diff -Naur a/build_filelist.c b/build_filelist.c
--- a/build_filelist.c	2017-01-12 13:29:09.000000000 -0700
+++ b/build_filelist.c	2017-03-30 13:46:33.773844000 -0600
@@ -58,7 +58,7 @@
             goto use_quote;
         s++;
     }
-    fprintf(f, str);
+    fprintf(f, "%s", str);
     return;
  use_quote:
     s = str;
diff -Naur a/riscvemu.c b/riscvemu.c
--- a/riscvemu.c	2017-01-12 13:29:09.000000000 -0700
+++ b/riscvemu.c	2017-03-30 13:46:13.287606000 -0600
@@ -2393,16 +2393,18 @@
                          uint64_t sector_num, uint8_t *buf, int n,
                          BlockDeviceCompletionFunc *cb, void *opaque)
 {
+	size_t xxx;
     BlockDeviceFile *bf = bs->opaque;
     //    printf("bf_read_async: sector_num=%" PRId64 " n=%d\n", sector_num, n);
     if (!bf->f)
         return -1;
+    xxx = 0;
     if (bf->mode == BF_MODE_SNAPSHOT) {
         int i;
         for(i = 0; i < n; i++) {
             if (!bf->sector_table[sector_num]) {
                 fseek(bf->f, sector_num * SECTOR_SIZE, SEEK_SET);
-                fread(buf, 1, SECTOR_SIZE, bf->f);
+                xxx = fread(buf, 1, SECTOR_SIZE, bf->f);
             } else {
                 memcpy(buf, bf->sector_table[sector_num], SECTOR_SIZE);
             }
@@ -2411,8 +2413,13 @@
         }
     } else {
         fseek(bf->f, sector_num * SECTOR_SIZE, SEEK_SET);
-        fread(buf, 1, n * SECTOR_SIZE, bf->f);
+        xxx = fread(buf, 1, n * SECTOR_SIZE, bf->f);
     }
+	if((ssize_t)xxx <= 0)
+	{
+		fprintf(stderr, "donb: xxx <= 0 (fread)\n");
+		return -1;
+	}
     /* synchronous read */
     return 0;
 }
@@ -2609,7 +2616,10 @@
                              const uint8_t *buf, int len)
 {
     int fd = (intptr_t)(bs->opaque);
-    write(fd, buf, len);
+    ssize_t x;
+    x = write(fd, buf, len);
+    if(x != len)
+	fprintf(stderr, "warning: donb: tun_write_packet failed");
 }
 
 /* configure with: