Accept relative file names in recursive exclude files.

This fixes bug #68616: exclude lists supplied with
--exclude-ignore-recursive now specify file names irrespective
of the actual name of the containing directory. This also fixes
processing of the VCS ignore files.

* src/exclist.c (struct exclist): New fields: prefix, prefix_len.
(info_attach_exclist): Store original directory name as prefix.
(info_free_exclist): Free prefix.
(excluded_name): Recompute rname at each loop stripping off the
directory prefix.

* tests/exclude21.at: New test.
* tests/exclude22.at: New test.
* tests/Makefile.am: Add new tests.
* tests/testsuite.at: Include new tests.

src/exclist.c

@@ -66,6 +66,8 @@ struct exclist
 {
   struct exclist *next, *prev;
   int flags;
+  char *prefix;
+  size_t prefix_len;
   struct exclude *excluded;
 };
 
@@ -111,6 +113,8 @@ info_attach_exclist (struct tar_stat_info *dir)
 	  struct exclist *ent = xmalloc (sizeof *ent);
 	  ent->excluded = ex;
 	  ent->flags = file->flags;
+	  ent->prefix_len = strlen (dir->orig_file_name);
+	  ent->prefix = xstrdup (dir->orig_file_name);
 	  ent->prev = tail;
 	  ent->next = NULL;
 
@@ -133,6 +137,7 @@ info_free_exclist (struct tar_stat_info *dir)
     {
       struct exclist *next = ep->next;
       free_exclude (ep->excluded);
+      free (ep->prefix);
       free (ep);
       ep = next;
     }
@@ -146,7 +151,6 @@ bool
 excluded_name (char const *name, struct tar_stat_info *st)
 {
   struct exclist *ep;
-  const char *rname = NULL;
   char *bname = NULL;
   bool result;
   int nr = 0;
@@ -164,12 +168,18 @@ excluded_name (char const *name, struct tar_stat_info *st)
     {
       for (ep = st->exclude_list; ep; ep = ep->next)
 	{
+	  const char *rname;
+
 	  if (ep->flags & nr)
 	    continue;
+
 	  if ((result = excluded_file_name (ep->excluded, name)))
 	    break;
 
-	  if (!rname)
+	  if (ep->prefix_len && strlen (name) > ep->prefix_len &&
+	      memcmp (name, ep->prefix, ep->prefix_len) == 0)
+	    rname = name + ep->prefix_len;
+          else
 	    rname = name + dotslashlen (name);
 	  if ((result = excluded_file_name (ep->excluded, rname)))
 	    break;

tests/Makefile.am

@@ -110,6 +110,8 @@ TESTSUITE_AT = \
  exclude18.at\
  exclude19.at\
  exclude20.at\
+ exclude21.at\
+ exclude22.at\
  extrac01.at\
  extrac02.at\
  extrac03.at\

tests/exclude21.at

@@ -0,0 +1,47 @@
+# Process this file with autom4te to create testsuite. -*- Autotest -*-
+
+# Test suite for GNU tar.
+# Copyright 2026 Free Software Foundation, Inc.
+
+# This file is part of GNU tar.
+
+# GNU tar is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# GNU tar is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([--exclude-ignore-recursive relative names])
+AT_KEYWORDS([exclude exclude-ignore-recursive extract exclude21])
+AT_TAR_CHECK([
+AT_SORT_PREREQ
+mkdir dir dir/subdir
+touch dir/file1 dir/file.ext dir/subdir/file2.foo dir/subdir/file3 \
+      dir/subdir/file4.txt dir/subdir/file5.ext
+cat > dir/ignorefile <<\EOT
+ignorefile
+*.ext
+EOT
+cat > dir/subdir/ignorefile <<\EOT
+file4.txt
+*.foo
+EOT
+tar -cf archive.tar --exclude-ignore-recursive=ignorefile dir
+rm -rf dir
+tar xfv archive.tar | sort
+],
+[0],
+[dir/
+dir/file1
+dir/subdir/
+dir/subdir/file3
+])
+
+AT_CLEANUP

tests/exclude22.at

@@ -0,0 +1,47 @@
+# Process this file with autom4te to create testsuite. -*- Autotest -*-
+
+# Test suite for GNU tar.
+# Copyright 2026 Free Software Foundation, Inc.
+
+# This file is part of GNU tar.
+
+# GNU tar is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# GNU tar is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([--exclude-ignore-recursive with transforms])
+AT_KEYWORDS([exclude exclude-ignore-recursive extract exclude22])
+AT_TAR_CHECK([
+mkdir dir dir/subdir
+touch dir/file1 dir/file.ext dir/subdir/file2.foo dir/subdir/file3 \
+      dir/subdir/file4.txt dir/subdir/file5.ext
+cat > dir/ignorefile <<\EOT
+ignorefile
+*.ext
+EOT
+cat > dir/subdir/ignorefile <<\EOT
+file4.txt
+*.foo
+EOT
+tar -cf archive.tar --exclude-ignore-recursive=ignorefile \
+    --transform='s/^dir/DIRECTORY/' dir
+rm -rf dir
+tar xfv archive.tar | sort
+],
+[0],
+[DIRECTORY/
+DIRECTORY/file1
+DIRECTORY/subdir/
+DIRECTORY/subdir/file3
+])
+
+AT_CLEANUP

tests/testsuite.at

@@ -317,6 +317,8 @@ m4_include([exclude17.at])
 m4_include([exclude18.at])
 m4_include([exclude19.at])
 m4_include([exclude20.at])
+m4_include([exclude21.at])
+m4_include([exclude22.at])
 
 AT_BANNER([Deletions])
 m4_include([delete01.at])