namei.c

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

/*
 * namei.c
 *
 * PURPOSE
 *      Inode name handling routines for the OSTA-UDF(tm) filesystem.
 *
 * CONTACTS
 *      E-mail regarding any portion of the Linux UDF file system should be
 *      directed to the development team mailing list (run by majordomo):
 *              [e-mail]
 *
 * COPYRIGHT
 *      This file is distributed under the terms of the GNU General Public
 *      License (GPL). Copies of the GPL can be obtained from:
 *              ftp://prep.ai.mit.edu/pub/gnu/GPL
 *      Each contributing author retains all rights to their own work.
 *
 *  (C) 1998-2000 Ben Fennema
 *  (C) 1999-2000 Stelias Computing Inc
 *
 * HISTORY
 *
 *  12/12/98 blf  Created. Split out the lookup code from dir.c
 *  04/19/99 blf  link, mknod, symlink support
 */

#include "udfdecl.h"

#include "udf_i.h"
#include "udf_sb.h"
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/quotaops.h>
#include <linux/locks.h>
#include <linux/smp_lock.h>
#include <linux/udf_fs.h>

static inline int udf_match(int len, const char * const name, struct qstr *qs)
{
	if (len != qs->len)
		return 0;
	return !memcmp(name, qs->name, len);
}

int udf_write_fi(struct inode *inode, struct FileIdentDesc *cfi,
	struct FileIdentDesc *sfi, struct udf_fileident_bh *fibh,
	Uint8 *impuse, Uint8 *fileident)
{
	Uint16 crclen = fibh->eoffset - fibh->soffset - sizeof(tag);
	Uint16 crc;
	Uint8 checksum = 0;
	int i;
	int offset;
	Uint16 liu = le16_to_cpu(cfi->lengthOfImpUse);
	Uint8 lfi = cfi->lengthFileIdent;
	int padlen = fibh->eoffset - fibh->soffset - liu - lfi -
		sizeof(struct FileIdentDesc);

	offset = fibh->soffset + sizeof(struct FileIdentDesc);

	if (impuse)
	{
		if (offset + liu < 0)
			memcpy((Uint8 *)sfi->impUse, impuse, liu);
		else if (offset >= 0)
			memcpy(fibh->ebh->b_data + offset, impuse, liu);
		else
		{
			memcpy((Uint8 *)sfi->impUse, impuse, -offset);
			memcpy(fibh->ebh->b_data, impuse - offset, liu + offset);
		}
	}

	offset += liu;

	if (fileident)
	{
		if (offset + lfi < 0)
			memcpy((Uint8 *)sfi->fileIdent + liu, fileident, lfi);
		else if (offset >= 0)
			memcpy(fibh->ebh->b_data + offset, fileident, lfi);
		else
		{
			memcpy((Uint8 *)sfi->fileIdent + liu, fileident, -offset);
			memcpy(fibh->ebh->b_data, fileident - offset, lfi + offset);
		}
	}

	offset += lfi;

	if (offset + padlen < 0)
		memset((Uint8 *)sfi->padding + liu + lfi, 0x00, padlen);
	else if (offset >= 0)
		memset(fibh->ebh->b_data + offset, 0x00, padlen);
	else
	{
		memset((Uint8 *)sfi->padding + liu + lfi, 0x00, -offset);
		memset(fibh->ebh->b_data, 0x00, padlen + offset);
	}

	crc = udf_crc((Uint8 *)cfi + sizeof(tag), sizeof(struct FileIdentDesc) -
		sizeof(tag), 0);

	if (fibh->sbh == fibh->ebh)
		crc = udf_crc((Uint8 *)sfi->impUse,
			crclen + sizeof(tag) - sizeof(struct FileIdentDesc), crc);
	else if (sizeof(struct FileIdentDesc) >= -fibh->soffset)
		crc = udf_crc(fibh->ebh->b_data + sizeof(struct FileIdentDesc) + fibh->soffset,
			crclen + sizeof(tag) - sizeof(struct FileIdentDesc), crc);
	else
	{
		crc = udf_crc((Uint8 *)sfi->impUse,
			-fibh->soffset - sizeof(struct FileIdentDesc), crc);
		crc = udf_crc(fibh->ebh->b_data, fibh->eoffset, crc);
	}

	cfi->descTag.descCRC = cpu_to_le32(crc);
	cfi->descTag.descCRCLength = cpu_to_le16(crclen);

	for (i=0; i<16; i++)
		if (i != 4)
			checksum += ((Uint8 *)&cfi->descTag)[i];

	cfi->descTag.tagChecksum = checksum;
	if (sizeof(struct FileIdentDesc) <= -fibh->soffset)
		memcpy((Uint8 *)sfi, (Uint8 *)cfi, sizeof(struct FileIdentDesc));
	else
	{
		memcpy((Uint8 *)sfi, (Uint8 *)cfi, -fibh->soffset);
		memcpy(fibh->ebh->b_data, (Uint8 *)cfi - fibh->soffset,
			sizeof(struct FileIdentDesc) + fibh->soffset);
	}

	if (fibh->sbh != fibh->ebh)
		mark_buffer_dirty_inode(fibh->ebh, inode);
	mark_buffer_dirty_inode(fibh->sbh, inode);
	return 0;
}

static struct FileIdentDesc *
udf_find_entry(struct inode *dir, struct dentry *dentry,
	struct udf_fileident_bh *fibh,
	struct FileIdentDesc *cfi)
{
	struct FileIdentDesc *fi=NULL;
	loff_t f_pos;
	int block, flen;
	char fname[255];
	char *nameptr;
	Uint8 lfi;
	Uint16 liu;
	loff_t size = (udf_ext0_offset(dir) + dir->i_size) >> 2;
	lb_addr bloc, eloc;
	Uint32 extoffset, elen, offset;
	struct buffer_head *bh = NULL;

	if (!dir)
		return NULL;

	f_pos = (udf_ext0_offset(dir) >> 2);

	fibh->soffset = fibh->eoffset = (f_pos & ((dir->i_sb->s_blocksize - 1) >> 2)) << 2;
	if (inode_bmap(dir, f_pos >> (dir->i_sb->s_blocksize_bits - 2),
		&bloc, &extoffset, &eloc, &elen, &offset, &bh) == EXTENT_RECORDED_ALLOCATED)
	{
		offset >>= dir->i_sb->s_blocksize_bits;
		block = udf_get_lb_pblock(dir->i_sb, eloc, offset);
		if ((++offset << dir->i_sb->s_blocksize_bits) < elen)
		{
			if (UDF_I_ALLOCTYPE(dir) == ICB_FLAG_AD_SHORT)
				extoffset -= sizeof(short_ad);
			else if (UDF_I_ALLOCTYPE(dir) == ICB_FLAG_AD_LONG)
				extoffset -= sizeof(long_ad);
		}
		else
			offset = 0;
	}
	else
	{
		udf_release_data(bh);
		return NULL;
	}

	if (!(fibh->sbh = fibh->ebh = udf_tread(dir->i_sb, block)))
	{
		udf_release_data(bh);
		return NULL;
	}

	while ( (f_pos < size) )
	{
		fi = udf_fileident_read(dir, &f_pos, fibh, cfi, &bloc, &extoffset, &eloc, &elen, &offset, &bh);

		if (!fi)
		{
			if (fibh->sbh != fibh->ebh)
				udf_release_data(fibh->ebh);
			udf_release_data(fibh->sbh);
			udf_release_data(bh);
			return NULL;
		}

		liu = le16_to_cpu(cfi->lengthOfImpUse);
		lfi = cfi->lengthFileIdent;

		if (fibh->sbh == fibh->ebh)
		{
			nameptr = fi->fileIdent + liu;
		}
		else
		{
			int poffset;	/* Unpaded ending offset */

			poffset = fibh->soffset + sizeof(struct FileIdentDesc) + liu + lfi;

			if (poffset >= lfi)
				nameptr = (Uint8 *)(fibh->ebh->b_data + poffset - lfi);
			else
			{
				nameptr = fname;
				memcpy(nameptr, fi->fileIdent + liu, lfi - poffset);
				memcpy(nameptr + lfi - poffset, fibh->ebh->b_data, poffset);
			}
		}

		if ( (cfi->fileCharacteristics & FILE_DELETED) != 0 )
		{
			if ( !UDF_QUERY_FLAG(dir->i_sb, UDF_FLAG_UNDELETE) )
				continue;
		}
	    
		if ( (cfi->fileCharacteristics & FILE_HIDDEN) != 0 )
		{
			if ( !UDF_QUERY_FLAG(dir->i_sb, UDF_FLAG_UNHIDE) )
				continue;
		}

		if (!lfi)
			continue;

		if ((flen = udf_get_filename(dir->i_sb, nameptr, fname, lfi)))
		{
			if (udf_match(flen, fname, &(dentry->d_name)))
			{
				udf_release_data(bh);
				return fi;
			}
		}
	}
	if (fibh->sbh != fibh->ebh)
		udf_release_data(fibh->ebh);
	udf_release_data(fibh->sbh);
	udf_release_data(bh);
	return NULL;
}

/*
 * udf_lookup
 *
 * PURPOSE
 *	Look-up the inode for a given name.
 *
 * DESCRIPTION
 *	Required - lookup_dentry() will return -ENOTDIR if this routine is not
 *	available for a directory. The filesystem is useless if this routine is
 *	not available for at least the filesystem's root directory.
 *
 *	This routine is passed an incomplete dentry - it must be completed by
 *	calling d_add(dentry, inode). If the name does not exist, then the
 *	specified inode must be set to null. An error should only be returned
 *	when the lookup fails for a reason other than the name not existing.
 *	Note that the directory inode semaphore is held during the call.
 *
 *	Refer to lookup_dentry() in fs/namei.c
 *	lookup_dentry() -> lookup() -> real_lookup() -> .
 *
 * PRE-CONDITIONS
 *	dir			Pointer to inode of parent directory.
 *	dentry			Pointer to dentry to complete.
 *
 * POST-CONDITIONS
 *	<return>		Zero on success.
 *
 * HISTORY
 *	July 1, 1997 - Andrew E. Mileski
 *	Written, tested, and released.
 */

static struct dentry *
udf_lookup(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = NULL;
	struct FileIdentDesc cfi, *fi;
	struct udf_fileident_bh fibh;

	if (dentry->d_name.len > UDF_NAME_LEN)
		return ERR_PTR(-ENAMETOOLONG);

#ifdef UDF_RECOVERY
	/* temporary shorthand for specifying files by inode number */
	if (!strncmp(dentry->d_name.name, ".B=", 3) )
	{
		lb_addr lb = { 0, simple_strtoul(dentry->d_name.name+3, NULL, 0) };
		inode = udf_iget(dir->i_sb, lb);
		if (!inode)
			return ERR_PTR(-EACCES);
	}
	else
#endif /* UDF_RECOVERY */

	if ((fi = udf_find_entry(dir, dentry, &fibh, &cfi)))
	{
		if (fibh.sbh != fibh.ebh)
			udf_release_data(fibh.ebh);
		udf_release_data(fibh.sbh);

		inode = udf_iget(dir->i_sb, lelb_to_cpu(cfi.icb.extLocation));
		if ( !inode )
			return ERR_PTR(-EACCES);
	}
	d_add(dentry, inode);
	return NULL;
}

static struct FileIdentDesc *
udf_add_entry(struct inode *dir, struct dentry *dentry,
	struct udf_fileident_bh *fibh,
	struct FileIdentDesc *cfi, int *err)
{
	struct super_block *sb;
	struct FileIdentDesc *fi=NULL;
	struct ustr unifilename;
	char name[UDF_NAME_LEN], fname[UDF_NAME_LEN];
	int namelen;
	loff_t f_pos;
	int flen;
	char *nameptr;
	loff_t size = (udf_ext0_offset(dir) + dir->i_size) >> 2;
	int nfidlen;
	Uint8 lfi;
	Uint16 liu;
	int block;
	lb_addr bloc, eloc;
	Uint32 extoffset, elen, offset;
	struct buffer_head *bh = NULL;

	sb = dir->i_sb;

	if (dentry)
	{
		if (!dentry->d_name.len)
		{
			*err = -EINVAL;
			return NULL;
		}

		if ( !(udf_char_to_ustr(&unifilename, dentry->d_name.name, dentry->d_name.len)) )
		{
			*err = -ENAMETOOLONG;
			return NULL;
		}

		if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8))
		{
			if ( !(namelen = udf_UTF8toCS0(name, &unifilename, UDF_NAME_LEN)) )
			{
				*err = -ENAMETOOLONG;
				return NULL;
			}
		}
		else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP))
		{
			if ( !(namelen = udf_NLStoCS0(UDF_SB(sb)->s_nls_map, name, &unifilename, UDF_NAME_LEN)) )
			{
				*err = -ENAMETOOLONG;
				return NULL;
			}
		}
		else
			return NULL;
	}
	else
		namelen = 0;

	nfidlen = (sizeof(struct FileIdentDesc) + namelen + 3) & ~3;

	f_pos = (udf_ext0_offset(dir) >> 2);

	fibh->soffset = fibh->eoffset = (f_pos & ((dir->i_sb->s_blocksize - 1) >> 2)) << 2;
	if (inode_bmap(dir, f_pos >> (dir->i_sb->s_blocksize_bits - 2),
		&bloc, &extoffset, &eloc, &elen, &offset, &bh) == EXTENT_RECORDED_ALLOCATED)
	{
		offset >>= dir->i_sb->s_blocksize_bits;
		block = udf_get_lb_pblock(dir->i_sb, eloc, offset);
		if ((++offset << dir->i_sb->s_blocksize_bits) < elen)
		{
			if (UDF_I_ALLOCTYPE(dir) == ICB_FLAG_AD_SHORT)
				extoffset -= sizeof(short_ad);
			else if (UDF_I_ALLOCTYPE(dir) == ICB_FLAG_AD_LONG)
				extoffset -= sizeof(long_ad);
		}
		else
			offset = 0;

		if (!(fibh->sbh = fibh->ebh = udf_tread(dir->i_sb, block)))
		{
			udf_release_data(bh);
			*err = -EIO;
			return NULL;
		}
	
		block = UDF_I_LOCATION(dir).logicalBlockNum;
	
		while ( (f_pos < size) )
		{
			fi = udf_fileident_read(dir, &f_pos, fibh, cfi, &bloc, &extoffset, &eloc, &elen, &offset, &bh);
	
			if (!fi)
			{
				if (fibh->sbh != fibh->ebh)
					udf_release_data(fibh->ebh);
				udf_release_data(fibh->sbh);
				udf_release_data(bh);
				*err = -EIO;
				return NULL;
			}
	
			liu = le16_to_cpu(cfi->lengthOfImpUse);
			lfi = cfi->lengthFileIdent;
	
			if (fibh->sbh == fibh->ebh)