1 /* mksdcard.c 2 ** 3 ** Copyright 2007, The Android Open Source Project 4 ** 5 ** Redistribution and use in source and binary forms, with or without 6 ** modification, are permitted provided that the following conditions are met: 7 ** * Redistributions of source code must retain the above copyright 8 ** notice, this list of conditions and the following disclaimer. 9 ** * Redistributions in binary form must reproduce the above copyright 10 ** notice, this list of conditions and the following disclaimer in the 11 ** documentation and/or other materials provided with the distribution. 12 ** * Neither the name of Google Inc. nor the names of its contributors may 13 ** be used to endorse or promote products derived from this software 14 ** without specific prior written permission. 15 ** 16 ** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR 17 ** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 18 ** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 19 ** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 20 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 21 ** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 22 ** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 23 ** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 24 ** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 25 ** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 /* a simple and portable program used to generate a blank FAT32 image file 29 * 30 * usage: mksdcard [-l label] <size> <filename> 31 */ 32 33 #include <time.h> 34 #include <stdio.h> 35 #include <stdlib.h> 36 #include <string.h> 37 #include <errno.h> 38 #include <unistd.h> 39 40 /* believe me, you *don't* want to change these constants !! */ 41 #define BYTES_PER_SECTOR 512 42 #define RESERVED_SECTORS 32 43 #define BACKUP_BOOT_SECTOR 6 44 #define NUM_FATS 2 45 46 /* sectors_per_disk is encoded as a signed int */ 47 #define MAX_SECTORS_PER_DISK 0x7FFFFFFF 48 #define MAX_DISK_SIZE ((Wide)MAX_SECTORS_PER_DISK * BYTES_PER_SECTOR) 49 50 typedef long long Wide; /* might be something else if you don't use GCC */ 51 typedef unsigned char Byte; 52 typedef Byte* Bytes; 53 54 #define BYTE_(p,i) (((Bytes)(p))[(i)]) 55 56 #define POKEB(p,v) BYTE_(p,0) = (Byte)(v) 57 #define POKES(p,v) ( BYTE_(p,0) = (Byte)(v), BYTE_(p,1) = (Byte)((v) >> 8) ) 58 #define POKEW(p,v) ( BYTE_(p,0) = (Byte)(v), BYTE_(p,1) = (Byte)((v) >> 8), BYTE_(p,2) = (Byte)((v) >> 16), BYTE_(p,3) = (Byte)((v) >> 24) ) 59 60 static Byte s_boot_sector [ BYTES_PER_SECTOR ]; /* boot sector */ 61 static Byte s_fsinfo_sector [ BYTES_PER_SECTOR ]; /* FS Info sector */ 62 static Byte s_fat_head [ BYTES_PER_SECTOR ]; /* first FAT sector */ 63 static Byte s_zero_sector [ BYTES_PER_SECTOR ]; /* empty sector */ 64 65 /* this is the date and time when creating the disk */ 66 static int 67 get_serial_id( void ) 68 { 69 unsigned short lo, hi, mid; 70 time_t now = time(NULL); 71 struct tm tm = gmtime( &now )[0]; 72 73 lo = (unsigned short)(tm.tm_mday + ((tm.tm_mon+1) << 8) + (tm.tm_sec << 8)); 74 hi = (unsigned short)(tm.tm_min + (tm.tm_hour << 8) + (tm.tm_year + 1900)); 75 76 return lo + (hi << 16); 77 } 78 79 static int 80 get_sectors_per_cluster( Wide disk_size ) 81 { 82 Wide disk_MB = disk_size/(1024*1024); 83 84 if (disk_MB < 260) 85 return 1; 86 87 if (disk_MB < 8192) 88 return 4; 89 90 if (disk_MB < 16384) 91 return 8; 92 93 if (disk_MB < 32768) 94 return 16; 95 96 return 32; 97 } 98 99 static int 100 get_sectors_per_fat( Wide disk_size, int sectors_per_cluster ) 101 { 102 Wide divider; 103 104 /* weird computation from MS - see fatgen103.doc for details */ 105 disk_size -= RESERVED_SECTORS * BYTES_PER_SECTOR; /* don't count 32 reserved sectors */ 106 disk_size /= BYTES_PER_SECTOR; /* disk size in sectors */ 107 divider = ((256 * sectors_per_cluster) + NUM_FATS) / 2; 108 109 return (int)( (disk_size + (divider-1)) / divider ); 110 } 111 112 static void 113 boot_sector_init( Bytes boot, Bytes info, Wide disk_size, const char* label ) 114 { 115 int sectors_per_cluster = get_sectors_per_cluster(disk_size); 116 int sectors_per_fat = get_sectors_per_fat(disk_size, sectors_per_cluster); 117 int sectors_per_disk = (int)(disk_size / BYTES_PER_SECTOR); 118 int serial_id = get_serial_id(); 119 int free_count; 120 121 if (label == NULL) 122 label = "SDCARD"; 123 124 POKEB(boot, 0xeb); 125 POKEB(boot+1, 0x5a); 126 POKEB(boot+2, 0x90); 127 strcpy( (char*)boot + 3, "MSWIN4.1" ); 128 POKES( boot + 0x0b, BYTES_PER_SECTOR ); /* sector size */ 129 POKEB( boot + 0xd, sectors_per_cluster ); /* sectors per cluster */ 130 POKES( boot + 0xe, RESERVED_SECTORS ); /* reserved sectors before first FAT */ 131 POKEB( boot + 0x10, NUM_FATS ); /* number of FATs */ 132 POKES( boot + 0x11, 0 ); /* max root directory entries for FAT12/FAT16, 0 for FAT32 */ 133 POKES( boot + 0x13, 0 ); /* total sectors, 0 to use 32-bit value at offset 0x20 */ 134 POKEB( boot + 0x15, 0xF8 ); /* media descriptor, 0xF8 == hard disk */ 135 POKES( boot + 0x16, 0 ); /* Sectors per FAT for FAT12/16, 0 for FAT32 */ 136 POKES( boot + 0x18, 9 ); /* Sectors per track (whatever) */ 137 POKES( boot + 0x1a, 2 ); /* Number of heads (whatever) */ 138 POKEW( boot + 0x1c, 0 ); /* Hidden sectors */ 139 POKEW( boot + 0x20, sectors_per_disk ); /* Total sectors */ 140 141 /* extension */ 142 POKEW( boot + 0x24, sectors_per_fat ); /* Sectors per FAT */ 143 POKES( boot + 0x28, 0 ); /* FAT flags */ 144 POKES( boot + 0x2a, 0 ); /* version */ 145 POKEW( boot + 0x2c, 2 ); /* cluster number of root directory start */ 146 POKES( boot + 0x30, 1 ); /* sector number of FS information sector */ 147 POKES( boot + 0x32, BACKUP_BOOT_SECTOR ); /* sector number of a copy of this boot sector */ 148 POKEB( boot + 0x40, 0x80 ); /* physical drive number */ 149 POKEB( boot + 0x42, 0x29 ); /* extended boot signature ?? */ 150 POKEW( boot + 0x43, serial_id ); /* serial ID */ 151 strncpy( (char*)boot + 0x47, label, 11 ); /* Volume Label */ 152 memcpy( boot + 0x52, "FAT32 ", 8 ); /* FAT system type, padded with 0x20 */ 153 154 POKEB( boot + BYTES_PER_SECTOR-2, 0x55 ); /* boot sector signature */ 155 POKEB( boot + BYTES_PER_SECTOR-1, 0xAA ); 156 157 /* FSInfo sector */ 158 free_count = sectors_per_disk - 32 - 2*sectors_per_fat; 159 160 POKEW( info + 0, 0x41615252 ); 161 POKEW( info + 484, 0x61417272 ); 162 POKEW( info + 488, free_count ); /* number of free clusters */ 163 POKEW( info + 492, 3 ); /* next free clusters, 0-1 reserved, 2 is used for the root dir */ 164 POKEW( info + 508, 0xAA550000 ); 165 } 166 167 static void 168 fat_init( Bytes fat ) 169 { 170 POKEW( fat, 0x0ffffff8 ); /* reserve cluster 1, media id in low byte */ 171 POKEW( fat + 4, 0x0fffffff ); /* reserve cluster 2 */ 172 POKEW( fat + 8, 0x0fffffff ); /* end of clust chain for root dir */ 173 } 174 175 176 static int 177 write_sector( FILE* file, Bytes sector ) 178 { 179 int result = fwrite( sector, 1, BYTES_PER_SECTOR, file ) != BYTES_PER_SECTOR; 180 if (result) { 181 fprintf(stderr, "Failed to write sector of %d bytes: %s\n", BYTES_PER_SECTOR, strerror(errno)); 182 } 183 return result; 184 } 185 186 static int 187 write_empty( FILE* file, Wide count ) 188 { 189 static Byte empty[256*1024]; 190 memset(empty, 0, sizeof(empty)); 191 192 count *= BYTES_PER_SECTOR; 193 while (count > 0) { 194 int len = sizeof(empty); 195 if (len > count) 196 len = count; 197 if ( fwrite( empty, 1, len, file ) != (size_t)len ) { 198 fprintf(stderr, "Failed to write %d bytes: %s\n", len, strerror(errno)); 199 return 1; 200 } 201 202 count -= len; 203 } 204 return 0; 205 } 206 207 static void usage (void) 208 { 209 fprintf(stderr, "mksdcard: create a blank FAT32 image to be used with the Android emulator\n" ); 210 fprintf(stderr, "usage: mksdcard [-l label] <size> <file>\n\n"); 211 fprintf(stderr, " if <size> is a simple integer, it specifies a size in bytes\n" ); 212 fprintf(stderr, " if <size> is an integer followed by 'K', it specifies a size in KiB\n" ); 213 fprintf(stderr, " if <size> is an integer followed by 'M', it specifies a size in MiB\n" ); 214 fprintf(stderr, " if <size> is an integer followed by 'G', it specifies a size in GiB\n" ); 215 fprintf(stderr, "\nMinimum size is 9M. The Android emulator cannot use smaller images.\n" ); 216 fprintf(stderr, "Maximum size is %lld bytes, %lldK, %lldM or %lldG\n", 217 MAX_DISK_SIZE, MAX_DISK_SIZE >> 10, MAX_DISK_SIZE >> 20, MAX_DISK_SIZE >> 30); 218 exit(1); 219 } 220 221 int main( int argc, char** argv ) 222 { 223 Wide disk_size; 224 int sectors_per_fat; 225 int sectors_per_disk; 226 char* end; 227 const char* label = NULL; 228 FILE* f = NULL; 229 230 for ( ; argc > 1 && argv[1][0] == '-'; argc--, argv++ ) 231 { 232 char* arg = argv[1] + 1; 233 switch (arg[0]) { 234 case 'l': 235 if (arg[1] != 0) 236 arg += 2; 237 else { 238 argc--; 239 argv++; 240 if (argc <= 1) 241 usage(); 242 arg = argv[1]; 243 } 244 label = arg; 245 break; 246 247 default: 248 usage(); 249 } 250 } 251 252 if (argc != 3) 253 usage(); 254 255 disk_size = strtoll( argv[1], &end, 10 ); 256 if (disk_size <= 0 || errno == EINVAL || errno == ERANGE) { 257 fprintf(stderr, "Invalid argument size '%s'\n\n", argv[1]); 258 usage(); 259 } 260 261 if (*end == 'K') 262 disk_size *= 1024; 263 else if (*end == 'M') 264 disk_size *= 1024*1024; 265 else if (*end == 'G') 266 disk_size *= 1024*1024*1024; 267 268 if (disk_size < 9*1024*1024) { 269 fprintf(stderr, "Invalid argument: size '%s' is too small.\n\n", argv[1]); 270 usage(); 271 } else if (disk_size > MAX_DISK_SIZE) { 272 fprintf(stderr, "Invalid argument: size '%s' is too large.\n\n", argv[1]); 273 usage(); 274 } 275 276 sectors_per_disk = disk_size / BYTES_PER_SECTOR; 277 sectors_per_fat = get_sectors_per_fat( disk_size, get_sectors_per_cluster( disk_size ) ); 278 279 boot_sector_init( s_boot_sector, s_fsinfo_sector, disk_size, NULL ); 280 fat_init( s_fat_head ); 281 282 f = fopen( argv[2], "wb" ); 283 if ( !f ) { 284 fprintf(stderr, "Could not create file '%s': %s\n", argv[2], strerror(errno)); 285 goto FailWrite; 286 } 287 288 /* here's the layout: 289 * 290 * boot_sector 291 * fsinfo_sector 292 * empty 293 * backup boot sector 294 * backup fsinfo sector 295 * RESERVED_SECTORS - 4 empty sectors (if backup sectors), or RESERVED_SECTORS - 2 (if no backup) 296 * first fat 297 * second fat 298 * zero sectors 299 */ 300 301 if ( write_sector( f, s_boot_sector ) ) goto FailWrite; 302 if ( write_sector( f, s_fsinfo_sector ) ) goto FailWrite; 303 if ( BACKUP_BOOT_SECTOR > 0 ) { 304 if ( write_empty( f, BACKUP_BOOT_SECTOR - 2 ) ) goto FailWrite; 305 if ( write_sector( f, s_boot_sector ) ) goto FailWrite; 306 if ( write_sector( f, s_fsinfo_sector ) ) goto FailWrite; 307 if ( write_empty( f, RESERVED_SECTORS - 2 - BACKUP_BOOT_SECTOR ) ) goto FailWrite; 308 } 309 else if ( write_empty( f, RESERVED_SECTORS - 2 ) ) goto FailWrite; 310 311 if ( write_sector( f, s_fat_head ) ) goto FailWrite; 312 if ( write_empty( f, sectors_per_fat-1 ) ) goto FailWrite; 313 314 if ( write_sector( f, s_fat_head ) ) goto FailWrite; 315 if ( write_empty( f, sectors_per_fat-1 ) ) goto FailWrite; 316 317 if ( write_empty( f, sectors_per_disk - RESERVED_SECTORS - 2*sectors_per_fat ) ) goto FailWrite; 318 319 fclose(f); 320 return 0; 321 322 FailWrite: 323 if (f != NULL) { 324 fclose(f); 325 unlink( argv[2] ); 326 fprintf(stderr, "File '%s' was not created.\n", argv[2]); 327 } 328 return 1; 329 } 330
