adduser/addgroup: support specifying uid/gid, add system

 account creation mode. By Tito.

function                                             old     new   delta
adduser_main                                         650     726     +76
addgroup_main                                        341     402     +61
addgroup_longopts                                      -      16     +16
adduser_longopts                                      97     103      +6
packed_usage                                       26161   26163      +2
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 4/0 up/down: 161/0)             Total: 161 bytes

1 files changed, 60 insertions, 22 deletions

diff --git a/loginutils/adduser.c b/loginutils/adduser.c
index df4fad694..a399d9e4c 100644
--- a/loginutils/adduser.c
+++ b/loginutils/adduser.c
@@ -9,38 +9,55 @@
  */
 #include "libbb.h"
 
+/* #define OPT_HOME           (1 << 0) */ /* unused */
+/* #define OPT_GECOS          (1 << 1) */ /* unused */
+#define OPT_SHELL          (1 << 2)
+#define OPT_GID            (1 << 3)
 #define OPT_DONT_SET_PASS  (1 << 4)
 #define OPT_SYSTEM_ACCOUNT (1 << 5)
 #define OPT_DONT_MAKE_HOME (1 << 6)
+#define OPT_UID            (1 << 7)
 
+/* We assume UID_T_MAX == INT_MAX */
 /* remix */
 /* recoded such that the uid may be passed in *p */
 static void passwd_study(struct passwd *p)
 {
-        int max;
+        int max = UINT_MAX;
 
-        if (getpwnam(p->pw_name))
-                bb_error_msg_and_die("login '%s' is in use", p->pw_name);
-
-        if (option_mask32 & OPT_SYSTEM_ACCOUNT) {
-                p->pw_uid = 0;
-                max = 999;
-        } else {
-                p->pw_uid = 1000;
-                max = 64999;
+        if (getpwnam(p->pw_name)) {
+                bb_error_msg_and_die("%s '%s' in use", "user", p->pw_name);
+                /* this format string is reused in adduser and addgroup */
         }
 
+        if (!(option_mask32 & OPT_UID)) {
+                if (option_mask32 & OPT_SYSTEM_ACCOUNT) {
+                        p->pw_uid = 100; /* FIRST_SYSTEM_UID */
+                        max = 999;       /* LAST_SYSTEM_UID */
+                } else {
+                        p->pw_uid = 1000; /* FIRST_UID */
+                        max = 64999;      /* LAST_UID */
+                }
+        }
         /* check for a free uid (and maybe gid) */
         while (getpwuid(p->pw_uid) || (p->pw_gid == (gid_t)-1 && getgrgid(p->pw_uid))) {
+                if (option_mask32 & OPT_UID) {
+                        /* -u N, cannot pick uid other than N: error */
+                        bb_error_msg_and_die("%s '%s' in use", "uid", itoa(p->pw_uid));
+                        /* this format string is reused in adduser and addgroup */
+                }
+                if (p->pw_uid == max) {
+                        bb_error_msg_and_die("no %cids left", 'u');
+                }
                 p->pw_uid++;
-                if (p->pw_uid > max)
-                        bb_error_msg_and_die("no free uids left");
         }
 
         if (p->pw_gid == (gid_t)-1) {
                 p->pw_gid = p->pw_uid; /* new gid = uid */
-                if (getgrnam(p->pw_name))
-                        bb_error_msg_and_die("group name '%s' is in use", p->pw_name);
+                if (getgrnam(p->pw_name)) {
+                        bb_error_msg_and_die("%s '%s' in use", "group", p->pw_name);
+                        /* this format string is reused in adduser and addgroup */
+                }
         }
 }
 
@@ -73,6 +90,7 @@ static const char adduser_longopts[] ALIGN1 =
                 "empty-password\0"      No_argument       "D"
                 "system\0"              No_argument       "S"
                 "no-create-home\0"      No_argument       "H"
+                "uid\0"                 Required_argument "u"
                 ;
 #endif
 
@@ -87,6 +105,7 @@ int adduser_main(int argc UNUSED_PARAM, char **argv)
         struct passwd pw;
         const char *usegroup = NULL;
         char *p;
+        unsigned opts;
 
 #if ENABLE_FEATURE_ADDUSER_LONG_OPTIONS
         applet_long_options = adduser_longopts;
@@ -102,8 +121,17 @@ int adduser_main(int argc UNUSED_PARAM, char **argv)
         pw.pw_dir = NULL;
 
         /* exactly one non-option arg */
-        opt_complementary = "=1";
-        getopt32(argv, "h:g:s:G:DSH", &pw.pw_dir, &pw.pw_gecos, &pw.pw_shell, &usegroup);
+        /* disable interactive passwd for system accounts */
+        opt_complementary = "=1:SD:u+";
+        if (sizeof(pw.pw_uid) == sizeof(int)) {
+                opts = getopt32(argv, "h:g:s:G:DSHu:", &pw.pw_dir, &pw.pw_gecos, &pw.pw_shell, &usegroup, &pw.pw_uid);
+        } else {
+                unsigned uid;
+                opts = getopt32(argv, "h:g:s:G:DSHu:", &pw.pw_dir, &pw.pw_gecos, &pw.pw_shell, &usegroup, &uid);
+                if (opts & OPT_UID) {
+                        pw.pw_uid = uid;
+                }
+        }
         argv += optind;
 
         /* fill in the passwd struct */
@@ -114,12 +142,22 @@ int adduser_main(int argc UNUSED_PARAM, char **argv)
                 pw.pw_dir = xasprintf("/home/%s", argv[0]);
         }
         pw.pw_passwd = (char *)"x";
+        if (opts & OPT_SYSTEM_ACCOUNT) {
+                if (!usegroup) {
+                        usegroup = "nogroup";
+                }
+                if (!(opts & OPT_SHELL)) {
+                        pw.pw_shell = (char *) "/bin/false";
+                }
+        }
         pw.pw_gid = usegroup ? xgroup2gid(usegroup) : -1; /* exits on failure */
 
         /* make sure everything is kosher and setup uid && maybe gid */
         passwd_study(&pw);
 
-        p = xasprintf("x:%u:%u:%s:%s:%s", pw.pw_uid, pw.pw_gid, pw.pw_gecos, pw.pw_dir, pw.pw_shell);
+        p = xasprintf("x:%u:%u:%s:%s:%s",
+                        (unsigned) pw.pw_uid, (unsigned) pw.pw_gid,
+                        pw.pw_gecos, pw.pw_dir, pw.pw_shell);
         if (update_passwd(bb_path_passwd_file, pw.pw_name, p, NULL) < 0) {
                 return EXIT_FAILURE;
         }
@@ -143,10 +181,10 @@ int adduser_main(int argc UNUSED_PARAM, char **argv)
         /* clear the umask for this process so it doesn't
          * screw up the permissions on the mkdir and chown. */
         umask(0);
-        if (!(option_mask32 & OPT_DONT_MAKE_HOME)) {
-                /* Set the owner and group so it is owned by the new user,
-                   then fix up the permissions to 2755. Can't do it before
-                   since chown will clear the setgid bit */
+        if (!(opts & OPT_DONT_MAKE_HOME)) {
+                /* set the owner and group so it is owned by the new user,
+                 * then fix up the permissions to 2755. Can't do it before
+                 * since chown will clear the setgid bit */
                 if (mkdir(pw.pw_dir, 0755)
                  || chown(pw.pw_dir, pw.pw_uid, pw.pw_gid)
                  || chmod(pw.pw_dir, 02755) /* set setgid bit on homedir */
@@ -155,7 +193,7 @@ int adduser_main(int argc UNUSED_PARAM, char **argv)
                 }
         }
 
-        if (!(option_mask32 & OPT_DONT_SET_PASS)) {
+        if (!(opts & OPT_DONT_SET_PASS)) {
                 /* interactively set passwd */
                 passwd_wrapper(pw.pw_name);
         }