gawk 3.1.6: rand.awk test case alignment problem

[Duncan Moore]

Hi,

Compiling gawk 3.1.6 on an ARM 710 platform and running the random
number test case gawk-3.1.6/test/rand.awk:

BEGIN {
        srand(2)
        for (i = 0; i < 19; i++)
                printf "%3d ", (1 + int(100 * rand()))
        print ""
}

with 'gawk -f rand.awk', gives:

 30   5  39  81  93  31  71  45  82  43  99  97 100  52  86  91  68
65  60

As I understand it, this is wrong, and the output should be identical
on every platform, since the RNG is built in to gawk. This is what
should be output:

 62  67  88   6  35  77   3  68  30  96  90  26  35   8  88  93  49
53  37

The reason for the error, is that char array 'state' in builtin.c is
not word aligned, and it is cast to an int*. This causes problems on
architectures that require ints to be word aligned. There is a comment
in random.c that this causes bus errors on the Sparc platform, but the
code does not appear to have been fixed. Other platforms could be
affected too.

A fix for this is:

diff -u -p gawk-3.1.6/builtin.c gawk-3.1.6.ro2/builtin.c
--- gawk-3.1.6/builtin.c        2007-09-30 19:57:05 +0000
+++ gawk-3.1.6.ro2/builtin.c    2008-01-21 19:38:12 +0000
@@ -2027,14 +2027,16 @@ do_cos(NODE *tree)
 /* do_rand --- do the rand function */

 static int firstrand = TRUE;
-static char state[256];
+#define SIZEOF_STATE 256
+static uint32_t istate[SIZEOF_STATE/sizeof(uint32_t)];
+static char *const state = (char *const) istate;

 /* ARGSUSED */
 NODE *
 do_rand(NODE *tree ATTRIBUTE_UNUSED)
 {
        if (firstrand) {
-               (void) initstate((unsigned) 1, state, sizeof state);
+               (void) initstate((unsigned) 1, state, SIZEOF_STATE);
                /* don't need to srandom(1), initstate() does it for us. */
                firstrand = FALSE;
                setstate(state);
@@ -2057,7 +2059,7 @@ do_srand(NODE *tree)
        long ret = save_seed;   /* SVR4 awk srand returns previous seed */

        if (firstrand) {
-               (void) initstate((unsigned) 1, state, sizeof state);
+               (void) initstate((unsigned) 1, state, SIZEOF_STATE);
                /* don't need to srandom(1), we're changing the seed below */
                firstrand = FALSE;
                (void) setstate(state);

Regards

Duncan Moore