fs_fat32dirent.c

/****************************************************************************
 * fs/fat/fs_fat32dirent.c
 *
 *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * NOTE:  If CONFIG_FAT_LFN is defined, then there may be some legal, patent
 * issues. The following was extracted from the entry "File Allocation Table
 * from Wikipedia, the free encyclopedia:
 *
 * "On December 3, 2003 Microsoft announced it would be offering licenses
 *  for use of its FAT specification and 'associated intellectual property',
 *  at the cost of a US$0.25 royalty per unit sold, with a $250,000 maximum
 *  royalty per license agreement.
 *
 *  o "U.S. Patent 5,745,902 (http://www.google.com/patents?vid=5745902) -
 *     Method and system for accessing a file using file names having
 *     different file name formats. ...
 *  o "U.S. Patent 5,579,517 (http://www.google.com/patents?vid=5579517) -
 *     Common name space for long and short filenames. ...
 *  o "U.S. Patent 5,758,352 (http://www.google.com/patents?vid=5758352) -
 *     Common name space for long and short filenames. ...
 *  o "U.S. Patent 6,286,013 (http://www.google.com/patents?vid=6286013) -
 *     Method and system for providing a common name space for long and
 *     short file names in an operating system. ...
 *
 * "Many technical commentators have concluded that these patents only cover
 *  FAT implementations that include support for long filenames, and that
 *  removable solid state media and consumer devices only using short names
 *  would be unaffected. ..."
 *
 * So you have been forewarned:  Use the long filename at your own risk!
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>

#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/fs.h>
#include <nuttx/fat.h>

#include "fs_internal.h"
#include "fs_fat32.h"

/****************************************************************************
 * Definitions
 ****************************************************************************/

/****************************************************************************
 * Private Types
 ****************************************************************************/

enum fat_case_e
{
  FATCASE_UNKNOWN = 0,
  FATCASE_UPPER,
  FATCASE_LOWER
};

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Private Variables
 ****************************************************************************/

/****************************************************************************
 * Public Variables
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: fat_lfnchecksum
 *
 * Desciption:  Caculate the checksum of .
 *
 ****************************************************************************/

#ifdef CONFIG_FAT_LFN
static uint8_t fat_lfnchecksum(const uint8_t *sfname)
{
  uint8_t sum = 0;
  int i;

  for (i = DIR_MAXFNAME; i; i--)
    {
      sum = ((sum & 1) << 7) + (sum >> 1) + *sfname++;
	}

  return sum;
}
#endif

/****************************************************************************
 * Name: fat_parsesfname
 *
 * Desciption:  Convert a user filename into a properly formatted FAT
 *   (short 8.3) filename as it would appear in a directory entry.  Here are
 *    the rules for the 8+3 short file name in the directory:
 *
 *   The first byte:
 *
 *     0xe5 = The directory is free
 *     0x00 = This directory and all following directories are free
 *     0x05 = Really 0xe5
 *     0x20 = May NOT be ' '
 *
 *   Other characters may be any characters except for the following:
 *
 *     0x00-0x1f = (except for 0x00 and 0x05 in the first byte)
 *     0x22      = '"'
 *     0x2a-0x2c = '*', '+', ','
 *     0x2e-0x2f = '.', '/'
 *     0x3a-0x3f = ':', ';', '<', '=', '>', '?'
 *     0x5b-0x5d = '[', '\\', ;]'
 *     0x7c      = '|'
 *
 *   '.' May only occur once within string and only within the first 9
 *   bytes.  The '.' is not save in the directory, but is implicit in
 *   8+3 format.
 *
 *   Lower case characters are not allowed in directory names (without some
 *   poorly documented operations on the NTRes directory byte).  Lower case
 *   codes may represent different characters in other character sets ("DOS
 *   code pages".  The logic below does not, at present, support any other
 *   character sets.
 *
 * Returned value:
 *   OK - The path refers to a valid 8.3 FAT file name and has been properly
 *        converted and stored in dirinfo.
 *   <0 - Otherwise an negated error is returned meaning that the string is
 *        not a valid 8+3 because:
 *
 *        1. Contains characters not in the printable character set,
 *        2. Contains forbidden characters or multiple '.' characters
 *        3. File name or extension is too long.
 *
 *        If CONFIG_FAT_LFN is defined and CONFIG_FAT_LCNAMES is NOT
 *        defined, then:
 *
 *        4a. File name or extension contains lower case characters.
 *
 *        If CONFIG_FAT_LFN is defined and CONFIG_FAT_LCNAMES is defined,
 *        then:
 *
 *        4b. File name or extension is not all the same case.
 *
 ****************************************************************************/

static inline int fat_parsesfname(const char **path,
                                   struct fat_dirinfo_s *dirinfo,
                                   char *terminator)