Fix crash in string.interpolate (Fixes: #2883)

CHANGES.md

@@ -29,6 +29,7 @@ Fixed:
 * Fixed input polling stop (#2769)
 * Fixed crash in external processes when received a `Unix.EINTR`
   event (#2861)
+* Fixed crash in `string.interpolate` (#2883)
 * Cleaned up srt support.
 
 ---

src/tools/utils.ml

@@ -20,6 +20,14 @@
 
  *****************************************************************************)
 
+(* Util to log exception and backtrace together
+   when log level is set to info and just exception
+   as severe otherwise. Backtrace should be captured as early
+   as possible. *)
+let log_exception ~(log : Log.t) ~bt msg =
+  if log#active 4 (* info *) then log#info "%s\n%s" msg bt
+  else log#severe "%s" msg
+
 (* Force locale to C *)
 external force_locale : unit -> unit = "liquidsoap_set_locale" [@@noalloc]
 
@@ -380,6 +388,7 @@ let unbreak_md md =
  * and interpolates them just like make does, using the hash table for
  * variable definitions. *)
 let interpolate =
+  let log = Log.make ["string"; "interpolate"] in
   (* TODO Use PCRE *)
   let quoted = "\"\\(\\([^\"\\]\\|\\(\\\\\"\\)\\)*\\)\"" in
   (* 3 groups *)
@@ -418,7 +427,13 @@ let interpolate =
           if p = "\\" then Str.matched_group 2 s
           else p ^ find (Str.matched_group 3 s))
     in
-    interpolate (process_if s)
+    try interpolate (process_if s)
+    with exn ->
+      let bt = Printexc.get_backtrace () in
+      log_exception ~log ~bt
+        (Printf.sprintf "Error while interpolating string: %s"
+           (Printexc.to_string exn));
+      s
 
 (** [which s] is equivalent to /usr/bin/which s, raises Not_found on error *)
 let which ~path s =
@@ -869,14 +884,6 @@ let string_of_matrix a =
   done;
   Strings.Mutable.to_string ans
 
-(* Util to log exception and backtrace together
-   when log level is set to info and just exception
-   as severe otherwise. Backtrace should be captured as early
-   as possible. *)
-let log_exception ~(log : Log.t) ~bt msg =
-  if log#active 4 (* info *) then log#info "%s\n%s" msg bt
-  else log#severe "%s" msg
-
 (** Operations on versions of Liquidsoap. *)
 module Version = struct
   type t = int list * string