Hi,

When using the aoss wrapper, poll() is never woken by POLLIN.

This happens with devices opened in either O_RDWR or O_RDONLY and is demonstrated by the trivial example below, which never prints "POLLIN".

The example performs correctly using the kernel OSS emulation. Is this a (known) bug in aoss? I've now seen it on different distributions and in the latest code from the repository.

Enabling ALSA_OSS_DEBUG shows that the struct pollfd is being correctly manipulated:

Orig enter POLL nfds: 1, timeout: 1000 fd=3, events=d, revents=0 Changed enter POLL nfds: 2, timeout: 1000 fd=5, events=2c, revents=0 fd=6, events=29, revents=0

Changed exit POLL nfds: 2, timeout: 1000 fd=5, events=2c, revents=4 fd=6, events=29, revents=0 Orig exit POLL nfds: 1, timeout: 1000 fd=3, events=d, revents=4

The file descriptors are:

lrwx------ 1 mark users 64 Jul 29 00:46 /proc/5399/fd/3 -> /dev/null lrwx------ 1 mark users 64 Jul 29 00:46 /proc/5399/fd/5 -> /dev/snd/pcmC0D0p lrwx------ 1 mark users 64 Jul 29 00:46 /proc/5399/fd/6 -> /dev/snd/pcmC0D0c

The pass through to the _poll() call inside poll_with_pcm() in alsa-oss.c isn't being woken by POLLIN for the capture device.

Mark

#include <errno.h> #include <fcntl.h> #include <stdio.h> #include <unistd.h> #include <sys/ioctl.h> #include <sys/poll.h> #include <sys/soundcard.h>

#define CHANNELS 2 #define SAMPLES 64

int main(int argc, char *argv[]) { int fd, p, r; struct pollfd pe; char buf[CHANNELS * SAMPLES];

/* Change below to O_RDWR, O_RDONLY or O_WRONLY */

fd = open("/dev/dsp", O_RDWR, 0); if(fd == -1) { perror("open"); return -1; }

p = AFMT_S16_LE; if(ioctl(fd, SNDCTL_DSP_SETFMT, &p) == -1) { perror("SNDCTL_DSP_SETFMT"); return -1; }

p = CHANNELS; if(ioctl(fd, SNDCTL_DSP_CHANNELS, &p) == -1) { perror("SNDCTL_DSP_CHANNELS"); return -1; }

p = 44100; if(ioctl(fd, SNDCTL_DSP_SPEED, &p) == -1) { perror("SNDCTL_DSP_SPEED"); return -1; }

if(fcntl(fd, F_SETFL, O_NONBLOCK) == -1) { perror("fcntl"); return -1; }

pe.fd = fd; pe.events = POLLERR | POLLIN | POLLOUT;

for(;;) { fputs("poll", stderr);

pe.revents = 0; poll(&pe, 1, 1000);

if(pe.revents & POLLOUT) { fputs(" POLLOUT", stderr); r = write(fd, buf, CHANNELS * SAMPLES); if(r == -1 && errno != EAGAIN) { perror("read"); return -1; } }

if(pe.revents & POLLIN) { fputs(" POLLIN", stderr); r = read(fd, buf, CHANNELS * SAMPLES); if(r == -1 && errno != EAGAIN) { perror("read"); return -1; } }

fputc('\n', stderr); }

close(fd); return 0; }