[Libguestfs] [PATCH 2/3] mllib: add and use last_part_of

[Pino Toscano]

Collect this small snippet to get the part of a string after the last
occurrency of a character; replace with it the current snippets doing
the same.

Should be just code motion.
---
 customize/password.ml                     | 4 +---
 mllib/common_utils.ml                     | 5 +++++
 mllib/common_utils.mli                    | 3 +++
 sysprep/sysprep_operation_user_account.ml | 4 +---
 v2v/convert_linux.ml                      | 4 +---
 v2v/utils.ml                              | 9 ++-------
 6 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/customize/password.ml b/customize/password.ml
index 25ce901..cb97804 100644
--- a/customize/password.ml
+++ b/customize/password.ml
@@ -97,9 +97,7 @@ let rec set_linux_passwords ?password_crypto (g : Guestfs.guestfs) root password
   let users = Array.to_list (g#aug_ls "/files/etc/shadow") in
   List.iter (
     fun userpath ->
-      let user =
-        let i = String.rindex userpath '/' in
-        String.sub userpath (i+1) (String.length userpath -i-1) in
+      let user = last_part_of userpath '/' in
       try
         (* Each line is: "user:[!!]password:..."
          * !! at the front of the password field means the account is locked.
diff --git a/mllib/common_utils.ml b/mllib/common_utils.ml
index 3737b4c..8601009 100644
--- a/mllib/common_utils.ml
+++ b/mllib/common_utils.ml
@@ -738,3 +738,8 @@ let guest_arch_compatible guest_arch =
   | x, y when x = y -> true
   | "x86_64", ("i386"|"i486"|"i586"|"i686") -> true
   | _ -> false
+
+(** Return the last part of a string, after the specified separator. *)
+let last_part_of str sep =
+  let i = String.rindex str sep in
+  String.sub str (i+1) (String.length str - (i+1))
diff --git a/mllib/common_utils.mli b/mllib/common_utils.mli
index a5b0a68..7d0b38f 100644
--- a/mllib/common_utils.mli
+++ b/mllib/common_utils.mli
@@ -178,3 +178,6 @@ val mkdir_p : string -> int -> unit
 val guest_arch_compatible : string -> bool
 (** Are guest arch and host_cpu compatible, in terms of being able
     to run commands in the libguestfs appliance? *)
+
+val last_part_of : string -> char -> string
+(** Return the last part of a string, after the specified separator. *)
diff --git a/sysprep/sysprep_operation_user_account.ml b/sysprep/sysprep_operation_user_account.ml
index 3f3b142..fe460b8 100644
--- a/sysprep/sysprep_operation_user_account.ml
+++ b/sysprep/sysprep_operation_user_account.ml
@@ -68,9 +68,7 @@ let user_account_perform g root side_effects =
         let uid = userpath ^ "/uid" in
         let uid = g#aug_get uid in
         let uid = int_of_string uid in
-        let username =
-          let i = String.rindex userpath '/' in
-          String.sub userpath (i+1) (String.length userpath -i-1) in
+        let username = last_part_of userpath '/' in
         if uid >= uid_min && uid <= uid_max
            && check_remove_user username then (
           changed := true;
diff --git a/v2v/convert_linux.ml b/v2v/convert_linux.ml
index 7967c0f..cadd515 100644
--- a/v2v/convert_linux.ml
+++ b/v2v/convert_linux.ml
@@ -795,10 +795,8 @@ let rec convert ~keep_serial_console (g : G.guestfs) inspect source =
        *)
       let mkinitrd_kv =
         let modpath = kernel.ki_modpath in
-        let len = String.length modpath in
         try
-          let i = String.rindex modpath '/' in
-          String.sub modpath (i+1) (len - (i+1))
+          last_part_of modpath '/'
         with
           Not_found ->
             invalid_arg (sprintf "invalid module path: %s" modpath) in
diff --git a/v2v/utils.ml b/v2v/utils.ml
index 1f8c357..4d6b08d 100644
--- a/v2v/utils.ml
+++ b/v2v/utils.ml
@@ -176,9 +176,7 @@ let find_virtio_win_drivers virtio_win =
         let paths = List.filter (g#is_file ~followsymlinks:false) paths in
         List.map (
           fun path ->
-            let i = String.rindex path '/' in
-            let len = String.length path in
-            let basename = String.sub path (i+1) (len - (i+1)) in
+            let basename = last_part_of path '/' in
             (path, sprintf "%s:%s" virtio_win path,
              basename,
              fun () -> g#read_file path)
@@ -198,10 +196,7 @@ let find_virtio_win_drivers virtio_win =
           let lc_path = String.lowercase path in
           let lc_basename = String.lowercase basename in
 
-          let extension =
-            let i = String.rindex lc_basename '.' in
-            let len = String.length lc_basename in
-            String.sub lc_basename (i+1) (len - (i+1)) in
+          let extension = last_part_of lc_basename '.' in
 
           (* Skip files without specific extensions. *)
           if extension <> "cat" && extension <> "inf" &&
-- 
2.1.0