ALSA: control-led: Replace sprintf() with sysfs_emit()

For sysfs outputs, it's safer to use a new helper, sysfs_emit(),
instead of the raw sprintf() & co.  This patch replaces such sprintf()
calls with sysfs_emit() while simplifying the open code in
list_show().

Link: https://lore.kernel.org/r/20220801165639.26030-4-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index 207828f30983550c2a526e34a20140f2cadc9a7b..f975cc85772bbce857fd2565fe720070a9f83bd9 100644 (file)
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -405,7 +405,7 @@ static ssize_t mode_show(struct device *dev,
        case MODE_ON:           str = "on"; break;
        case MODE_OFF:          str = "off"; break;
        }
-       return sprintf(buf, "%s\n", str);
+       return sysfs_emit(buf, "%s\n", str);
 }
 
 static ssize_t mode_store(struct device *dev,
@@ -443,7 +443,7 @@ static ssize_t brightness_show(struct device *dev,
 {
        struct snd_ctl_led *led = container_of(dev, struct snd_ctl_led, dev);
 
-       return sprintf(buf, "%u\n", ledtrig_audio_get(led->trigger_type));
+       return sysfs_emit(buf, "%u\n", ledtrig_audio_get(led->trigger_type));
 }
 
 static DEVICE_ATTR_RW(mode);
@@ -618,8 +618,7 @@ static ssize_t list_show(struct device *dev,
        struct snd_ctl_led_card *led_card = container_of(dev, struct snd_ctl_led_card, dev);
        struct snd_card *card;
        struct snd_ctl_led_ctl *lctl;
-       char *buf2 = buf;
-       size_t l;
+       size_t l = 0;
 
        card = snd_card_ref(led_card->number);
        if (!card)
@@ -627,23 +626,19 @@ static ssize_t list_show(struct device *dev,
        down_read(&card->controls_rwsem);
        mutex_lock(&snd_ctl_led_mutex);
        if (snd_ctl_led_card_valid[led_card->number]) {
-               list_for_each_entry(lctl, &led_card->led->controls, list)
-                       if (lctl->card == card) {
-                               if (buf2 - buf > PAGE_SIZE - 16)
-                                       break;
-                               if (buf2 != buf)
-                                       *buf2++ = ' ';
-                               l = scnprintf(buf2, 15, "%u",
-                                               lctl->kctl->id.numid +
-                                                       lctl->index_offset);
-                               buf2[l] = '\0';
-                               buf2 += l + 1;
-                       }
+               list_for_each_entry(lctl, &led_card->led->controls, list) {
+                       if (lctl->card != card)
+                               continue;
+                       if (l)
+                               l += sysfs_emit_at(buf, l, " ");
+                       l += sysfs_emit_at(buf, l, "%u",
+                                          lctl->kctl->id.numid + lctl->index_offset);
+               }
        }
        mutex_unlock(&snd_ctl_led_mutex);
        up_read(&card->controls_rwsem);
        snd_card_unref(card);
-       return buf2 - buf;
+       return l;
 }
 
 static DEVICE_ATTR_WO(attach);