hwc: Handle properly event data string from driver
Now that multiple events are handled by the vsync thread,
the data read from the driver needs to be null terminated.
Also memset vdata string to zero to ensure that data from a
previously read event isn't considered part of the current
event with a shorter data string.
Change-Id: Iff63e3a817c289ebca8a735ec2484c067b3ff3cf
diff --git a/libhwcomposer/hwc_vsync.cpp b/libhwcomposer/hwc_vsync.cpp
index 722916a..89f8044 100644
--- a/libhwcomposer/hwc_vsync.cpp
+++ b/libhwcomposer/hwc_vsync.cpp
@@ -157,7 +157,9 @@
}
}
- pread(pfd[dpy][ev].fd, vdata , MAX_DATA, 0);
+ memset(&vdata, '\0', sizeof(vdata));
+ // Read once from the fds to clear the first notify
+ pread(pfd[dpy][ev].fd, vdata , MAX_DATA - 1, 0);
if (pfd[dpy][ev].fd >= 0)
pfd[dpy][ev].events = POLLPRI | POLLERR;
}
@@ -170,7 +172,10 @@
for (int dpy = HWC_DISPLAY_PRIMARY; dpy < num_displays; dpy++) {
for(size_t ev = 0; ev < num_events; ev++) {
if (pfd[dpy][ev].revents & POLLPRI) {
- ssize_t len = pread(pfd[dpy][ev].fd, vdata, MAX_DATA, 0);
+ // Clear vdata before writing into it
+ memset(&vdata, '\0', sizeof(vdata));
+ ssize_t len = pread(pfd[dpy][ev].fd, vdata,
+ MAX_DATA - 1, 0);
if (UNLIKELY(len < 0)) {
// If the read was just interrupted - it is not
// a fatal error. Just continue in this case
@@ -179,6 +184,7 @@
__FUNCTION__, ev, dpy, strerror(errno));
continue;
}
+ vdata[len] = '\0';
event_list[ev].callback(ctx, dpy, vdata);
}
}