Don't expose the implementation of the pivot_root state.

MANIFEST

@@ -686,6 +686,7 @@ plugins/sudoers/mkdefaults
 plugins/sudoers/parse.h
 plugins/sudoers/parse_ldif.c
 plugins/sudoers/pivot.c
+plugins/sudoers/pivot.h
 plugins/sudoers/po/README
 plugins/sudoers/po/ast.mo
 plugins/sudoers/po/ast.po

plugins/sudoers/pivot.h

@@ -0,0 +1,35 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2023 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef SUDOERS_PIVOT_H
+#define SUDOERS_PIVOT_H
+
+#define SUDOERS_PIVOT_INITIALIZER { -1, -1 }
+
+struct sudoers_pivot {
+    int saved_root;
+    int saved_cwd;
+};
+typedef struct sudoers_pivot sudoers_pivot_t;
+
+bool pivot_root(const char *new_root, sudoers_pivot_t cookie);
+bool unpivot_root(sudoers_pivot_t cookie);
+int  pivot_get_root(sudoers_pivot_t cookie);
+int  pivot_get_cwd(sudoers_pivot_t cookie);
+
+#endif /* SUDOERS_PIVOT_H */