From 3de7d1c82953675e79952f3da81a6d5fce985193 Mon Sep 17 00:00:00 2001
From: Garen Tyler <garentyler@garen.dev>
Date: Fri, 3 Nov 2023 19:23:31 -0600
Subject: [PATCH] move growproc to assoc fn

---
 kernel/rustkernel/src/proc/process.rs | 49 ++++++++++++++++-----------
 kernel/rustkernel/src/syscall.rs      |  9 ++---
 2 files changed, 34 insertions(+), 24 deletions(-)

diff --git a/kernel/rustkernel/src/proc/process.rs b/kernel/rustkernel/src/proc/process.rs
index 28cbc6b..a0a281e 100644
--- a/kernel/rustkernel/src/proc/process.rs
+++ b/kernel/rustkernel/src/proc/process.rs
@@ -44,7 +44,7 @@ extern "C" {
 pub static NEXT_PID: AtomicI32 = AtomicI32::new(1);
 
 #[repr(C)]
-#[derive(PartialEq, Default)]
+#[derive(Copy, Clone, Debug, Default, PartialEq)]
 pub enum ProcessState {
     #[default]
     Unused,
@@ -55,6 +55,11 @@ pub enum ProcessState {
     Zombie,
 }
 
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub enum ProcessError {
+    Allocation,
+}
+
 /// Per-process state.
 #[repr(C)]
 pub struct Process {
@@ -124,6 +129,10 @@ impl Process {
         }
     }
 
+    pub fn alloc_pid() -> i32 {
+        NEXT_PID.fetch_add(1, Ordering::SeqCst)
+    }
+
     /// Free a proc structure and the data hanging from it, including user pages.
     /// self.lock must be held.
     pub unsafe fn free(&mut self) {
@@ -145,6 +154,24 @@ impl Process {
         self.state = ProcessState::Unused;
     }
 
+    /// Grow or shrink user memory.
+    pub unsafe fn grow_memory(&mut self, num_bytes: i32) -> Result<(), ProcessError> {
+        let mut size = self.sz;
+
+        if num_bytes > 0 {
+            size = uvmalloc(self.pagetable, size, size.wrapping_add(num_bytes as u64), PTE_W);
+
+            if size == 0 {
+                return Err(ProcessError::Allocation);
+            }
+        } else if num_bytes < 0 {
+            size = uvmdealloc(self.pagetable, size, size.wrapping_add(num_bytes as u64));
+        }
+
+        self.sz = size;
+        Ok(())
+    }
+
     /// Kill the process with the given pid.
     /// Returns true if the process was killed.
     /// The victim won't exit until it tries to return
@@ -193,7 +220,7 @@ pub extern "C" fn myproc() -> *mut Process {
 
 #[no_mangle]
 pub extern "C" fn allocpid() -> i32 {
-    NEXT_PID.fetch_add(1, Ordering::SeqCst)
+    Process::alloc_pid()
 }
 
 /// Free a proc structure and the data hanging from it, including user pages.
@@ -215,24 +242,6 @@ pub unsafe extern "C" fn reparent(p: *mut Process) {
     }
 }
 
-/// Grow or shrink user memory by n bytes.
-/// Return 0 on success, -1 on failure.
-pub unsafe fn growproc(n: i32) -> i32 {
-    let p = Process::current().unwrap();
-    let mut sz = p.sz;
-
-    if n > 0 {
-        sz = uvmalloc(p.pagetable, sz, sz.wrapping_add(n as u64), PTE_W);
-        if sz == 0 {
-            return -1;
-        }
-    } else if n < 0 {
-        sz = uvmdealloc(p.pagetable, sz, sz.wrapping_add(n as u64));
-    }
-    p.sz = sz;
-    0
-}
-
 /// Kill the process with the given pid.
 /// The victim won't exit until it tries to return
 /// to user space (see usertrap() in trap.c).
diff --git a/kernel/rustkernel/src/syscall.rs b/kernel/rustkernel/src/syscall.rs
index db37775..c770335 100644
--- a/kernel/rustkernel/src/syscall.rs
+++ b/kernel/rustkernel/src/syscall.rs
@@ -142,12 +142,13 @@ impl Syscall {
             Syscall::Sbrk => {
                 let mut n = 0i32;
                 argint(0, addr_of_mut!(n));
-                let addr = Process::current().unwrap().sz;
+                let proc = Process::current().unwrap();
+                let addr = proc.sz;
 
-                if process::growproc(n) < 0 {
-                    -1i64 as u64
-                } else {
+                if unsafe { proc.grow_memory(n).is_ok() } {
                     addr
+                } else {
+                    -1i64 as u64
                 }
             }
             Syscall::Sleep => {