) = device else {
             return Err(());
         };
         let mut buf = vec![0; len];
         device.read(pos as usize, &mut buf).map_err(|_| ())?;
+        self.files.write()[fd as usize].1 += len as u64;
         Ok(buf.into())
     }
 
-    fn write(&self, _fd: u64, _pos: u64, _data: &[u8]) -> Result<(), ()> {
+    fn write(&self, _fd: u64, _data: &[u8]) -> Result<(), ()> {
         todo!()
     }
 
@@ -84,7 +90,41 @@ impl file_rpc::Server for AhciState {
     }
 
     fn dup(&self, fd: u64) -> Option<u64> {
-        Some(fd)
+        let mut files = self.files.write();
+        let file = files[fd as usize].clone();
+        files.push(file);
+        Some((files.len() - 1) as u64)
+    }
+
+    #[allow(clippy::significant_drop_tightening)]
+    fn seek(&self, fd: u64, pos: file_rpc::SeekFrom) -> u64 {
+        let mut files = self.files.write();
+        let file = &mut files[fd as usize];
+        match pos {
+            file_rpc::SeekFrom::Start(offset) => {
+                file.1 = offset;
+            },
+            file_rpc::SeekFrom::End(_offset) => {
+                todo!();
+                //if offset <= 0 {
+                //    file.1 = file.len as u64 - (-offset) as u64;
+                //}
+            },
+            file_rpc::SeekFrom::Current(offset) => {
+                if offset > 0 {
+                    //file.1 = u64::min(file.1 + offset as u64, file.len as u64);
+                    file.1 += offset as u64;
+                } else {
+                    let offset = (-offset) as u64;
+                    if offset > file.1 {
+                        file.1 = 0;
+                    } else {
+                        file.1 -= offset;
+                    }
+                }
+            },
+        }
+        file.1
     }
 }
 
@@ -202,6 +242,7 @@ fn main() {
     let state = AhciState {
         hba: Arc::new(Mutex::new(hba)),
         dev_port_map: Arc::new(dev_port_map.clone()),
+        files: Arc::new(RwLock::new(Vec::new())),
     };
 
     dev_driver_rpc::register_server(Box::new(state.clone()));