[Extlib] change return type and behavior of mkdir

src/libraries/stdlib/extlib.ml

@@ -233,17 +233,27 @@ external address_of_value: 'a -> int = "address_of_value" [@@noalloc]
   hence interrupting the process, might not work: child processes still need to
   run some daemons, such as [flush_all] which is registered by default. *)
 
-let rec mkdir ?(parents=false) name perm =
-  try Unix.mkdir name perm
-  with
-  | Unix.Unix_error (Unix.ENOENT,_,_) when parents ->
-    let parent_name = Filename.dirname name in
-    if name <> parent_name then
-      begin
-        mkdir ~parents parent_name perm;
-        Unix.mkdir name perm
-      end
-  | e -> raise e
+let rec mkdir ?(parents=false) (name: Filepath.Normalized.t) perm =
+  if Filepath.exists name then
+    if not (Filepath.is_dir name) then
+      failwith (Format.asprintf "mkdir: %a exists but is not a directory"
+                  Filepath.Normalized.pretty name)
+    else false
+  else begin
+    begin
+      try Unix.mkdir (name:>string) perm
+      with
+      | Unix.Unix_error (Unix.ENOENT,_,_) when parents ->
+        let parent_name = Filepath.dirname name in
+        if name <> parent_name then
+          begin
+            ignore (mkdir ~parents parent_name perm);
+            Unix.mkdir (name:>string) perm
+          end
+      | e -> raise e
+    end;
+    true
+  end
 
 let pid = Unix.getpid ()
 let safe_at_exit f =

src/libraries/stdlib/extlib.mli

@@ -256,7 +256,7 @@ external address_of_value: 'a -> int = "address_of_value" [@@noalloc]
 (** {2 System commands} *)
 (* ************************************************************************* *)
 
-val mkdir : ?parents:bool -> string -> Unix.file_perm -> unit
+val mkdir : ?parents:bool -> Filepath.Normalized.t -> Unix.file_perm -> bool
 (** [mkdir ?parents name perm] creates directory [name] with permission
     [perm]. If [parents] is true, recursively create parent directories
     if needed. [parents] defaults to false.
@@ -264,8 +264,13 @@ val mkdir : ?parents:bool -> string -> Unix.file_perm -> unit
     and then fail to create the children, e.g. if [perm] does not allow
     user execution of the created directory. This will leave the filesystem
     in a modified state before raising an exception.
+    Returns [true] if the directory was created, [false] otherwise.
     @raise Unix.Unix_error if cannot create [name] or its parents.
-    @since 19.0-Potassium  *)
+    @since 19.0-Potassium
+    @since Frama-C+dev added check for existence of path (error if exists
+    but not a directory, otherwise do nothing if directory already exists).
+    Changed type of [name] argument and return type.
+*)
 
 val safe_at_exit : (unit -> unit) -> unit
 (** Register function to call with [Stdlib.at_exit], but only