Re: sound: bebop: strncmp length oddity
From: Takashi Sakamoto
Date: Thu Nov 17 2016 - 15:07:56 EST
s/bebop/bebob/
(BeBoB is 'BridgeCo enhanced Breakout Box'.)
I'm sorry to miss this post, Joe. I was busy to prepare for Audio
mini-conference on Linux Plumber Conference. I realized that Nicolas
posted a patch for this issue.
[alsa-devel] [PATCH 1/1] ALSA: bebob: use the right string length in
check_audiophile_booted()
http://mailman.alsa-project.org/pipermail/alsa-devel/2016-October/114073.html
On Nov 17 2016 20:47, Takashi Iwai wrote:
On Sat, 29 Oct 2016 23:37:00 +0200,
Joe Perches wrote:
15 isn't the length of the string, is that really what's desired?
linux/next/sound/firewire/bebob/bebop.c
-----------------------------
static bool
check_audiophile_booted(struct fw_unit *unit)
{
char name[24] = {0};
if (fw_csr_string(unit->directory, CSR_MODEL, name, sizeof(name)) < 0)
return false;
return strncmp(name, "FW Audiophile Bootloader", 15) != 0;
}
Indeed it looks bogus. Even "FW...." string is already 24 letters, so
it's over name[] array size.
Sakamoto-san, could you fix it properly?
It's OK just to compare first a few characters, while I left whole
string for our information because model-specific information is easily
lost.
For M-Audio's FireWire Audiophile, modalias of
'ieee1394:ven00000D6Cmo00010060sp' hits this unit only. However the unit
has two states relevant to loaded firmware. Initial firmware returns 'FW
Audiophile Bootloader', while functional firmware returns 'FW
Audiophile'. Just comparing the first 15 characters is the shortest way
to defferentiate them. (Actually 14 characters. I guess that I did avoid
comparison based on LWS...)
Therefore, changing comparison range is not for bug fix, just for
readers. But I agree with these patches because the code is a bit
confusing. I'll post a patch soon for this aim with appropriate
information, sorry for Nicolas.
Thanks
Takashi Sakamoto