Re: [HACKERS] Re: Cancel key now ready

Here is a patch that will auto-seed any request for random from the
user. This will prevent users from seeing random values that use our
postmaster cancel seed.

---------------------------------------------------------------------------

Index: src/backend/utils/adt/misc.c
===================================================================
RCS file: /usr/local/cvsroot/pgsql/src/backend/utils/adt/misc.c,v
retrieving revision 1.12
diff -c -r1.12 misc.c
*** misc.c 1998/02/24 03:47:26 1.12
--- misc.c 1998/06/09 19:16:16
***************
*** 13,18 ****
--- 13,19 ----
*/
#include <sys/types.h>
#include <sys/file.h>
+ #include <time.h>
#include "postgres.h"
#include "utils/datum.h"
#include "catalog/pg_type.h"
***************
*** 60,65 ****
--- 61,69 ----
* will return about 1/10 of the tuples in TEMP
*
*/
+
+ static bool random_initialized = false;
+
bool
oidrand(Oid o, int32 X)
{
***************
*** 68,73 ****
--- 72,88 ----
if (X == 0)
return true;

+ /*
+ * We do this because the cancel key is actually a random, so we don't
+ * want them to be able to request random numbers using our postmaster
+ * seeded value.
+ */
+ if (!random_initialized)
+ {
+ srandom((unsigned int)time(NULL));
+ random_initialized = true;
+ }
+
result = (random() % X == 0);
return result;
}
***************
*** 81,86 ****
--- 96,102 ----
oidsrand(int32 X)
{
srand(X);
+ random_initialized = true;
return true;
}

--
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