[patch ada]: Fix MSG_WAITALL handling for windows native targets

[Kai Tietz]

2011/3/28 Arnaud Charlet <charlet@adacore.com>:
> Kai,
>
> Here are Thomas comments on your patch:
>
> --
>> Split submitted patch from thread "[patch ada]: Fix issues about
>> multilib build of native windows and handle MSG_WAITALL for windows
>> native targets"
>> into separate ones.
>>
>> ChangeLog gcc/ada (ada_wt.txt)
>>
>> 2011-03-28  Kai Tietz
>>
>>       * g-socthi-mingw.adb (C_Recvmsg): Handle MSG_WAITALL for
>>       windows native targets.
>>       * s-oscons-tmplt.c (MSG_WAITALL): Define it for native windows
>>       targets to flag value.
>
>>        Fill  : constant Boolean :=
>> -                (C.unsigned (Flags) and SOSC.MSG_WAITALL) /= 0;
>> +                SOSC.MSG_WAITALL /= -1
>> +                and then (C.unsigned (Flags) and SOSC.MSG_WAITALL) /= 0;
>>        --  Is the MSG_WAITALL flag set? If so we need to fully fill all vectors
>
> Not sure about this. The other change (to s-oscons-tmplt.c) causes
> SOSC.MSG_WAITALL to always be defined to 8 in the Windows case, so the
> new test against -1 (which would have been relevant without the other
> change) now becomes redundant.

Well, I can remove it from patch. But IMHO it would be good to fix
here logic, even if it has obviously no effect here anymore.  As often
such code simply gets copy & pasted and then a latent bug can be
copied.

>>  #ifndef MSG_WAITALL
>> +#ifdef __MINWGW32__
>> +/* We use it on windows native targets, so set to flag value.  */
>> +# define MSG_WAITALL (1 << 3)
>> +#else
>
> The comment is completely meaningless and should be rewritten. In
> particular a note should be added to explain why this will work even
> though MSG_WAITALL is not defined in the Winsock header files.

Yes, I wrote some more details about this definition.  It is related
to the use of winsock/winsock2. The define MSG_WAITALL is just defined
for wsock API 2. Nevertheless we link internally against wsock2-API
(ws2_32), and so it is available anyway.

Updated patch attached.

Regards,
Kai
-------------- next part --------------
Index: gcc/gcc/ada/g-socthi-mingw.adb
===================================================================
--- gcc.orig/gcc/ada/g-socthi-mingw.adb	2011-03-28 11:40:51.941851800 +0200
+++ gcc/gcc/ada/g-socthi-mingw.adb	2011-03-28 13:09:04.309293900 +0200
@@ -277,7 +277,8 @@ package body GNAT.Sockets.Thin is
       use type C.size_t;
 
       Fill  : constant Boolean :=
-                (C.unsigned (Flags) and SOSC.MSG_WAITALL) /= 0;
+                SOSC.MSG_WAITALL /= -1
+                and then (C.unsigned (Flags) and SOSC.MSG_WAITALL) /= 0;
       --  Is the MSG_WAITALL flag set? If so we need to fully fill all vectors
 
       Res   : C.int;
Index: gcc/gcc/ada/s-oscons-tmplt.c
===================================================================
--- gcc.orig/gcc/ada/s-oscons-tmplt.c	2011-03-28 11:40:51.949851800 +0200
+++ gcc/gcc/ada/s-oscons-tmplt.c	2011-03-28 13:13:51.479759900 +0200
@@ -1084,6 +1084,11 @@ CND(MSG_PEEK, "Peek at incoming data")
 CND(MSG_EOR, "Send end of record")
 
 #ifndef MSG_WAITALL
+#ifdef __MINWGW32__
+/* The value of MSG_WAITALL is 8.  Nevertheless winsock.h doesn't
+   define it, but it is still usable as we link to winsock2 API.  */
+# define MSG_WAITALL (1 << 3)
+#else
 # define MSG_WAITALL -1
 #endif
 CND(MSG_WAITALL, "Wait for full reception")