mllib: password: Replace password string with password_selector type.

This is just code motion, there is no functional change.

builder/builder.ml

@@ -466,7 +466,7 @@ let main () =
         let pw = make_random_password () in
         msg (f_"Random root password: %s [did you mean to use --root-password?]")
           pw;
-        pw in
+        Password.Set_password pw in
 
     match g#inspect_get_type root with
     | "linux" ->

builder/cmdline.ml

@@ -137,7 +137,7 @@ let parse_cmdline () =
 
   let root_password = ref None in
   let set_root_password arg =
-    let pw = get_password ~prog arg in
+    let pw = parse_selector ~prog arg in
     root_password := Some pw
   in
 

mllib/password.ml

@@ -21,7 +21,9 @@ open Printf
 
 type password_crypto = [`MD5 | `SHA256 | `SHA512 ]
 
-type password_map = (string, string) Hashtbl.t
+type password_selector = Set_password of string
+
+type password_map = (string, password_selector) Hashtbl.t
 
 let password_crypto_of_string ~prog = function
   | "md5" -> `MD5
@@ -32,7 +34,7 @@ let password_crypto_of_string ~prog = function
       prog arg;
     exit 1
 
-let rec get_password ~prog arg =
+let rec parse_selector ~prog arg =
   let i =
     try String.index arg ':'
     with Not_found ->
@@ -43,8 +45,8 @@ let rec get_password ~prog arg =
     String.sub arg 0 i, String.sub arg (i+1) (len-(i+1)) in
 
   match key with
-  | "file" -> read_password_from_file value
-  | "password" -> value
+  | "file" -> Set_password (read_password_from_file value)
+  | "password" -> Set_password value
   | _ ->
     eprintf (f_"%s: password format, \"%s:...\" is not recognized; see the man page.\n") prog key;
     exit 1
@@ -78,10 +80,12 @@ let rec set_linux_passwords ~prog ?password_crypto g root passwords =
            *)
           let i = String.index line ':' in
           let user = String.sub line 0 i in
-          let password = Hashtbl.find passwords user in
+          let selector = Hashtbl.find passwords user in
           let j = String.index_from line (i+1) ':' in
           let rest = String.sub line j (String.length line - j) in
-          user ^ ":" ^ encrypt password crypto ^ rest
+          match selector with
+          | Set_password password ->
+            user ^ ":" ^ encrypt password crypto ^ rest
         with Not_found -> line
     ) shadow in
 

mllib/password.mli

@@ -21,11 +21,15 @@ type password_crypto = [ `MD5 | `SHA256 | `SHA512 ]
 val password_crypto_of_string : prog:string -> string -> password_crypto
 (** Parse --password-crypto parameter on command line. *)
 
-val get_password : prog:string -> string -> string
-(** Parse various --password/--root-password/--user passwords on command line.*)
+type password_selector = Set_password of string
 
-type password_map = (string, string) Hashtbl.t
+val parse_selector : prog:string -> string -> password_selector
+(** Parse the selector field in --password/--root-password.  Note this
+    doesn't parse the username part.  Exits if the format is not valid. *)
+
+type password_map = (string, password_selector) Hashtbl.t
+(** A map of username -> selector. *)
 
 val set_linux_passwords : prog:string -> ?password_crypto:password_crypto -> Guestfs.guestfs -> string -> password_map -> unit
-(** Adjust the passwords of a Linux guest according to the (username,
-    password) map. *)
+(** Adjust the passwords of a Linux guest according to the
+    password map. *)

sysprep/sysprep_operation_password.ml

@@ -39,7 +39,7 @@ and set_user_password arg =
   set_password (String.sub arg 0 i) (String.sub arg (i+1) (len-(i+1)))
 
 and set_password user arg =
-  let pw = get_password ~prog arg in
+  let pw = parse_selector ~prog arg in
 
   if Hashtbl.mem passwords user then (
     eprintf (f_"virt-sysprep: password: multiple --root-password/--password options set the password for user '%s' twice.\n") user;