x>>32 warning in io.c

[jw schultz]

On Thu, Mar 20, 2003 at 09:37:23PM -0800, Steve Mor Moritsugu wrote:
> I download rsync.2.5.6, configure, make clean, but make gives this warning:
> 
> "io.c", line 653: warning: shift count negative or too big: >> 32
> "io.c", line 653: warning: shift count negative or too big: >> 32
> "io.c", line 653: warning: shift count negative or too big: >> 32
> "io.c", line 653: warning: shift count negative or too big: >> 32
> 
> Another 32 bit shift (<<32) at line 385 does not cause a warning because 
> of this test at line 379:
> #ifdef NO_INT64
> I verified that NO_INT64 is defined on my system in rsync.h
> 
> However there is no #ifdef NO_INT64 test protecting line 653.
> Here are lines 652,653, and 654 from io.c in subr write_longint:
> 
>                               SIVAL(b,0,(x&0xFFFFFFFF));
>                               SIVAL(b,4,((x>>32)&0xFFFFFFFF));
>                               writefd(f,b,8);
> 
> On my system, x>>32 evaluates to the value x, not 0 (since the
> shift count is invalid). This will cause the upper 4 bytes of b to be
> the same as the lower 4 bytes of b, even if x is a small value.
> I am considering using this hack for line 653 to prevent possible problems:
> 
>                                SIVAL(b,4,((0)&0xFFFFFFFF));
> 
> I really don't do much C programming so I am fumbling in the dark
> here. Maybe my hack would make things worse. I have not seen any 
> problems yet (rsync can copy test files that cmp verifies later). make 
> only shows one other warning or error:
> "popt/popt.c", line 910: warning: macro redefined: _ABS

Nice catch.  What platform doesn't support 64bit ints?

I've attached a patch.  I can't really test it but give it a
try and let us know.

-- 
________________________________________________________________
	J.W. Schultz            Pegasystems Technologies
	email address:		jw at pegasys.ws

		Remember Cernan and Schmitt
-------------- next part --------------
Index: io.c
===================================================================
RCS file: /data/cvs/rsync/io.c,v
retrieving revision 1.105
diff -u -b -r1.105 io.c
--- io.c	11 Apr 2002 02:11:50 -0000	1.105
+++ io.c	21 Mar 2003 07:00:54 -0000
@@ -648,11 +648,16 @@
 		return;
 	}
 
+#ifdef NO_INT64
+	rprintf(FERROR,"Integer overflow - attempted 64 bit offset\n");
+	exit_cleanup(RERR_UNSUPPORTED);
+#else
 	write_int(f, (int32)0xFFFFFFFF);
 	SIVAL(b,0,(x&0xFFFFFFFF));
 	SIVAL(b,4,((x>>32)&0xFFFFFFFF));
 
 	writefd(f,b,8);
+#endif
 }
 
 void write_buf(int f,char *buf,size_t len)