iochannel: remove fd from poll() when we don't care from events

This should make it unlikely that we loop on SIGHUP indefinitely.

Also, this makes it possible for callbacks not to process all events and
still not busy loop.

1 files changed, 75 insertions, 52 deletions

diff --git a/src/pulsecore/iochannel.c b/src/pulsecore/iochannel.c
index b40c9815..48330079 100644
--- a/src/pulsecore/iochannel.c
+++ b/src/pulsecore/iochannel.c
@@ -28,7 +28,6 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <errno.h>
-
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
@@ -65,24 +64,71 @@ struct pa_iochannel {
     pa_io_event* input_event, *output_event;
 };
 
-static void enable_mainloop_sources(pa_iochannel *io) {
+static void callback(pa_mainloop_api* m, pa_io_event *e, int fd, pa_io_event_flags_t f, void *userdata);
+
+static void delete_events(pa_iochannel *io) {
+    pa_assert(io);
+
+    if (io->input_event)
+        io->mainloop->io_free(io->input_event);
+
+    if (io->output_event && io->output_event != io->input_event)
+        io->mainloop->io_free(io->output_event);
+
+    io->input_event = io->output_event = NULL;
+}
+
+static void enable_events(pa_iochannel *io) {
     pa_assert(io);
 
-    if (io->input_event == io->output_event && io->input_event) {
+    if (io->hungup) {
+        delete_events(io);
+        return;
+    }
+
+    if (io->ifd == io->ofd && io->ifd >= 0) {
         pa_io_event_flags_t f = PA_IO_EVENT_NULL;
-        pa_assert(io->input_event);
 
         if (!io->readable)
             f |= PA_IO_EVENT_INPUT;
         if (!io->writable)
             f |= PA_IO_EVENT_OUTPUT;
 
-        io->mainloop->io_enable(io->input_event, f);
+        pa_assert(io->input_event == io->output_event);
+
+        if (f != PA_IO_EVENT_NULL) {
+            if (io->input_event)
+                io->mainloop->io_enable(io->input_event, f);
+            else
+                io->input_event = io->output_event = io->mainloop->io_new(io->mainloop, io->ifd, f, callback, io);
+        } else
+            delete_events(io);
+
     } else {
-        if (io->input_event)
-            io->mainloop->io_enable(io->input_event, io->readable ? PA_IO_EVENT_NULL : PA_IO_EVENT_INPUT);
-        if (io->output_event)
-            io->mainloop->io_enable(io->output_event, io->writable ? PA_IO_EVENT_NULL : PA_IO_EVENT_OUTPUT);
+
+        if (io->ifd >= 0) {
+            if (!io->readable) {
+                if (io->input_event)
+                    io->mainloop->io_enable(io->input_event, PA_IO_EVENT_INPUT);
+                else
+                    io->input_event = io->mainloop->io_new(io->mainloop, io->ifd, PA_IO_EVENT_INPUT, callback, io);
+            } else if (io->input_event) {
+                io->mainloop->io_free(io->input_event);
+                io->input_event = NULL;
+            }
+        }
+
+        if (io->ofd >= 0) {
+            if (!io->writable) {
+                if (io->output_event)
+                    io->mainloop->io_enable(io->output_event, PA_IO_EVENT_OUTPUT);
+                else
+                    io->output_event = io->mainloop->io_new(io->mainloop, io->ofd, PA_IO_EVENT_OUTPUT, callback, io);
+            } else if (io->input_event) {
+                io->mainloop->io_free(io->output_event);
+                io->output_event = NULL;
+            }
+        }
     }
 }
 
@@ -113,7 +159,7 @@ static void callback(pa_mainloop_api* m, pa_io_event *e, int fd, pa_io_event_fla
     }
 
     if (changed) {
-        enable_mainloop_sources(io);
+        enable_events(io);
 
         if (io->callback)
             io->callback(io, io->userdata);
@@ -126,49 +172,25 @@ pa_iochannel* pa_iochannel_new(pa_mainloop_api*m, int ifd, int ofd) {
     pa_assert(m);
     pa_assert(ifd >= 0 || ofd >= 0);
 
-    io = pa_xnew(pa_iochannel, 1);
+    io = pa_xnew0(pa_iochannel, 1);
     io->ifd = ifd;
     io->ofd = ofd;
-    io->ifd_type = io->ofd_type = 0;
     io->mainloop = m;
 
-    io->userdata = NULL;
-    io->callback = NULL;
-    io->readable = FALSE;
-    io->writable = FALSE;
-    io->hungup = FALSE;
-    io->no_close = FALSE;
-
-    io->input_event = io->output_event = NULL;
-
-    if (ifd == ofd) {
-        pa_assert(ifd >= 0);
+    if (io->ifd >= 0)
         pa_make_fd_nonblock(io->ifd);
-        io->input_event = io->output_event = m->io_new(m, ifd, PA_IO_EVENT_INPUT|PA_IO_EVENT_OUTPUT, callback, io);
-    } else {
-
-        if (ifd >= 0) {
-            pa_make_fd_nonblock(io->ifd);
-            io->input_event = m->io_new(m, ifd, PA_IO_EVENT_INPUT, callback, io);
-        }
 
-        if (ofd >= 0) {
-            pa_make_fd_nonblock(io->ofd);
-            io->output_event = m->io_new(m, ofd, PA_IO_EVENT_OUTPUT, callback, io);
-        }
-    }
+    if (io->ofd >= 0 && io->ofd != io->ifd)
+        pa_make_fd_nonblock(io->ofd);
 
+    enable_events(io);
     return io;
 }
 
 void pa_iochannel_free(pa_iochannel*io) {
     pa_assert(io);
 
-    if (io->input_event)
-        io->mainloop->io_free(io->input_event);
-
-    if (io->output_event && (io->output_event != io->input_event))
-        io->mainloop->io_free(io->output_event);
+    delete_events(io);
 
     if (!io->no_close) {
         if (io->ifd >= 0)
@@ -207,8 +229,8 @@ ssize_t pa_iochannel_write(pa_iochannel*io, const void*data, size_t l) {
     pa_assert(io->ofd >= 0);
 
     if ((r = pa_write(io->ofd, data, l, &io->ofd_type)) >= 0) {
-        io->writable = FALSE;
-        enable_mainloop_sources(io);
+        io->writable = io->hungup = FALSE;
+        enable_events(io);
     }
 
     return r;
@@ -222,8 +244,12 @@ ssize_t pa_iochannel_read(pa_iochannel*io, void*data, size_t l) {
     pa_assert(io->ifd >= 0);
 
     if ((r = pa_read(io->ifd, data, l, &io->ifd_type)) >= 0) {
-        io->readable = FALSE;
-        enable_mainloop_sources(io);
+
+        /* We also reset the hangup flag here to ensure that another
+         * IO callback is triggered so that we will again call into
+         * user code */
+        io->readable = io->hungup = FALSE;
+        enable_events(io);
     }
 
     return r;
@@ -296,18 +322,15 @@ ssize_t pa_iochannel_write_with_creds(pa_iochannel*io, const void*data, size_t l
         u->gid = getgid();
     }
 
-    memset(&mh, 0, sizeof(mh));
-    mh.msg_name = NULL;
-    mh.msg_namelen = 0;
+    pa_zero(mh);
     mh.msg_iov = &iov;
     mh.msg_iovlen = 1;
     mh.msg_control = &cmsg;
     mh.msg_controllen = sizeof(cmsg);
-    mh.msg_flags = 0;
 
     if ((r = sendmsg(io->ofd, &mh, MSG_NOSIGNAL)) >= 0) {
-        io->writable = FALSE;
-        enable_mainloop_sources(io);
+        io->writable = io->hungup = FALSE;
+        enable_events(io);
     }
 
     return r;
@@ -363,8 +386,8 @@ ssize_t pa_iochannel_read_with_creds(pa_iochannel*io, void*data, size_t l, pa_cr
             }
         }
 
-        io->readable = FALSE;
-        enable_mainloop_sources(io);
+        io->readable = io->hungup = FALSE;
+        enable_events(io);
     }
 
     return r;