Fixing safety declarations in the userspace module

src/userspace.rs

@@ -6,6 +6,10 @@ use std::process::exit;
 use std::slice;
 
 /// Write error message to stderr
+///
+/// # Safety
+/// This function should only be called by the library, which should ensure that the `buffer`
+/// contains exactly `nbytes` bytes.
 #[no_mangle]
 pub unsafe extern "C" fn zan_write(buffer: *const u8, nbytes: usize) {
     let buf = slice::from_raw_parts(buffer, nbytes);
@@ -14,10 +18,10 @@ pub unsafe extern "C" fn zan_write(buffer: *const u8, nbytes: usize) {
 
 /// Abort the program by exiting with error code
 #[no_mangle]
-pub unsafe extern "C" fn zan_abort() {
+pub extern "C" fn zan_abort() {
     exit(1);
 }
 
 /// Right now this does nothing, but it would be great to disable UNIX signals for example
 #[no_mangle]
-pub unsafe fn zan_disable_interrupts() {}
+pub fn zan_disable_interrupts() {}