Better error messages, allow larger-than-needed input when reading.

src/platform/vboot_reference/vkernel/kernel_image.c

 /* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  * Functions for generating and manipulating a verified boot kernel image.
  * (Userland portion)
  */
 #include "kernel_image.h"
 
 #include <fcntl.h>
@@ skipping 158 matching lines @@
     if (st.remaining_len < on_disk_padding)
       st.overrun = -1;
     st.remaining_buf += on_disk_padding;
     st.remaining_len -= on_disk_padding;
   }
 
   /* Read kernel image data. */
   image->kernel_data = (uint8_t*) Malloc(image->kernel_len);
   StatefulMemcpy(&st, image->kernel_data, image->kernel_len);
 
-  if(st.overrun || st.remaining_len != 0) {  /* Overrun or underrun. */
+  if(st.overrun) {

[gauravsh, 2010/05/28 07:22:43]

add a comment here that underruns are ok here?

     Free(kernel_buf);
     return NULL;
   }
   Free(kernel_buf);
   return image;
 }
 
 int GetKernelHeaderLen(const KernelImage* image) {
   return (FIELD_LEN(header_version) + FIELD_LEN(header_len) +
           FIELD_LEN(firmware_sign_algorithm) +
@@ skipping 561 matching lines @@
   // Clean up and return the blob.
 done3:
   Free(bootloader_buf);
 done2:
   Free(config_buf);
 done1:
   Free(kernel_buf);
 done0:
   return blob;
 }