start_stop_daemon: add -chuid support

coreutils/chown.c

@@ -56,7 +56,6 @@ static int fileAction(const char *fileName, struct stat *statbuf,
 int chown_main(int argc, char **argv);
 int chown_main(int argc, char **argv)
 {
-	char *groupName;
 	int retval = EXIT_SUCCESS;
 
 	opt_complementary = "-2";
@@ -65,24 +64,7 @@ int chown_main(int argc, char **argv)
 
 	if (OPT_NODEREF) chown_func = lchown;
 
-	/* First, check if there is a group name here */
-	groupName = strchr(*argv, '.'); /* deprecated? */
-	if (!groupName)
-		groupName = strchr(*argv, ':');
-	else
-		*groupName = ':'; /* replace '.' with ':' */
-
-	/* First, try parsing "user[:[group]]" */
-	if (!groupName) { /* "user" */
-		ugid.uid = get_ug_id(*argv, xuname2uid);
-	} else if (groupName == *argv) { /* ":group" */
-		ugid.gid = get_ug_id(groupName + 1, xgroup2gid);
-	} else {
-		if (!groupName[1]) /* "user:" */
-			*groupName = '\0';
-		if (!get_uidgid(&ugid, *argv, 1))
-			bb_error_msg_and_die("unknown user/group %s", *argv);
-	}
+	parse_chown_usergroup_or_die(&ugid, argv[0]);
 
 	/* Ok, ready to do the deed now */
 	argv++;

debianutils/start_stop_daemon.c

@@ -14,12 +14,11 @@
 
 static int signal_nr = 15;
 static int user_id = -1;
-static int quiet;
 static char *userspec;
-static char *chuid;
 static char *cmdname;
 static char *execname;
 static char *pidfile;
+static smallint quiet;
 
 struct pid_list {
 	struct pid_list *next;
@@ -222,20 +221,28 @@ static const struct option long_options[] = {
 enum {
 	CTX_STOP       = 0x1,
 	CTX_START      = 0x2,
-	OPT_BACKGROUND = 0x4,
-	OPT_QUIET      = 0x8,
-	OPT_MAKEPID    = 0x10,
-	OPT_OKNODO     = 0x20 * ENABLE_FEATURE_START_STOP_DAEMON_FANCY,
-	OPT_VERBOSE    = 0x40 * ENABLE_FEATURE_START_STOP_DAEMON_FANCY,
-	OPT_NICELEVEL  = 0x80 * ENABLE_FEATURE_START_STOP_DAEMON_FANCY,
+	OPT_BACKGROUND = 0x4, // -b
+	OPT_QUIET      = 0x8, // -q
+	OPT_MAKEPID    = 0x10, // -m
+	OPT_a          = 0x20, // -a
+	OPT_n          = 0x40, // -n
+	OPT_s          = 0x80, // -s
+	OPT_u          = 0x100, // -u
+	OPT_c          = 0x200, // -c
+	OPT_x          = 0x400, // -x
+	OPT_p          = 0x800, // -p
+	OPT_OKNODO     = 0x1000 * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -o
+	OPT_VERBOSE    = 0x2000 * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -v
+	OPT_NICELEVEL  = 0x4000 * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -N
 };
 
 int start_stop_daemon_main(int argc, char **argv);
 int start_stop_daemon_main(int argc, char **argv)
 {
 	unsigned opt;
-	char *signame = NULL;
-	char *startas = NULL;
+	char *signame;
+	char *startas;
+	char *chuid;
 #if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
 //	char *retry_arg = NULL;
 //	int retries = -1;
@@ -247,22 +254,22 @@ int start_stop_daemon_main(int argc, char **argv)
 
 	/* Check required one context option was given */
 	opt_complementary = "K:S:?:K--S:S--K:m?p:K?xpun:S?xa";
-	opt = getopt32(argc, argv, "KSbqm"
-//		USE_FEATURE_START_STOP_DAEMON_FANCY("ovN:R:")
-		USE_FEATURE_START_STOP_DAEMON_FANCY("ovN:")
-		"a:n:s:u:c:x:p:"
+	opt = getopt32(argc, argv, "KSbqma:n:s:u:c:x:p:"
+		USE_FEATURE_START_STOP_DAEMON_FANCY("ovN:"),
+//		USE_FEATURE_START_STOP_DAEMON_FANCY("ovN:R:"),
+		&startas, &cmdname, &signame, &userspec, &chuid, &execname, &pidfile
 		USE_FEATURE_START_STOP_DAEMON_FANCY(,&opt_N)
 //		USE_FEATURE_START_STOP_DAEMON_FANCY(,&retry_arg)
-		,&startas, &cmdname, &signame, &userspec, &chuid, &execname, &pidfile);
+	);
 
 	quiet = (opt & OPT_QUIET) && !(opt & OPT_VERBOSE);
 
-	if (signame) {
+	if (opt & OPT_s) {
 		signal_nr = get_signum(signame);
 		if (signal_nr < 0) bb_show_usage();
 	}
 
-	if (!startas)
+	if (!(opt & OPT_a))
 		startas = execname;
 
 //	USE_FEATURE_START_STOP_DAEMON_FANCY(
@@ -303,11 +310,11 @@ int start_stop_daemon_main(int argc, char **argv)
 		fprintf(pidf, "%d\n", pidt);
 		fclose(pidf);
 	}
-	if (chuid) {
-		user_id = bb_strtou(chuid, NULL, 10);
-		if (errno)
-			user_id = xuname2uid(chuid);
-		xsetuid(user_id);
+	if (opt & OPT_c) {
+		struct bb_uidgid_t ugid;
+		parse_chown_usergroup_or_die(&ugid, chuid);
+		if (ugid.gid != (gid_t) -1) xsetgid(ugid.gid);
+		if (ugid.uid != (uid_t) -1) xsetuid(ugid.uid);
 	}
 #if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
 	if (opt & OPT_NICELEVEL) {

include/libbb.h

@@ -443,7 +443,10 @@ struct bb_uidgid_t {
 	uid_t uid;
 	gid_t gid;
 };
+/* always sets uid and gid */
 int get_uidgid(struct bb_uidgid_t*, const char*, int numeric_ok);
+/* chown-like handling of "user[:[group]" */
+void parse_chown_usergroup_or_die(struct bb_uidgid_t *u, char *user_group);
 /* what is this? */
 /*extern char *bb_getug(char *buffer, char *idname, long id, int bufsize, char prefix);*/
 char *bb_getpwuid(char *name, long uid, int bufsize);

include/usage.h

@@ -2893,7 +2893,7 @@
        "\n	-N|--nicelevel <N>		Add N to process's nice level" \
 	) \
        "\n	-s|--signal <signal>		Signal to send (default TERM)" \
-       "\n	-U|--chuid <username>|<uid>	Start process with this name"
+       "\n	-c|--chuid <user>[:[<group>]]	Change to specified user/group"
 
 #define stat_trivial_usage \
        "[OPTION] FILE..."

libpwdgrp/uidgid_get.c

@@ -27,6 +27,7 @@ ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "busybox.h"
 
+/* Always sets uid and gid */
 int get_uidgid(struct bb_uidgid_t *u, const char *ug, int numeric_ok)
 {
 	struct passwd *pwd;
@@ -53,6 +54,7 @@ int get_uidgid(struct bb_uidgid_t *u, const char *ug, int numeric_ok)
 			goto skip;
 		}
 	}
+	/* Either it is not numeric, or caller disallows numeric username */
 	pwd = getpwnam(user);
 	if (!pwd)
 		return 0;
@@ -75,6 +77,40 @@ int get_uidgid(struct bb_uidgid_t *u, const char *ug, int numeric_ok)
 	return 1;
 }
 
+/* chown-like:
+ * "user" sets uid only,
+ * ":group" sets gid only
+ * "user:" sets uid and gid (to user's primary group id)
+ * "user:group" sets uid and gid
+ * ('unset' uid or gid is actually set to -1)
+ */
+void parse_chown_usergroup_or_die(struct bb_uidgid_t *u, char *user_group)
+{
+	char *group;
+
+	u->uid = -1;
+	u->gid = -1;
+
+	/* Check if there is a group name */
+	group = strchr(user_group, '.'); /* deprecated? */
+	if (!group)
+		group = strchr(user_group, ':');
+	else
+		*group = ':'; /* replace '.' with ':' */
+
+	/* Parse "user[:[group]]" */
+	if (!group) { /* "user" */
+		u->uid = get_ug_id(user_group, xuname2uid);
+	} else if (group == user_group) { /* ":group" */
+		u->gid = get_ug_id(group + 1, xgroup2gid);
+	} else {
+		if (!group[1]) /* "user:" */
+			*group = '\0';
+		if (!get_uidgid(u, user_group, 1))
+			bb_error_msg_and_die("unknown user/group %s", user_group);
+	}
+}
+
 #if 0
 #include <stdio.h>
 int main()