forked from nerd2/gexto
/
group_descriptor.go
240 lines (206 loc) · 7.64 KB
/
group_descriptor.go
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package gexto
import (
"github.com/lunixbochs/struc"
"math/bits"
)
type GroupDescriptor struct {
Block_bitmap_lo uint32 `struc:"uint32,little"`
Inode_bitmap_lo uint32 `struc:"uint32,little"`
Inode_table_lo uint32 `struc:"uint32,little"`
Free_blocks_count_lo uint16 `struc:"uint16,little"`
Free_inodes_count_lo uint16 `struc:"uint16,little"`
Used_dirs_count_lo uint16 `struc:"uint16,little"`
Flags uint16 `struc:"uint16,little"`
Exclude_bitmap_lo uint32 `struc:"uint32,little"`
Block_bitmap_csum_lo uint16 `struc:"uint16,little"`
Inode_bitmap_csum_lo uint16 `struc:"uint16,little"`
Itable_unused_lo uint16 `struc:"uint16,little"`
Checksum uint16 `struc:"uint16,little"`
Block_bitmap_hi uint32 `struc:"uint32,little"`
Inode_bitmap_hi uint32 `struc:"uint32,little"`
Inode_table_hi uint32 `struc:"uint32,little"`
Free_blocks_count_hi uint16 `struc:"uint16,little"`
Free_inodes_count_hi uint16 `struc:"uint16,little"`
Used_dirs_count_hi uint16 `struc:"uint16,little"`
Itable_unused_hi uint16 `struc:"uint16,little"`
Exclude_bitmap_hi uint32 `struc:"uint32,little"`
Block_bitmap_csum_hi uint16 `struc:"uint16,little"`
Inode_bitmap_csum_hi uint16 `struc:"uint16,little"`
Reserved uint32 `struc:"uint32,little"`
fs *fs
num int64
address int64
};
func (bgd *GroupDescriptor) GetInodeBitmapLoc() int64 {
if bgd.fs.sb.FeatureIncompat64bit() {
return (int64(bgd.Inode_bitmap_hi) << 32) | int64(bgd.Inode_bitmap_lo)
} else {
return int64(bgd.Inode_bitmap_lo)
}
}
func (bgd *GroupDescriptor) GetInodeTableLoc() int64 {
if bgd.fs.sb.FeatureIncompat64bit() {
return (int64(bgd.Inode_table_hi) << 32) | int64(bgd.Inode_table_lo)
} else {
return int64(bgd.Inode_table_lo)
}
}
func (bgd *GroupDescriptor) GetBlockBitmapLoc() int64 {
if bgd.fs.sb.FeatureIncompat64bit() {
return (int64(bgd.Block_bitmap_hi) << 32) | int64(bgd.Block_bitmap_lo)
} else {
return int64(bgd.Block_bitmap_lo)
}
}
func (bgd *GroupDescriptor) UpdateCsumAndWriteback() {
cs := NewChecksummer(bgd.fs.sb)
cs.Write(bgd.fs.sb.Uuid[:])
cs.WriteUint32(uint32(bgd.num))
bgd.Checksum = 0
struc.Pack(cs, bgd)
bgd.Checksum = uint16(cs.Get() & 0xFFFF)
bgd.fs.dev.Seek(bgd.address, 0)
struc.Pack(bgd.fs.dev, bgd)
}
func(bgd *GroupDescriptor) GetFreeInode() *Inode {
start := bgd.GetInodeBitmapLoc() * bgd.fs.sb.GetBlockSize()
bgd.fs.dev.Seek(start, 0)
subInodeNum := int64(-1)
if bgd.Flags & BG_INODE_UNINIT != 0 {
b := make([]byte, bgd.fs.sb.InodePer_group/8)
b[0] = 1
bgd.fs.dev.Write(b)
bgd.Flags &= 0xFFFF ^ BG_INODE_UNINIT
bgd.UpdateCsumAndWriteback()
subInodeNum = 0
} else {
// Find free inode in bitmap
for i := 0; i < int(bgd.fs.sb.InodePer_group/8); i++ {
b := make([]byte, 1)
bgd.fs.dev.Read(b)
if b[0] != 0xFF {
//log.Println("free at ", bgd.num, start, i)
bitNum := bits.TrailingZeros8(^b[0])
subInodeNum = int64(i)*8 + int64(bitNum)
b[0] |= 1 << uint(bitNum)
bgd.fs.dev.Seek(-1, 1)
bgd.fs.dev.Write(b)
break
}
}
}
if subInodeNum < 0 {
//log.Println("!!!! bgd full !!!", bgd.num, bgd.Free_inodes_count_lo)
return nil
}
if bgd.Flags & BG_INODE_ZEROED == 0 {
bgd.fs.dev.Seek(bgd.GetInodeTableLoc() * bgd.fs.sb.GetBlockSize(), 0)
bgd.fs.dev.Write(make([]byte, int64(bgd.fs.sb.InodePer_group) / int64(bgd.fs.sb.Inode_size)))
bgd.Flags |= BG_INODE_ZEROED
bgd.UpdateCsumAndWriteback()
}
// Update inode bitmap checksum
checksummer := NewChecksummer(bgd.fs.sb)
checksummer.Write(bgd.fs.sb.Uuid[:])
bgd.fs.dev.Seek(start, 0)
b := make([]byte, int64(bgd.fs.sb.InodePer_group) / 8)
bgd.fs.dev.Read(b)
checksummer.Write(b)
bgd.Inode_bitmap_csum_lo = uint16(checksummer.Get() & 0xFFFF)
bgd.Inode_bitmap_csum_hi = uint16(checksummer.Get() >> 16)
bgd.Free_inodes_count_lo--
bgd.Itable_unused_lo--
bgd.UpdateCsumAndWriteback()
bgd.fs.sb.Free_inodeCount--
bgd.fs.sb.UpdateCsumAndWriteback()
// Insert in Inode table
inode := &Inode{
Mode: 0,
Links_count: 1,
Flags: 524288, //TODO: what
BlockOrExtents: [60]byte{0x0a, 0xf3, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00},
fs: bgd.fs,
address: bgd.GetInodeTableLoc() * bgd.fs.sb.GetBlockSize() + subInodeNum * int64(bgd.fs.sb.Inode_size),
num: 1 + bgd.num * int64(bgd.fs.sb.InodePer_group) + subInodeNum,
}
inode.UpdateCsumAndWriteback()
return inode
}
func (bgd *GroupDescriptor) setBitRange(offset int64, start int64, n int64) {
if start < 0 || start > int64(bgd.fs.sb.BlockPer_group) {
return
}
n = (n + bgd.fs.sb.GetBlockSize() - 1) / bgd.fs.sb.GetBlockSize()
for i := start; i < start + n; i++ {
b := make([]byte, 1)
bgd.fs.dev.Seek(offset + i / 8, 0)
bgd.fs.dev.Read(b)
b[0] |= 1 << uint(i % 8)
bgd.fs.dev.Seek(-1, 1)
bgd.fs.dev.Write(b)
}
bgd.Free_blocks_count_lo-=uint16(n)
}
func (bgd *GroupDescriptor) GetFreeBlocks(n int64) (int64, int64) {
// Find free block in bitmap
start := bgd.GetBlockBitmapLoc() * bgd.fs.sb.GetBlockSize()
if bgd.Flags & BG_BLOCK_UNINIT != 0 {
bgd.fs.dev.Seek(start, 0)
bgd.fs.dev.Write(make([]byte, bgd.fs.sb.BlockPer_group/8))
bgd.Free_blocks_count_lo = uint16(bgd.fs.sb.BlockPer_group)
if !bgd.fs.sb.FeatureRoCompatSparse_super() || bgd.num <= 1 || bgd.num % 3 == 0 || bgd.num % 5 == 0 || bgd.num % 7 == 0 {
bgd.setBitRange(start, 0, bgd.fs.sb.GetBlockSize()+(bgd.fs.sb.numBlockGroups*32)+int64(bgd.fs.sb.Reserved_gdt_blocks)*bgd.fs.sb.GetBlockSize())
}
bgd.setBitRange(start, bgd.GetInodeBitmapLoc() - bgd.num * int64(bgd.fs.sb.BlockPer_group) * bgd.fs.sb.GetBlockSize(), int64(bgd.fs.sb.InodePer_group)/8)
bgd.setBitRange(start, bgd.GetBlockBitmapLoc() - bgd.num * int64(bgd.fs.sb.BlockPer_group) * bgd.fs.sb.GetBlockSize(), int64(bgd.fs.sb.BlockPer_group)/8)
bgd.setBitRange(start, bgd.GetInodeTableLoc() - bgd.num * int64(bgd.fs.sb.BlockPer_group) * bgd.fs.sb.GetBlockSize(), int64(bgd.fs.sb.Inode_size)*int64(bgd.fs.sb.InodePer_group)/8)
bgd.UpdateCsumAndWriteback()
blocksFree := int64(0)
for i := int64(0); i < bgd.fs.sb.numBlockGroups; i++ {
blocksFree += int64(bgd.fs.getBlockGroupDescriptor(i).Free_blocks_count_lo)
}
bgd.fs.sb.Free_blockCount_lo = uint32(blocksFree)
bgd.fs.sb.UpdateCsumAndWriteback()
bgd.Flags &= 0xFFFF ^ BG_BLOCK_UNINIT
bgd.UpdateCsumAndWriteback()
}
subBlockNum := int64(-1)
bgd.fs.dev.Seek(start, 0)
for i := 0; i < int(bgd.fs.sb.BlockPer_group/8); i++ {
b := make([]byte, 1)
bgd.fs.dev.Read(b)
if b[0] != 0xFF {
bitNum := bits.TrailingZeros8(^b[0])
numFree := bits.TrailingZeros8(uint8((uint16(b[0]) | 0x100) >> uint(bitNum)))
//log.Println(bgd.num, i, b[0], bitNum, numFree, n)
if n > int64(numFree) {
n = int64(numFree)
}
subBlockNum = int64(i)*8 + int64(bitNum)
b[0] |= (1 << uint(bitNum+int(n))) - 1
//log.Println("Found free blocks. GD", bgd.num, subBlockNum, bitNum, b[0], n)
bgd.fs.dev.Seek(-1, 1)
bgd.fs.dev.Write(b)
break
}
}
if subBlockNum < 0 {
return 0, 0
}
// Update block bitmap checksum
checksummer := NewChecksummer(bgd.fs.sb)
checksummer.Write(bgd.fs.sb.Uuid[:])
bgd.fs.dev.Seek(start, 0)
b := make([]byte, int64(bgd.fs.sb.ClusterPer_group) / 8)
bgd.fs.dev.Read(b)
checksummer.Write(b)
bgd.Block_bitmap_csum_lo = uint16(checksummer.Get() & 0xFFFF)
bgd.Block_bitmap_csum_hi = uint16(checksummer.Get() >> 16)
newFreeBlocks := ((uint32(bgd.Free_blocks_count_hi) << 16) | uint32(bgd.Free_blocks_count_lo)) - uint32(n)
bgd.Free_blocks_count_hi = uint16(newFreeBlocks >> 16)
bgd.Free_blocks_count_lo = uint16(newFreeBlocks)
bgd.UpdateCsumAndWriteback()
bgd.fs.sb.Free_blockCount_lo-=uint32(n)
bgd.fs.sb.UpdateCsumAndWriteback()
return bgd.address / bgd.fs.sb.GetBlockSize() + subBlockNum - 1, n
}