X-Git-Url: https://git.ucc.asn.au/?a=blobdiff_plain;f=Modules%2FFilesystems%2FExt2%2Fread.c;fp=Modules%2FFilesystems%2FExt2%2Fread.c;h=81f5ee64fec7cc3ef3cefbf3601d154965929b87;hb=923a9dc473851ec2bb1c94021bbf139724e7e8a5;hp=0000000000000000000000000000000000000000;hpb=f4646f2b6d64e42d1eec1d97877ae23eac6863f6;p=tpg%2Facess2.git

diff --git a/Modules/Filesystems/Ext2/read.c b/Modules/Filesystems/Ext2/read.c
new file mode 100644
index 00000000..81f5ee64
--- /dev/null
+++ b/Modules/Filesystems/Ext2/read.c
@@ -0,0 +1,88 @@
+/*
+ * Acess OS
+ * Ext2 Driver Version 1
+ */
+/**
+ * \file read.c
+ * \brief Second Extended Filesystem Driver
+ * \todo Implement file full write support
+ */
+#define DEBUG	1
+#define VERBOSE	0
+#include "ext2_common.h"
+
+// === PROTOTYPES ===
+Uint64		Ext2_Read(tVFS_Node *node, Uint64 offset, Uint64 length, void *buffer);
+
+// === CODE ===
+/**
+ * \fn Uint64 Ext2_Read(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer)
+ * \brief Read from a file
+ */
+Uint64 Ext2_Read(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer)
+{
+	tExt2_Disk	*disk = Node->ImplPtr;
+	tExt2_Inode	inode;
+	Uint64	base;
+	Uint	block;
+	Uint64	remLen;
+	
+	ENTER("pNode XOffset XLength pBuffer", Node, Offset, Length, Buffer);
+	
+	// Get Inode
+	Ext2_int_ReadInode(disk, Node->Inode, &inode);
+	
+	// Sanity Checks
+	if(Offset >= inode.i_size) {
+		LEAVE('i', 0);
+		return 0;
+	}
+	if(Offset + Length > inode.i_size)
+		Length = inode.i_size - Offset;
+	
+	block = Offset / disk->BlockSize;
+	Offset = Offset / disk->BlockSize;
+	base = Ext2_int_GetBlockAddr(disk, inode.i_block, block);
+	if(base == 0) {
+		Warning("[EXT2 ] NULL Block Detected in INode 0x%llx", Node->Inode);
+		LEAVE('i', 0);
+		return 0;
+	}
+	
+	// Read only block
+	if(Length <= disk->BlockSize - Offset)
+	{
+		VFS_ReadAt( disk->FD, base+Offset, Length, Buffer);
+		LEAVE('X', Length);
+		return Length;
+	}
+	
+	// Read first block
+	remLen = Length;
+	VFS_ReadAt( disk->FD, base + Offset, disk->BlockSize - Offset, Buffer);
+	remLen -= disk->BlockSize - Offset;
+	Buffer += disk->BlockSize - Offset;
+	block ++;
+	
+	// Read middle blocks
+	while(remLen > disk->BlockSize)
+	{
+		base = Ext2_int_GetBlockAddr(disk, inode.i_block, block);
+		if(base == 0) {
+			Warning("[EXT2 ] NULL Block Detected in INode 0x%llx", Node->Inode);
+			LEAVE('i', 0);
+			return 0;
+		}
+		VFS_ReadAt( disk->FD, base, disk->BlockSize, Buffer);
+		Buffer += disk->BlockSize;
+		remLen -= disk->BlockSize;
+		block ++;
+	}
+	
+	// Read last block
+	base = Ext2_int_GetBlockAddr(disk, inode.i_block, block);
+	VFS_ReadAt( disk->FD, base, remLen, Buffer);
+	
+	LEAVE('X', Length);
+	return Length;
+}