Remove resource_sceme, Fix syscall crate name, add fmap

kernel/syscall/fs.rs

@@ -293,3 +293,27 @@ pub fn fevent(fd: usize, flags: usize) -> Result<usize> {
     context::event::register(fd, file.scheme, event_id);
     Ok(0)
 }
+
+pub fn funmap(virtual_address: usize) -> Result<usize> {
+    if virtual_address == 0 {
+        Ok(0)
+    } else {
+        let contexts = context::contexts();
+        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
+        let context = context_lock.read();
+
+        let mut grants = context.grants.lock();
+
+        for i in 0 .. grants.len() {
+            let start = grants[i].start_address().get();
+            let end = start + grants[i].size();
+            if virtual_address >= start && virtual_address < end {
+                grants.remove(i).unmap();
+
+                return Ok(0);
+            }
+        }
+
+        Err(Error::new(EFAULT))
+    }
+}

kernel/syscall/mod.rs

@@ -41,6 +41,7 @@ pub extern fn syscall(a: usize, b: usize, c: usize, d: usize, e: usize, f: usize
                     SYS_CLOSE => close(b),
                     SYS_DUP => dup(b, validate_slice(c as *const u8, d)?),
                     SYS_FEVENT => fevent(b, c),
+                    SYS_FUNMAP => funmap(b),
                     _ => file_op(a, b, c, d)
                 }
             },

kernel/syscall/process.rs

@@ -367,11 +367,12 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<usize> {
                     context.heap = Some(heap_shared);
                 }
 
+                // Copy grant mapping
                 if ! grants.lock().is_empty() {
-                    let frame = active_table.p4()[2].pointed_frame().expect("user heap not mapped");
+                    let frame = active_table.p4()[2].pointed_frame().expect("user grants not mapped");
                     let flags = active_table.p4()[2].flags();
                     active_table.with(&mut new_table, &mut temporary_page, |mapper| {
-                        mapper.p4_mut()[1].set(frame, flags);
+                        mapper.p4_mut()[2].set(frame, flags);
                     });
                 }
                 context.grants = grants;