| 1 | /*
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| 2 | * Copyright (c) 2008 Jakub Jermar
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | *
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| 9 | * - Redistributions of source code must retain the above copyright
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| 10 | * notice, this list of conditions and the following disclaimer.
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| 11 | * - Redistributions in binary form must reproduce the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer in the
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| 13 | * documentation and/or other materials provided with the distribution.
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| 14 | * - The name of the author may not be used to endorse or promote products
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| 15 | * derived from this software without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | */
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| 28 |
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| 29 | /** @addtogroup fs
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| 30 | * @{
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| 31 | */
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| 32 |
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| 33 | /**
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| 34 | * @file fat_dentry.c
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| 35 | * @brief Functions that work with FAT directory entries.
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| 36 | */
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| 37 |
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| 38 | #include "fat_dentry.h"
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| 39 | #include <ctype.h>
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| 40 | #include <str.h>
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| 41 |
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| 42 | static bool is_d_char(const char ch)
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| 43 | {
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| 44 | if (isalnum(ch) || ch == '_')
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| 45 | return true;
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| 46 | else
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| 47 | return false;
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| 48 | }
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| 49 |
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| 50 | /** Compare path component with the name read from the dentry.
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| 51 | *
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| 52 | * This function compares the path component with the name read from the dentry.
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| 53 | * The comparison is case insensitive and tolerates a mismatch on the trailing
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| 54 | * dot character at the end of the name (i.e. when there is a dot, but no
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| 55 | * extension).
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| 56 | *
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| 57 | * @param name Node name read from the dentry.
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| 58 | * @param component Path component.
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| 59 | *
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| 60 | * @return Zero on match, non-zero otherwise.
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| 61 | */
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| 62 | int fat_dentry_namecmp(char *name, const char *component)
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| 63 | {
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| 64 | int rc;
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| 65 | size_t size;
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| 66 |
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| 67 | if (!(rc = stricmp(name, component)))
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| 68 | return rc;
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| 69 | if (!str_chr(name, '.')) {
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| 70 | /*
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| 71 | * There is no '.' in the name, so we know that there is enough
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| 72 | * space for appending an extra '.' to name.
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| 73 | */
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| 74 | size = str_size(name);
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| 75 | name[size] = '.';
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| 76 | name[size + 1] = '\0';
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| 77 | rc = stricmp(name, component);
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| 78 | }
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| 79 | return rc;
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| 80 | }
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| 81 |
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| 82 | bool fat_dentry_name_verify(const char *name)
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| 83 | {
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| 84 | unsigned int i;
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| 85 | unsigned int dot = 0;
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| 86 | bool dot_found = false;
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| 87 |
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| 88 |
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| 89 | for (i = 0; name[i]; i++) {
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| 90 | if (name[i] == '.') {
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| 91 | if (dot_found) {
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| 92 | return false;
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| 93 | } else {
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| 94 | dot_found = true;
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| 95 | dot = i;
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| 96 | }
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| 97 | } else {
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| 98 | if (!is_d_char(name[i]))
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| 99 | return false;
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| 100 | }
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| 101 | }
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| 102 |
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| 103 | if (dot_found) {
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| 104 | if (dot > FAT_NAME_LEN)
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| 105 | return false;
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| 106 | if (i - dot > FAT_EXT_LEN + 1)
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| 107 | return false;
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| 108 | } else {
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| 109 | if (i > FAT_NAME_LEN)
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| 110 | return false;
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| 111 | }
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| 112 |
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| 113 | return true;
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| 114 | }
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| 115 |
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| 116 | void fat_dentry_name_get(const fat_dentry_t *d, char *buf)
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| 117 | {
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| 118 | unsigned int i;
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| 119 |
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| 120 | for (i = 0; i < FAT_NAME_LEN; i++) {
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| 121 | if (d->name[i] == FAT_PAD)
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| 122 | break;
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| 123 |
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| 124 | if (d->name[i] == FAT_DENTRY_E5_ESC)
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| 125 | *buf++ = 0xe5;
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| 126 | else {
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| 127 | if (d->lcase & FAT_LCASE_LOWER_NAME)
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| 128 | *buf++ = tolower(d->name[i]);
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| 129 | else
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| 130 | *buf++ = d->name[i];
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| 131 | }
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| 132 | }
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| 133 |
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| 134 | if (d->ext[0] != FAT_PAD)
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| 135 | *buf++ = '.';
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| 136 |
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| 137 | for (i = 0; i < FAT_EXT_LEN; i++) {
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| 138 | if (d->ext[i] == FAT_PAD) {
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| 139 | *buf = '\0';
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| 140 | return;
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| 141 | }
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| 142 |
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| 143 | if (d->ext[i] == FAT_DENTRY_E5_ESC)
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| 144 | *buf++ = 0xe5;
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| 145 | else {
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| 146 | if (d->lcase & FAT_LCASE_LOWER_EXT)
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| 147 | *buf++ = tolower(d->ext[i]);
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| 148 | else
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| 149 | *buf++ = d->ext[i];
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| 150 | }
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| 151 | }
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| 152 |
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| 153 | *buf = '\0';
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| 154 | }
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| 155 |
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| 156 | void fat_dentry_name_set(fat_dentry_t *d, const char *name)
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| 157 | {
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| 158 | unsigned int i;
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| 159 | const char fake_ext[] = " ";
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| 160 | bool lower_name = true;
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| 161 | bool lower_ext = true;
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| 162 |
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| 163 | for (i = 0; i < FAT_NAME_LEN; i++) {
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| 164 | switch ((uint8_t) *name) {
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| 165 | case 0xe5:
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| 166 | d->name[i] = FAT_DENTRY_E5_ESC;
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| 167 | name++;
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| 168 | break;
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| 169 | case '\0':
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| 170 | case '.':
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| 171 | d->name[i] = FAT_PAD;
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| 172 | break;
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| 173 | default:
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| 174 | if (isalpha(*name)) {
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| 175 | if (!islower(*name))
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| 176 | lower_name = false;
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| 177 | }
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| 178 |
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| 179 | d->name[i] = toupper(*name++);
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| 180 | break;
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| 181 | }
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| 182 | }
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| 183 |
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| 184 | if (*name++ != '.')
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| 185 | name = fake_ext;
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| 186 |
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| 187 | for (i = 0; i < FAT_EXT_LEN; i++) {
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| 188 | switch ((uint8_t) *name) {
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| 189 | case 0xe5:
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| 190 | d->ext[i] = FAT_DENTRY_E5_ESC;
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| 191 | name++;
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| 192 | break;
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| 193 | case '\0':
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| 194 | d->ext[i] = FAT_PAD;
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| 195 | break;
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| 196 | default:
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| 197 | if (isalpha(*name)) {
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| 198 | if (!islower(*name))
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| 199 | lower_ext = false;
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| 200 | }
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| 201 |
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| 202 | d->ext[i] = toupper(*name++);
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| 203 | break;
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| 204 | }
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| 205 | }
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| 206 |
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| 207 | if (lower_name)
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| 208 | d->lcase |= FAT_LCASE_LOWER_NAME;
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| 209 | else
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| 210 | d->lcase &= ~FAT_LCASE_LOWER_NAME;
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| 211 |
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| 212 | if (lower_ext)
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| 213 | d->lcase |= FAT_LCASE_LOWER_EXT;
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| 214 | else
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| 215 | d->lcase &= ~FAT_LCASE_LOWER_EXT;
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| 216 | }
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| 217 |
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| 218 | fat_dentry_clsf_t fat_classify_dentry(const fat_dentry_t *d)
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| 219 | {
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| 220 | if (d->attr & FAT_ATTR_VOLLABEL) {
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| 221 | /* volume label entry */
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| 222 | return FAT_DENTRY_SKIP;
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| 223 | }
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| 224 | if (d->name[0] == FAT_DENTRY_ERASED) {
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| 225 | /* not-currently-used entry */
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| 226 | return FAT_DENTRY_FREE;
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| 227 | }
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| 228 | if (d->name[0] == FAT_DENTRY_UNUSED) {
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| 229 | /* never used entry */
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| 230 | return FAT_DENTRY_LAST;
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| 231 | }
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| 232 | if (d->name[0] == FAT_DENTRY_DOT) {
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| 233 | /*
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| 234 | * Most likely '.' or '..'.
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| 235 | * It cannot occur in a regular file name.
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| 236 | */
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| 237 | return FAT_DENTRY_SKIP;
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| 238 | }
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| 239 | return FAT_DENTRY_VALID;
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| 240 | }
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| 241 |
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| 242 | /** Compute checksum of Node name.
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| 243 | *
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| 244 | * Returns an unsigned byte checksum computed on an unsigned byte
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| 245 | * array. The array must be 11 bytes long and is assumed to contain
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| 246 | * a name stored in the format of a MS-DOS directory entry.
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| 247 | *
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| 248 | * @param name Node name read from the dentry.
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| 249 | *
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| 250 | * @return An 8-bit unsigned checksum of the name.
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| 251 | */
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| 252 | uint8_t fat_dentry_chksum(uint8_t *name)
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| 253 | {
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| 254 | uint8_t i, sum=0;
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| 255 | for (i=0; i<(FAT_NAME_LEN+FAT_EXT_LEN); i++) {
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| 256 | sum = ((sum & 1) ? 0x80 : 0) + (sum >> 1) + name[i];
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| 257 | }
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| 258 | return sum;
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| 259 | }
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| 260 |
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| 261 |
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| 262 | /**
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| 263 | * @}
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| 264 | */
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