[xen stable-4.16] tools/oxenstored: validate config file before live update

[patchbot@xxxxxxx]

commit fd1c70442d3aa962be4d041d5f8fce9d2fa72ce1
Author:     Edwin Török <edvin.torok@xxxxxxxxxx>
AuthorDate: Tue May 11 15:56:50 2021 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Feb 9 15:58:51 2023 +0000

    tools/oxenstored: validate config file before live update
    
    The configuration file can contain typos or various errors that could 
prevent
    live update from succeeding (e.g. a flag only valid on a different version).
    Unknown entries in the config file would be ignored on startup normally,
    add a strict --config-test that live-update can use to check that the 
config file
    is valid *for the new binary*.
    
    For compatibility with running old code during live update recognize
    --live --help as an equivalent to --config-test.
    
    Signed-off-by: Edwin Török <edvin.torok@xxxxxxxxxx>
    Acked-by: Christian Lindig <christian.lindig@xxxxxxxxxx>
    (cherry picked from commit e6f07052ce4a0f0b7d4dc522d87465efb2d9ee86)
---
 tools/ocaml/xenstored/parse_arg.ml | 26 ++++++++++++++++++++++++++
 tools/ocaml/xenstored/xenstored.ml | 11 +++++++++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/tools/ocaml/xenstored/parse_arg.ml 
b/tools/ocaml/xenstored/parse_arg.ml
index 7c0478e76a..5e4ca6f1f7 100644
--- a/tools/ocaml/xenstored/parse_arg.ml
+++ b/tools/ocaml/xenstored/parse_arg.ml
@@ -26,8 +26,14 @@ type config =
        restart: bool;
        live_reload: bool;
        disable_socket: bool;
+       config_test: bool;
 }
 
+let get_config_filename config_file =
+       match config_file with
+       | Some name -> name
+       | None      -> Define.default_config_dir ^ "/oxenstored.conf"
+
 let do_argv =
        let pidfile = ref "" and tracefile = ref "" (* old xenstored 
compatibility *)
        and domain_init = ref true
@@ -38,6 +44,8 @@ let do_argv =
        and restart = ref false
        and live_reload = ref false
        and disable_socket = ref false
+       and config_test = ref false
+       and help = ref false
        in
 
        let speclist =
@@ -55,10 +63,27 @@ let do_argv =
                  ("-T", Arg.Set_string tracefile, ""); (* for compatibility *)
                  ("--restart", Arg.Set restart, "Read database on starting");
                  ("--live", Arg.Set live_reload, "Read live dump on startup");
+                 ("--config-test", Arg.Set config_test, "Test validity of 
config file");
                  ("--disable-socket", Arg.Unit (fun () -> disable_socket := 
true), "Disable socket");
+                 ("--help", Arg.Set help, "Display this list of options")
                ] in
        let usage_msg = "usage : xenstored [--config-file <filename>] 
[--no-domain-init] [--help] [--no-fork] [--reraise-top-level] [--restart] 
[--disable-socket]" in
        Arg.parse speclist (fun _ -> ()) usage_msg;
+       let () =
+               if !help then begin
+                       if !live_reload then
+                               (*
+                                * Transform --live --help into --config-test 
for backward compat with
+                                * running code during live update.
+                                * Caller will validate config and exit
+                                *)
+                               config_test := true
+                       else begin
+                               Arg.usage_string speclist usage_msg |> 
print_endline;
+                               exit 0
+                       end
+               end
+       in
        {
                domain_init = !domain_init;
                activate_access_log = !activate_access_log;
@@ -70,4 +95,5 @@ let do_argv =
                restart = !restart;
                live_reload = !live_reload;
                disable_socket = !disable_socket;
+               config_test = !config_test;
        }
diff --git a/tools/ocaml/xenstored/xenstored.ml 
b/tools/ocaml/xenstored/xenstored.ml
index 4d5851c5cb..e2638a5af2 100644
--- a/tools/ocaml/xenstored/xenstored.ml
+++ b/tools/ocaml/xenstored/xenstored.ml
@@ -88,7 +88,7 @@ let default_pidfile = Paths.xen_run_dir ^ "/xenstored.pid"
 
 let ring_scan_interval = ref 20
 
-let parse_config filename =
+let parse_config ?(strict=false) filename =
        let pidfile = ref default_pidfile in
        let options = [
                ("merge-activate", Config.Set_bool Transaction.do_coalesce);
@@ -129,11 +129,12 @@ let parse_config filename =
                ("xenstored-port", Config.Set_string Domains.xenstored_port); ] 
in
        begin try Config.read filename options (fun _ _ -> raise Not_found)
        with
-       | Config.Error err -> List.iter (fun (k, e) ->
+       | Config.Error err as e -> List.iter (fun (k, e) ->
                match e with
                | "unknown key" -> eprintf "config: unknown key %s\n" k
                | _             -> eprintf "config: %s: %s\n" k e
                ) err;
+               if strict then raise e
        | Sys_error m -> eprintf "error: config: %s\n" m;
        end;
        !pidfile
@@ -358,6 +359,12 @@ let tweak_gc () =
 let () =
        Printexc.set_uncaught_exception_handler 
Logging.fallback_exception_handler;
        let cf = do_argv in
+       if cf.config_test then begin
+               let path = config_filename cf in
+               let _pidfile:string = parse_config ~strict:true path in
+               Printf.printf "Configuration valid at %s\n%!" path;
+               exit 0
+       end;
        let pidfile =
                if Sys.file_exists (config_filename cf) then
                        parse_config (config_filename cf)
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.16