[alsa-devel] [PATCH] amidi: add delay option

[Clemens Ladisch]

Felipe F. Tonello wrote:
> This patch adds a new options to amidi tool to add a delay (in milliseconds)
> to each MIDI message.
>
> This is very useful when sending firmware updates to a remote device via SysEx
> or any other use that requires this delay in between messages.

> +	case 0xf4:
> +	case 0xf5:
> +		return 0; /* ignore */
> +	case 0xf7:
> +		return 0; /* ignore */

Silent data loss is bad.

> +	case 0x00 ... 0x7f:
> +		return rstate_len ?: rstate_len - 1;

rstate_len - 1 == -1

> +				int len = message_length(*data);
> +
> +				/* check for variable length */
> +				if (len == -1) {
> +					int i = 0;
> +					while (data[i++] != 0xf7);

Possible buffer overflow.

> +				if (len > 0 &&
> +				    (err = snd_rawmidi_write(output, data, len)) < 0) {

Same here.


The most robust way to find message boundaries probably would be a state
machine.  However, there is actually no requirement to find all message
boundaries; the _actual_ requirement is to insert pauses between SysEx
messages.  So don't bother to try to parse everything; just search for
F0 or F7.


Regards,
Clemens