Automatically determine user and group.

slock.c

@@ -409,6 +409,8 @@ main(int argc, char **argv) {
 	int s, nlocks, nscreens;
     int event_base, error_base;
 
+    char *username, *groupname;
+
 	ARGBEGIN {
 	case 'v':
 		puts("slock-"VERSION);
@@ -417,15 +419,25 @@ main(int argc, char **argv) {
 		usage();
 	} ARGEND
 
+    if(strlen(user) && strlen(group)) {
+        username = (char *)user;
+        groupname = (char *)group;
+    } else {
+        username = getenv("USER");
+        groupname = username;
+    }
+
+    printf("%s:%s\n", username, groupname);
+
 	/* validate drop-user and -group */
 	errno = 0;
-	if (!(pwd = getpwnam(user)))
-		die("slock: getpwnam %s: %s\n", user,
+	if (!(pwd = getpwnam(username)))
+		die("slock: getpwnam %s: %s\n", username,
 		    errno ? strerror(errno) : "user entry not found");
 	duid = pwd->pw_uid;
 	errno = 0;
-	if (!(grp = getgrnam(group)))
-		die("slock: getgrnam %s: %s\n", group,
+	if (!(grp = getgrnam(groupname)))
+		die("slock: getgrnam %s: %s\n", groupname,
 		    errno ? strerror(errno) : "group entry not found");
 	dgid = grp->gr_gid;