diff options
Diffstat (limited to 'util/libreboot-utils/lib')
| -rw-r--r-- | util/libreboot-utils/lib/rand.c | 48 |
1 files changed, 36 insertions, 12 deletions
diff --git a/util/libreboot-utils/lib/rand.c b/util/libreboot-utils/lib/rand.c index 63cb3fcd..c0dc8064 100644 --- a/util/libreboot-utils/lib/rand.c +++ b/util/libreboot-utils/lib/rand.c @@ -79,42 +79,66 @@ #endif int -win_lottery(char **buf) /* are u lucky? */ +win_lottery(void) /* are u lucky? */ { - size_t size = 0; - int rval; + size_t size = rsize(); + size_t size2 = rsize(); + int rval = 0; - char *s1 = rmalloc(&size); - char *s2 = rmalloc(&size); + char *s1 = NULL; + char *s2 = NULL; - if (scmp(s1, s2, BUFSIZ + 1, &rval) >= 0 && - rval == 0) + if (size != size2) + goto out; + + s1 = mkrbuf(size); + s2 = mkrbuf(size); + + if (!memcmp(s1, s2, size)) rval = 1; /* winner! */ else rval = 0; - (void) scat(s1, s2, BUFSIZ << 1, buf); - +out: free_if_null(&s1); free_if_null(&s2); return rval; } +size_t +rsize(void) +{ + size_t rval = 0; + size_t size = 67108864; + + /* clamp rand to prevent modulo bias */ + size_t limit = SIZE_MAX - (SIZE_MAX % size); + + do { + rset(&rval, sizeof(rval)); + } while (rval >= limit); + + return rval % size; +} + + void * rmalloc(size_t *rval) { + size_t size = 16777216; + /* clamp rand to prevent modulo bias */ - size_t limit = SIZE_MAX - (SIZE_MAX % BUFSIZ); + size_t limit = SIZE_MAX - (SIZE_MAX % size); if (if_err(rval == NULL, EFAULT)) return NULL; do { rset(rval, sizeof(*rval)); - } while (*rval >= limit); + } while (*rval >= limit || *rval == 0); - return mkrstr(*rval %= BUFSIZ); + return mkrstr(*rval %= size); } char * |
