seedrng: prepare read_new_seed() to not need a "success" retval

We do not expect /dev/[u]random to be not openable/readable.
If they are, just bail out (something is obviously very wrong).

function                                             old     new   delta
seedrng_main                                        1077    1076      -1
.rodata                                           104939  104929     -10

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 12 insertions, 10 deletions

diff --git a/util-linux/seedrng.c b/util-linux/seedrng.c
index 82c69b72b..3f4c5c0c8 100644
--- a/util-linux/seedrng.c
+++ b/util-linux/seedrng.c
@@ -79,25 +79,27 @@ static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable)
 {
         ssize_t ret;
 
-        *is_creditable = false;
         ret = getrandom(seed, len, GRND_NONBLOCK);
         if (ret == (ssize_t)len) {
                 *is_creditable = true;
                 return 0;
-        } else if (ret < 0 && errno == ENOSYS) {
+        }
+        if (ret < 0 && errno == ENOSYS) {
                 struct pollfd random_fd = {
-                        .fd = open("/dev/random", O_RDONLY),
+                        .fd = xopen("/dev/random", O_RDONLY),
                         .events = POLLIN
                 };
-                if (random_fd.fd < 0)
-                        return -1;
                 *is_creditable = poll(&random_fd, 1, 0) == 1;
                 close(random_fd.fd);
-        } else if (getrandom(seed, len, GRND_INSECURE) == (ssize_t)len)
-                return 0;
-        if (open_read_close("/dev/urandom", seed, len) == (ssize_t)len)
-                return 0;
-        return -1;
+        } else {
+                *is_creditable = false;
+                if (getrandom(seed, len, GRND_INSECURE) == (ssize_t)len)
+                        return 0;
+        }
+        errno = 0;
+        if (open_read_close("/dev/urandom", seed, len) != (ssize_t)len)
+                bb_perror_msg_and_die("can't read '%s'", "/dev/urandom");
+        return 0;
 }
 
 static void seed_rng(uint8_t *seed, size_t len, bool credit)