mllib: factor out mounting of guest root

Introduce and use a new inspect_mount_root function to mount all the
mountpoints of a root in the guest, replacing the same code doing that
in different tools.

inspect_mount_root_ro is inspect_mount_root with readonly mount option.

builder/builder.ml

@@ -664,15 +664,7 @@ let main () =
   let root =
     match Array.to_list (g#inspect_os ()) with
     | [root] ->
-      let mps = g#inspect_get_mountpoints root in
-      let cmp (a,_) (b,_) =
-        compare (String.length a) (String.length b) in
-      let mps = List.sort cmp mps in
-      List.iter (
-        fun (mp, dev) ->
-          try g#mount dev mp
-          with G.Error msg -> warning (f_"%s (ignored)") msg
-      ) mps;
+      inspect_mount_root g root;
       root
     | _ ->
       error (f_"no guest operating systems or multiboot OS found in this disk image\nThis is a failure of the source repository.  Use -v for more information.")

customize/customize_main.ml

@@ -197,14 +197,7 @@ read the man page virt-customize(1).
         (* Mount up the disks, like guestfish -i.
          * See [ocaml/examples/inspect_vm.ml].
          *)
-        let mps = g#inspect_get_mountpoints root in
-        let cmp (a,_) (b,_) = compare (String.length a) (String.length b) in
-        let mps = List.sort cmp mps in
-        List.iter (
-          fun (mp, dev) ->
-            try g#mount dev mp;
-            with Guestfs.Error msg -> warning (f_"%s (ignored)") msg
-        ) mps;
+        inspect_mount_root g root;
 
         (* Do the customization. *)
         Customize_run.run g root ops;

get-kernel/get_kernel.ml

@@ -122,14 +122,7 @@ read the man page virt-get-kernel(1).
 
 let rec do_fetch ~transform_fn ~outputdir g root =
   (* Mount up the disks. *)
-  let mps = g#inspect_get_mountpoints root in
-  let cmp (a,_) (b,_) = compare (String.length a) (String.length b) in
-  let mps = List.sort cmp mps in
-  List.iter (
-    fun (mp, dev) ->
-      try g#mount_ro dev mp
-      with Guestfs.Error msg -> warning (f_"%s (ignored)") msg
-  ) mps;
+  inspect_mount_root_ro g root;
 
   let files =
     let typ = g#inspect_get_type root in

mllib/common_utils.ml

@@ -833,3 +833,21 @@ let read_first_line_from_file filename =
 let is_regular_file path = (* NB: follows symlinks. *)
   try (Unix.stat path).Unix.st_kind = Unix.S_REG
   with Unix.Unix_error _ -> false
+
+let inspect_mount_root g ?mount_opts_fn root =
+  let mps = g#inspect_get_mountpoints root in
+  let cmp (a,_) (b,_) =
+    compare (String.length a) (String.length b) in
+  let mps = List.sort cmp mps in
+  List.iter (
+    fun (mp, dev) ->
+      let mountfn =
+        match mount_opts_fn with
+        | Some fn -> g#mount_options (fn mp)
+        | None -> g#mount in
+      try mountfn dev mp
+      with Guestfs.Error msg -> warning (f_"%s (ignored)") msg
+  ) mps
+
+let inspect_mount_root_ro =
+  inspect_mount_root ~mount_opts_fn:(fun _ -> "ro")

mllib/common_utils.mli

@@ -273,3 +273,14 @@ val read_first_line_from_file : string -> string
 
 val is_regular_file : string -> bool
 (** Checks whether the file is a regular file. *)
+
+val inspect_mount_root : Guestfs.guestfs -> ?mount_opts_fn:(string -> string) -> string -> unit
+(** Mounts all the mount points of the specified root, just like
+    [guestfish -i] does.
+
+    [mount_opts_fn] represents a function providing the mount options
+    for each mount point. *)
+
+val inspect_mount_root_ro : Guestfs.guestfs -> string -> unit
+(** Like [inspect_mount_root], but mounting every mount point as
+    read-only. *)

sysprep/main.ml

@@ -227,17 +227,7 @@ read the man page virt-sysprep(1).
         (* Mount up the disks, like guestfish -i.
          * See [ocaml/examples/inspect_vm.ml].
          *)
-        let mps = g#inspect_get_mountpoints root in
-        let cmp (a,_) (b,_) = compare (String.length a) (String.length b) in
-        let mps = List.sort cmp mps in
-        List.iter (
-          fun (mp, dev) ->
-            (* Get mount options for this mountpoint. *)
-            let opts = mount_opts mp in
-
-            try g#mount_options opts dev mp;
-            with Guestfs.Error msg -> warning (f_"%s (ignored)") msg
-        ) mps;
+        inspect_mount_root ~mount_opts_fn:mount_opts g root;
 
         let side_effects = new Sysprep_operation.filesystem_side_effects in
 

v2v/test-harness/v2v_test_harness.ml

@@ -86,14 +86,7 @@ let run ~test ?input_disk ?input_xml ?(test_plan = default_plan) () =
       | _ ->
         failwithf "multiple roots found in disk image %s" filename in
 
-    let mps = g#inspect_get_mountpoints root in
-    let cmp (a,_) (b,_) = compare (String.length a) (String.length b) in
-    let mps = List.sort cmp mps in
-    List.iter (
-      fun (mp, dev) ->
-        try g#mount_ro dev mp
-        with G.Error msg -> eprintf "%s (ignored)\n" msg
-    ) mps;
+    inspect_mount_root_ro g root;
 
     g, root
   in