1 files changed, 19 insertions, 41 deletions

diff --git a/util/nvmutil/nvmutil.c b/util/nvmutil/nvmutil.c
index b718ac6e..df6167be 100644
--- a/util/nvmutil/nvmutil.c
+++ b/util/nvmutil/nvmutil.c
@@ -1133,16 +1133,8 @@ rhex(void)
 	static size_t n = 0;
 	static uint8_t rnum[12];
 
-	if (use_prng) {
-		/*
-		 * On very old Unix systems that
-		 * lack /dev/random and /dev/urandom
-		 */
+	if (use_prng)
 		return fallback_rand();
-	}
-
-	if (urandom_fd < 0)
-		err(ECANCELED, "Your operating system has no /dev/[u]random");
 
 	if (!n) {
 		n = sizeof(rnum);
@@ -1585,6 +1577,10 @@ rw_file_exact(int fd, uint8_t *mem, size_t len,
 	return rc;
 }
 
+/*
+ * May not return all requested bytes (len).
+ * Use rw_file_exact for guaranteed length.
+ */
 static ssize_t
 rw_file_once(int fd, uint8_t *mem, size_t len,
     off_t off, int rw_type, size_t rc)
@@ -1596,43 +1592,25 @@ rw_file_once(int fd, uint8_t *mem, size_t len,
 read_again:
 	rv = do_rw(fd, mem + rc, len - rc, off + rc, rw_type);
 
-	if (rv < 0 && errno == EINTR) {
+	if (rv < 0 && errno == EINTR)
 		goto read_again;
-	} else if (rv < 0) {
-		errno = EIO;
-		return -1;
-	}
 
-	/*
-	 * Theoretical bug: if a buggy libc returned
-	 * a size larger than SSIZE_MAX, the cast may
-	 * cause an overflow. Specifications guarantee
-	 * this won't happen, but spec != implementation
-	 */
-	if ((size_t)rv > SSIZE_MAX) {
-		errno = EIO;
+	if (rv < 0)
 		return -1;
-		/* we will not tolerate your buggy libc */
-	}
 
-	if ((size_t)rv > (len - rc) /* Prevent overflow */
-	    || rv == 0) { /* Prevent infinite 0-byte loop */
-		if (rv == 0) {
-			/*
-			 * Fault tolerance against infinite
-			 * zero-byte loop: re-try a finite
-			 * number of times. This mitigates
-			 * otherwise OK but slow filesystems
-			 * e.g. NFS or slow media.
-			 */
-			if (retries_on_zero++ < max_retries)
-				goto read_again;
-		}
-		errno = EIO;
-		return -1;
-	}
+	if ((size_t)rv > SSIZE_MAX /* theoretical buggy libc */
+	    || (size_t)rv > (len - rc))/* don't overflow */
+		goto err_rw_file_once;
+
+	if (rv != 0)
+		return rv;
 
-	return rv;
+	if (retries_on_zero++ < max_retries)
+		goto read_again;
+
+err_rw_file_once:
+	errno = EIO;
+	return -1;
 }
 
 static ssize_t