[alsa-devel] [PATCH - JACK PCM plugin] jack: Write only valid values to the internal hw_ptr

[Wischer, Timo (ADITG/ESB)]

Hello all,

any comments so far?

It would be great if someone could have a look
because I have some further fixes pending.

Best regards

Timo Wischer

Advanced Driver Information Technology GmbH
Engineering Software Base (ADITG/ESB)
Robert-Bosch-Str. 200
31139 Hildesheim
Germany

Tel. +49 5121 49 6938
Fax +49 5121 49 6999
twischer at de.adit-jv.com

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Geschäftsführung: Wilhelm Grabow, Ken Yaguchi

________________________________________
From: Wischer, Timo (ADITG/ESB)
Sent: Monday, January 22, 2018 9:37 AM
To: patch at alsa-project.org
Cc: alsa-devel at alsa-project.org; Wischer, Timo (ADITG/ESB)
Subject: [PATCH - JACK PCM plugin] jack: Write only valid values to the internal hw_ptr

From: Timo Wischer <twischer at de.adit-jv.com>

Otherwise the ALSA thread could for example read a hw_ptr >
buffer_size

Signed-off-by: Timo Wischer <twischer at de.adit-jv.com>

diff --git a/jack/pcm_jack.c b/jack/pcm_jack.c
index 4468ede..3aed332 100644
--- a/jack/pcm_jack.c
+++ b/jack/pcm_jack.c
@@ -137,6 +137,7 @@ static int
 snd_pcm_jack_process_cb(jack_nframes_t nframes, snd_pcm_ioplug_t *io)
 {
        snd_pcm_jack_t *jack = io->private_data;
+       snd_pcm_uframes_t hw_ptr;
        const snd_pcm_channel_area_t *areas;
        snd_pcm_uframes_t xfer = 0;
        unsigned int channel;
@@ -155,12 +156,13 @@ snd_pcm_jack_process_cb(jack_nframes_t nframes, snd_pcm_ioplug_t *io)
                        return 0;
                }
        }
-
+
+       hw_ptr = jack->hw_ptr;
        areas = snd_pcm_ioplug_mmap_areas(io);

        while (xfer < nframes) {
                snd_pcm_uframes_t frames = nframes - xfer;
-               snd_pcm_uframes_t offset = jack->hw_ptr;
+               snd_pcm_uframes_t offset = hw_ptr;
                snd_pcm_uframes_t cont = io->buffer_size - offset;

                if (cont < frames)
@@ -173,10 +175,11 @@ snd_pcm_jack_process_cb(jack_nframes_t nframes, snd_pcm_ioplug_t *io)
                                snd_pcm_area_copy(&areas[channel], offset, &jack->areas[channel], xfer, frames, io->format);
                }

-               jack->hw_ptr += frames;
-               jack->hw_ptr %= io->buffer_size;
+               hw_ptr += frames;
+               hw_ptr %= io->buffer_size;
                xfer += frames;
        }
+       jack->hw_ptr = hw_ptr;

        pcm_poll_unblock_check(io); /* unblock socket for polling if needed */

--
2.7.4