ALSA: usb-audio: simplify mixer control name handling

In get_term_name(), remove hard-coded return values and a strlen() call,
and return the number of bytes copied by strscpy() directly.

Since get_term_name() may now return -E2BIG on string truncation, check
name_len < 0 and return early from get_connector_control_name() if
needed. Also replace strlcat() with strscpy().

Other get_term_name() callers only check the return value for non-zero
and are not affected by this change.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20260504212008.147373-4-thorsten.blum@linux.dev
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 9d9ed68166c88c625cff96b860154121db0227bc..9afa674cbb3eedcae9db23133d8c93beefe6aa14 100644 (file)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -665,17 +665,13 @@ static int get_term_name(struct snd_usb_audio *chip, struct usb_audio_term *iter
                        return 0;
                switch (iterm->type >> 16) {
                case UAC3_SELECTOR_UNIT:
-                       strscpy(name, "Selector", maxlen);
-                       return 8;
+                       return strscpy(name, "Selector", maxlen);
                case UAC3_PROCESSING_UNIT:
-                       strscpy(name, "Process Unit", maxlen);
-                       return 12;
+                       return strscpy(name, "Process Unit", maxlen);
                case UAC3_EXTENSION_UNIT:
-                       strscpy(name, "Ext Unit", maxlen);
-                       return 8;
+                       return strscpy(name, "Ext Unit", maxlen);
                case UAC3_MIXER_UNIT:
-                       strscpy(name, "Mixer", maxlen);
-                       return 5;
+                       return strscpy(name, "Mixer", maxlen);
                default:
                        return scnprintf(name, maxlen, "Unit %d", iterm->id);
                }
@@ -683,25 +679,18 @@ static int get_term_name(struct snd_usb_audio *chip, struct usb_audio_term *iter
 
        switch (iterm->type & 0xff00) {
        case 0x0100:
-               strscpy(name, "PCM", maxlen);
-               return 3;
+               return strscpy(name, "PCM", maxlen);
        case 0x0200:
-               strscpy(name, "Mic", maxlen);
-               return 3;
+               return strscpy(name, "Mic", maxlen);
        case 0x0400:
-               strscpy(name, "Headset", maxlen);
-               return 7;
+               return strscpy(name, "Headset", maxlen);
        case 0x0500:
-               strscpy(name, "Phone", maxlen);
-               return 5;
+               return strscpy(name, "Phone", maxlen);
        }
 
-       for (names = iterm_names; names->type; names++) {
-               if (names->type == iterm->type) {
-                       strscpy(name, names->name, maxlen);
-                       return strlen(names->name);
-               }
-       }
+       for (names = iterm_names; names->type; names++)
+               if (names->type == iterm->type)
+                       return strscpy(name, names->name, maxlen);
 
        return 0;
 }
@@ -1983,7 +1972,9 @@ static void get_connector_control_name(struct usb_mixer_interface *mixer,
        int name_len = get_term_name(mixer->chip, term, name, name_size, 0);
 
        if (name_len == 0)
-               strscpy(name, "Unknown", name_size);
+               name_len = strscpy(name, "Unknown", name_size);
+       if (name_len < 0)
+               return;
 
        /*
         *  sound/core/ctljack.c has a convention of naming jack controls
@@ -1991,9 +1982,9 @@ static void get_connector_control_name(struct usb_mixer_interface *mixer,
         * indicating Input or Output after the terminal name.
         */
        if (is_input)
-               strlcat(name, " - Input Jack", name_size);
+               strscpy(name + name_len, " - Input Jack", name_size - name_len);
        else
-               strlcat(name, " - Output Jack", name_size);
+               strscpy(name + name_len, " - Output Jack", name_size - name_len);
 }
 
 /* get connector value to "wake up" the USB audio */