From c17976eba549f44cbc34233cfaac4faddb3918c0 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Wed, 30 Sep 2026 21:18:49 -0700
Subject: [PATCH] tar: drop RTU support

Masscomp, which became Concurrent, dropped support for RTU
in the early 2000s, and there is no longer a need for tar
to worry about it.
* src/create.c (file_dumpable_p, dump_regular_file, dump_file0):
Do not worry about S_ISCTG; assume it always returns 0.
---
 NEWS            | 5 ++++-
 doc/intern.texi | 8 ++++----
 src/create.c    | 8 ++------
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/NEWS b/NEWS
index 5018327b..7b05757f 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,4 @@
-GNU tar NEWS - User visible changes. 2026-08-21
+GNU tar NEWS - User visible changes. 2026-09-30
 Please send GNU tar bug reports to <bug-tar@gnu.org>
 
 version 1.35.90 (git)
@@ -44,6 +44,9 @@ option.
    Formerly, the behavior was undocumented and differed from one tar
    version to the next.
 
+** Support for RTU-style contiguous files has been withdrawn.
+   RTU’s supplier dropped support for RTU decades ago.
+
 * Bug fixes
 
 ** When extracting, tar no longer follows symbolic links to targets
diff --git a/doc/intern.texi b/doc/intern.texi
index 436bf622..87f45b0d 100644
--- a/doc/intern.texi
+++ b/doc/intern.texi
@@ -242,10 +242,10 @@ FIFO file archives the existence of this file and not its contents.
 
 @item @code{CONTTYPE}
 This specifies a contiguous file, which is the same as a normal
-file except that, in operating systems which support it, all its
-space is allocated contiguously on the disk.  Operating systems
-which do not allow contiguous allocation should silently treat this
-type as a normal file.
+file except that in the old RTU operating system that implemented it,
+all the file space was allocated contiguously on disk.
+Today's operating systems do not consider contiguous files to be a
+separate type, and @command{tar} extracts these files like regular files.
 
 @item @code{A} @dots{} @code{Z}
 These are reserved for custom implementations.  Some of these are
diff --git a/src/create.c b/src/create.c
index 89d50937..ec8331e5 100644
--- a/src/create.c
+++ b/src/create.c
@@ -454,7 +454,7 @@ file_dumpable_p (struct stat const *st)
 {
   if (S_ISDIR (st->st_mode))
     return true;
-  if (! (S_ISREG (st->st_mode) || S_ISCTG (st->st_mode)))
+  if (!S_ISREG (st->st_mode))
     return false;
   if (dev_null_output)
     return totals_option && sparse_option && ST_IS_SPARSE (*st);
@@ -1028,10 +1028,6 @@ dump_regular_file (int fd, struct tar_stat_info *st)
   if (!blk)
     return dump_status_fail;
 
-  /* Mark contiguous files, if we support them.  */
-  if (archive_format != V7_FORMAT && S_ISCTG (st->stat.st_mode))
-    blk->header.typeflag = CONTTYPE;
-
   finish_header (st, blk, block_ordinal);
 
   mv_begin_write (st->file_name, st->stat.st_size, st->stat.st_size);
@@ -1712,7 +1708,7 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p)
   if (!is_dir && dump_hard_link (st))
     return allocated;
 
-  if (is_dir || S_ISREG (st->stat.st_mode) || S_ISCTG (st->stat.st_mode))
+  if (is_dir || S_ISREG (st->stat.st_mode))
     {
       bool ok;
       struct stat st2;