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 df4fad6..a399d9e 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);
 	}