3 files changed, 20 insertions, 49 deletions

diff --git a/util/libreboot-utils/include/common.h b/util/libreboot-utils/include/common.h
index 71f28fad..be76fd0a 100644
--- a/util/libreboot-utils/include/common.h
+++ b/util/libreboot-utils/include/common.h
@@ -391,8 +391,8 @@ void *rmalloc(size_t *size); /* don't ever use this */
 void rset(void *buf, size_t n);
 void *mkrbuf(size_t n);
 char *mkrstr(size_t n);
-int win_lottery(void);
-size_t rsize(void);
+int win_lottery(char **s);
+size_t rsize(size_t n);
 
 /* Helper functions for command: dump
  */
diff --git a/util/libreboot-utils/lib/rand.c b/util/libreboot-utils/lib/rand.c
index 58cb211e..6b02525c 100644
--- a/util/libreboot-utils/lib/rand.c
+++ b/util/libreboot-utils/lib/rand.c
@@ -72,62 +72,31 @@
  * or your program dies.
  */
 
-#define MAX_ALLOC (2 << 16)
+#define MAX_ALLOC (1 << 17)
 
 int
-win_lottery(void) /* are u lucky? */
+win_lottery(char **s) /* are u lucky? */
 {
-	size_t size = rsize();
-	size_t size2 = rsize();
-	char *s = NULL; 
-
-	if (size &&
-	    size == size2 &&
-	    size <= MAX_ALLOC << 1) {
-
-		if (!memcmp(s = mkrbuf(size << 1),
-		    s + size, size))
-			size2 = 1; /* winner! */
-		else
-			size2 = 0;
-	} else {
-		return 0;
-	}
-
-	free_if_null(&s);
-	return (int)size2;
-}
-
-size_t
-rsize(void)
-{
-	size_t rval = 0;
-
-	/* clamp rand to prevent modulo bias */
-	size_t limit = SIZE_MAX - (SIZE_MAX % MAX_ALLOC);
-
-	do {
-		rset(&rval, sizeof(rval));
-	} while (rval >= limit);
-
-	return rval % MAX_ALLOC;
+	size_t size[2] = { rsize(MAX_ALLOC), rsize(MAX_ALLOC) };
+	return (size[0] && size[0] == size[1] && size[0] <= MAX_ALLOC << 1 &&
+	    s != NULL) && (memcmp(*s = mkrbuf(size[0] << 1), *s + size[0],
+	    size[0]) ? 0 : 1);
 }
 
-
 void *
 rmalloc(size_t *rval)
 {
-	/* clamp rand to prevent modulo bias */
-	size_t limit = SIZE_MAX - (SIZE_MAX % MAX_ALLOC);
-
-	if (if_err(rval == NULL, EFAULT))
-		return NULL;
+	return if_err(rval == NULL, EFAULT) ?
+	    NULL : mkrstr(*rval = rsize(MAX_ALLOC));
+}
 
-	do {
-		rset(rval, sizeof(*rval));
-	} while (*rval >= limit || *rval == 0);
+size_t
+rsize(size_t n)
+{
+	size_t rval = SIZE_MAX;
+	for (; rval >= SIZE_MAX - (SIZE_MAX % n); rset(&rval, sizeof(rval)));
 
-	return mkrstr(*rval %= MAX_ALLOC);
+	return rval % n;
 }
 
 char *
diff --git a/util/libreboot-utils/lottery.c b/util/libreboot-utils/lottery.c
index 4c3b0f70..2214ce5a 100644
--- a/util/libreboot-utils/lottery.c
+++ b/util/libreboot-utils/lottery.c
@@ -12,7 +12,9 @@
 int
 main(int argc, char *argv[])
 {
+	char *s;
 	int lucky;
+
 #if defined(__OpenBSD__) && defined(OpenBSD)
 #if (OpenBSD) >= 509
 	if (pledge("stdio", NULL) == -1)
@@ -21,7 +23,7 @@ main(int argc, char *argv[])
 #endif
 	setvbuf(stdout, NULL, _IONBF, 0);
 
-	lucky = win_lottery();
+	lucky = win_lottery(&s);
 
 	printf("%s\n", lucky ? "You won!" : "You lose! Sorry!");
 	return lucky ? EXIT_SUCCESS : EXIT_FAILURE;