syscall: Pass &str to write syscall instead of single char

common/src/syscalls/definition.rs

@@ -54,7 +54,7 @@ scalar_enum! {
 }
 
 syscalls!(
-    sys_write_char(c: char) -> ();
+    sys_write<'a>(s: &'a str) -> Result<(), ValidationError>;
     sys_read_input() -> Option<u8>;
     sys_read_input_wait() -> u8;
     sys_exit(status: isize) -> ();

kernel/src/syscalls/handler.rs

@@ -4,6 +4,7 @@ use common::{
     ref_conversion::RefToPointer,
     syscalls::{
         kernel::KernelSyscalls, SysExecuteError, SysSocketError, SysWaitError, SyscallStatus,
+        ValidationError,
     },
     unwrap_or_return,
 };
@@ -57,8 +58,10 @@ impl KernelSyscalls for SyscallHandler {
     fn sys_panic(&mut self) {
         panic!("Userspace triggered kernel panic");
     }
-    fn sys_write_char(&mut self, c: UserspaceArgument<char>) {
-        print!("{}", *c);
+    fn sys_write(&mut self, s: UserspaceArgument<&str>) -> Result<(), ValidationError> {
+        let s = s.validate(self)?;
+        print!("{s}");
+        Ok(())
     }
 
     fn sys_read_input(&mut self) -> Option<u8> {

todo.md

@@ -2,4 +2,3 @@
 
 - Multiple terminals with Ctrl+{1..10}
 - Sleep for processes
-- Better syscall return type

userspace/src/print.rs

@@ -1,6 +1,6 @@
 use core::fmt::{self, Write};
 
-use common::{mutex::Mutex, syscalls::sys_write_char};
+use common::{mutex::Mutex, syscalls::sys_write};
 
 #[macro_export]
 macro_rules! print {
@@ -22,9 +22,7 @@ struct Writer;
 
 impl Write for Writer {
     fn write_str(&mut self, s: &str) -> fmt::Result {
-        for c in s.chars() {
-            sys_write_char(c);
-        }
+        sys_write(s).unwrap();
         Ok(())
     }
 }