fix alloca_limit for recursive calls

src/ext.rs

@@ -1,5 +1,6 @@
 //! Extensions and macros
 use std::cell::RefCell;
+use std::ptr;
 
 #[macro_export] macro_rules! basic_enum {
     ($(#[$meta:meta])* $vis:vis $name:ident $(; $tcomment:literal)?: $($var:ident $(=> $comment:literal)?),+ $(,)?) => {
@@ -138,16 +139,34 @@ where F: FnOnce(&mut [u8]) -> T
 	    static BUFFER: RefCell<Vec<u8>> = RefCell::new(vec![0u8; STACK_SIZE_LIMIT*2]);
 	}
 	BUFFER.with(move |buf| {
-	    let mut buf = buf.borrow_mut();
-	    if buf.len() < size {
-		buf.resize(size, 0);
+	    // If the borrow fails then `f` has recursively called into this function, so for that we allocate a new buffer instead of reusing this static one.
+	    if let Ok(mut buf) = buf.try_borrow_mut() {
+		if buf.len() < size {
+		    buf.resize(size, 0);
+		}
+		let res = f(&mut buf[..size]);
+		bytes::blank(&mut buf[..size]);
+		res
+	    } else {
+		f(&mut vec![0u8; size])		
 	    }
-	    f(&mut buf[..size])
 	})
     } else {
 	stackalloc::alloca_zeroed(size, f)
-	//
-	// TODO: Is this okay to do? I'm not sure it is.. We'll see
+	    
+	// I don't think this is okay to do.
 	//stackalloc::alloca(size, move |buf| f(unsafe { stackalloc::helpers::slice_assume_init_mut(buf) }))
     }
 }
+
+pub mod bytes
+{
+    use super::*;
+    /// `bzero` this slice
+    pub fn blank(slice: &mut [u8])
+    {
+	unsafe {
+	    ptr::write_bytes(slice.as_mut_ptr(), 0, slice.len());
+	}
+    }
+}