libudev: clarify that udev_monitor_receive_device() is non-blocking

[elogind.git] / src / libudev / libudev-monitor.c

diff --git a/src/libudev/libudev-monitor.c b/src/libudev/libudev-monitor.c
index 566e9761aa0eb55beef90384f7faa3e33f36f09a..2ad9e1c3adbc1d134d36f31f8b557382dde49fab 100644 (file)
--- a/src/libudev/libudev-monitor.c
+++ b/src/libudev/libudev-monitor.c
@@ -494,6 +494,11 @@ tag:
  *
  * Only socket connections with uid=0 are accepted.
  *
+ * The monitor socket is by default set to NONBLOCK. A variant of poll() on
+ * the file descriptor returned by udev_monitor_get_fd() should to be used to
+ * wake up when new devices arrive, or alternatively the file descriptor
+ * switched into blocking mode.
+ *
  * The initial refcount is 1, and needs to be decremented to
  * release the resources of the udev device.
  *
@@ -578,7 +583,7 @@ retry:
                             nlh->magic, htonl(UDEV_MONITOR_MAGIC));
                         return NULL;
                 }
-                if (nlh->properties_off+32 > buflen)
+                if (nlh->properties_off+32 > (size_t)buflen)
                         return NULL;
                 bufpos = nlh->properties_off;
         } else {