305 lines
10 KiB
C
305 lines
10 KiB
C
/* mksdcard.c
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**
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** Copyright 2007, The Android Open Source Project
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**
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** Redistribution and use in source and binary forms, with or without
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** modification, are permitted provided that the following conditions are met:
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** * Redistributions of source code must retain the above copyright
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** notice, this list of conditions and the following disclaimer.
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** * Redistributions in binary form must reproduce the above copyright
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** notice, this list of conditions and the following disclaimer in the
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** documentation and/or other materials provided with the distribution.
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** * Neither the name of Google Inc. nor the names of its contributors may
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** be used to endorse or promote products derived from this software
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** without specific prior written permission.
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**
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** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR
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** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/* a simple and portable program used to generate a blank FAT32 image file
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*
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* usage: mksdcard [-l label] <size> <filename>
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*/
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#include <time.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <unistd.h>
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/* believe me, you *don't* want to change these constants !! */
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#define BYTES_PER_SECTOR 512
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#define RESERVED_SECTORS 32
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#define BACKUP_BOOT_SECTOR 6
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#define NUM_FATS 2
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typedef long long Wide; /* might be something else if you don't use GCC */
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typedef unsigned char Byte;
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typedef Byte* Bytes;
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#define BYTE_(p,i) (((Bytes)(p))[(i)])
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#define POKEB(p,v) BYTE_(p,0) = (Byte)(v)
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#define POKES(p,v) ( BYTE_(p,0) = (Byte)(v), BYTE_(p,1) = (Byte)((v) >> 8) )
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#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) )
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static Byte s_boot_sector [ BYTES_PER_SECTOR ]; /* boot sector */
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static Byte s_fsinfo_sector [ BYTES_PER_SECTOR ]; /* FS Info sector */
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static Byte s_fat_head [ BYTES_PER_SECTOR ]; /* first FAT sector */
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static Byte s_zero_sector [ BYTES_PER_SECTOR ]; /* empty sector */
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/* this is the date and time when creating the disk */
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static int
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get_serial_id( void )
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{
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unsigned short lo, hi, mid;
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time_t now = time(NULL);
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struct tm tm = gmtime( &now )[0];
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lo = (unsigned short)(tm.tm_mday + ((tm.tm_mon+1) << 8) + (tm.tm_sec << 8));
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hi = (unsigned short)(tm.tm_min + (tm.tm_hour << 8) + (tm.tm_year + 1900));
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return lo + (hi << 16);
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}
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static int
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get_sectors_per_cluster( Wide disk_size )
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{
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Wide disk_MB = disk_size/(1024*1024);
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if (disk_MB < 260)
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return 1;
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if (disk_MB < 8192)
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return 4;
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if (disk_MB < 16384)
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return 8;
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if (disk_MB < 32768)
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return 16;
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return 32;
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}
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static int
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get_sectors_per_fat( Wide disk_size, int sectors_per_cluster )
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{
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Wide divider;
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/* weird computation from MS - see fatgen103.doc for details */
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disk_size -= RESERVED_SECTORS * BYTES_PER_SECTOR; /* don't count 32 reserved sectors */
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disk_size /= BYTES_PER_SECTOR; /* disk size in sectors */
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divider = ((256 * sectors_per_cluster) + NUM_FATS) / 2;
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return (int)( (disk_size + (divider-1)) / divider );
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}
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static void
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boot_sector_init( Bytes boot, Bytes info, Wide disk_size, const char* label )
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{
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int sectors_per_cluster = get_sectors_per_cluster(disk_size);
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int sectors_per_fat = get_sectors_per_fat(disk_size, sectors_per_cluster);
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int sectors_per_disk = (int)(disk_size / BYTES_PER_SECTOR);
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int serial_id = get_serial_id();
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int free_count;
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if (label == NULL)
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label = "SDCARD";
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POKEB(boot, 0xeb);
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POKEB(boot+1, 0x5a);
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POKEB(boot+2, 0x90);
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strcpy( (char*)boot + 3, "MSWIN4.1" );
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POKES( boot + 0x0b, BYTES_PER_SECTOR ); /* sector size */
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POKEB( boot + 0xd, sectors_per_cluster ); /* sectors per cluster */
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POKES( boot + 0xe, RESERVED_SECTORS ); /* reserved sectors before first FAT */
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POKEB( boot + 0x10, NUM_FATS ); /* number of FATs */
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POKES( boot + 0x11, 0 ); /* max root directory entries for FAT12/FAT16, 0 for FAT32 */
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POKES( boot + 0x13, 0 ); /* total sectors, 0 to use 32-bit value at offset 0x20 */
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POKEB( boot + 0x15, 0xF8 ); /* media descriptor, 0xF8 == hard disk */
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POKES( boot + 0x16, 0 ); /* Sectors per FAT for FAT12/16, 0 for FAT32 */
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POKES( boot + 0x18, 9 ); /* Sectors per track (whatever) */
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POKES( boot + 0x1a, 2 ); /* Number of heads (whatever) */
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POKEW( boot + 0x1c, 0 ); /* Hidden sectors */
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POKEW( boot + 0x20, sectors_per_disk ); /* Total sectors */
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/* extension */
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POKEW( boot + 0x24, sectors_per_fat ); /* Sectors per FAT */
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POKES( boot + 0x28, 0 ); /* FAT flags */
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POKES( boot + 0x2a, 0 ); /* version */
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POKEW( boot + 0x2c, 2 ); /* cluster number of root directory start */
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POKES( boot + 0x30, 1 ); /* sector number of FS information sector */
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POKES( boot + 0x32, BACKUP_BOOT_SECTOR ); /* sector number of a copy of this boot sector */
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POKEB( boot + 0x40, 0x80 ); /* physical drive number */
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POKEB( boot + 0x42, 0x29 ); /* extended boot signature ?? */
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POKEW( boot + 0x43, serial_id ); /* serial ID */
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strncpy( (char*)boot + 0x47, label, 11 ); /* Volume Label */
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memcpy( boot + 0x52, "FAT32 ", 8 ); /* FAT system type, padded with 0x20 */
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POKEB( boot + BYTES_PER_SECTOR-2, 0x55 ); /* boot sector signature */
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POKEB( boot + BYTES_PER_SECTOR-1, 0xAA );
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/* FSInfo sector */
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free_count = sectors_per_disk - 32 - 2*sectors_per_fat;
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POKEW( info + 0, 0x41615252 );
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POKEW( info + 484, 0x61417272 );
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POKEW( info + 488, free_count ); /* number of free clusters */
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POKEW( info + 492, 3 ); /* next free clusters, 0-1 reserved, 2 is used for the root dir */
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POKEW( info + 508, 0xAA550000 );
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}
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static void
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fat_init( Bytes fat )
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{
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POKEW( fat, 0x0ffffff8 ); /* reserve cluster 1, media id in low byte */
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POKEW( fat + 4, 0x0fffffff ); /* reserve cluster 2 */
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POKEW( fat + 8, 0x0fffffff ); /* end of clust chain for root dir */
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}
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static int
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write_sector( FILE* file, Bytes sector )
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{
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return fwrite( sector, 1, 512, file ) != 512;
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}
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static int
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write_empty( FILE* file, Wide count )
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{
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static Byte empty[64*1024];
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count *= 512;
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while (count > 0) {
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int len = sizeof(empty);
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if (len > count)
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len = count;
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if ( fwrite( empty, 1, len, file ) != (size_t)len )
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return 1;
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count -= len;
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}
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return 0;
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}
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static void usage (void)
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{
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fprintf(stderr, "mksdcard: create a blank FAT32 image to be used with the Android emulator\n" );
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fprintf(stderr, "usage: mksdcard [-l label] <size> <file>\n\n");
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fprintf(stderr, " if <size> is a simple integer, it specifies a size in bytes\n" );
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fprintf(stderr, " if <size> is an integer followed by 'K', it specifies a size in KiB\n" );
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fprintf(stderr, " if <size> is an integer followed by 'M', it specifies a size in MiB\n" );
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exit(1);
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}
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int main( int argc, char** argv )
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{
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Wide disk_size;
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int sectors_per_fat;
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int sectors_per_disk;
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char* end;
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const char* label = NULL;
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FILE* f;
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for ( ; argc > 1 && argv[1][0] == '-'; argc--, argv++ )
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{
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char* arg = argv[1] + 1;
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switch (arg[0]) {
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case 'l':
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if (arg[1] != 0)
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arg += 2;
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else {
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argc--;
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argv++;
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if (argc <= 1)
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usage();
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arg = argv[1];
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}
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label = arg;
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break;
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default:
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usage();
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}
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}
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if (argc != 3)
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usage();
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disk_size = strtol( argv[1], &end, 10 );
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if (disk_size == 0 && errno == EINVAL)
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usage();
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if (*end == 'K')
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disk_size *= 1024;
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else if (*end == 'M')
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disk_size *= 1024*1024;
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if (disk_size < 8*1024*1024)
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fprintf(stderr, "### WARNING : SD Card images < 8 MB cannot be used with the Android emulator\n");
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sectors_per_disk = disk_size / 512;
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sectors_per_fat = get_sectors_per_fat( disk_size, get_sectors_per_cluster( disk_size ) );
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boot_sector_init( s_boot_sector, s_fsinfo_sector, disk_size, NULL );
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fat_init( s_fat_head );
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f = fopen( argv[2], "wb" );
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if ( !f ) {
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fprintf(stderr, "could not create file '%s', aborting...\n", argv[2] );
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}
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/* here's the layout:
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*
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* boot_sector
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* fsinfo_sector
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* empty
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* backup boot sector
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* backup fsinfo sector
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* RESERVED_SECTORS - 4 empty sectors (if backup sectors), or RESERVED_SECTORS - 2 (if no backup)
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* first fat
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* second fat
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* zero sectors
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*/
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if ( write_sector( f, s_boot_sector ) ) goto FailWrite;
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if ( write_sector( f, s_fsinfo_sector ) ) goto FailWrite;
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if ( BACKUP_BOOT_SECTOR > 0 ) {
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if ( write_empty( f, BACKUP_BOOT_SECTOR - 2 ) ) goto FailWrite;
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if ( write_sector( f, s_boot_sector ) ) goto FailWrite;
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if ( write_sector( f, s_fsinfo_sector ) ) goto FailWrite;
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if ( write_empty( f, RESERVED_SECTORS - 2 - BACKUP_BOOT_SECTOR ) ) goto FailWrite;
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}
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else
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if ( write_empty( f, RESERVED_SECTORS - 2 ) ) goto FailWrite;
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if ( write_sector( f, s_fat_head ) ) goto FailWrite;
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if ( write_empty( f, sectors_per_fat-1 ) ) goto FailWrite;
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if ( write_sector( f, s_fat_head ) ) goto FailWrite;
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if ( write_empty( f, sectors_per_fat-1 ) ) goto FailWrite;
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if ( write_empty( f, sectors_per_disk - RESERVED_SECTORS - 2*sectors_per_fat ) ) goto FailWrite;
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fclose(f);
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return 0;
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FailWrite:
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fprintf(stderr, "could not write to '%s', aborting...\n", argv[2] );
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unlink( argv[2] );
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fclose(f);
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return 1;
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}
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