Allow disabling of subordinate IDs.

* configure.in: Add configure options --enable-subordinate-ids /
	--disable-subordinate-ids. Enabled by default.
	* lib/prototypes.h: Include <config.h> before using its macros.
	* lib/commonio.h, lib/commonio.c: Define commonio_append only when
	ENABLE_SUBIDS is defined.
	* lib/prototypes.h, libmisc/find_new_sub_gids.c,
	libmisc/find_new_sub_uids.c: Likewise.
	* lib/subordinateio.h, lib/subordinateio.c: Likewise.
	* libmisc/user_busy.c: Only check if subordinate IDs are in use if
	ENABLE_SUBIDS is defined.
	* src/Makefile.am: Create newgidmap and newuidmap only if
	ENABLE_SUBIDS is defined.
	* src/newusers.c: Check for ENABLE_SUBIDS to enable support for
	subordinate IDs.
	* src/useradd.c: Likewise.
	* src/userdel.c: Likewise.
	* src/usermod.c: Likewise.
	* man/Makefile.am: Install man1/newgidmap.1, man1/newuidmap.1,
	man5/subgid.5, and man5/subuid.5 only if ENABLE_SUBIDS is defined.
	* man/fr/Makefile.am: Install man1/newgidmap.1, man1/newuidmap.1,
	man5/subgid.5, and man5/subuid.5 (not translated yet).
	* man/generate_mans.mak: Add xsltproc conditionals
	subids/no_subids.
	* man/login.defs.d/SUB_GID_COUNT.xml: Add dependency on subids
	condition.
	* man/login.defs.d/SUB_UID_COUNT.xml: Likewise.
	* man/usermod.8.xml: Document options for subordinate IDs and
	reference subgid(5) / subuid(5) depending on the subids condition.

lib/commonio.c

@@ -1113,6 +1113,7 @@ int commonio_update (struct commonio_db *db, const void *eptr)
 	return 1;
 }
 
+#ifdef ENABLE_SUBIDS
 int commonio_append (struct commonio_db *db, const void *eptr)
 {
 	struct commonio_entry *p;
@@ -1143,6 +1144,7 @@ int commonio_append (struct commonio_db *db, const void *eptr)
 	db->changed = true;
 	return 1;
 }
+#endif				/* ENABLE_SUBIDS */
 
 void commonio_del_entry (struct commonio_db *db, const struct commonio_entry *p)
 {

lib/commonio.h

@@ -146,7 +146,9 @@ extern int commonio_lock_nowait (struct commonio_db *, bool log);
 extern int commonio_open (struct commonio_db *, int);
 extern /*@observer@*/ /*@null@*/const void *commonio_locate (struct commonio_db *, const char *);
 extern int commonio_update (struct commonio_db *, const void *);
+#ifdef ENABLE_SUBIDS
 extern int commonio_append (struct commonio_db *, const void *);
+#endif				/* ENABLE_SUBIDS */
 extern int commonio_remove (struct commonio_db *, const char *);
 extern int commonio_rewind (struct commonio_db *);
 extern /*@observer@*/ /*@null@*/const void *commonio_next (struct commonio_db *);

lib/prototypes.h

@@ -42,6 +42,8 @@
 #ifndef _PROTOTYPES_H
 #define _PROTOTYPES_H
 
+#include <config.h>
+
 #include <sys/stat.h>
 #ifdef USE_UTMPX
 #include <utmpx.h>
@@ -149,6 +151,7 @@ extern int find_new_uid (bool sys_user,
                          uid_t *uid,
                          /*@null@*/uid_t const *preferred_uid);
 
+#ifdef ENABLE_SUBIDS
 /* find_new_sub_gids.c */
 extern int find_new_sub_gids (const char *owner,
 			      gid_t *range_start, unsigned long *range_count);
@@ -156,6 +159,7 @@ extern int find_new_sub_gids (const char *owner,
 /* find_new_sub_uids.c */
 extern int find_new_sub_uids (const char *owner,
 			      uid_t *range_start, unsigned long *range_count);
+#endif				/* ENABLE_SUBIDS */
 
 
 /* get_gid.c */

lib/subordinateio.c

@@ -3,6 +3,9 @@
  */
 
 #include <config.h>
+
+#ifdef ENABLE_SUBIDS
+
 #include "prototypes.h"
 #include "defines.h"
 #include <stdio.h>
@@ -507,3 +510,7 @@ gid_t sub_gid_find_free_range(gid_t min, gid_t max, unsigned long count)
 	start = find_free_range (&subordinate_gid_db, min, max, count);
 	return start == ULONG_MAX ? (gid_t) -1 : start;
 }
+#else				/* !ENABLE_SUBIDS */
+extern int errno;		/* warning: ANSI C forbids an empty source file */
+#endif				/* !ENABLE_SUBIDS */
+

lib/subordinateio.h

@@ -5,6 +5,10 @@
 #ifndef _SUBORDINATEIO_H
 #define _SUBORDINATEIO_H
 
+#include <config.h>
+
+#ifdef ENABLE_SUBIDS
+
 #include <sys/types.h>
 
 extern int sub_uid_close(void);
@@ -34,5 +38,6 @@ extern int sub_gid_unlock (void);
 extern int sub_gid_add (const char *owner, gid_t start, unsigned long count);
 extern int sub_gid_remove (const char *owner, gid_t start, unsigned long count);
 extern uid_t sub_gid_find_free_range(gid_t min, gid_t max, unsigned long count);
+#endif				/* ENABLE_SUBIDS */
 
 #endif