From 3034e3d3649c71770a11de94d38412d4abd4ef98 Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Thu, 2 Apr 2009 14:05:21 +0000
Subject: [PATCH] Change the way that the random() SQL function prevents the
 maximum negative integer so that it is testable. (CVS 6436)

FossilOrigin-Name: 995f2b9b1031fadc85e179701536b9dd4153654b
---
 manifest      | 12 ++++++------
 manifest.uuid |  2 +-
 src/func.c    | 15 ++++++++++++---
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/manifest b/manifest
index 3c52616f89..59561aa6d1 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Use\sALWAYS\sand\sNEVER\smacros\son\sunchangeable\sconditions\swithin\sfunc.c.\s(CVS\s6435)
-D 2009-04-02T13:36:37
+C Change\sthe\sway\sthat\sthe\srandom()\sSQL\sfunction\sprevents\sthe\smaximum\nnegative\sinteger\sso\sthat\sit\sis\stestable.\s(CVS\s6436)
+D 2009-04-02T14:05:22
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 583e87706abc3026960ed759aff6371faf84c211
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -113,7 +113,7 @@ F src/date.c e6263ed8950642f593cb1a2cc8a73dd726cc7888
 F src/delete.c eb1066b2f35489fee46ad765d2b66386fc7d8adf
 F src/expr.c 14853cd56107292de6af664a24c6255111a4257d
 F src/fault.c dc88c821842157460750d2d61a8a8b4197d047ff
-F src/func.c 25edae19b56f7355ce7f25490ce61877b499633f
+F src/func.c 99ae90d46154952e08282fcdfe72d08e9601e174
 F src/global.c 448419c44ce0701104c2121b0e06919b44514c0c
 F src/hash.c 5824e6ff7ba78cd34c8d6cd724367713583e5b55
 F src/hash.h 28f38ebb1006a5beedcb013bcdfe31befe7437ae
@@ -714,7 +714,7 @@ F tool/speedtest16.c c8a9c793df96db7e4933f0852abb7a03d48f2e81
 F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
-P 868a487f5fd7c795e04a08de36a85ba1e06bc8c6
-R 80e3c0460455c327fb300729860153c0
+P eb65e64e7ed5edbe506365971d4d81ea037098d3
+R 8df4d225606e2ef05ef65f87475b71e8
 U drh
-Z 3dc25af9134f67a49baddf7ad8bedd6e
+Z 5cdbeb238444c4b2ca5bad90a2a75082
diff --git a/manifest.uuid b/manifest.uuid
index 88ef3ec342..8035b62021 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-eb65e64e7ed5edbe506365971d4d81ea037098d3
\ No newline at end of file
+995f2b9b1031fadc85e179701536b9dd4153654b
\ No newline at end of file
diff --git a/src/func.c b/src/func.c
index 537d35be18..6cb8d5aa9f 100644
--- a/src/func.c
+++ b/src/func.c
@@ -16,7 +16,7 @@
 ** sqliteRegisterBuildinFunctions() found at the bottom of the file.
 ** All other code has file scope.
 **
-** $Id: func.c,v 1.229 2009/04/02 13:36:37 drh Exp $
+** $Id: func.c,v 1.230 2009/04/02 14:05:22 drh Exp $
 */
 #include "sqliteInt.h"
 #include <stdlib.h>
@@ -362,8 +362,17 @@ static void randomFunc(
   sqlite_int64 r;
   UNUSED_PARAMETER2(NotUsed, NotUsed2);
   sqlite3_randomness(sizeof(r), &r);
-  if( (r<<1)==0 ) r = 0;  /* Prevent 0x8000.... as the result so that we */
-                          /* can always do abs() of the result */
+  if( r<0 ){
+    /* We need to prevent a random number of 0x8000000000000000 
+    ** (or -9223372036854775808) since when you do abs() of that
+    ** number of you get the same value back again.  To do this
+    ** in a way that is testable, mask the sign bit off of negative
+    ** values, resulting in a positive value.  Then take the 
+    ** 2s complement of that positive value.  The end result can
+    ** therefore be no less than -9223372036854775807.
+    */
+    r = -(r ^ (((sqlite3_int64)1)<<63));
+  }
   sqlite3_result_int64(context, r);
 }
 
-- 
2.47.2