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Re: New command to check NT's hibernation state

From: Vladimir 'φ-coder/phcoder' Serbinenko
Subject: Re: New command to check NT's hibernation state
Date: Sat, 03 Dec 2011 11:41:58 +0100
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20111114 Icedove/3.1.16

On 03.12.2011 05:57, Peter Lustig wrote:
/* nthibr.c - tests whether an MS Windows system partition is hibernated */
  *  GRUB  --  GRand Unified Bootloader
  *  Copyright (C) 2007,2008,2009,2011  Free Software Foundation, Inc.
  *  GRUB is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation, either version 3 of the License, or
  *  (at your option) any later version.
  *  GRUB is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  GNU General Public License for more details.
  *  You should have received a copy of the GNU General Public License
  *  along with GRUB.  If not, see<>.



/* Define this 'empty' array to let the '-h' and '-u' switches be processed */
static const struct grub_arg_option options[] = {
   {0, 0, 0, 0, 0, 0}

No need for empty array. passing 0 instead of this array works.
static grub_err_t
grub_cmd_nthibr (grub_extcmd_context_t ctxt __attribute__ ((unused)),
                  int argc, char **args)
   grub_err_t status = GRUB_ERR_NONE;
   char *partition_name, *hibr_file_path = 0, hibr_file_magic[5];
   grub_size_t name_length;
   grub_ssize_t magic_size;
   grub_disk_t partition;
   grub_file_t hibr_file = 0;

   /* Check argument count */
   if (!argc)
       status = grub_error (GRUB_ERR_BAD_ARGUMENT,
                            N_("too few arguments specified"));
       goto exit;
   else if (argc>  1)
       status = grub_error (GRUB_ERR_BAD_ARGUMENT,
                            N_("too many arguments specified"));
       goto exit;

   partition_name = args[0];
   name_length = grub_strlen (partition_name);

   /* Check if partition specifier 'looks right' */
   if (partition_name[0] != '(' || partition_name[name_length - 1] != ')')
       status = grub_error (GRUB_ERR_BAD_FILENAME,
                            N_("invalid partition specifier"));
       goto exit;

I would recommend adding '(' and ')' if none found rather than giving error.
   /* Check if partition actually exists */
   partition_name[name_length - 1] = '\0';
   partition = grub_disk_open (partition_name + 1);
   if (!partition)
       status = grub_error (GRUB_ERR_UNKNOWN_DEVICE,
                            N_("partition not found"));
No need to run grub_error here. grub_disk_open already sets grub_errno and grub_errmsg. Just status = grub_errno is enough.
       goto exit;
       grub_disk_close (partition);
       partition_name[name_length - 1] = ')';

No need for 'else' clause (goto already takes care of it)
   /* Build path to 'hiberfil.sys' */
   hibr_file_path = grub_malloc (grub_strlen (partition_name)
                                 + grub_strlen ("/hiberfil.sys") + 1);
   if (!hibr_file_path)
       status = grub_error (GRUB_ERR_OUT_OF_MEMORY,
                            N_("out of memory"));
       goto exit;
       grub_strcpy (hibr_file_path, partition_name);
       grub_strcat (hibr_file_path, "/hiberfil.sys");

Same here (no need for grub_error and else)
   /* Try to open 'hiberfil.sys' */
   hibr_file = grub_file_open (hibr_file_path);
   if (!hibr_file)
       status = grub_error (GRUB_ERR_FILE_NOT_FOUND,
                            N_("'hiberfil.sys' not found"));
       goto exit;

   /* Try to read magic number of 'hiberfil.sys' */
   magic_size = sizeof (hibr_file_magic) - 1;
   grub_memset (hibr_file_magic, 0, sizeof (hibr_file_magic));
   if (grub_file_read (hibr_file, hibr_file_magic, magic_size)<  magic_size)
       status = grub_error (GRUB_ERR_BAD_FILE_TYPE,
                            N_("'hiberfil.sys' too small"));
you need to conditionalize call to grub_error. if (!grub_errno) ... since incomplete read may indicate an FS problem in which case you want the original error message to remain.
       goto exit;

   /* Return SUCCESS if magic indicates file is active; else return FAILURE */
   if (!grub_strncasecmp ("hibr", hibr_file_magic, magic_size))
     grub_puts (N_("The system is hibernated."));
       grub_puts (N_("The system is NOT hibernated."));
       status = GRUB_ERR_TEST_FAILURE;

We also do grub_error (GRUB_ERR_TEST_FAILURE, "false");
   /* Ensure unmanaged resources are cleaned up */
   if (hibr_file_path)
     grub_free (hibr_file_path);
grub_free already checks for not-NULL pointers.
   if (hibr_file)
     grub_file_close (hibr_file);

   return status;
You can eliminate status and the need of keeping one by using return grub_errno;

Vladimir 'φ-coder/phcoder' Serbinenko

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