[hackers] [slstatus] Print unknown_str in case of error || SiIky

[git]

commit 9ca1ac62f9aa6e01afb3697cc4b966d085be9d3a
Author:     SiIky <si...@users.noreply.github.com>
AuthorDate: Sat Feb 17 18:08:27 2018 +0000
Commit:     SiIky <si...@users.noreply.github.com>
CommitDate: Sat Feb 17 18:08:27 2018 +0000

    Print unknown_str in case of error
    
    func can return NULL in case of error, but no checking is done when
    printing, and unknown_str wasn't being used anywhere.

diff --git a/slstatus.c b/slstatus.c
index 89a3268..19bc127 100644
--- a/slstatus.c
+++ b/slstatus.c
@@ -87,8 +87,10 @@ main(int argc, char *argv[])
 
                status[0] = '\0';
                for (i = len = 0; i < LEN(args); i++) {
+                       const char * res = args[i].func(args[i].args);
+                       res = (res == NULL) ? unknown_str : res;
                        len += snprintf(status + len, sizeof(status) - len,
-                                       args[i].fmt, 
args[i].func(args[i].args));
+                                       args[i].fmt, res);
 
                        if (len >= sizeof(status)) {
                                status[sizeof(status) - 1] = '\0';