libreboot-utils: tidy up the rand code

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

1 files changed, 12 insertions, 41 deletions

diff --git a/util/libreboot-utils/lib/mkhtemp.c b/util/libreboot-utils/lib/mkhtemp.c
index 2fb2f01a..191d657c 100644
--- a/util/libreboot-utils/lib/mkhtemp.c
+++ b/util/libreboot-utils/lib/mkhtemp.c
@@ -886,53 +886,30 @@ err:
 int
 mkhtemp_fill_random(char *p, size_t xc)
 {
-	size_t chx = 0;
-	int rand_failures = 0;
-
-	size_t r;
-
-	int saved_rand_error = 0;
 	static char ch[] =
 	    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 
+	size_t chx = 0;
+	size_t r;
+
 	/* clamp rand to prevent modulo bias
-	 * (reduced risk of entropy leak)
 	 */
 	size_t limit = ((size_t)-1) - (((size_t)-1) % (sizeof(ch) - 1));
-
 	int saved_errno = errno;
 
-	if (p == NULL) {
-		errno = EFAULT;
-		goto err_mkhtemp_fill_random;
-	}
+	if (if_err(p == NULL, EFAULT))
+		return -1;
 
 	for (chx = 0; chx < xc; chx++) {
 
-		do {
-			saved_rand_error = errno;
-			rand_failures = 0;
 retry_rand:
-			errno = 0;
-
-			/* on bsd: uses arc4random
-			   on linux: uses getrandom
-			   on OLD linux: /dev/urandom
-			   on old/other unix: /dev/urandom
-			 */
-			r = rlong();
-
-			if (errno > 0) {
-				if (++rand_failures <= 8)
-					goto retry_rand;
-
-				goto err_mkhtemp_fill_random;
-			}
-
-			rand_failures = 0;
-			errno = saved_rand_error;
-
-		} while (r >= limit);
+		/* on bsd: uses arc4random
+		   on linux: uses getrandom
+		   *never returns error*
+		 */
+		r = rlong(); /* always returns successful */
+		if (r >= limit)
+			goto retry_rand;
 
 		p[chx] = ch[r % (sizeof(ch) - 1)];
 	}
@@ -940,12 +917,6 @@ retry_rand:
 	errno = saved_errno;
 	return 0;
 
-err_mkhtemp_fill_random:
-
-	if (errno == saved_errno)
-		errno = ECANCELED;
-
-	return -1;
 }
 
 /* WARNING: **ONCE** per file.