protocol: expose chunker and digest function

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

proxmox-protocol/src/c_chunker.rs

@@ -0,0 +1,45 @@
+//! C API for the Chunker.
+
+use std::os::raw::c_void;
+
+use crate::Chunker;
+
+/// Creates a new chunker instance.
+#[no_mangle]
+pub extern "C" fn proxmox_chunker_new(chunk_size_avg: u64) -> *mut Chunker {
+    Box::leak(Box::new(Chunker::new(chunk_size_avg as usize)))
+}
+
+/// Drops an instance of a chunker. The pointer must be valid or `NULL`.
+#[no_mangle]
+pub extern "C" fn proxmox_chunker_done(me: *mut Chunker) {
+    if !me.is_null() {
+        unsafe {
+            Box::from_raw(me);
+        }
+    }
+}
+
+/// Scan the specified data for a chunk border. Returns 0 if none was found, or a positive offset
+/// to a border.
+#[no_mangle]
+pub extern "C" fn proxmox_chunker_scan(
+    me: *mut Chunker,
+    data: *const c_void,
+    size: u64,
+) -> u64 {
+    let me = unsafe { &mut *me };
+    me.scan(unsafe {
+        std::slice::from_raw_parts(data as *const u8, size as usize)
+    }) as u64
+}
+
+/// Compute a chunk digest. This is mostly a convenience method to avoid having to lookup the right
+/// digest method for your language of choice.
+#[no_mangle]
+pub extern "C" fn proxmox_chunk_digest(data: *const c_void, size: u64, out_digest: *mut [u8; 32]) {
+    let digest = crate::FixedChunk::from_data(unsafe {
+        std::slice::from_raw_parts(data as *const u8, size as usize)
+    });
+    unsafe { *out_digest = digest.0 };
+}

proxmox-protocol/src/lib.rs

@@ -17,3 +17,4 @@ mod types;
 pub use types::*;
 
 pub mod c_client;
+pub mod c_chunker;