[PATCH] If EAGAIN == EWOULDBLOCK, only need to check errno for one of them

[Alan Coopersmith]

Solaris <sys/errno.h> has:
 #define EWOULDBLOCK       EAGAIN
so checking (errno == EAGAIN || errno == EWOULDBLOCK) is overkill.

This leads cppcheck 1.62 to complain:
[xserver/os/io.c:365] -> [xserver/os/io.c:365]: (style) Same expression on both sides of '||'.
[xserver/os/io.c:941] -> [xserver/os/io.c:941]: (style) Same expression on both sides of '||'.

This quiets it, and reduces the number of calls Solaris Studio cc
generates to the __errno() function to get the thread-specific errno value.

Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
---
 os/io.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/os/io.c b/os/io.c
index 922a8eb..3e56fc2 100644
--- a/os/io.c
+++ b/os/io.c
@@ -102,12 +102,17 @@ typedef struct _connectionOutput {
 static ConnectionInputPtr AllocateInputBuffer(void);
 static ConnectionOutputPtr AllocateOutputBuffer(void);
 
-/* check for both EAGAIN and EWOULDBLOCK, because some supposedly POSIX
+/* If EAGAIN and EWOULDBLOCK are distinct errno values, then we check errno
+ * for both EAGAIN and EWOULDBLOCK, because some supposedly POSIX
  * systems are broken and return EWOULDBLOCK when they should return EAGAIN
  */
 #ifndef WIN32
-#define ETEST(err) (err == EAGAIN || err == EWOULDBLOCK)
-#else                           /* WIN32 The socket errorcodes differ from the normal errors */
+# if (EAGAIN != EWOULDBLOCK)
+#  define ETEST(err) (err == EAGAIN || err == EWOULDBLOCK)
+# else
+#  define ETEST(err) (err == EAGAIN)
+# endif
+#else   /* WIN32 The socket errorcodes differ from the normal errors */
 #define ETEST(err) (err == EAGAIN || err == WSAEWOULDBLOCK)
 #endif
 
-- 
1.7.9.2