Fix typo in pg_srand48 (srand48 in older branches).

tglsfdc · tglsfdc · commit f655a9fd2677 · 2011-09-03T16:18:01.000-04:00
"&gt;" should be "&gt;&gt;".  This typo results in failure to use all of the bits
of the provided seed.

This might rise to the level of a security bug if we were relying on
srand48 for any security-critical purposes, but we are not --- in fact,
it's not used at all unless the platform lacks srandom(), which is
improbable.  Even on such a platform the exposure seems minimal.

Reported privately by Andres Freund.
diff --git a/src/port/rand.c b/src/port/rand.c
@@ -71,7 +71,7 @@ srand48(long seed)
 {
 	_rand48_seed[0] = RAND48_SEED_0;
 	_rand48_seed[1] = (unsigned short) seed;
-	_rand48_seed[2] = (unsigned short) (seed > 16);
+	_rand48_seed[2] = (unsigned short) (seed >> 16);
 	_rand48_mult[0] = RAND48_MULT_0;
 	_rand48_mult[1] = RAND48_MULT_1;
 	_rand48_mult[2] = RAND48_MULT_2;

Original file line number	Diff line number	Diff line change
`@@ -71,7 +71,7 @@ srand48(long seed)`
`71`	`71`	`{`
`72`	`72`	`_rand48_seed[0] = RAND48_SEED_0;`
`73`	`73`	`_rand48_seed[1] = (unsigned short) seed;`
`74`		`- _rand48_seed[2] = (unsigned short) (seed > 16);`
	`74`	`+ _rand48_seed[2] = (unsigned short) (seed >> 16);`
`75`	`75`	`_rand48_mult[0] = RAND48_MULT_0;`
`76`	`76`	`_rand48_mult[1] = RAND48_MULT_1;`
`77`	`77`	`_rand48_mult[2] = RAND48_MULT_2;`