userbdctl: show 'mapped' user range only inside of userns

Outside of userns the concept makes no sense, there cannot be users
mapped from further outside.

(cherry picked from commit e412fc5)
(cherry picked from commit aed4e90)
(cherry picked from commit 421c23f)
(cherry picked from commit de65927)

Author: poettering

src/userdb/userdbctl.c

@@ -23,6 +23,7 @@
 #include "user-util.h"
 #include "userdb.h"
 #include "verbs.h"
+#include "virt.h"
 
 static enum {
         OUTPUT_CLASSIC,
@@ -130,10 +131,16 @@ static int show_user(UserRecord *ur, Table *table) {
         return 0;
 }
 
+static bool test_show_mapped(void) {
+        /* Show mapped user range only in environments where user mapping is a thing. */
+        return running_in_userns() > 0;
+}
+
 static const struct {
         uid_t first, last;
         const char *name;
         UserDisposition disposition;
+        bool (*test)(void);
 } uid_range_table[] = {
         {
                 .first = 1,
@@ -166,6 +173,7 @@ static const struct {
                 .last = MAP_UID_MAX,
                 .name = "mapped",
                 .disposition = USER_REGULAR,
+                .test = test_show_mapped,
         },
 };
 
@@ -180,6 +188,9 @@ static int table_add_uid_boundaries(Table *table, const UidRange *p) {
                 if (!uid_range_covers(p, uid_range_table[i].first, uid_range_table[i].last - uid_range_table[i].first + 1))
                         continue;
 
+                if (uid_range_table[i].test && !uid_range_table[i].test())
+                        continue;
+
                 name = strjoin(special_glyph(SPECIAL_GLYPH_ARROW_DOWN),
                                " begin ", uid_range_table[i].name, " users ",
                                special_glyph(SPECIAL_GLYPH_ARROW_DOWN));
@@ -541,6 +552,9 @@ static int table_add_gid_boundaries(Table *table, const UidRange *p) {
                                       uid_range_table[i].last - uid_range_table[i].first + 1))
                         continue;
 
+                if (uid_range_table[i].test && !uid_range_table[i].test())
+                        continue;
+
                 name = strjoin(special_glyph(SPECIAL_GLYPH_ARROW_DOWN),
                                " begin ", uid_range_table[i].name, " groups ",
                                special_glyph(SPECIAL_GLYPH_ARROW_DOWN));