Fix the value of the 'arch' variable when the current OS is 32bit on …

…a 64bit machine

master_changes.md

@@ -61,6 +61,7 @@ users)
 ## Show
 
 ## Var/Option
+  * Fix the value of the 'arch' variable when the current OS is 32bit on a 64bit machine [#5950 @kit-ty-kate - fix #5949]
 
 ## Update / Upgrade
 
@@ -261,3 +262,4 @@ users)
   * `OpamStd.Env`: add `env_string_list` for parsing string list environment variables (comma separated) [#5682 @desumn]
   * `OpamHash`: export `compare_kind` [#5561 @rjbou]
   * `OpamFilename`: add `might_escape` to check if a path is escapable, ie contains `<sep>..<sep>` [#5561 @rjbou]
+  * Add `OpamStd.Sys.getconf` [#5950 @kit-ty-kate]

src/core/opamStd.ml

@@ -995,19 +995,22 @@ module OpamSys = struct
 
   let etc () = "/etc"
 
-  let uname =
+  let memo_command =
     let memo = Hashtbl.create 7 in
-    fun arg ->
-      try Hashtbl.find memo arg with Not_found ->
+    fun cmd arg ->
+      try Hashtbl.find memo (cmd, arg) with Not_found ->
         let r =
           try
-            with_process_in "uname" arg
+            with_process_in cmd arg
               (fun ic -> Some (OpamString.strip (input_line ic)))
           with Unix.Unix_error _ | Sys_error _ | Not_found -> None
         in
-        Hashtbl.add memo arg r;
+        Hashtbl.add memo (cmd, arg) r;
         r
 
+  let uname = memo_command "uname"
+  let getconf = memo_command "getconf"
+
   let system =
     let system = Lazy.from_fun OpamStubs.getPathToSystem in
     fun () -> Lazy.force system

src/core/opamStd.mli

@@ -513,6 +513,9 @@ module Sys : sig
   (** The output of the command "uname", with the given argument. Memoised. *)
   val uname: string -> string option
 
+  (** The output of the command "getconf", with the given argument. Memoised. *)
+  val getconf: string -> string option
+
   (** Append .exe (only if missing) to executable filenames on Windows *)
   val executable_name : string -> string
 

src/state/opamSysPoll.ml

@@ -47,9 +47,23 @@ let poll_arch () =
       end
     | _ -> None
   in
-  match raw with
-  | None | Some "" -> None
-  | Some a -> Some (normalise_arch a)
+  let normalised =
+    match raw with
+    | None | Some "" -> None
+    | Some a -> Some (normalise_arch a)
+  in
+  match Sys.os_type with
+  | "Unix" | "Cygwin" ->
+    (match normalised with
+     | Some ("x86_64" | "arm64" | "ppc64" as arch) ->
+       (match OpamStd.Sys.getconf "LONG_BIT", arch with
+        | Some "32", "x86_64" -> Some "x86_32"
+        | Some "32", "arm64" -> Some "arm32"
+        | Some "32", "ppc64" -> Some "ppc32"
+        | _ -> normalised
+        | exception (Unix.Unix_error _ | Sys_error _ | Not_found) -> normalised)
+     | _ -> normalised)
+  | _ -> normalised
 let arch = Lazy.from_fun poll_arch
 
 let normalise_os raw =