[PATCH proxmox 1/9] proxmox-sys: add len and as_non_null method to Mmap

[Robert Obkircher <r.obkircher@proxmox.com>]

Allow access to the raw parts of the slice without materializing a
reference to it.

Signed-off-by: Robert Obkircher <r.obkircher@proxmox.com>
---
 proxmox-sys/src/mmap.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/proxmox-sys/src/mmap.rs b/proxmox-sys/src/mmap.rs
index e15ca1db..d54ed6e6 100644
--- a/proxmox-sys/src/mmap.rs
+++ b/proxmox-sys/src/mmap.rs
@@ -18,6 +18,7 @@ pub struct Mmap<T> {
     len: usize,
 }
 
+/// Memory can be used and unmapped on another thread.
 unsafe impl<T> Send for Mmap<T> where T: Send {}
 unsafe impl<T> Sync for Mmap<T> where T: Sync {}
 
@@ -68,6 +69,20 @@ impl<T> Mmap<T> {
         }
         .map_err(SysError::into_io_error)
     }
+
+    pub fn is_empty(&self) -> bool {
+        self.len == 0
+    }
+
+    /// Return the length (without creating a reference to the slice)
+    pub fn len(&self) -> usize {
+        self.len
+    }
+
+    /// Return the underlying pointer (without creating a reference to the slice)
+    pub fn as_non_null(&self) -> NonNull<T> {
+        self.data
+    }
 }
 
 impl<T> std::ops::Deref for Mmap<T> {
-- 
2.47.3