Fix handling of revents in snd_pcm_poll_descriptors_revents()

The revents parameter is ambiguously defined whether it's a pointer
to a single event or an arary.

This patch defines the behavior of revents more strictly (in the
function description): it's a pointer of a single event.

Also fixed snd_pcm_wait_nocheck() to follow that rule.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index 74d1d1a4bd6083cd461b6d793c0ae41cca912f16..b44956fb1b9a6695004687d8e67952f460b32976 100644 (file)
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -1430,7 +1430,7 @@ int snd_pcm_poll_descriptors(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int s
  * \param pcm PCM handle
  * \param pfds array of poll descriptors
  * \param nfds count of poll descriptors
- * \param revents returned events
+ * \param revents pointer to the returned (single) event
  * \return zero if success, otherwise a negative error code
  *
  * This function does "demangling" of the revents mask returned from
@@ -1440,6 +1440,9 @@ int snd_pcm_poll_descriptors(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int s
  * syscall returned that some events are waiting, this function might
  * return empty set of events. In this case, application should
  * do next event waiting using poll() or select().
+ *
+ * Note: Even if multiple poll descriptors are used (i.e. pfds > 1),
+ * this function returns only a single event.
  */
 int snd_pcm_poll_descriptors_revents(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int nfds, unsigned short *revents)
 {
@@ -2338,8 +2341,8 @@ int snd_pcm_wait(snd_pcm_t *pcm, int timeout)
 int snd_pcm_wait_nocheck(snd_pcm_t *pcm, int timeout)
 {
        struct pollfd *pfd;
-       unsigned short *revents;
-       int i, npfds, pollio, err, err_poll;
+       unsigned short revents = 0;
+       int npfds, err, err_poll;
        
        npfds = snd_pcm_poll_descriptors_count(pcm);
        if (npfds <= 0 || npfds >= 16) {
@@ -2347,7 +2350,6 @@ int snd_pcm_wait_nocheck(snd_pcm_t *pcm, int timeout)
                return -EIO;
        }
        pfd = alloca(sizeof(*pfd) * npfds);
-       revents = alloca(sizeof(*revents) * npfds);
        err = snd_pcm_poll_descriptors(pcm, pfd, npfds);
        if (err < 0)
                return err;
@@ -2356,7 +2358,6 @@ int snd_pcm_wait_nocheck(snd_pcm_t *pcm, int timeout)
                return -EIO;
        }
        do {
-               pollio = 0;
                err_poll = poll(pfd, npfds, timeout);
                if (err_poll < 0) {
                        if (errno == EINTR)
@@ -2365,28 +2366,23 @@ int snd_pcm_wait_nocheck(snd_pcm_t *pcm, int timeout)
                 }
                if (! err_poll)
                        break;
-               err = snd_pcm_poll_descriptors_revents(pcm, pfd, npfds, revents);
+               err = snd_pcm_poll_descriptors_revents(pcm, pfd, npfds, &revents);
                if (err < 0)
                        return err;
-               for (i = 0; i < npfds; i++) {
-                       if (revents[i] & (POLLERR | POLLNVAL)) {
-                               /* check more precisely */
-                               switch (snd_pcm_state(pcm)) {
-                               case SND_PCM_STATE_XRUN:
-                                       return -EPIPE;
-                               case SND_PCM_STATE_SUSPENDED:
-                                       return -ESTRPIPE;
-                               case SND_PCM_STATE_DISCONNECTED:
-                                       return -ENODEV;
-                               default:
-                                       return -EIO;
-                               }
+               if (revents & (POLLERR | POLLNVAL)) {
+                       /* check more precisely */
+                       switch (snd_pcm_state(pcm)) {
+                       case SND_PCM_STATE_XRUN:
+                               return -EPIPE;
+                       case SND_PCM_STATE_SUSPENDED:
+                               return -ESTRPIPE;
+                       case SND_PCM_STATE_DISCONNECTED:
+                               return -ENODEV;
+                       default:
+                               return -EIO;
                        }
-                       if ((revents[i] & (POLLIN | POLLOUT)) == 0)
-                               continue;
-                       pollio++;
                }
-       } while (! pollio);
+       } while (!(revents & (POLLIN | POLLOUT)));
 #if 0 /* very useful code to test poll related problems */
        {
                snd_pcm_sframes_t avail_update;