libreboot-utils: tidy up the rand code

Signed-off-by: Leah Rowe <leah@libreboot.org>

1 files changed, 14 insertions, 19 deletions

diff --git a/util/libreboot-utils/lib/rand.c b/util/libreboot-utils/lib/rand.c
index 2f88b420..0b156e51 100644
--- a/util/libreboot-utils/lib/rand.c
+++ b/util/libreboot-utils/lib/rand.c
@@ -59,6 +59,7 @@ rlong(void)
 {
 	size_t rval;
 	int saved_errno = errno;
+	errno = 0;
 
 #if (defined(__OpenBSD__) && (OpenBSD) >= 201) || \
     defined(__FreeBSD__) || \
@@ -71,30 +72,23 @@ rlong(void)
 
 	size_t off = 0;
 	size_t len = sizeof(rval);
-
 	ssize_t rc;
 
-	if (!len)
-		goto err;
-
-	while (off < len) {
-
-		rc = (ssize_t)syscall(SYS_getrandom,
-		    (char *)&rval + off, len - off, 0);
-
-		if (rc < 0) {
-			if (errno == EINTR || errno == EAGAIN)
-				continue;
+retry_rand:
+	rc = (ssize_t)syscall(SYS_getrandom,
+	    (char *)&rval + off, len - off, 0);
 
-			goto err; /* possibly unsupported by kernel */
-		}
+	if (rc < 0) {
+		if (errno == EINTR || errno == EAGAIN)
+			goto retry_rand;
 
-		off += (size_t)rc;
+		goto err; /* possibly unsupported by kernel */
 	}
 
-	goto out;
+	if ((off += (size_t)rc) < len)
+		goto retry_rand;
 
-	return rval;
+	goto out;
 err:
 	/*
 	 * getrandom can return with error, butt arc4random
@@ -103,8 +97,9 @@ err:
 	 * BSD. So a rand failure is to be interpreted as
 	 * a major systems failure, and we act accordingly.
 	 */
-	err_no_cleanup(1, ECANCELED, "Randomisation failure");
-	exit(1);
+	err_no_cleanup(1, ECANCELED,
+	    "Randomisation failure, possibly unsupported in your kernel.");
+	exit(EXIT_FAILURE);
 
 #else
 #error Unsupported operating system (possibly unsecure randomisation)