Don't get failed assertion for `tail -f directory'.

Revert most of 1999-10-20 change.  Instead, ...
(IS_TAILABLE_FILE_TYPE): Define to produce similar result.
(recheck): Use it here.
(tail_file): Use it here.

diff --git a/src/tail.c b/src/tail.c
index a2a8979b1b8c21cd5ab190bc280aecf95d742c7b..aaf2593140ca42d43758c71c0621192766240391 100644 (file)
--- a/src/tail.c
+++ b/src/tail.c
@@ -1,5 +1,5 @@
 /* tail -- output the last part of file(s)
-   Copyright (C) 89, 90, 91, 1995-1999 Free Software Foundation, Inc.
+   Copyright (C) 89, 90, 91, 1995-2000 Free Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -84,6 +84,10 @@ enum Follow_mode
   Follow_descriptor = 2
 };
 
+/* The types of files for which tail works.  */
+#define IS_TAILABLE_FILE_TYPE(Mode) \
+  (S_ISREG (Mode) || S_ISFIFO (Mode) || S_ISCHR (Mode))
+
 static char const *const follow_mode_string[] =
 {
   "descriptor", "name", 0
@@ -748,6 +752,13 @@ recheck (struct File_spec *f)
          error (0, errno, "%s", pretty_name (f));
        }
     }
+  else if (!IS_TAILABLE_FILE_TYPE (new_stats.st_mode))
+    {
+      fail = 1;
+      f->errnum = -1;
+      error (0, 0, _("`%s' has been replaced with an untailable file"),
+            pretty_name (f));
+    }
   else
     {
       f->errnum = 0;
@@ -1133,6 +1144,13 @@ tail_file (struct File_spec *f, off_t n_units)
              f->errnum = errno;
              error (0, errno, "%s", pretty_name (f));
            }
+         else if (!IS_TAILABLE_FILE_TYPE (stats.st_mode))
+           {
+             error (0, 0, _("%s: cannot follow end of this type of file"),
+                    pretty_name (f));
+             errors = 1;
+             f->errnum = -1;
+           }
 
          if (errors)
            {