tree-wide: use isatty_safe() more

src/basic/terminal-util.c

@@ -1052,8 +1052,8 @@ bool on_tty(void) {
 
         if (cached_on_tty < 0)
                 cached_on_tty =
-                        isatty(STDOUT_FILENO) > 0 &&
-                        isatty(STDERR_FILENO) > 0;
+                        isatty_safe(STDOUT_FILENO) &&
+                        isatty_safe(STDERR_FILENO);
 
         return cached_on_tty;
 }

src/basic/user-util.c

@@ -27,6 +27,7 @@
 #include "random-util.h"
 #include "string-util.h"
 #include "strv.h"
+#include "terminal-util.h"
 #include "user-util.h"
 #include "utf8.h"
 
@@ -120,7 +121,7 @@ char* getlogname_malloc(void) {
         uid_t uid;
         struct stat st;
 
-        if (isatty(STDIN_FILENO) && fstat(STDIN_FILENO, &st) >= 0)
+        if (isatty_safe(STDIN_FILENO) && fstat(STDIN_FILENO, &st) >= 0)
                 uid = st.st_uid;
         else
                 uid = getuid();