2 files changed, 21 insertions, 20 deletions

diff --git a/coreutils/id.c b/coreutils/id.c
index b2f3b20e1..cf642c209 100644
--- a/coreutils/id.c
+++ b/coreutils/id.c
@@ -45,7 +45,7 @@ int id_main(int argc UNUSED_PARAM, char **argv)
         uid_t uid;
         gid_t gid;
         gid_t *groups;
-        int grp;
+        int n;
         unsigned long flags;
         short status;
 #if ENABLE_SELINUX
@@ -72,17 +72,17 @@ int id_main(int argc UNUSED_PARAM, char **argv)
                 /* in this case PRINT_REAL is the same */
         }
 
-        grp = getgroups(0, 0);
-        groups = (gid_t *)xmalloc(sizeof(gid_t) * grp);
-        getgroups(grp, (gid_t *)groups);
+        n = getgroups(0, NULL);
+        groups = xmalloc(sizeof(groups[0]) * n);
+        getgroups(n, groups);
 
-        if (flags & (JUST_ALL_GROUPS)) {
-                while (grp--) {
+        if (flags & JUST_ALL_GROUPS) {
+                while (n--) {
                         if (flags & NAME_NOT_NUMBER)
                                 printf("%s", bb_getgrgid(NULL, 0, *groups++));
                         else
-                                printf("%d", *groups++);
-                        bb_putchar((grp > 0) ? ' ' : '\n');
+                                printf("%d", (int) *groups++);
+                        bb_putchar((n > 0) ? ' ' : '\n');
                 }
                 /* exit */
                 fflush_stdout_and_exit(EXIT_SUCCESS);
@@ -105,7 +105,7 @@ int id_main(int argc UNUSED_PARAM, char **argv)
 #if ENABLE_SELINUX
                 if (flags & JUST_CONTEXT) {
                         selinux_or_die();
-                        if (argc - optind == 1) {
+                        if (argv[optind]) {
                                 bb_error_msg_and_die("user name can't be passed with -Z");
                         }
 
@@ -122,16 +122,17 @@ int id_main(int argc UNUSED_PARAM, char **argv)
         /* Print full info like GNU id */
         /* bb_getpwuid(0) doesn't exit on failure (returns NULL) */
         status = printf_full(uid, bb_getpwuid(NULL, 0, uid), "uid=");
-        bb_putchar(' ');
-        status |= printf_full(gid, bb_getgrgid(NULL, 0, gid), "gid=");
-        printf(" groups=");
-        while (grp--) {
-                status |= printf_full(*groups, bb_getgrgid(NULL, 0, *groups), "");
-                if (grp > 0)
-                        bb_putchar(',');
-                groups++;
+        status |= printf_full(gid, bb_getgrgid(NULL, 0, gid), " gid=");
+        {
+                const char *msg = " groups=";
+                while (n--) {
+                        status |= printf_full(*groups, bb_getgrgid(NULL, 0, *groups), msg);
+                        msg = ",";
+                        groups++;
+                }
         }
-        /* Don't free groups */
+        /* we leak groups vector... */
+
 #if ENABLE_SELINUX
         if (is_selinux_enabled()) {
                 security_context_t mysid;
diff --git a/include/usage.h b/include/usage.h
index 951be53de..f4fc2e67a 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -1602,9 +1602,9 @@
         USE_SELINUX( \
      "\n        -Z      Print the security context" \
         ) \
-     "\n        -G      Print all group IDs" \
-     "\n        -g      Print group ID" \
      "\n        -u      Print user ID" \
+     "\n        -g      Print group ID" \
+     "\n        -G      Print supplementary group IDs" \
      "\n        -n      Print name instead of a number" \
      "\n        -r      Print real user ID instead of effective ID" \