i386/libsaio/msdos.c

   1 /*
   2  * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 2.0 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1998 Robert Nordier
  24  * All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in
  33  *    the documentation and/or other materials provided with the
  34  *    distribution.
  35  *
  36  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
  37  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  38  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  39  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY
  40  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  41  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  42  * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  43  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
  44  * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  45  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
  46  * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  47  */
  48
  49 #include "libsaio.h"
  50 #include "sl.h"
  51
  52 #include "msdos_private.h"
  53 #include "msdos.h"
  54
  55 #define LABEL_LENGTH            11
  56 #define MAX_DOS_BLOCKSIZE       2048
  57
  58 #define CLUST_FIRST     2               /* first legal cluster number */
  59 #define CLUST_RSRVD     0xfffffff6      /* reserved cluster range */
  60
  61
  62 #define false 0
  63 #define true 1
  64
  65 #if DEBUG
  66 #define DLOG(x) { outb(0x80, (x)); getc(); }
  67 #else
  68 #define DLOG(x)
  69 #endif
  70
  71 #if UNUSED
  72 /*
  73  * Check a volume label.
  74  */
  75 static int
  76 oklabel(const char *src)
  77 {
  78     int c, i;
  79
  80     for (i = 0, c = 0; i <= 11; i++) {
  81         c = (u_char)*src++;
  82         if (c < ' ' + !i || strchr("\"*+,./:;<=>?[\\]|", c))
  83             break;
  84     }
  85     return i && !c;
  86 }
  87 #endif /* UNUSED */
  88
  89 /* Fix up volume label. */
  90 static void
  91 fixLabel(char *label, char *str, long strMaxLen)
  92 {
  93     int                 i;
  94     //unsigned char     labelUTF8[LABEL_LENGTH*3];
  95
  96     /* Convert leading 0x05 to 0xE5 for multibyte languages like Japanese */
  97     if (label[0] == 0x05)
  98         label[0] = 0xE5;
  99
 100 #if UNUSED
 101     /* Check for illegal characters */
 102     if (!oklabel(label))
 103         label[0] = 0;
 104 #endif /* UNUSED */
 105
 106     /* Remove any trailing spaces */
 107     for (i=LABEL_LENGTH-1; i>=0; --i) {
 108         if (label[i] == ' ')
 109             label[i] = 0;
 110         else
 111             break;
 112     }
 113
 114     /* TODO: Convert it to UTF-8 from DOSLatin1 encoding */
 115     strncpy(str, label, strMaxLen);
 116 }
 117
 118
 119 void
 120 MSDOSGetDescription(CICell ih, char *str, long strMaxLen)
 121 {
 122     struct direntry     *dirp;
 123     union bootsector    *bsp;
 124     struct bpb33        *b33;
 125     struct bpb50        *b50;
 126     struct bpb710       *b710;
 127     u_int16_t           bps;
 128     int8_t              spc;
 129     int                 rootDirSectors;
 130     int                 i, finished;
 131     char                *buf;
 132     char                label[LABEL_LENGTH+1];
 133
 134     DLOG(0);
 135     buf = (char *)malloc(MAX_DOS_BLOCKSIZE);
 136     if (buf == 0) goto error;
 137
 138     DLOG(1);
 139     /*
 140      * Read the boot sector of the filesystem, and then check the
 141      * boot signature.  If not a dos boot sector then error out.
 142      *
 143      * NOTE: 2048 is a maximum sector size in current...
 144      */
 145     Seek(ih, 0);
 146     Read(ih, (long)buf, MAX_DOS_BLOCKSIZE);
 147
 148     DLOG(2);
 149     bsp = (union bootsector *)buf;
 150     b33 = (struct bpb33 *)bsp->bs33.bsBPB;
 151     b50 = (struct bpb50 *)bsp->bs50.bsBPB;
 152     b710 = (struct bpb710 *)bsp->bs710.bsBPB;
 153
 154     DLOG(3);
 155     /* [2699033]
 156      *
 157      * The first three bytes are an Intel x86 jump instruction.  It should be one
 158      * of the following forms:
 159      *    0xE9 0x?? 0x??
 160      *    0xEC 0x?? 0x90
 161      * where 0x?? means any byte value is OK.
 162      */
 163     if (bsp->bs50.bsJump[0] != 0xE9
 164         && (bsp->bs50.bsJump[0] != 0xEB || bsp->bs50.bsJump[2] != 0x90)) {
 165         goto error;
 166     }
 167
 168     DLOG(4);
 169     /* It is possible that the above check could match a partition table, or some */
 170     /* non-FAT disk meant to boot a PC.  Check some more fields for sensible values. */
 171
 172     /* We only work with 512, 1024, and 2048 byte sectors */
 173     bps = OSSwapLittleToHostInt16(b33->bpbBytesPerSec);
 174     if ((bps < 0x200) || (bps & (bps - 1)) || (bps > 0x800)) {
 175         goto error;
 176     }
 177
 178     DLOG(5);
 179     /* Check to make sure valid sectors per cluster */
 180     spc = b33->bpbSecPerClust;
 181     if ((spc == 0 ) || (spc & (spc - 1))) {
 182         goto error;
 183     }
 184
 185     DLOG(6);
 186     /* we know this disk, find the volume label */
 187     /* First, find the root directory */
 188     label[0] = '\0';
 189     finished = false;
 190     rootDirSectors = ((OSSwapLittleToHostInt16(b50->bpbRootDirEnts) * sizeof(struct direntry)) +
 191                       (bps-1)) / bps;
 192
 193     DLOG(7);
 194
 195     if (rootDirSectors) {                       /* FAT12 or FAT16 */
 196         int firstRootDirSecNum;
 197         u_int8_t *rootDirBuffer;
 198         int j;
 199
 200         rootDirBuffer = (u_int8_t *)malloc(MAX_DOS_BLOCKSIZE);
 201
 202         DLOG(8);
 203         firstRootDirSecNum = OSSwapLittleToHostInt16(b33->bpbResSectors) +
 204             (b33->bpbFATs * OSSwapLittleToHostInt16(b33->bpbFATsecs));
 205         for (i=0; i< rootDirSectors; i++) {
 206             Seek(ih, (firstRootDirSecNum+i)*bps);
 207             Read(ih, (long)rootDirBuffer, bps);
 208             dirp = (struct direntry *)rootDirBuffer;
 209             for (j=0; j<bps; j+=sizeof(struct direntry), dirp++) {
 210                 if (dirp->deName[0] == SLOT_EMPTY) {
 211                     finished = true;
 212                     break;
 213                 }
 214                 else if (dirp->deName[0] == SLOT_DELETED)
 215                     continue;
 216                 else if (dirp->deAttributes == ATTR_WIN95)
 217                     continue;
 218                 else if (dirp->deAttributes & ATTR_VOLUME) {
 219                     strncpy(label, (char *)dirp->deName, LABEL_LENGTH);
 220                     finished = true;
 221                     break;
 222                 }
 223             }   /* j */
 224             if (finished == true) {
 225                 break;
 226             }
 227         }       /* i */
 228
 229         free(rootDirBuffer);
 230
 231     } else {    /* FAT32 */
 232         u_int32_t cluster;
 233         u_int32_t bytesPerCluster;
 234         u_int8_t *rootDirBuffer;
 235         off_t readOffset;
 236
 237         DLOG(9);
 238         bytesPerCluster = bps * spc;
 239         rootDirBuffer = malloc(bytesPerCluster);
 240         cluster = OSSwapLittleToHostInt32(b710->bpbRootClust);
 241
 242         DLOG(0x20);
 243         finished = false;
 244         while (!finished && cluster >= CLUST_FIRST && cluster < CLUST_RSRVD) {
 245
 246             DLOG(0x21);
 247             /* Find sector where clusters start */
 248             readOffset = OSSwapLittleToHostInt16(b710->bpbResSectors) +
 249                 (b710->bpbFATs * OSSwapLittleToHostInt16(b710->bpbBigFATsecs));
 250             /* Find sector where "cluster" starts */
 251             readOffset += ((off_t) cluster - CLUST_FIRST) * (off_t) spc;
 252             /* Convert to byte offset */
 253             readOffset *= (off_t) bps;
 254
 255             DLOG(0x22);
 256             /* Read in "cluster" */
 257             Seek(ih, readOffset);
 258             Read(ih, (long)rootDirBuffer, bytesPerCluster);
 259             dirp = (struct direntry *) rootDirBuffer;
 260
 261             DLOG(0x23);
 262             /* Examine each directory entry in this cluster */
 263             for (i=0; i < bytesPerCluster; i += sizeof(struct direntry), dirp++) {
 264
 265                 DLOG(0x24);
 266                 if (dirp->deName[0] == SLOT_EMPTY) {
 267                     finished = true;    // Reached end of directory (never used entry)
 268                     break;
 269                 }
 270                 else if (dirp->deName[0] == SLOT_DELETED)
 271                     continue;
 272                 else if (dirp->deAttributes == ATTR_WIN95)
 273                     continue;
 274                 else if (dirp->deAttributes & ATTR_VOLUME) {
 275                     DLOG(0x31);
 276                     strncpy(label, (char *)dirp->deName, LABEL_LENGTH);
 277                     finished = true;
 278                     break;
 279                 }
 280                 DLOG(0x25);
 281             }
 282             if (finished)
 283                 break;
 284
 285             DLOG(0x26);
 286             /* Find next cluster in the chain by reading the FAT */
 287
 288             /* Find first sector of FAT */
 289             readOffset = OSSwapLittleToHostInt16(b710->bpbResSectors);
 290             /* Find sector containing "cluster" entry in FAT */
 291             readOffset += (cluster * 4) / bps;
 292             /* Convert to byte offset */
 293             readOffset *= bps;
 294
 295             DLOG(0x27);
 296             /* Read one sector of the FAT */
 297             Seek(ih, readOffset);
 298             Read(ih, (long)rootDirBuffer, bps);
 299
 300             DLOG(0x28);
 301             cluster = OSReadLittleInt32(rootDirBuffer + ((cluster * 4) % bps), 0);
 302             cluster &= 0x0FFFFFFF;      // ignore reserved upper bits
 303         }
 304
 305         free(rootDirBuffer);
 306
 307     }   /* rootDirSectors */
 308
 309     DLOG(10);
 310     /* else look in the boot blocks */
 311     if (str[0] == '\0') {
 312         if (OSSwapLittleToHostInt16(b50->bpbRootDirEnts) == 0) { /* It's FAT32 */
 313             strncpy(label, (char *)((struct extboot *)bsp->bs710.bsExt)->exVolumeLabel, LABEL_LENGTH);
 314         }
 315         else if (((struct extboot *)bsp->bs50.bsExt)->exBootSignature == EXBOOTSIG) {
 316             strncpy(label, (char *)((struct extboot *)bsp->bs50.bsExt)->exVolumeLabel, LABEL_LENGTH);
 317         }
 318     }
 319
 320     fixLabel(label, str, strMaxLen);
 321
 322     free(buf);
 323     return;
 324
 325  error:
 326     DLOG(0xee);
 327     if (buf) free(buf);
 328     return;
 329 }