id: fix "id <user>" case. Requires getgrouplist().

function                                             old     new   delta
getgrouplist_internal                                  -     200    +200
id_main                                              462     539     +77
bb_internal_getgrouplist                               -      67     +67
bb__parsespent                                       119     117      -2
bb_internal_initgroups                               213      58    -155
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 1/2 up/down: 344/-157)          Total: 187 bytes

1 files changed, 40 insertions, 10 deletions

diff --git a/coreutils/id.c b/coreutils/id.c
index 5225f357c..aa27ed394 100644
--- a/coreutils/id.c
+++ b/coreutils/id.c
@@ -38,14 +38,25 @@ static int printf_full(unsigned id, const char *arg, const char *prefix)
         return status;
 }
 
+#if (defined(__GLIBC__) && !defined(__UCLIBC__))
+#define HAVE_getgrouplist 1
+#elif ENABLE_USE_BB_PWD_GRP
+#define HAVE_getgrouplist 1
+#else
+#define HAVE_getgrouplist 0
+#endif
+
 int id_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int id_main(int argc UNUSED_PARAM, char **argv)
 {
+        const char *username;
         struct passwd *p;
         uid_t uid;
         gid_t gid;
+#if HAVE_getgrouplist
         gid_t *groups;
         int n;
+#endif
         unsigned flags;
         short status;
 #if ENABLE_SELINUX
@@ -55,6 +66,7 @@ int id_main(int argc UNUSED_PARAM, char **argv)
         /* Don't allow more than one username */
         opt_complementary = "?1:u--g:g--u:G--u:u--G:g--G:G--g:r?ugG:n?ugG" USE_SELINUX(":u--Z:Z--u:g--Z:Z--g");
         flags = getopt32(argv, "rnugG" USE_SELINUX("Z"));
+        username = argv[optind];
 
         /* This values could be overwritten later */
         uid = geteuid();
@@ -64,19 +76,34 @@ int id_main(int argc UNUSED_PARAM, char **argv)
                 gid = getgid();
         }
 
-        if (argv[optind]) {
-                p = getpwnam(argv[optind]);
+        if (username) {
+#if HAVE_getgrouplist
+                int m;
+#endif
+                p = getpwnam(username);
                 /* xuname2uid is needed because it exits on failure */
-                uid = xuname2uid(argv[optind]);
-                gid = p->pw_gid;
-                /* in this case PRINT_REAL is the same */
+                uid = xuname2uid(username);
+                gid = p->pw_gid; /* in this case PRINT_REAL is the same */
+
+#if HAVE_getgrouplist
+                n = 16;
+                groups = NULL;
+                do {
+                        m = n;
+                        groups = xrealloc(groups, sizeof(groups[0]) * m);
+                        getgrouplist(username, gid, groups, &n); /* GNUism? */
+                } while (n > m);
+#endif
+        } else {
+#if HAVE_getgrouplist
+                n = getgroups(0, NULL);
+                groups = xmalloc(sizeof(groups[0]) * n);
+                getgroups(n, groups);
+#endif
         }
 
-        n = getgroups(0, NULL);
-        groups = xmalloc(sizeof(groups[0]) * n);
-        getgroups(n, groups);
-
         if (flags & JUST_ALL_GROUPS) {
+#if HAVE_getgrouplist
                 while (n--) {
                         if (flags & NAME_NOT_NUMBER)
                                 printf("%s", bb_getgrgid(NULL, 0, *groups++));
@@ -84,6 +111,7 @@ int id_main(int argc UNUSED_PARAM, char **argv)
                                 printf("%u", (unsigned) *groups++);
                         bb_putchar((n > 0) ? ' ' : '\n');
                 }
+#endif
                 /* exit */
                 fflush_stdout_and_exit(EXIT_SUCCESS);
         }
@@ -105,7 +133,7 @@ int id_main(int argc UNUSED_PARAM, char **argv)
 #if ENABLE_SELINUX
                 if (flags & JUST_CONTEXT) {
                         selinux_or_die();
-                        if (argv[optind]) {
+                        if (username) {
                                 bb_error_msg_and_die("user name can't be passed with -Z");
                         }
 
@@ -123,6 +151,7 @@ int id_main(int argc UNUSED_PARAM, char **argv)
         /* bb_getpwuid(0) doesn't exit on failure (returns NULL) */
         status = printf_full(uid, bb_getpwuid(NULL, 0, uid), "uid=");
         status |= printf_full(gid, bb_getgrgid(NULL, 0, gid), " gid=");
+#if HAVE_getgrouplist
         {
                 const char *msg = " groups=";
                 while (n--) {
@@ -132,6 +161,7 @@ int id_main(int argc UNUSED_PARAM, char **argv)
                 }
         }
         /* we leak groups vector... */
+#endif
 
 #if ENABLE_SELINUX
         if (is_selinux_enabled()) {