Add ucontext_t

Cargo.lock

@@ -7,6 +7,7 @@ name = "burritos"
 version = "0.1.0"
 dependencies = [
  "lazy_static",
+ "libc",
 ]
 
 [[package]]
@@ -14,3 +15,9 @@ name = "lazy_static"
 version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
+[[package]]
+name = "libc"
+version = "0.2.139"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "201de327520df007757c1f0adce6e827fe8562fbc28bfd9c15571c66ca1f5f79"

Cargo.toml

@@ -5,3 +5,4 @@ edition = "2021"
 
 [dependencies]
 lazy_static = "1.4.0"
+libc = { version = "0.2.139", features = ["extra_traits"] }

src/kernel/mod.rs

@@ -2,4 +2,5 @@ mod process;
 pub mod thread;
 pub mod scheduler;
 pub mod mgerror;
-pub mod system;
+pub mod system;
+mod ucontext;

src/kernel/thread.rs

@@ -1,14 +1,10 @@
-use std::sync::Arc;
+use std::{sync::Arc};
 
-use super::{process::Process, mgerror::ErrorCode, system::{ObjectType, G_ALIVE, G_SCHEDULER}};
+use super::{process::Process, mgerror::ErrorCode, system::{ObjectType, G_ALIVE, G_SCHEDULER}, ucontext::UContextT};
 use crate::{simulator::machine::{NUM_INT_REGS, NUM_FP_REGS, STACK_REG}};
 
 const SIMULATORSTACKSIZE: usize = 32 * 1024;
-
-#[derive(PartialEq)]
-struct SimulatorContext {
-    // todo
-}
+const STACK_FENCEPOST: u32 = 0xdeadbeef;
 
 #[derive(PartialEq)]
 struct ThreadContext {
@@ -21,7 +17,7 @@ struct ThreadContext {
 pub struct Thread {
     name: String,
     process: Option<Process>,
-    simulation_context: SimulatorContext,
+    // simulation_context: UContextT,
     thread_context: ThreadContext,
     stack_pointer: i32,
     object_type: ObjectType
@@ -33,7 +29,7 @@ impl Thread {
         Self {
             name,
             process: None,
-            simulation_context: SimulatorContext {  },
+            // simulation_context: UContextT::new(),
             thread_context: ThreadContext { 
                 int_registers: [0; NUM_INT_REGS], 
                 float_registers: [0; NUM_FP_REGS], 
@@ -79,7 +75,18 @@ impl Thread {
     }
 
     fn init_simulator_context(&self, base_stack_addr: [i8; SIMULATORSTACKSIZE]) {
-        todo!();
+        // let res = self.simulation_context.get_context();
+        // if res != 0 {
+        //     panic!("getcontext returns non-zero value {}", res);
+        // }
+        // self.simulation_context.buf.uc_stack.ss_sp = base_stack_addr;
+        // self.simulation_context.buf.uc_stack.ss_size = base_stack_addr.len();
+        // self.simulation_context.buf.uc_stack.ss_flags = 0;
+        // self.simulation_context.buf.uc_link = UContextT::new().buf;
+        // self.simulation_context.make_context(start_thread_execution, 0);
+
+        // self.simulation_context.stackBottom = base_stack_addr.to_vec();
+        // self.simulation_context.stackBottom[0] = STACK_FENCEPOST;
     }
 
     /// Wait for another thread to finish its execution
@@ -147,4 +154,8 @@ impl Drop for Thread {
         todo!();
     }
 
+}
+
+fn start_thread_execution() {
+    
 }

src/kernel/ucontext.rs

@@ -0,0 +1,72 @@
+
+use std::mem::MaybeUninit;
+
+use libc::{ucontext_t, getcontext, setcontext, makecontext};
+
+/// Safe wrapper for ucontext_t struct of linux-gnu libc
+/// 
+/// setcontext and getcontext are unsafe function, this wrap unsafe libc functions 
+/// 
+/// This struct doesn't work on windows, because this struct is unavailable
+/// 
+/// todo ucontext_t is not thread-safe (doesn't implements Send and Sync trait), and cannot be use in Threads as rust require var in Mutex (see system.rs) to have everything inside to implements thread-safe traits
+#[derive(PartialEq)]
+pub struct UContextT {
+    #[cfg(not(target_os = "windows"))] // struct non disponible sur la libc sur windows
+    pub buf: ucontext_t,
+    pub stackBottom: Vec<i8>
+}
+
+#[cfg(not(target_os = "windows"))]
+impl UContextT {
+
+    pub fn new() -> Self {
+        let mut context = MaybeUninit::<ucontext_t>::uninit();
+        unsafe { getcontext(context.as_mut_ptr()) };
+        Self {
+            buf: unsafe  { context.assume_init() },
+            stackBottom: Vec::default(),
+        }
+    }
+
+    /// Get user context and store it in variable pointed to by UCP.
+    /// 
+    /// Use `man getcontext` for more informations
+    pub fn get_context(&mut self) -> i32 {
+        unsafe {
+            getcontext(&mut self.buf)
+        }
+    }
+
+    /// Set user context from information of variable pointed to by UCP.
+    /// 
+    /// Use `man setcontext` for more informations
+    pub fn set_context(&mut self) -> i32 {
+        unsafe {
+            setcontext(&self.buf)
+        }
+    }
+
+    pub fn make_context(&mut self, func: extern "C" fn(), args: i32) {
+        unsafe {
+            makecontext(&mut self.buf, func, args)
+        }
+    }
+    
+}
+
+#[cfg(target_os = "windows")] 
+impl UContextT {
+
+    pub fn new() -> Self {
+        Self {}
+    }
+
+    pub fn get_context(&mut self) {
+        // no op
+    }
+
+    pub fn set_context(&mut self) {
+        // no op
+    }
+}