From 0b83a3629ab44633a2a4cd4ef7fc6ece171f0446 Mon Sep 17 00:00:00 2001
From: Stephen Marz <stephen.marz@utk.edu>
Date: Tue, 19 May 2020 09:27:57 -0400
Subject: [PATCH] Get set up to support file descriptors in user space.

---
 risc_v/src/cpu.rs     |  2 +-
 risc_v/src/elf.rs     |  2 +-
 risc_v/src/process.rs | 23 ++++++++++++++++-------
 3 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/risc_v/src/cpu.rs b/risc_v/src/cpu.rs
index 0240f98..5324094 100755
--- a/risc_v/src/cpu.rs
+++ b/risc_v/src/cpu.rs
@@ -7,7 +7,7 @@
 // The frequency of QEMU is 10 MHz
 pub const FREQ: u64 = 10_000_000;
 // Let's do this 250 times per second for switching
-pub const CONTEXT_SWITCH_TIME: u64 = FREQ / 250;
+pub const CONTEXT_SWITCH_TIME: u64 = FREQ / 500;
 
 /// In 64-bit mode, we're given three different modes for the MMU:
 /// 0 - The MMU is off -- no protection and no translation PA = VA
diff --git a/risc_v/src/elf.rs b/risc_v/src/elf.rs
index d00565b..e8cf030 100755
--- a/risc_v/src/elf.rs
+++ b/risc_v/src/elf.rs
@@ -169,7 +169,7 @@ impl File {
 			          pid:         my_pid,
 			          root:        zalloc(1) as *mut Table,
 			          state:       ProcessState::Running,
-			          data:        ProcessData::zero(),
+			          data:        ProcessData::new(),
 			          sleep_until: 0,
 			          program:     zalloc(program_pages) };
 
diff --git a/risc_v/src/process.rs b/risc_v/src/process.rs
index 1d8c6f3..416c480 100644
--- a/risc_v/src/process.rs
+++ b/risc_v/src/process.rs
@@ -10,6 +10,7 @@ use crate::{cpu::{build_satp,
                   SatpMode,
 				  TrapFrame,
 				  Registers},
+			fs::Inode,
             page::{alloc,
                    dealloc,
                    map,
@@ -249,7 +250,7 @@ pub fn add_kernel_process(func: fn()) -> u16 {
 					pid:         my_pid,
 					root:        zalloc(1) as *mut Table,
 					state:       ProcessState::Running,
-					data:        ProcessData::zero(),
+					data:        ProcessData::new(),
 					sleep_until: 0,
 					program:		null_mut()
 					};
@@ -334,7 +335,7 @@ pub fn add_kernel_process_args(func: fn(args_ptr: usize), args: usize) -> u16 {
 			          pid:         my_pid,
 			          root:        zalloc(1) as *mut Table,
 			          state:       ProcessState::Running,
-			          data:        ProcessData::zero(),
+			          data:        ProcessData::new(),
 					  sleep_until: 0, 
 					  program:		null_mut(),
 					};
@@ -501,7 +502,7 @@ impl Process {
 			          pid:         unsafe { NEXT_PID },
 			          root:        zalloc(1) as *mut Table,
 			          state:       ProcessState::Running,
-			          data:        ProcessData::zero(),
+			          data:        ProcessData::new(),
 					  sleep_until: 0, 
 					  program:     null_mut()
 					};
@@ -570,7 +571,6 @@ impl Drop for Process {
 	/// Since we're storing ownership of a Process in the linked list,
 	/// we can cause it to deallocate automatically when it is removed.
 	fn drop(&mut self) {
-		// println!("Dropping process {}", self.get_pid());
 		// We allocate the stack as a page.
 		dealloc(self.stack);
 		// This is unsafe, but it's at the drop stage, so we won't
@@ -589,6 +589,13 @@ impl Drop for Process {
 	}
 }
 
+pub enum FileDescriptor {
+	File(Inode),
+	Device(usize),
+	Network,
+	Unknown,
+}
+
 // The private data in a process contains information
 // that is relevant to where we are, including the path
 // and open file descriptors.
@@ -596,16 +603,18 @@ impl Drop for Process {
 // private process data. This is essentially our resource control block (RCB).
 #[allow(dead_code)]
 pub struct ProcessData {
-	environ: BTreeMap<String, String>
+	environ: BTreeMap<String, String>,
+	fdesc: BTreeMap<u16, FileDescriptor>,
 }
 
 // This is private data that we can query with system calls.
 // If we want to implement CFQ (completely fair queuing), which
 // is a per-process block queuing algorithm, we can put that here.
 impl ProcessData {
-	pub fn zero() -> Self {
+	pub fn new() -> Self {
 		ProcessData { 
-			environ: BTreeMap::new()
+			environ: BTreeMap::new(),
+			fdesc: BTreeMap::new(),
 		 }
 	}
 }