[PATCH] tools/ocaml/mmap: Drop the len parameter from Xenmmap.write

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Strings in Ocaml carry their own length.  Absolutely nothing good can come
from having caml_string_length(data) be different to len.

Use the appropriate accessor, String_val(), but retain the workaround for the
Ocaml -safe-string constness bug in the same way as we've done elsewhere in
Xen.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Christian Lindig <christian.lindig@xxxxxxxxxx>
CC: David Scott <dave@xxxxxxxxxx>
CC: Edwin Török <edwin.torok@xxxxxxxxx>
CC: Rob Hoes <Rob.Hoes@xxxxxxxxxx>
---
 tools/ocaml/libs/mmap/xenmmap.ml      |  4 ++--
 tools/ocaml/libs/mmap/xenmmap.mli     |  2 +-
 tools/ocaml/libs/mmap/xenmmap_stubs.c | 11 +++++------
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/tools/ocaml/libs/mmap/xenmmap.ml b/tools/ocaml/libs/mmap/xenmmap.ml
index fd6735649f4c..746ca6e21c52 100644
--- a/tools/ocaml/libs/mmap/xenmmap.ml
+++ b/tools/ocaml/libs/mmap/xenmmap.ml
@@ -25,7 +25,7 @@ external mmap: Unix.file_descr -> mmap_prot_flag -> 
mmap_map_flag
 external unmap: mmap_interface -> unit = "stub_mmap_final"
 (* read: interface -> start -> length -> data *)
 external read: mmap_interface -> int -> int -> string = "stub_mmap_read"
-(* write: interface -> data -> start -> length -> unit *)
-external write: mmap_interface -> string -> int -> int -> unit = 
"stub_mmap_write"
+(* write: interface -> data -> start -> unit *)
+external write: mmap_interface -> string -> int -> unit = "stub_mmap_write"
 (* getpagesize: unit -> size of page *)
 external getpagesize: unit -> int = "stub_mmap_getpagesize"
diff --git a/tools/ocaml/libs/mmap/xenmmap.mli 
b/tools/ocaml/libs/mmap/xenmmap.mli
index d097b68a8fdf..5d6aa19ca6cb 100644
--- a/tools/ocaml/libs/mmap/xenmmap.mli
+++ b/tools/ocaml/libs/mmap/xenmmap.mli
@@ -22,7 +22,7 @@ external mmap : Unix.file_descr -> mmap_prot_flag -> 
mmap_map_flag -> int -> int
   -> mmap_interface = "stub_mmap_init"
 external unmap : mmap_interface -> unit = "stub_mmap_final"
 external read : mmap_interface -> int -> int -> string = "stub_mmap_read"
-external write : mmap_interface -> string -> int -> int -> unit
+external write : mmap_interface -> string -> int -> unit
   = "stub_mmap_write"
 
 external getpagesize : unit -> int = "stub_mmap_getpagesize"
diff --git a/tools/ocaml/libs/mmap/xenmmap_stubs.c 
b/tools/ocaml/libs/mmap/xenmmap_stubs.c
index c85b1fcce7d5..c15a565aaa52 100644
--- a/tools/ocaml/libs/mmap/xenmmap_stubs.c
+++ b/tools/ocaml/libs/mmap/xenmmap_stubs.c
@@ -99,27 +99,26 @@ CAMLprim value stub_mmap_read(value intf, value start, 
value len)
                caml_invalid_argument("len invalid");
 
        data = caml_alloc_string(c_len);
-       memcpy((char *) data, Intf_val(intf)->addr + c_start, c_len);
+       memcpy((char *)String_val(data), Intf_val(intf)->addr + c_start, c_len);
 
        CAMLreturn(data);
 }
 
-CAMLprim value stub_mmap_write(value intf, value data,
-                               value start, value len)
+CAMLprim value stub_mmap_write(value intf, value data, value start)
 {
-       CAMLparam4(intf, data, start, len);
+       CAMLparam3(intf, data, start);
        int c_start;
        int c_len;
 
        c_start = Int_val(start);
-       c_len = Int_val(len);
+       c_len = caml_string_length(data);
 
        if (c_start > Intf_val(intf)->len)
                caml_invalid_argument("start invalid");
        if (c_start + c_len > Intf_val(intf)->len)
                caml_invalid_argument("len invalid");
 
-       memcpy(Intf_val(intf)->addr + c_start, (char *) data, c_len);
+       memcpy(Intf_val(intf)->addr + c_start, String_val(data), c_len);
 
        CAMLreturn(Val_unit);
 }
-- 
2.30.2