source: mainline/uspace/srv/fs/fat/fat_dentry.c

/*
 * Copyright (c) 2008 Jakub Jermar
 * Copyright (c) 2011 Oleg Romanenko
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/** @addtogroup fat
 * @{
 */

/**
 * @file        fat_dentry.c
 * @brief       Functions that work with FAT directory entries.
 */

#include "fat_dentry.h"
#include <ctype.h>
#include <str.h>
#include <errno.h>
#include <byteorder.h>
#include <assert.h>
#include <stddef.h>
#include <stdint.h>

/** Compare path component with the name read from the dentry.
 *
 * This function compares the path component with the name read from the dentry.
 * The comparison is case insensitive and tolerates a mismatch on the trailing
 * dot character at the end of the name (i.e. when there is a dot, but no
 * extension).
 *
 * @param name          Node name read from the dentry.
 * @param component     Path component.
 *
 * @return              Zero on match, non-zero otherwise.
 */
int fat_dentry_namecmp(char *name, const char *component)
{
        int rc;
        size_t size;

        if (!(rc = str_casecmp(name, component)))
                return rc;
        if (!str_chr(name, '.')) {
                /*
                 * There is no '.' in the name, so we know that there is enough
                 * space for appending an extra '.' to name.
                 */
                size = str_size(name);
                name[size] = '.';
                name[size + 1] = '\0';
                rc = str_casecmp(name, component);
        }
        return rc;
}

void fat_dentry_name_get(const fat_dentry_t *d, char *buf)
{
        unsigned int i;

        for (i = 0; i < FAT_NAME_LEN; i++) {
                if (d->name[i] == FAT_PAD)
                        break;

                if (d->name[i] == FAT_DENTRY_E5_ESC)
                        *buf++ = 0xe5;
                else {
                        if (d->lcase & FAT_LCASE_LOWER_NAME)
                                *buf++ = tolower(d->name[i]);
                        else
                                *buf++ = d->name[i];
                }
        }

        if (d->ext[0] != FAT_PAD)
                *buf++ = '.';

        for (i = 0; i < FAT_EXT_LEN; i++) {
                if (d->ext[i] == FAT_PAD) {
                        *buf = '\0';
                        return;
                }

                if (d->ext[i] == FAT_DENTRY_E5_ESC)
                        *buf++ = 0xe5;
                else {
                        if (d->lcase & FAT_LCASE_LOWER_EXT)
                                *buf++ = tolower(d->ext[i]);
                        else
                                *buf++ = d->ext[i];
                }
        }

        *buf = '\0';
}

void fat_dentry_name_set(fat_dentry_t *d, const char *name)
{
        unsigned int i;
        const char fake_ext[] = "   ";
        bool lower_name = true;
        bool lower_ext = true;

        for (i = 0; i < FAT_NAME_LEN; i++) {
                switch ((uint8_t) *name) {
                case 0xe5:
                        d->name[i] = FAT_DENTRY_E5_ESC;
                        name++;
                        break;
                case '\0':
                case '.':
                        d->name[i] = FAT_PAD;
                        break;
                default:
                        if (isalpha(*name)) {
                                if (!islower(*name))
                                        lower_name = false;
                        }

                        d->name[i] = toupper(*name++);
                        break;
                }
        }

        if (*name++ != '.')
                name = fake_ext;

        for (i = 0; i < FAT_EXT_LEN; i++) {
                switch ((uint8_t) *name) {
                case 0xe5:
                        d->ext[i] = FAT_DENTRY_E5_ESC;
                        name++;
                        break;
                case '\0':
                        d->ext[i] = FAT_PAD;
                        break;
                default:
                        if (isalpha(*name)) {
                                if (!islower(*name))
                                        lower_ext = false;
                        }

                        d->ext[i] = toupper(*name++);
                        break;
                }
        }

        if (lower_name)
                d->lcase |= FAT_LCASE_LOWER_NAME;
        else
                d->lcase &= ~FAT_LCASE_LOWER_NAME;

        if (lower_ext)
                d->lcase |= FAT_LCASE_LOWER_EXT;
        else
                d->lcase &= ~FAT_LCASE_LOWER_EXT;
}

void fat_dentry_vollabel_get(const fat_dentry_t *d, char *buf)
{
        unsigned int i;

        for (i = 0; i < FAT_NAME_LEN; i++) {
                if (d->name[i] == FAT_PAD)
                        break;

                if (d->name[i] == FAT_DENTRY_E5_ESC)
                        *buf++ = 0xe5;
                else
                        *buf++ = d->name[i];
        }

        for (i = 0; i < FAT_EXT_LEN; i++) {
                if (d->ext[i] == FAT_PAD) {
                        *buf = '\0';
                        return;
                }

                if (d->ext[i] == FAT_DENTRY_E5_ESC)
                        *buf++ = 0xe5;
                else
                        *buf++ = d->ext[i];
        }

        *buf = '\0';
}

fat_dentry_clsf_t fat_classify_dentry(const fat_dentry_t *d)
{
        if (d->attr == FAT_ATTR_LFN) {
                /* long name entry */
                if (FAT_LFN_ORDER(d) & FAT_LFN_ERASED)
                        return FAT_DENTRY_FREE;
                else
                        return FAT_DENTRY_LFN;
        }
        if (d->attr & FAT_ATTR_VOLLABEL) {
                /* volume label entry */
                return FAT_DENTRY_VOLLABEL;
        }
        if (d->name[0] == FAT_DENTRY_ERASED) {
                /* not-currently-used entry */
                return FAT_DENTRY_FREE;
        }
        if (d->name[0] == FAT_DENTRY_UNUSED) {
                /* never used entry */
                return FAT_DENTRY_LAST;
        }
        if (d->name[0] == FAT_DENTRY_DOT) {
                /*
                 * Most likely '.' or '..'.
                 * It cannot occur in a regular file name.
                 */
                return FAT_DENTRY_SKIP;
        }
        return FAT_DENTRY_VALID;
}

/** Compute checksum of Node name.
 *
 * Returns an unsigned byte checksum computed on an unsigned byte
 * array. The array must be 11 bytes long and is assumed to contain
 * a name stored in the format of a MS-DOS directory entry.
 *
 * @param name          Node name read from the dentry.
 *
 * @return              An 8-bit unsigned checksum of the name.
 */
uint8_t fat_dentry_chksum(uint8_t *name)
{
        uint8_t i, sum = 0;

        for (i = 0; i < (FAT_NAME_LEN + FAT_EXT_LEN); i++)
                sum = ((sum & 1) ? 0x80 : 0) + (sum >> 1) + name[i];

        return sum;
}

/** Get number of bytes in a string with size limit.
 *
 * @param str  NULL-terminated (or not) string. The pointer comes from a packed
 *             structure and as such is expected to be unaligned.
 * @param size Maximum number of bytes to consider.
 *
 * @return Number of bytes in string (without 0 and ff).
 *
 */
size_t fat_lfn_str_nlength(const unaligned_uint16_t *str, size_t size)
{
        size_t offset = 0;

        while (offset < size) {
                if (str[offset] == 0 || str[offset] == FAT_LFN_PAD)
                        break;
                offset++;
        }
        return offset;
}

/** Get number of bytes in a FAT long entry occuped by characters.
 *
 * @param d FAT long entry.
 *
 * @return Number of bytes.
 *
 */
size_t fat_lfn_size(const fat_dentry_t *d)
{
        size_t size = 0;

        size += fat_lfn_str_nlength(FAT_LFN_PART1(d), FAT_LFN_PART1_SIZE);
        size += fat_lfn_str_nlength(FAT_LFN_PART2(d), FAT_LFN_PART2_SIZE);
        size += fat_lfn_str_nlength(FAT_LFN_PART3(d), FAT_LFN_PART3_SIZE);

        return size;
}

size_t fat_lfn_get_entry(const fat_dentry_t *d, uint16_t *dst, size_t *offset)
{
        int i;
        for (i = FAT_LFN_PART3_SIZE - 1; i >= 0 && *offset > 0; i--) {
                if (d->lfn.part3[i] == 0 || d->lfn.part3[i] == FAT_LFN_PAD)
                        continue;
                (*offset)--;
                dst[(*offset)] = uint16_t_le2host(d->lfn.part3[i]);
        }
        for (i = FAT_LFN_PART2_SIZE - 1; i >= 0 && *offset > 0; i--) {
                if (d->lfn.part2[i] == 0 || d->lfn.part2[i] == FAT_LFN_PAD)
                        continue;
                (*offset)--;
                dst[(*offset)] = uint16_t_le2host(d->lfn.part2[i]);
        }
        for (i = FAT_LFN_PART1_SIZE - 1; i >= 0 && *offset > 0; i--) {
                if (d->lfn.part1[i] == 0 || d->lfn.part1[i] == FAT_LFN_PAD)
                        continue;
                (*offset)--;
                dst[(*offset)] = uint16_t_le2host(d->lfn.part1[i]);
        }
        return *offset;
}

size_t fat_lfn_set_entry(const uint16_t *src, size_t *offset, size_t size,
    fat_dentry_t *d)
{
        size_t idx;
        for (idx = 0; idx < FAT_LFN_PART1_SIZE; idx++) {
                if (*offset < size) {
                        d->lfn.part1[idx] = host2uint16_t_le(src[*offset]);
                        (*offset)++;
                } else
                        d->lfn.part1[idx] = FAT_LFN_PAD;
        }
        for (idx = 0; idx < FAT_LFN_PART2_SIZE; idx++) {
                if (*offset < size) {
                        d->lfn.part2[idx] = host2uint16_t_le(src[*offset]);
                        (*offset)++;
                } else
                        d->lfn.part2[idx] = FAT_LFN_PAD;
        }
        for (idx = 0; idx < FAT_LFN_PART3_SIZE; idx++) {
                if (*offset < size) {
                        d->lfn.part3[idx] = host2uint16_t_le(src[*offset]);
                        (*offset)++;
                } else
                        d->lfn.part3[idx] = FAT_LFN_PAD;
        }

        if (src[*offset] == 0)
                offset++;
        FAT_LFN_ATTR(d) = FAT_ATTR_LFN;
        d->lfn.type = 0;
        d->lfn.firstc_lo = 0;

        return *offset;
}

void str_to_ascii(char *dst, const char *src, size_t count, uint8_t pad)
{
        char32_t ch;
        size_t off = 0;
        size_t i = 0;

        while (i < count) {
                if ((ch = str_decode(src, &off, STR_NO_LIMIT)) != 0) {
                        if (ascii_check(ch) && IS_D_CHAR(ch))
                                *dst = toupper(ch);
                        else
                                *dst = pad;
                } else
                        break;

                dst++;
                i++;
        }
        *dst = '\0';
}

bool fat_valid_name(const char *name)
{
        char32_t ch;
        size_t offset = 0;
        bool result = true;

        while ((ch = str_decode(name, &offset, STR_NO_LIMIT)) != 0) {
                if (str_chr(FAT_STOP_CHARS, ch) != NULL) {
                        result = false;
                        break;
                }
        }
        return result;
}

bool fat_valid_short_name(const char *name)
{
        unsigned int i;
        unsigned int dot = 0;
        bool dot_found = false;

        for (i = 0; name[i]; i++) {
                if (name[i] == '.') {
                        if (dot_found) {
                                return false;
                        } else {
                                dot_found = true;
                                dot = i;
                        }
                } else {
                        if (!IS_D_CHAR(name[i]))
                                return false;
                }
        }

        if (dot_found) {
                if (dot > FAT_NAME_LEN)
                        return false;
                if (i - dot > FAT_EXT_LEN + 1)
                        return false;
        } else {
                if (i > FAT_NAME_LEN)
                        return false;
        }

        return true;
}

/**
 * @}
 */