Add ucontext_t

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
+    }
+}