[ALSA] seq_midi_event: fix parsing of missing data bytes
Clemens Ladisch [Fri, 10 Aug 2007 07:40:09 +0000 (09:40 +0200)]
Reorganize the encoder logic to prevent status bytes that appear where
data bytes are expected from being interpreted as data bytes.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

sound/core/seq/seq_midi_event.c

index 45ba6fc..a15f5e6 100644 (file)
@@ -65,32 +65,32 @@ static struct status_event_list {
        void (*decode)(struct snd_seq_event *ev, unsigned char *buf);
 } status_event[] = {
        /* 0x80 - 0xef */
-       {SNDRV_SEQ_EVENT_NOTEOFF,       2, note_event, note_decode},
-       {SNDRV_SEQ_EVENT_NOTEON,        2, note_event, note_decode},
-       {SNDRV_SEQ_EVENT_KEYPRESS,      2, note_event, note_decode},
-       {SNDRV_SEQ_EVENT_CONTROLLER,    2, two_param_ctrl_event, two_param_decode},
-       {SNDRV_SEQ_EVENT_PGMCHANGE,     1, one_param_ctrl_event, one_param_decode},
-       {SNDRV_SEQ_EVENT_CHANPRESS,     1, one_param_ctrl_event, one_param_decode},
-       {SNDRV_SEQ_EVENT_PITCHBEND,     2, pitchbend_ctrl_event, pitchbend_decode},
+       {SNDRV_SEQ_EVENT_NOTEOFF,        2, note_event, note_decode},
+       {SNDRV_SEQ_EVENT_NOTEON,         2, note_event, note_decode},
+       {SNDRV_SEQ_EVENT_KEYPRESS,       2, note_event, note_decode},
+       {SNDRV_SEQ_EVENT_CONTROLLER,     2, two_param_ctrl_event, two_param_decode},
+       {SNDRV_SEQ_EVENT_PGMCHANGE,      1, one_param_ctrl_event, one_param_decode},
+       {SNDRV_SEQ_EVENT_CHANPRESS,      1, one_param_ctrl_event, one_param_decode},
+       {SNDRV_SEQ_EVENT_PITCHBEND,      2, pitchbend_ctrl_event, pitchbend_decode},
        /* invalid */
-       {SNDRV_SEQ_EVENT_NONE,          0, NULL, NULL},
+       {SNDRV_SEQ_EVENT_NONE,          -1, NULL, NULL},
        /* 0xf0 - 0xff */
-       {SNDRV_SEQ_EVENT_SYSEX,         1, NULL, NULL}, /* sysex: 0xf0 */
-       {SNDRV_SEQ_EVENT_QFRAME,        1, one_param_event, one_param_decode}, /* 0xf1 */
-       {SNDRV_SEQ_EVENT_SONGPOS,       2, songpos_event, songpos_decode}, /* 0xf2 */
-       {SNDRV_SEQ_EVENT_SONGSEL,       1, one_param_event, one_param_decode}, /* 0xf3 */
-       {SNDRV_SEQ_EVENT_NONE,          0, NULL, NULL}, /* 0xf4 */
-       {SNDRV_SEQ_EVENT_NONE,          0, NULL, NULL}, /* 0xf5 */
-       {SNDRV_SEQ_EVENT_TUNE_REQUEST,  0, NULL, NULL}, /* 0xf6 */
-       {SNDRV_SEQ_EVENT_NONE,          0, NULL, NULL}, /* 0xf7 */
-       {SNDRV_SEQ_EVENT_CLOCK,         0, NULL, NULL}, /* 0xf8 */
-       {SNDRV_SEQ_EVENT_NONE,          0, NULL, NULL}, /* 0xf9 */
-       {SNDRV_SEQ_EVENT_START,         0, NULL, NULL}, /* 0xfa */
-       {SNDRV_SEQ_EVENT_CONTINUE,      0, NULL, NULL}, /* 0xfb */
-       {SNDRV_SEQ_EVENT_STOP,          0, NULL, NULL}, /* 0xfc */
-       {SNDRV_SEQ_EVENT_NONE,          0, NULL, NULL}, /* 0xfd */
-       {SNDRV_SEQ_EVENT_SENSING,       0, NULL, NULL}, /* 0xfe */
-       {SNDRV_SEQ_EVENT_RESET,         0, NULL, NULL}, /* 0xff */
+       {SNDRV_SEQ_EVENT_SYSEX,          1, NULL, NULL}, /* sysex: 0xf0 */
+       {SNDRV_SEQ_EVENT_QFRAME,         1, one_param_event, one_param_decode}, /* 0xf1 */
+       {SNDRV_SEQ_EVENT_SONGPOS,        2, songpos_event, songpos_decode}, /* 0xf2 */
+       {SNDRV_SEQ_EVENT_SONGSEL,        1, one_param_event, one_param_decode}, /* 0xf3 */
+       {SNDRV_SEQ_EVENT_NONE,          -1, NULL, NULL}, /* 0xf4 */
+       {SNDRV_SEQ_EVENT_NONE,          -1, NULL, NULL}, /* 0xf5 */
+       {SNDRV_SEQ_EVENT_TUNE_REQUEST,   0, NULL, NULL}, /* 0xf6 */
+       {SNDRV_SEQ_EVENT_NONE,          -1, NULL, NULL}, /* 0xf7 */
+       {SNDRV_SEQ_EVENT_CLOCK,          0, NULL, NULL}, /* 0xf8 */
+       {SNDRV_SEQ_EVENT_NONE,          -1, NULL, NULL}, /* 0xf9 */
+       {SNDRV_SEQ_EVENT_START,          0, NULL, NULL}, /* 0xfa */
+       {SNDRV_SEQ_EVENT_CONTINUE,       0, NULL, NULL}, /* 0xfb */
+       {SNDRV_SEQ_EVENT_STOP,           0, NULL, NULL}, /* 0xfc */
+       {SNDRV_SEQ_EVENT_NONE,          -1, NULL, NULL}, /* 0xfd */
+       {SNDRV_SEQ_EVENT_SENSING,        0, NULL, NULL}, /* 0xfe */
+       {SNDRV_SEQ_EVENT_RESET,          0, NULL, NULL}, /* 0xff */
 };
 
 static int extra_decode_ctrl14(struct snd_midi_event *dev, unsigned char *buf, int len,
@@ -256,25 +256,27 @@ int snd_midi_event_encode_byte(struct snd_midi_event *dev, int c,
        }
 
        spin_lock_irqsave(&dev->lock, flags);
-       if (dev->qlen > 0) {
-               /* rest of command */
-               dev->buf[dev->read++] = c;
-               if (dev->type != ST_SYSEX)
-                       dev->qlen--;
-       } else {
+       if ((c & 0x80) &&
+           (c != MIDI_CMD_COMMON_SYSEX_END || dev->type != ST_SYSEX)) {
                /* new command */
+               dev->buf[0] = c;
+               if ((c & 0xf0) == 0xf0) /* system messages */
+                       dev->type = (c & 0x0f) + ST_SPECIAL;
+               else
+                       dev->type = (c >> 4) & 0x07;
                dev->read = 1;
-               if (c & 0x80) {
-                       dev->buf[0] = c;
-                       if ((c & 0xf0) == 0xf0) /* special events */
-                               dev->type = (c & 0x0f) + ST_SPECIAL;
-                       else
-                               dev->type = (c >> 4) & 0x07;
-                       dev->qlen = status_event[dev->type].qlen;
-               } else {
-                       /* process this byte as argument */
+               dev->qlen = status_event[dev->type].qlen;
+       } else {
+               if (dev->qlen > 0) {
+                       /* rest of command */
                        dev->buf[dev->read++] = c;
+                       if (dev->type != ST_SYSEX)
+                               dev->qlen--;
+               } else {
+                       /* running status */
+                       dev->buf[1] = c;
                        dev->qlen = status_event[dev->type].qlen - 1;
+                       dev->read = 2;
                }
        }
        if (dev->qlen == 0) {