Merge 46ee98d into 95f8260

lib/mirage_block_safe.ml

@@ -41,6 +41,23 @@ let rec check_buffers op sector_size = function
     >>= fun () ->
     check_buffers op sector_size bs
 
+let check_in_range op size_sectors offset =
+  if offset < 0L || offset >= size_sectors
+  then fatalf "%s: sector offset out of range 0 <= %Ld < %Ld" op offset size_sectors
+  else Lwt.return (`Ok ())
+
+let check op sector_size size_sectors offset buffers =
+  let open Mirage_block_monad.Infix in
+  check_buffers op sector_size buffers
+  >>= fun () ->
+  check_in_range op size_sectors offset
+  >>= fun () ->
+  let length = List.fold_left (fun acc b -> Cstruct.len b + acc) 0 buffers in
+  let next_sector = Int64.(add offset (of_int @@ length / sector_size)) in
+  if next_sector > size_sectors
+  then fatalf "%s: sector offset out of range %Ld > %Ld" op next_sector size_sectors
+  else Lwt.return (`Ok ())
+
 module BLOCK(B: V1_LWT.BLOCK) = struct
   include B
 
@@ -52,7 +69,7 @@ module BLOCK(B: V1_LWT.BLOCK) = struct
     B.get_info t
     >>= fun info ->
     let open Mirage_block_monad.Infix in
-    check_buffers "read" info.sector_size buffers
+    check "read" info.sector_size info.size_sectors offset buffers
     >>= fun () ->
     unsafe_read t offset buffers
 
@@ -61,7 +78,7 @@ module BLOCK(B: V1_LWT.BLOCK) = struct
     B.get_info t
     >>= fun info ->
     let open Mirage_block_monad.Infix in
-    check_buffers "write" info.sector_size buffers
+    check "write" info.sector_size info.size_sectors offset buffers
     >>= fun () ->
     unsafe_write t offset buffers
 end

lib_test/tests.ml

@@ -153,6 +153,77 @@ let safe_good_buffer_length () =
     return () in
   Lwt_main.run t
 
+let safe_bad_sector_start () =
+  let t =
+    Ramdisk.connect ~name:"ramdisk"
+    >>= fun x ->
+    let ramdisk = expect_ok "ramdisk" x in
+    let module Safe = Mirage_block.Make_safe_BLOCK(Ramdisk) in
+    Ramdisk.get_info ramdisk
+    >>= fun info ->
+    let sector = Cstruct.create info.Ramdisk.sector_size in
+    Safe.read ramdisk (-1L) [ sector ]
+    >>= fun x ->
+    expect_unknown x;
+    Safe.write ramdisk (-1L) [ sector ]
+    >>= fun x ->
+    expect_unknown x;
+    return () in
+  Lwt_main.run t
+
+let safe_good_sector_start () =
+  let t =
+    Ramdisk.connect ~name:"ramdisk"
+    >>= fun x ->
+    let ramdisk = expect_ok "ramdisk" x in
+    let module Safe = Mirage_block.Make_safe_BLOCK(Ramdisk) in
+    Ramdisk.get_info ramdisk
+    >>= fun info ->
+    Safe.read ramdisk 0L []
+    >>= fun x ->
+    expect_ok "Safe.read" x;
+    Safe.write ramdisk 0L []
+    >>= fun x ->
+    expect_ok "Safe.write" x;
+    return () in
+  Lwt_main.run t
+
+let safe_bad_sector_end () =
+  let t =
+    Ramdisk.connect ~name:"ramdisk"
+    >>= fun x ->
+    let ramdisk = expect_ok "ramdisk" x in
+    let module Safe = Mirage_block.Make_safe_BLOCK(Ramdisk) in
+    Ramdisk.get_info ramdisk
+    >>= fun info ->
+    let sector = Cstruct.create info.Ramdisk.sector_size in
+    Safe.read ramdisk info.Ramdisk.size_sectors [ sector ]
+    >>= fun x ->
+    expect_unknown x;
+    Safe.write ramdisk info.Ramdisk.size_sectors [ sector ]
+    >>= fun x ->
+    expect_unknown x;
+    return () in
+  Lwt_main.run t
+
+let safe_good_sector_end () =
+  let t =
+    Ramdisk.connect ~name:"ramdisk"
+    >>= fun x ->
+    let ramdisk = expect_ok "ramdisk" x in
+    let module Safe = Mirage_block.Make_safe_BLOCK(Ramdisk) in
+    Ramdisk.get_info ramdisk
+    >>= fun info ->
+    let sector = Cstruct.create info.Ramdisk.sector_size in
+    Safe.read ramdisk (Int64.pred info.Ramdisk.size_sectors) [ sector ]
+    >>= fun x ->
+    expect_ok "Safe.read" x;
+    Safe.write ramdisk (Int64.pred info.Ramdisk.size_sectors) [ sector ]
+    >>= fun x ->
+    expect_ok "Safe.write" x;
+    return () in
+  Lwt_main.run t
+
 let tests = [
   "ramdisk compare" >:: ramdisk_compare;
   "different compare" >:: different_compare;
@@ -161,6 +232,10 @@ let tests = [
   "sparse copy an empty disk" >:: sparse_copy;
   "safe wrapper catches bad buffer lengths" >:: safe_bad_buffer_length;
   "safe wrapper accepts good buffer lengths" >:: safe_good_buffer_length;
+  "safe wrapper catches bad sector start" >:: safe_bad_sector_start;
+  "safe wrapper accepts good sector start" >:: safe_good_sector_start;
+  "safe wrapper catches bad sector end" >:: safe_bad_sector_end;
+  "safe wrapper accepts good sector end" >:: safe_good_sector_end;
 ]
 
 let _ =