crnlib: additional way to test if a path is a directory

For some unknown reasons open() fails at this point on macOS
if the file is on a network file system and it is not in the
current directory, same with `stat()` and variants.

But opendir() works if the path is a directory, so let's assume
what is not a directory is a regular file. This assumption
may be wrong, this is why this guess is only done if two
other implementations failed to detect the file type first.

crnlib/crn_find_files.cpp

@@ -206,24 +206,55 @@ bool find_files::find_internal(const char* pBasepath, const char* pRelpath, cons
     if ((strcmp(ep->d_name, ".") == 0) || (strcmp(ep->d_name, "..") == 0))
       continue;
 
-    bool is_directory = 0;
-    bool is_file = 0;
+    bool is_directory = false;
+    bool is_file = false;
+    bool guessed = false;
 
-    if ( ep->d_type != 0 ) {
+    /* This is the faster guess as it doesn't require any
+    extra IO as everything is already read. */
+    if (ep->d_type != 0) {
       is_directory = (ep->d_type & DT_DIR) != 0;
       is_file = (ep->d_type & DT_REG) != 0;
-    } else {
+      guessed = true;
+    }
+
+    /* Not all filesystems implement d_type which is optional,
+	especially network file systems and non-native ones.
+    See https://github.com/DaemonEngine/crunch/issues/37 */
+    if (!guessed) {
       struct stat s;
       if (stat(ep->d_name, &s) == 0) {
         is_directory = S_ISDIR(s.st_mode);
         is_file = S_ISREG(s.st_mode);
+        guessed = true;
       }
-      else {
-        console::error("Cannot detect if given path is a file or a directory");
-        return false;
+    }
+
+    /* Some macOS and FreeBSD versions fail to open the file on NFS
+    if the file is not in the current directory when running crunch.
+    See https://github.com/DaemonEngine/crunch/issues/63 */
+    if (!guessed) {
+      DIR* df = opendir(ep->d_name);
+      if (df) {
+        is_directory = true;
+        guessed = true;
+      } else if (errno == ENOTDIR) {
+        // HACK: Assume it is a regular file if not a directory.
+        is_file = true;
+        guessed = true;
       }
     }
 
+    if (!guessed) {
+      console::error("Cannot detect if the given path is a file or a directory");
+      return false;
+    }
+
+    if (!is_file && !is_directory) {
+      console::error("The given path is not a file neither a directory");
+      return false;
+    }
+
     dynamic_string filename(ep->d_name);
 
     if (is_directory) {