udp_send: Silence gcc warning.

Ubuntu Lucid's gcc-4.3.3 emits the following warning about not checking
the return value of write() even if the result is casted to void.

	udp_send.c: In function ‘udp_close_target’:
	udp_send.c:65: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result

The usual approach to store the return value in a dummy variable is
not optimal because the upcoming gcc-4.6 will warn that the variable
is set but otherwise unused.

Likely there are more places in the paraslash code which have the same
problem, so this patch introduce the do_nothing macro in para.h which,
creatively enough, does nothing. The new macro is employed like

	if (write(...))
		do_nothing;

This gets rid of the warning on Lucid and does not give new warning
on gcc-4.6.

diff --git a/para.h b/para.h
index 29c5c2b89c4ac3e0ca820c26c07cd8be4755f266..08eb0ee6c20ab1a7779cc3f10de2b5fca094f44b 100644 (file)
--- a/para.h
+++ b/para.h
@@ -221,6 +221,9 @@ _static_inline_ long int para_random(unsigned max)
 /** Used to avoid a shortcoming in vim's syntax highlighting. */
 #define EMBRACE(...) { __VA_ARGS__}
 
+/** A nice cup of STFU for Mr gcc. */
+#define do_nothing do {/* nothing */} while (0)
+
 /**
  * The sample formats supported by paraslash.
  *

diff --git a/udp_send.c b/udp_send.c
index 4fb10b444be321c51e7d33da2442fd6b8a469138..b4494eb7edb9e9fd26c1f4d20e9b81b06472c625 100644 (file)
--- a/udp_send.c
+++ b/udp_send.c
@@ -57,8 +57,13 @@ static void udp_close_target(struct sender_client *sc)
        const char *buf;
        size_t len = vss_get_fec_eof_packet(&buf);
 
-       /* ignore return value, closing the target anyway. */
-       (void)write(sc->fd, buf, len);
+       /*
+        * Ignore the return value of wirte() since we are closing the target
+        * anyway. The sole purpose of the "do_nothing" statement is to silence
+        * gcc.
+        */
+       if (write(sc->fd, buf, len))
+               do_nothing;
 }
 
 static void udp_delete_target(struct sender_client *sc, const char *msg)