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

2 files changed, 87 insertions, 33 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()) {
diff --git a/libpwdgrp/pwd_grp.c b/libpwdgrp/pwd_grp.c
index 206519084..98b8367ca 100644
--- a/libpwdgrp/pwd_grp.c
+++ b/libpwdgrp/pwd_grp.c
@@ -620,43 +620,67 @@ struct spwd *sgetspent(const char *string)
 }
 #endif
 
-int initgroups(const char *user, gid_t gid)
+static gid_t *getgrouplist_internal(int *ngroups_ptr, const char *user, gid_t gid)
 {
         FILE *grfile;
         gid_t *group_list;
-        int num_groups, rv;
-        char **m;
+        int ngroups;
         struct group group;
         char buff[PWD_BUFFER_SIZE];
 
-        rv = -1;
-        grfile = fopen_for_read(_PATH_GROUP);
-        if (grfile != NULL) {
-
-                /* We alloc space for 8 gids at a time. */
-                group_list = xmalloc(8 * sizeof(gid_t *));
-                *group_list = gid;
-                num_groups = 1;
+        /* We alloc space for 8 gids at a time. */
+        group_list = xmalloc(8 * sizeof(group_list[0]));
+        group_list[0] = gid;
+        ngroups = 1;
 
+        grfile = fopen_for_read(_PATH_GROUP);
+        if (grfile) {
                 while (!bb__pgsreader(bb__parsegrent, &group, buff, sizeof(buff), grfile)) {
+                        char **m;
                         assert(group.gr_mem); /* Must have at least a NULL terminator. */
-                        if (group.gr_gid != gid) {
-                                for (m = group.gr_mem; *m; m++) {
-                                        if (!strcmp(*m, user)) {
-                                                group_list = xrealloc_vector(group_list, 3, num_groups);
-                                                group_list[num_groups++] = group.gr_gid;
-                                                break;
-                                        }
-                                }
+                        if (group.gr_gid == gid)
+                                continue;
+                        for (m = group.gr_mem; *m; m++) {
+                                if (strcmp(*m, user) != 0)
+                                        continue;
+                                group_list = xrealloc_vector(group_list, 3, ngroups);
+                                group_list[ngroups++] = group.gr_gid;
+                                break;
                         }
                 }
-
-                rv = setgroups(num_groups, group_list);
-                free(group_list);
                 fclose(grfile);
         }
+        *ngroups_ptr = ngroups;
+        return group_list;
+}
 
-        return rv;
+int initgroups(const char *user, gid_t gid)
+{
+        int ngroups;
+        gid_t *group_list = getgrouplist_internal(&ngroups, user, gid);
+
+        if (!group_list)
+                return -1;
+
+        ngroups = setgroups(ngroups, group_list);
+        free(group_list);
+        return ngroups;
+}
+
+/* TODO: uclibc needs this ported to it! */
+int getgrouplist(const char *user, gid_t gid, gid_t *groups, int *ngroups)
+{
+        int ngroups_old = *ngroups;
+        gid_t *group_list = getgrouplist_internal(ngroups, user, gid);
+
+        if (*ngroups <= ngroups_old) {
+                ngroups_old = *ngroups;
+                memcpy(groups, group_list, ngroups_old * sizeof(groups[0]));
+        } else {
+                ngroups_old = -1;
+        }
+        free(group_list);
+        return ngroups_old;
 }
 
 int putpwent(const struct passwd *__restrict p, FILE *__restrict f)