aplay: fix the CPU busy loop in the pause handler

Use the standard poll mechanism to ensure that there's
something in the input to avoid busy loop on the file
descriptor with the non-block mode set.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

diff --git a/aplay/aplay.c b/aplay/aplay.c
index ae609880bfd7fc6c4c4589ef1166eaccc60ac1cf..d385da25fea15f0e592cb45cb39f26c28258522d 100644 (file)
--- a/aplay/aplay.c
+++ b/aplay/aplay.c
@@ -1553,6 +1553,19 @@ static void done_stdin(void)
        tcsetattr(fileno(stdin), TCSANOW, &term);
 }
 
+static char wait_for_input(void)
+{
+       struct pollfd pfd;
+       unsigned char b;
+
+       do {
+               pfd.fd = fileno(stdin);
+               pfd.events = POLLIN;
+               poll(&pfd, 1, -1);
+       } while (read(fileno(stdin), &b, 1) != 1);
+       return b;
+}
+
 static void do_pause(void)
 {
        int err;
@@ -1571,7 +1584,7 @@ static void do_pause(void)
                return;
        }
        while (1) {
-               while (read(fileno(stdin), &b, 1) != 1);
+               b = wait_for_input();
                if (b == ' ' || b == '\r') {
                        while (read(fileno(stdin), &b, 1) == 1);
                        if (snd_pcm_state(handle) == SND_PCM_STATE_SUSPENDED)
@@ -1596,7 +1609,7 @@ static void check_stdin(void)
                                while (read(fileno(stdin), &b, 1) == 1);
                                fprintf(stderr, _("\r=== PAUSE ===                                                            "));
                                fflush(stderr);
-                       do_pause();
+                               do_pause();
                                fprintf(stderr, "                                                                          \r");
                                fflush(stderr);
                        }