--- /dev/null
+/*
+ * Acess OS
+ * Ext2 Driver Version 1
+ */
+/**
+ * \file write.c
+ * \brief Second Extended Filesystem Driver
+ * \todo Implement file full write support
+ */
+#define DEBUG 1
+#define VERBOSE 0
+#include "ext2_common.h"
+
+// === PROTOYPES ===
+Uint64 Ext2_Write(tVFS_Node *node, Uint64 offset, Uint64 length, void *buffer);
+Uint32 Ext2_int_AllocateBlock(tExt2_Disk *Disk, Uint32 PrevBlock);
+void Ext2_int_DeallocateBlock(tExt2_Disk *Disk, Uint32 Block);
+ int Ext2_int_AppendBlock(tExt2_Disk *Disk, tExt2_Inode *Inode, Uint32 Block);
+
+// === CODE ===
+/**
+ * \fn Uint64 Ext2_Write(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer)
+ * \brief Write to a file
+ */
+Uint64 Ext2_Write(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer)
+{
+ tExt2_Disk *disk = Node->ImplPtr;
+ tExt2_Inode inode;
+ Uint64 base;
+ Uint64 retLen;
+ Uint block;
+ Uint64 allocSize;
+ int bNewBlocks = 0;
+
+ Debug_HexDump("Ext2_Write", Buffer, Length);
+
+ Ext2_int_ReadInode(disk, Node->Inode, &inode);
+
+ // Get the ammount of space already allocated
+ // - Round size up to block size
+ // - block size is a power of two, so this will work
+ allocSize = (inode.i_size + disk->BlockSize-1) & ~(disk->BlockSize-1);
+
+ // Are we writing to inside the allocated space?
+ if( Offset > allocSize ) return 0;
+
+ if( Offset < allocSize )
+ {
+ // Will we go out of it?
+ if(Offset + Length > allocSize) {
+ bNewBlocks = 1;
+ retLen = allocSize - Offset;
+ } else
+ retLen = Length;
+
+ // Within the allocated space
+ block = Offset / disk->BlockSize;
+ Offset %= disk->BlockSize;
+ base = Ext2_int_GetBlockAddr(disk, inode.i_block, block);
+
+ // Write only block (if only one)
+ if(Offset + retLen <= disk->BlockSize) {
+ VFS_WriteAt(disk->FD, base+Offset, retLen, Buffer);
+ if(!bNewBlocks) return Length;
+ goto addBlocks; // Ugh! A goto, but it seems unavoidable
+ }
+
+ // Write First Block
+ VFS_WriteAt(disk->FD, base+Offset, disk->BlockSize-Offset, Buffer);
+ Buffer += disk->BlockSize-Offset;
+ retLen -= disk->BlockSize-Offset;
+ block ++;
+
+ // Write middle blocks
+ while(retLen > disk->BlockSize)
+ {
+ base = Ext2_int_GetBlockAddr(disk, inode.i_block, block);
+ VFS_WriteAt(disk->FD, base, disk->BlockSize, Buffer);
+ Buffer += disk->BlockSize;
+ retLen -= disk->BlockSize;
+ block ++;
+ }
+
+ // Write last block
+ base = Ext2_int_GetBlockAddr(disk, inode.i_block, block);
+ VFS_WriteAt(disk->FD, base, retLen, Buffer);
+ if(!bNewBlocks) return Length; // Writing in only allocated space
+ }
+ else
+ base = Ext2_int_GetBlockAddr(disk, inode.i_block, allocSize/disk->BlockSize-1);
+
+addBlocks:
+ Warning("[EXT2 ] File extending is untested");
+
+ // Allocate blocks and copy data to them
+ retLen = Length - (allocSize-Offset);
+ while( retLen > disk->BlockSize )
+ {
+ // Allocate a block
+ block = Ext2_int_AllocateBlock(disk, base/disk->BlockSize);
+ if(!block) return Length - retLen;
+ // Add it to this inode
+ if( !Ext2_int_AppendBlock(disk, &inode, block) ) {
+ Ext2_int_DeallocateBlock(disk, block);
+ goto ret;
+ }
+ // Copy data to the node
+ base = block * disk->BlockSize;
+ VFS_WriteAt(disk->FD, base, disk->BlockSize, Buffer);
+ // Update pointer and size remaining
+ inode.i_size += disk->BlockSize;
+ Buffer += disk->BlockSize;
+ retLen -= disk->BlockSize;
+ }
+ // Last block :D
+ block = Ext2_int_AllocateBlock(disk, base/disk->BlockSize);
+ if(!block) goto ret;
+ if( !Ext2_int_AppendBlock(disk, &inode, block) ) {
+ Ext2_int_DeallocateBlock(disk, block);
+ goto ret;
+ }
+ base = block * disk->BlockSize;
+ VFS_WriteAt(disk->FD, base, retLen, Buffer);
+ inode.i_size += retLen;
+ retLen = 0;
+
+ret: // Makes sure the changes to the inode are committed
+ Ext2_int_WriteInode(disk, Node->Inode, &inode);
+ return Length - retLen;
+}
+
+/**
+ * \fn Uint32 Ext2_int_AllocateBlock(tExt2_Disk *Disk, Uint32 PrevBlock)
+ * \brief Allocate a block from the best possible location
+ * \param Disk EXT2 Disk Information Structure
+ * \param PrevBlock Previous block ID in the file
+ */
+Uint32 Ext2_int_AllocateBlock(tExt2_Disk *Disk, Uint32 PrevBlock)
+{
+ int bpg = Disk->SuperBlock.s_blocks_per_group;
+ Uint blockgroup = PrevBlock / bpg;
+ Uint bitmap[Disk->BlockSize/sizeof(Uint)];
+ Uint bitsperblock = 8*Disk->BlockSize;
+ int i, j = 0;
+ Uint block;
+
+ // Are there any free blocks?
+ if(Disk->SuperBlock.s_free_blocks_count == 0) return 0;
+
+ if(Disk->Groups[blockgroup].bg_free_blocks_count > 0)
+ {
+ // Search block group's bitmap
+ for(i = 0; i < bpg; i++)
+ {
+ // Get the block in the bitmap block
+ j = i & (bitsperblock-1);
+
+ // Read in if needed
+ if(j == 0) {
+ VFS_ReadAt(
+ Disk->FD,
+ (Uint64)Disk->Groups[blockgroup].bg_block_bitmap + i / bitsperblock,
+ Disk->BlockSize,
+ bitmap
+ );
+ }
+
+ // Fast Check
+ if( bitmap[j/32] == -1 ) {
+ j = (j + 31) & ~31;
+ continue;
+ }
+
+ // Is the bit set?
+ if( bitmap[j/32] & (1 << (j%32)) )
+ continue;
+
+ // Ooh! We found one
+ break;
+ }
+ if( i < bpg ) {
+ Warning("[EXT2 ] Inconsistency detected, Group Free Block count is non-zero when no free blocks exist");
+ goto checkAll; // Search the entire filesystem for a free block
+ // Goto needed for neatness
+ }
+
+ // Mark as used
+ bitmap[j/32] |= (1 << (j%32));
+ VFS_WriteAt(
+ Disk->FD,
+ (Uint64)Disk->Groups[blockgroup].bg_block_bitmap + i / bitsperblock,
+ Disk->BlockSize,
+ bitmap
+ );
+ block = i;
+ Disk->Groups[blockgroup].bg_free_blocks_count --;
+ #if EXT2_UPDATE_WRITEBACK
+ //Ext2_int_UpdateBlockGroup(Disk, blockgroup);
+ #endif
+ }
+ else
+ {
+ checkAll:
+ Warning("[EXT2 ] TODO - Implement using blocks outside the current block group");
+ return 0;
+ }
+
+ // Reduce global count
+ Disk->SuperBlock.s_free_blocks_count --;
+ #if EXT2_UPDATE_WRITEBACK
+ Ext2_int_UpdateSuperblock(Disk);
+ #endif
+
+ return block;
+}
+
+/**
+ * \brief Deallocates a block
+ */
+void Ext2_int_DeallocateBlock(tExt2_Disk *Disk, Uint32 Block)
+{
+}
+
+/**
+ * \brief Append a block to an inode
+ */
+int Ext2_int_AppendBlock(tExt2_Disk *Disk, tExt2_Inode *Inode, Uint32 Block)
+{
+ int nBlocks;
+ int dwPerBlock = Disk->BlockSize / 4;
+ Uint32 *blocks;
+ Uint32 id1, id2;
+
+ nBlocks = (Inode->i_size + Disk->BlockSize - 1) / Disk->BlockSize;
+
+ // Direct Blocks
+ if( nBlocks < 12 ) {
+ Inode->i_block[nBlocks] = Block;
+ return 0;
+ }
+
+ blocks = malloc( Disk->BlockSize );
+ if(!blocks) return 1;
+
+ nBlocks -= 12;
+ // Single Indirect
+ if( nBlocks < dwPerBlock)
+ {
+ // Allocate/Get Indirect block
+ if( nBlocks == 0 ) {
+ Inode->i_block[12] = Ext2_int_AllocateBlock(Disk, Inode->i_block[0]);
+ if( !Inode->i_block[12] ) {
+ free(blocks);
+ return 1;
+ }
+ memset(blocks, 0, Disk->BlockSize);
+ }
+ else
+ VFS_ReadAt(Disk->FD, Inode->i_block[12]*Disk->BlockSize, Disk->BlockSize, blocks);
+
+ blocks[nBlocks] = Block;
+
+ VFS_WriteAt(Disk->FD, Inode->i_block[12]*Disk->BlockSize, Disk->BlockSize, blocks);
+ free(blocks);
+ return 0;
+ }
+
+ nBlocks += dwPerBlock;
+ // Double Indirect
+ if( nBlocks < dwPerBlock*dwPerBlock )
+ {
+ // Allocate/Get Indirect block
+ if( nBlocks == 0 ) {
+ Inode->i_block[13] = Ext2_int_AllocateBlock(Disk, Inode->i_block[0]);
+ if( !Inode->i_block[13] ) {
+ free(blocks);
+ return 1;
+ }
+ memset(blocks, 0, Disk->BlockSize);
+ }
+ else
+ VFS_ReadAt(Disk->FD, Inode->i_block[13]*Disk->BlockSize, Disk->BlockSize, blocks);
+
+ // Allocate / Get Indirect lvl2 Block
+ if( nBlocks % dwPerBlock == 0 ) {
+ id1 = Ext2_int_AllocateBlock(Disk, Inode->i_block[0]);
+ if( !id1 ) {
+ free(blocks);
+ return 1;
+ }
+ blocks[nBlocks/dwPerBlock] = id1;
+ // Write back indirect 1 block
+ VFS_WriteAt(Disk->FD, Inode->i_block[13]*Disk->BlockSize, Disk->BlockSize, blocks);
+ memset(blocks, 0, Disk->BlockSize);
+ }
+ else {
+ id1 = blocks[nBlocks / dwPerBlock];
+ VFS_ReadAt(Disk->FD, id1*Disk->BlockSize, Disk->BlockSize, blocks);
+ }
+
+ blocks[nBlocks % dwPerBlock] = Block;
+
+ VFS_WriteAt(Disk->FD, id1*Disk->BlockSize, Disk->BlockSize, blocks);
+ free(blocks);
+ return 0;
+ }
+
+ nBlocks -= dwPerBlock*dwPerBlock;
+ // Triple Indirect
+ if( nBlocks < dwPerBlock*dwPerBlock*dwPerBlock )
+ {
+ // Allocate/Get Indirect block
+ if( nBlocks == 0 ) {
+ Inode->i_block[14] = Ext2_int_AllocateBlock(Disk, Inode->i_block[0]);
+ if( !Inode->i_block[14] ) {
+ free(blocks);
+ return 1;
+ }
+ memset(blocks, 0, Disk->BlockSize);
+ }
+ else
+ VFS_ReadAt(Disk->FD, Inode->i_block[14]*Disk->BlockSize, Disk->BlockSize, blocks);
+
+ // Allocate / Get Indirect lvl2 Block
+ if( (nBlocks/dwPerBlock) % dwPerBlock == 0 && nBlocks % dwPerBlock == 0 )
+ {
+ id1 = Ext2_int_AllocateBlock(Disk, Inode->i_block[0]);
+ if( !id1 ) {
+ free(blocks);
+ return 1;
+ }
+ blocks[nBlocks/dwPerBlock] = id1;
+ // Write back indirect 1 block
+ VFS_WriteAt(Disk->FD, Inode->i_block[14]*Disk->BlockSize, Disk->BlockSize, blocks);
+ memset(blocks, 0, Disk->BlockSize);
+ }
+ else {
+ id1 = blocks[nBlocks / (dwPerBlock*dwPerBlock)];
+ VFS_ReadAt(Disk->FD, id1*Disk->BlockSize, Disk->BlockSize, blocks);
+ }
+
+ // Allocate / Get Indirect Level 3 Block
+ if( nBlocks % dwPerBlock == 0 ) {
+ id2 = Ext2_int_AllocateBlock(Disk, id1);
+ if( !id2 ) {
+ free(blocks);
+ return 1;
+ }
+ blocks[(nBlocks/dwPerBlock)%dwPerBlock] = id2;
+ // Write back indirect 1 block
+ VFS_WriteAt(Disk->FD, id1*Disk->BlockSize, Disk->BlockSize, blocks);
+ memset(blocks, 0, Disk->BlockSize);
+ }
+ else {
+ id2 = blocks[(nBlocks/dwPerBlock)%dwPerBlock];
+ VFS_ReadAt(Disk->FD, id2*Disk->BlockSize, Disk->BlockSize, blocks);
+ }
+
+ blocks[nBlocks % dwPerBlock] = Block;
+
+ VFS_WriteAt(Disk->FD, id2*Disk->BlockSize, Disk->BlockSize, blocks);
+ free(blocks);
+ return 0;
+ }
+
+ Warning("[EXT2 ] Inode %i cannot have a block appended to it, all indirects used");
+ free(blocks);
+ return 1;
+}
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