Adding upstream version 2.13.1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

gl/lib/unlinkat.c

@@ -0,0 +1,124 @@
+/* Work around unlinkat bugs on Solaris 9 and Hurd.
+
+   Copyright (C) 2009-2024 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
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 <https://www.gnu.org/licenses/>.  */
+
+/* Written by Eric Blake.  */
+
+#include <config.h>
+
+#include <unistd.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#include <stdlib.h>
+
+#include "filename.h"
+#include "openat.h"
+
+#if HAVE_UNLINKAT
+
+# undef unlinkat
+
+/* unlinkat without AT_REMOVEDIR does not honor trailing / on Solaris 9.
+   Hurd has the same issue.
+
+   unlinkat without AT_REMOVEDIR erroneously ignores ".." on Darwin 14.
+
+   Solve these in a similar manner to unlink.  */
+
+int
+rpl_unlinkat (int fd, char const *name, int flag)
+{
+  size_t len;
+  int result = 0;
+  /* rmdir behavior has no problems with trailing slash.  */
+  if (flag & AT_REMOVEDIR)
+    return unlinkat (fd, name, flag);
+
+  len = strlen (name);
+  if (len && ISSLASH (name[len - 1]))
+    {
+      /* See the lengthy comment in unlink.c why we disobey the POSIX
+         rule of letting unlink("link-to-dir/") attempt to unlink a
+         directory.  */
+      struct stat st;
+      result = fstatat (fd, name, &st, AT_SYMLINK_NOFOLLOW);
+      if (result == 0 || errno == EOVERFLOW)
+        {
+          /* Trailing NUL will overwrite the trailing slash.  */
+          char *short_name = malloc (len);
+          if (!short_name)
+            {
+              errno = EPERM;
+              return -1;
+            }
+          memcpy (short_name, name, len);
+          while (len && ISSLASH (short_name[len - 1]))
+            short_name[--len] = '\0';
+          if (len && (fstatat (fd, short_name, &st, AT_SYMLINK_NOFOLLOW)
+                      || S_ISLNK (st.st_mode)))
+            {
+              free (short_name);
+              errno = EPERM;
+              return -1;
+            }
+          free (short_name);
+          result = 0;
+        }
+    }
+  if (!result)
+    {
+# if UNLINK_PARENT_BUG
+      if (len >= 2 && name[len - 1] == '.' && name[len - 2] == '.'
+          && (len == 2 || ISSLASH (name[len - 3])))
+        {
+          errno = EISDIR; /* could also use EPERM */
+          return -1;
+        }
+# endif
+      result = unlinkat (fd, name, flag);
+    }
+  return result;
+}
+
+#else /* !HAVE_UNLINKAT */
+
+/* Replacement for Solaris' function by the same name.
+   <https://www.google.com/search?q=unlinkat+site:docs.oracle.com>
+   First, try to simulate it via (unlink|rmdir) ("/proc/self/fd/FD/FILE").
+   Failing that, simulate it via save_cwd/fchdir/(unlink|rmdir)/restore_cwd.
+   If either the save_cwd or the restore_cwd fails (relatively unlikely),
+   then give a diagnostic and exit nonzero.
+   Otherwise, this function works just like Solaris' unlinkat.  */
+
+# define AT_FUNC_NAME unlinkat
+# define AT_FUNC_F1 rmdir
+# define AT_FUNC_F2 unlink
+# define AT_FUNC_USE_F1_COND AT_REMOVEDIR
+# define AT_FUNC_POST_FILE_PARAM_DECLS , int flag
+# define AT_FUNC_POST_FILE_ARGS        /* empty */
+# include "at-func.c"
+# undef AT_FUNC_NAME
+# undef AT_FUNC_F1
+# undef AT_FUNC_F2
+# undef AT_FUNC_USE_F1_COND
+# undef AT_FUNC_POST_FILE_PARAM_DECLS
+# undef AT_FUNC_POST_FILE_ARGS
+
+#endif /* !HAVE_UNLINKAT */