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- implemented reading MBR from file (TODO: read boot sector)

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- value of 'sectors_per_fat' must be 32 bit (for FAT32)
- some other small fixes
This commit is contained in:
Volker Ruppert 2010-12-31 15:39:27 +00:00
parent 2946d0ac26
commit 6d0b6c69b9
2 changed files with 78 additions and 15 deletions
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85
bochs/iodev/vvfat.cc
View File

@ -1,5 +1,5 @@
/////////////////////////////////////////////////////////////////////////
// $Id: vvfat.cc,v 1.6 2010-12-30 12:30:58 vruppert Exp $
// $Id: vvfat.cc,v 1.7 2010-12-31 15:39:27 vruppert Exp $
/////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2010 The Bochs Project
@ -25,11 +25,12 @@
// ADDITIONS:
// - win32 specific directory functions (required for MSVC)
// - configurable disk geometry
// - read MBR from file
// TODO:
// - write support
// - FAT32 support
// - read MBR and boot sector from file
// - read boot sector from file
// Define BX_PLUGGABLE in files that can be compiled into plugins. For
// platforms that require a special tag on exported symbols, BX_PLUGGABLE
@ -1001,7 +1002,7 @@ int vvfat_image_t::init_directories(const char* dirname)
infosector = (infosector_t*)(first_sectors + (offset_to_bootsector + 1) * 0x200);
infosector->signature1 = htod32(0x41615252);
infosector->signature2 = htod32(0x61417272);
infosector->free_clusters = htod32(cluster_count - cluster - 2);
infosector->free_clusters = htod32(cluster_count - cluster + 2);
infosector->mra_cluster = htod32(2);
infosector->magic[0] = 0x55;
infosector->magic[1] = 0xaa;
@ -1010,21 +1011,77 @@ int vvfat_image_t::init_directories(const char* dirname)
return 0;
}
bx_bool vvfat_image_t::read_sector_from_file(const char *path, Bit8u *buffer, Bit32u sector)
{
int fd = ::open(path, O_RDONLY
#ifdef O_BINARY
| O_BINARY
#endif
#ifdef O_LARGEFILE
| O_LARGEFILE
#endif
);
if (fd < 0)
return 0;
int offset = sector * 0x200;
if (::lseek(fd, offset, SEEK_SET) != offset) {
return 0;
::close(fd);
}
int result = ::read(fd, buffer, 0x200);
::close(fd);
bx_bool bootsig = ((buffer[0x1fe] == 0x55) && (buffer[0x1ff] == 0xaa));
return (result == 0x200) && bootsig;
}
int vvfat_image_t::open(const char* dirname)
{
Bit32u size_in_mb;
char path[BX_PATHNAME_LEN];
Bit8u sector_buffer[0x200];
// TODO: read MBR file (if present) and use it's values
if (cylinders == 0) {
cylinders = 1024;
heads = 16;
sectors = 63;
use_mbr_file = 0;
use_boot_file = 0;
fat_type = 0;
snprintf(path, BX_PATHNAME_LEN, "%s/%s", dirname, VVFAT_MBR);
if (read_sector_from_file(path, sector_buffer, 0)) {
mbr_t* real_mbr = (mbr_t*)sector_buffer;
partition_t* partition = &(real_mbr->partition[0]);
if ((partition->fs_type != 0) && (partition->length_sector_long > 0)) {
if ((partition->fs_type == 0x06) || (partition->fs_type == 0x0e)) {
fat_type = 16;
} else if ((partition->fs_type == 0x0b) || (partition->fs_type == 0x0c)) {
fat_type = 32;
} else {
BX_ERROR(("MBR file: unsupported FS type = 0x%02x", partition->fs_type));
}
if (fat_type != 0) {
sector_count = partition->start_sector_long + partition->length_sector_long;
sectors = partition->start_sector_long;
if (partition->end_CHS.head > 16) {
heads = 16;
} else {
heads = partition->end_CHS.head + 1;
}
cylinders = sector_count / (heads * sectors);
memcpy(&first_sectors[0], sector_buffer, 0x200);
use_mbr_file = 1;
}
}
}
if (!use_mbr_file) {
if (cylinders == 0) {
cylinders = 1024;
heads = 16;
sectors = 63;
}
sector_count = cylinders * heads * sectors;
}
offset_to_bootsector = sectors;
sector_count = cylinders * heads * sectors;
hd_size = sector_count * 512;
size_in_mb = (Bit32u)(hd_size >> 20);
if (size_in_mb >= 2047) {
if ((size_in_mb >= 2047) || (fat_type == 32)) {
fat_type = 32;
sectors_per_cluster = 8;
first_cluster_of_root_dir = 2;
@ -1039,8 +1096,10 @@ int vvfat_image_t::open(const char* dirname)
sectors_per_cluster = 32;
} else if (size_in_mb >= 255) {
sectors_per_cluster = 16;
} else {
} else if (size_in_mb >= 127) {
sectors_per_cluster = 8;
} else {
sectors_per_cluster = 4;
}
first_cluster_of_root_dir = 0;
root_entries = 512;
@ -1050,7 +1109,7 @@ int vvfat_image_t::open(const char* dirname)
current_cluster = 0xffff;
current_fd = 0;
if (offset_to_bootsector > 0)
if ((!use_mbr_file) && (offset_to_bootsector > 0))
init_mbr();
init_directories(dirname);
@ -1242,7 +1301,7 @@ ssize_t vvfat_image_t::write(const void* buf, size_t count)
{
Bit32u scount = (Bit32u)(count / 512);
if (sector_num < (offset_to_bootsector + 1))
if (sector_num < (offset_to_bootsector + reserved_sectors))
return -1;
BX_ERROR(("VVFAT write not supported yet: sector=%d, count=%d", sector_num, scount));

8
bochs/iodev/vvfat.h
View File

@ -1,5 +1,5 @@
/////////////////////////////////////////////////////////////////////////
// $Id: vvfat.h,v 1.3 2010-12-30 12:30:58 vruppert Exp $
// $Id: vvfat.h,v 1.4 2010-12-31 15:39:27 vruppert Exp $
/////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2010 The Bochs Project
@ -135,6 +135,7 @@ class vvfat_image_t : public device_image_t
int find_mapping_for_cluster_aux(int cluster_num, int index1, int index2);
mapping_t* find_mapping_for_cluster(int cluster_num);
int read_cluster(int cluster_num);
bx_bool read_sector_from_file(const char *path, Bit8u *buffer, Bit32u sector);
Bit8u *first_sectors;
Bit32u offset_to_bootsector;
@ -144,7 +145,7 @@ class vvfat_image_t : public device_image_t
Bit16u cluster_size;
Bit8u sectors_per_cluster;
Bit8u sectors_per_fat;
Bit32u sectors_per_fat;
Bit32u sector_count;
Bit32u cluster_count; // total number of clusters of this partition
Bit32u max_fat_value;
@ -163,6 +164,9 @@ class vvfat_image_t : public device_image_t
const char *path;
Bit32u sector_num;
bx_bool use_mbr_file;
bx_bool use_boot_file;
};
#endif