Split out the kernel symbol detection code.

[virt-mem.git] / uname / virt_uname.ml

diff --git a/uname/virt_uname.ml b/uname/virt_uname.ml
index 54c0148..6004bb8 100644 (file)
--- a/uname/virt_uname.ml
+++ b/uname/virt_uname.ml
@@ -17,17 +17,81 @@
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  *)
 
+open Printf
+
 open Virt_mem_gettext.Gettext
+open Virt_mem_utils
+open Virt_mem_mmap
+
+let run debug images =
+  (* Print new_utsname structure from bitstring. *)
+  let print_new_utsname name bs =
+    (* Truncate an OCaml string at the first ASCII NUL character, ie. as
+     * if it were a C string.
+     *)
+    let truncate str =
+      try
+       let i = String.index str '\000' in
+       String.sub str 0 i
+      with
+       Not_found -> str
+    in
+    (* Expect the first (sysname) field to always be "Linux", which is
+     * also a good way to tell if we're synchronized to the right bit of
+     * memory.
+     *)
+    bitmatch bs with
+    | { "Linux\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000" : 65*8 : string;
+       nodename : 65*8 : string;
+       release : 65*8 : string;
+       version : 65*8 : string;
+       machine : 65*8 : string;
+       domainname : 65*8 : string } ->
+       printf "%s: Linux %s %s %s %s %s\n"
+         name
+         (truncate nodename) (truncate release)
+         (truncate version) (truncate machine) (truncate domainname)
+    | { _ } ->
+       eprintf (f_"%s: unexpected system_utsname in kernel image\n")
+         name
+  in
+
+  List.iter (
+    fun (_, name, arch, mem, lookup_ksym) ->
+      (* In Linux 2.6.25, the symbol is init_uts_ns.
+       * http://lxr.linux.no/linux/init/version.c
+       *)
+      try
+       let addr = lookup_ksym "init_uts_ns" in
 
-let usage = s_"NAME
-  virt-uname - uname command for virtual machines
+       let bs = Bitstring.bitstring_of_string (get_bytes mem addr (65*6+4)) in
+       (bitmatch bs with
+        | { _ : 32 : int;              (* the kref, atomic_t, always 32 bits *)
+            new_utsname : -1 : bitstring } ->
+            print_new_utsname name new_utsname
+        | { _ } ->
+            eprintf (f_"%s: unexpected init_uts_ns in kernel image\n")
+              name)
+      with
+       Not_found ->
+         (* In Linux 2.6.9, the symbol is system_utsname.
+          * http://lxr.linux.no/linux-bk+v2.6.9/include/linux/utsname.h#L24
+          *)
+         try
+           let addr = lookup_ksym "system_utsname" in
 
-SUMMARY
-  virt-uname [-options] [domains]
+           let bs =
+             Bitstring.bitstring_of_string (get_bytes mem addr (65*6)) in
+           print_new_utsname name bs
+         with
+           Not_found ->
+             eprintf (f_"%s: could not find utsname in kernel image\n") name
+  ) images
 
-DESCRIPTION
-  virt-uname prints the uname information such as OS version,
-  architecture and node name for virtual machines running under
-  libvirt."
+let summary = s_"uname command for virtual machines"
+let description = s_"\
+virt-uname prints the uname information such as OS version,
+architecture and node name for virtual machines running under
+libvirt."
 
-let verbose, images = Virt_mem.start usage
+let () = Virt_mem.register "uname" summary description ~run