[Qemu-devel] [RFC] [PATCHv7 04/22] aio / timers: add ppoll support with qemu_poll_ns

[Alex Bligh <alex@alex.org.uk>]

Add qemu_poll_ns which works like g_poll but takes a nanosecond
timeout.

Signed-off-by: Alex Bligh <alex@alex.org.uk>
---
 configure            |   19 +++++++++++++++++++
 include/qemu/timer.h |   12 ++++++++++++
 qemu-timer.c         |   24 ++++++++++++++++++++++++
 3 files changed, 55 insertions(+)

diff --git a/configure b/configure
index f0761ea..4e54d1b 100755
--- a/configure
+++ b/configure
@@ -2818,6 +2818,22 @@ if compile_prog "" "" ; then
   dup3=yes
 fi
 
+# check for ppoll support
+ppoll=no
+cat > $TMPC << EOF
+#include <poll.h>
+
+int main(void)
+{
+    struct pollfd pfd = { .fd = 0, .events = 0, .revents = 0 };
+    ppoll(&pfd, 1, 0, 0);
+    return 0;
+}
+EOF
+if compile_prog "" "" ; then
+  ppoll=yes
+fi
+
 # check for epoll support
 epoll=no
 cat > $TMPC << EOF
@@ -3809,6 +3825,9 @@ fi
 if test "$dup3" = "yes" ; then
   echo "CONFIG_DUP3=y" >> $config_host_mak
 fi
+if test "$ppoll" = "yes" ; then
+  echo "CONFIG_PPOLL=y" >> $config_host_mak
+fi
 if test "$epoll" = "yes" ; then
   echo "CONFIG_EPOLL=y" >> $config_host_mak
 fi
diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index c96fe2b..7cf6ed0 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -81,6 +81,18 @@ int64_t qemu_clock_deadline_ns(QEMUClock *clock);
  */
 int qemu_timeout_ns_to_ms(int64_t ns);
 
+/**
+ * qemu_poll_ns:
+ * @fds: Array of file descriptors
+ * @nfds: number of file descriptors
+ * @timeout: timeout in nanoseconds
+ *
+ * Perform a poll like g_poll but with a timeout in nanoseconds.
+ * See g_poll documentation for further details.
+ *
+ * Returns: number of fds ready
+ */
+int qemu_poll_ns(GPollFD *fds, uint nfds, int64_t timeout);
 void qemu_clock_enable(QEMUClock *clock, bool enabled);
 void qemu_clock_warp(QEMUClock *clock);
 
diff --git a/qemu-timer.c b/qemu-timer.c
index 0617e3e..3109bd8 100644
--- a/qemu-timer.c
+++ b/qemu-timer.c
@@ -37,6 +37,10 @@
 #include <mmsystem.h>
 #endif
 
+#ifdef CONFIG_PPOLL
+#include <poll.h>
+#endif
+
 /***********************************************************/
 /* timers */
 
@@ -328,6 +332,26 @@ int qemu_timeout_ns_to_ms(int64_t ns)
 }
 
 
+/* qemu implementation of g_poll which uses a nanosecond timeout but is
+ * otherwise identical to g_poll
+ */
+int qemu_poll_ns(GPollFD *fds, uint nfds, int64_t timeout)
+{
+#ifdef CONFIG_PPOLL
+    if (timeout < 0) {
+        return ppoll((struct pollfd *)fds, nfds, NULL, NULL);
+    } else {
+        struct timespec ts;
+        ts.tv_sec = timeout / 1000000000LL;
+        ts.tv_nsec = timeout % 1000000000LL;
+        return ppoll((struct pollfd *)fds, nfds, &ts, NULL);
+    }
+#else
+    return g_poll(fds, nfds, qemu_timeout_ns_to_ms(timeout));
+#endif
+}
+
+
 QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
                           QEMUTimerCB *cb, void *opaque)
 {
-- 
1.7.9.5