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dolphin/Source/Core/Common/SDCardUtil.cpp

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// Copyright 2009 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
/* mksdcard.c
**
** Copyright 2007, The Android Open Source Project
**
** 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.
** * Neither the name of Google Inc. nor the names of its contributors may
** be used to endorse or promote products derived from this software
** without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY Google Inc. ``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 Google Inc. 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.
*/
// A simple and portable piece of code used to generate a blank FAT32 image file.
// Modified for Dolphin.
#include "Common/SDCardUtil.h"
#include <algorithm>
#include <cstddef>
#include <cstdio>
#include <cstring>
#include <ctime>
#include <string>
#include "Common/CommonFuncs.h"
#include "Common/CommonTypes.h"
#include "Common/IOFile.h"
#include "Common/Logging/Log.h"
#ifndef _WIN32
#include <unistd.h> // for unlink()
#endif
namespace Common
{
// Believe me, you *don't* want to change these constants !!
enum : u32
{
BYTES_PER_SECTOR = 512,
RESERVED_SECTORS = 32,
BACKUP_BOOT_SECTOR = 6,
NUM_FATS = 2
};
static u8 s_boot_sector[BYTES_PER_SECTOR]; /* Boot sector */
static u8 s_fsinfo_sector[BYTES_PER_SECTOR]; /* FS Info sector */
static u8 s_fat_head[BYTES_PER_SECTOR]; /* First FAT sector */
template <typename T>
static void WriteData(u8* out, T data)
{
std::memcpy(out, &data, sizeof(data));
}
/* This is the date and time when creating the disk */
static unsigned int get_serial_id()
{
const time_t now = std::time(nullptr);
const struct tm tm = std::gmtime(&now)[0];
const u16 lo = static_cast<u16>(tm.tm_mday + ((tm.tm_mon + 1) << 8) + (tm.tm_sec << 8));
const u16 hi = static_cast<u16>(tm.tm_min + (tm.tm_hour << 8) + (tm.tm_year + 1900));
return lo + (hi << 16);
}
static unsigned int get_sectors_per_cluster(u64 disk_size)
{
u64 disk_MB = disk_size / (1024 * 1024);
if (disk_MB < 260)
return 1;
if (disk_MB < 8192)
return 4;
if (disk_MB < 16384)
return 8;
if (disk_MB < 32768)
return 16;
return 32;
}
static unsigned int get_sectors_per_fat(u64 disk_size, u32 sectors_per_cluster)
{
/* Weird computation from MS - see fatgen103.doc for details */
disk_size -= RESERVED_SECTORS * BYTES_PER_SECTOR; /* Don't count 32 reserved sectors */
disk_size /= BYTES_PER_SECTOR; /* Disk size in sectors */
const u64 divider = ((256 * sectors_per_cluster) + NUM_FATS) / 2;
return static_cast<u32>((disk_size + (divider - 1)) / divider);
}
static void boot_sector_init(u8* boot, u8* info, u64 disk_size, const char* label)
{
const u32 sectors_per_cluster = get_sectors_per_cluster(disk_size);
const u32 sectors_per_fat = get_sectors_per_fat(disk_size, sectors_per_cluster);
const u32 sectors_per_disk = static_cast<u32>(disk_size / BYTES_PER_SECTOR);
const u32 serial_id = get_serial_id();
if (label == nullptr)
label = "DOLPHINSD";
WriteData<u8>(boot, 0xeb);
WriteData<u8>(boot + 1, 0x5a);
WriteData<u8>(boot + 2, 0x90);
strcpy((char*)boot + 3, "MSWIN4.1");
WriteData<u16>(boot + 0x0b, BYTES_PER_SECTOR); // Sector size
WriteData<u8>(boot + 0xd, sectors_per_cluster); // Sectors per cluster
WriteData<u16>(boot + 0xe, RESERVED_SECTORS); // Reserved sectors before first FAT
WriteData<u8>(boot + 0x10, NUM_FATS); // Number of FATs
WriteData<u16>(boot + 0x11, 0); // Max root directory entries for FAT12/FAT16, 0 for FAT32
WriteData<u16>(boot + 0x13, 0); // Total sectors, 0 to use 32-bit value at offset 0x20
WriteData<u8>(boot + 0x15, 0xF8); // Media descriptor, 0xF8 == hard disk
WriteData<u16>(boot + 0x16, 0); // Sectors per FAT for FAT12/16, 0 for FAT32
WriteData<u16>(boot + 0x18, 9); // Sectors per track (whatever)
WriteData<u16>(boot + 0x1a, 2); // Number of heads (whatever)
WriteData<u32>(boot + 0x1c, 0); // Hidden sectors
WriteData<u32>(boot + 0x20, sectors_per_disk); // Total sectors
// Extension
WriteData<u32>(boot + 0x24, sectors_per_fat); // Sectors per FAT
WriteData<u16>(boot + 0x28, 0); // FAT flags
WriteData<u16>(boot + 0x2a, 0); // Version
WriteData<u32>(boot + 0x2c, 2); // Cluster number of root directory start
WriteData<u16>(boot + 0x30, 1); // Sector number of FS information sector
WriteData<u16>(boot + 0x32, BACKUP_BOOT_SECTOR); // Sector number of a copy of this boot sector
WriteData<u8>(boot + 0x40, 0x80); // Physical drive number
WriteData<u8>(boot + 0x42, 0x29); // Extended boot signature ??
WriteData<u32>(boot + 0x43, serial_id); // Serial ID
strncpy((char*)boot + 0x47, label, 11); // Volume Label
memcpy(boot + 0x52, "FAT32 ", 8); // FAT system type, padded with 0x20
WriteData<u8>(boot + BYTES_PER_SECTOR - 2, 0x55); // Boot sector signature
WriteData<u8>(boot + BYTES_PER_SECTOR - 1, 0xAA);
/* FSInfo sector */
const u32 free_count = sectors_per_disk - 32 - 2 * sectors_per_fat;
WriteData<u32>(info + 0, 0x41615252);
WriteData<u32>(info + 484, 0x61417272);
WriteData<u32>(info + 488, free_count); // Number of free clusters
// Next free clusters, 0-1 reserved, 2 is used for the root dir
WriteData<u32>(info + 492, 3);
WriteData<u32>(info + 508, 0xAA550000);
}
static void fat_init(u8* fat)
{
WriteData<u32>(fat, 0x0ffffff8); // Reserve cluster 1, media id in low byte
WriteData<u32>(fat + 4, 0x0fffffff); // Reserve cluster 2
WriteData<u32>(fat + 8, 0x0fffffff); // End of cluster chain for root dir
}
static bool write_sector(File::IOFile& file, const u8* sector)
{
return file.WriteBytes(sector, BYTES_PER_SECTOR);
}
static bool write_empty(File::IOFile& file, std::size_t count)
{
static constexpr u8 empty[64 * 1024] = {};
count *= BYTES_PER_SECTOR;
while (count > 0)
{
const std::size_t len = std::min(sizeof(empty), count);
if (!file.WriteBytes(empty, len))
return false;
count -= len;
}
return true;
}
bool SDCardCreate(u64 disk_size /*in MB*/, const std::string& filename)
{
// Convert MB to bytes
disk_size *= 1024 * 1024;
if (disk_size < 0x800000 || disk_size > 0x800000000ULL)
{
ERROR_LOG_FMT(COMMON, "Trying to create SD Card image of size {}MB is out of range (8MB-32GB)",
disk_size / (1024 * 1024));
return false;
}
// Pretty unlikely to overflow.
const u32 sectors_per_disk = static_cast<u32>(disk_size / BYTES_PER_SECTOR);
const u32 sectors_per_fat = get_sectors_per_fat(disk_size, get_sectors_per_cluster(disk_size));
boot_sector_init(s_boot_sector, s_fsinfo_sector, disk_size, nullptr);
fat_init(s_fat_head);
File::IOFile file(filename, "wb");
if (!file)
{
ERROR_LOG_FMT(COMMON, "Could not create file '{}', aborting...", filename);
return false;
}
/* Here's the layout:
*
* boot_sector
* fsinfo_sector
* empty
* backup boot sector
* backup fsinfo sector
* RESERVED_SECTORS - 4 empty sectors (if backup sectors), or RESERVED_SECTORS - 2 (if no backup)
* first fat
* second fat
* zero sectors
*/
if (!write_sector(file, s_boot_sector))
goto FailWrite;
if (!write_sector(file, s_fsinfo_sector))
goto FailWrite;
if constexpr (BACKUP_BOOT_SECTOR > 0)
{
if (!write_empty(file, BACKUP_BOOT_SECTOR - 2))
goto FailWrite;
if (!write_sector(file, s_boot_sector))
goto FailWrite;
if (!write_sector(file, s_fsinfo_sector))
goto FailWrite;
if (!write_empty(file, RESERVED_SECTORS - 2 - BACKUP_BOOT_SECTOR))
goto FailWrite;
}
else
{
if (!write_empty(file, RESERVED_SECTORS - 2))
goto FailWrite;
}
if (!write_sector(file, s_fat_head))
goto FailWrite;
if (!write_empty(file, sectors_per_fat - 1))
goto FailWrite;
if (!write_sector(file, s_fat_head))
goto FailWrite;
if (!write_empty(file, sectors_per_fat - 1))
goto FailWrite;
if (!write_empty(file, sectors_per_disk - RESERVED_SECTORS - 2 * sectors_per_fat))
goto FailWrite;
return true;
FailWrite:
ERROR_LOG_FMT(COMMON, "Could not write to '{}', aborting...", filename);
if (unlink(filename.c_str()) < 0)
ERROR_LOG_FMT(COMMON, "unlink({}) failed: {}", filename, LastStrerrorString());
return false;
}
} // namespace Common
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