+static gint drop_root(void) {
+ struct passwd *pw;
+ struct group * gr;
+ gint r;
+
+ if (!(pw = getpwnam(AVAHI_USER))) {
+ avahi_log_error( "Failed to find user '"AVAHI_USER"'.");
+ return -1;
+ }
+
+ if (!(gr = getgrnam(AVAHI_GROUP))) {
+ avahi_log_error( "Failed to find group '"AVAHI_GROUP"'.");
+ return -1;
+ }
+
+ avahi_log_info("Found user '"AVAHI_USER"' (UID %lu) and group '"AVAHI_GROUP"' (GID %lu).", (unsigned long) pw->pw_uid, (unsigned long) gr->gr_gid);
+
+ if (initgroups(AVAHI_USER, gr->gr_gid) != 0) {
+ avahi_log_error("Failed to change group list: %s", strerror(errno));
+ return -1;
+ }
+
+#if defined(HAVE_SETRESGID)
+ r = setresgid(gr->gr_gid, gr->gr_gid, gr->gr_gid);
+#elif defined(HAVE_SETREGID)
+ r = setregid(gr->gr_gid, gr->gr_gid);
+#else
+ if ((r = setgid(gr->gr_gid)) >= 0)
+ r = setegid(gr->gr_gid);
+#endif
+
+ if (r < 0) {
+ avahi_log_error("Failed to change GID: %s", strerror(errno));
+ return -1;
+ }
+
+#if defined(HAVE_SETRESUID)
+ r = setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid);
+#elif defined(HAVE_SETREUID)
+ r = setreuid(pw->pw_uid, pw->pw_uid);
+#else
+ if ((r = setuid(pw->pw_uid)) >= 0)
+ r = seteuid(pw->pw_uid);
+#endif
+
+ if (r < 0) {
+ avahi_log_error("Failed to change UID: %s", strerror(errno));
+ return -1;
+ }
+
+ g_setenv("USER", pw->pw_name, 1);
+ g_setenv("LOGNAME", pw->pw_name, 1);
+ g_setenv("HOME", pw->pw_dir, 1);
+
+ avahi_log_info("Successfully dropped root privileges.");
+
+ return 0;
+}
+