util: unify usage of on_tty() in util.c

1 files changed, 11 insertions, 5 deletions

diff --git a/src/shared/util.c b/src/shared/util.c
index 462b541b41..527a5800fe 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -2175,28 +2175,25 @@ int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
 }
 
 int ask(char *ret, const char *replies, const char *text, ...) {
-        bool on_tty;
 
         assert(ret);
         assert(replies);
         assert(text);
 
-        on_tty = isatty(STDOUT_FILENO);
-
         for (;;) {
                 va_list ap;
                 char c;
                 int r;
                 bool need_nl = true;
 
-                if (on_tty)
+                if (on_tty())
                         fputs(ANSI_HIGHLIGHT_ON, stdout);
 
                 va_start(ap, text);
                 vprintf(text, ap);
                 va_end(ap);
 
-                if (on_tty)
+                if (on_tty())
                         fputs(ANSI_HIGHLIGHT_OFF, stdout);
 
                 fflush(stdout);
@@ -3820,6 +3817,15 @@ void columns_cache_reset(int signum) {
         cached_columns = 0;
 }
 
+bool on_tty(void) {
+        static int cached_on_tty = -1;
+
+        if (_unlikely_(cached_on_tty < 0))
+                cached_on_tty = isatty(STDOUT_FILENO) > 0;
+
+        return cached_on_tty;
+}
+
 int fd_lines(int fd) {
         struct winsize ws;
         zero(ws);