Better error handling with [realpath] + bug fix.

frontend/main.ml

@@ -114,13 +114,13 @@ let run : config -> string -> unit = fun cfg c_file ->
       Coq_pp.print_stmt_locs := false
     end;
   (* Split the file path into a file name and absolute directory path. *)
+  let c_file =
+    try Filename.realpath c_file with Invalid_argument(_) ->
+      panic "File [%s] disappeared..." c_file
+  in
   let c_file_name = Filename.basename c_file in
   let c_file_name_no_ext = Filename.remove_extension c_file_name in
-  let c_file_dir =
-    let c_file_dir = Filename.dirname c_file in
-    try Filename.realpath c_file_dir with Invalid_argument(_) ->
-      panic "Directory [%s] disappeared..." c_file_dir
-  in
+  let c_file_dir = Filename.dirname c_file in
   (* Locate the RefinedC project root and the relitive logical directory. *)
   let find_root_and_dir_path dir =
     let rec find acc dir =

frontend/stubs.c

 #include <limits.h>
 #include <stdlib.h>
+#include <errno.h>
 #include <caml/mlvalues.h>
 #include <caml/alloc.h>
 #include <caml/fail.h>
@@ -10,8 +11,29 @@ CAMLprim value c_realpath(value v) {
   char *output_path = realpath(input_path, NULL);
 
   // Checking for error.
-  if (output_path == NULL)
-    caml_invalid_argument("Extra.Filename.realpath\0");
+  if (output_path == NULL){
+    switch(errno){
+      case EACCES:
+        caml_invalid_argument("Extra.Filename.realpath (EACCESS)\0");
+      case EINVAL:
+        caml_invalid_argument("Extra.Filename.realpath (EINVAL)\0");
+      case EIO:
+        caml_invalid_argument("Extra.Filename.realpath (EIO)\0");
+      case ELOOP:
+        caml_invalid_argument("Extra.Filename.realpath (ELOOP)\0");
+      case ENAMETOOLONG:
+        caml_invalid_argument("Extra.Filename.realpath (ENAMETOOLONG)\0");
+      case ENOENT:
+        caml_invalid_argument("Extra.Filename.realpath (ENOENT)\0");
+      case ENOMEM:
+        caml_invalid_argument("Extra.Filename.realpath (ENOMEM)\0");
+      case ENOTDIR:
+        caml_invalid_argument("Extra.Filename.realpath (ENOTDIR)\0");
+      default:
+        // Should not be reachable.
+        caml_invalid_argument("Extra.Filename.realpath (unknown)\0");
+    }
+  }
 
   // Preparing the result value.
   value res = caml_copy_string(output_path);