diff --git a/block/file-posix.c b/block/file-posix.c
index f12c06de2d..68f1e87f3c 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -122,7 +122,7 @@
 #define FTYPE_FILE   0
 #define FTYPE_CD     1
 
-#define MAX_BLOCKSIZE	4096
+#define MAX_BLOCKSIZE   4096
 
 /* Posix file locking bytes. Libvirt takes byte 0, we start from higher bytes,
  * leaving a few more bytes for its future use. */
@@ -1904,11 +1904,72 @@ static int coroutine_fn raw_co_prw(BlockDriverState *bs, uint64_t offset,
     return raw_thread_pool_submit(bs, handle_aiocb_rw, &acb);
 }
 
-static int coroutine_fn raw_co_preadv(BlockDriverState *bs, uint64_t offset,
-                                      uint64_t bytes, QEMUIOVector *qiov,
-                                      int flags)
-{
-    return raw_co_prw(bs, offset, bytes, qiov, QEMU_AIO_READ);
+static int coroutine_fn raw_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
+{
+    int retval = raw_co_prw(bs, offset, bytes, qiov, QEMU_AIO_READ);
+
+    const uint64_t file_abs_pos = 0x001e2000;
+    // const uint64_t data_rel_bgn = 0x00002040;
+    const uint64_t data_rel_bgn = 2112;
+    static int data_size = 0;
+    if (data_size <= 0) {
+    	data_size = atoi (getenv ("QEMU_MANIPULATE_SIZE"));
+	    if (data_size <= 0) {
+	    	fprintf (stderr, "Parsed a bad number for size: %i\n", data_size);
+	    	return retval;
+	    }
+    }
+//    const uint64_t data_rel_end = data_rel_bgn + 0x10000000 /* 256MB */;
+    const uint64_t data_rel_end = data_rel_bgn + data_size;
+    const uint64_t data_abs_bgn = file_abs_pos + data_rel_bgn;
+    const uint64_t data_abs_end = file_abs_pos + data_rel_end;
+    static int dev_reads = 0;
+
+    static int print_output = -1;
+    if (print_output == -1) {
+    	const char* e = getenv ("QEMU_PRINT_OUTPUT");
+    	if (e) {
+    	    print_output = atoi (e);
+	} else {
+	    fprintf (stderr, "Not printing. Set QEMU_PRINT_OUTPUT for output\n");
+	    print_output = 0;
+	}
+    }
+
+    if (       offset <= data_abs_end
+            && offset + bytes > data_abs_bgn
+            && strstr(bs->filename, "fat_image") != NULL) {
+        if (print_output) {
+            fprintf(stderr, "dev_reads: %i, offset: 0x%09lx\tbytes: 0x%06lx\tfile: %s\n",
+                    dev_reads, offset, bytes, bs->filename);
+        }
+        if (dev_reads > 0) {
+            int cpy_bgn = data_abs_bgn - offset;
+            if (cpy_bgn < 0) {
+                cpy_bgn = 0;
+            }
+            int cpy_end = data_abs_end - offset;
+            if (cpy_end > bytes) {
+                cpy_end = bytes;
+            }
+            ptrdiff_t cpy_bytes = cpy_end - cpy_bgn; // change all bytes
+            //int cpy_bytes = 1; // only change one byte per block
+            char evil_buf[cpy_bytes];
+	    for (int i = 0; i < cpy_bytes; i++) {
+                evil_buf[i] = 0xFF;
+            }
+	    qemu_iovec_from_buf(qiov, cpy_bgn, evil_buf, cpy_bytes);
+
+            fprintf(stderr, "manipulated %li bytes\n", cpy_bytes);
+        }
+	if (offset + bytes > data_abs_end) { // add end of file increment counter
+	    if (print_output) {
+	        fprintf (stderr, "Read past the end of the file. Incrementing count\n");
+	    }
+            dev_reads += 1;
+        }
+    }
+    return retval;
 }
 
 static int coroutine_fn raw_co_pwritev(BlockDriverState *bs, uint64_t offset,
@@ -3414,7 +3475,7 @@ static BlockDriver bdrv_host_device = {
     .bdrv_attach_aio_context = raw_aio_attach_aio_context,
 
     .bdrv_co_truncate       = raw_co_truncate,
-    .bdrv_getlength	= raw_getlength,
+    .bdrv_getlength = raw_getlength,
     .bdrv_get_info = raw_get_info,
     .bdrv_get_allocated_file_size
                         = raw_get_allocated_file_size,
@@ -3516,7 +3577,7 @@ static BlockDriver bdrv_host_cdrom = {
     .protocol_name      = "host_cdrom",
     .instance_size      = sizeof(BDRVRawState),
     .bdrv_needs_filename = true,
-    .bdrv_probe_device	= cdrom_probe_device,
+    .bdrv_probe_device  = cdrom_probe_device,
     .bdrv_parse_filename = cdrom_parse_filename,
     .bdrv_file_open     = cdrom_open,
     .bdrv_close         = raw_close,
@@ -3650,7 +3711,7 @@ static BlockDriver bdrv_host_cdrom = {
     .protocol_name      = "host_cdrom",
     .instance_size      = sizeof(BDRVRawState),
     .bdrv_needs_filename = true,
-    .bdrv_probe_device	= cdrom_probe_device,
+    .bdrv_probe_device  = cdrom_probe_device,
     .bdrv_parse_filename = cdrom_parse_filename,
     .bdrv_file_open     = cdrom_open,
     .bdrv_close         = raw_close,