filename: add might_escape function

master_changes.md

@@ -246,3 +246,4 @@ users)
 ## opam-core
   * `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]

src/core/opamFilename.ml

@@ -9,6 +9,16 @@
 (*                                                                        *)
 (**************************************************************************)
 
+let might_escape ~sep path =
+  let sep =
+    match sep with
+    | `Unix -> Re.char '/'
+    | `Windows -> Re.alt Re.[  char '\\'; char '/' ]
+    | `Unspecified -> Re.str Filename.dir_sep
+  in
+  List.exists (String.equal Filename.parent_dir_name)
+    Re.(split (compile sep) path)
+
 module Base = struct
   include OpamStd.AbstractString
 

src/core/opamFilename.mli

@@ -12,6 +12,9 @@
 (** Higher level file and directory name manipulation AND file operations,
     wrappers on OpamSystem using the filename type *)
 
+(* Returns [true] if string contains '..' between directory separators *)
+val might_escape: sep:[`Unix | `Windows | `Unspecified ] -> string -> bool
+
 (** Basenames *)
 module Base: sig
   include OpamStd.ABSTRACT