namei.c

linux 内核源代码

/*
 * namei.c
 *
 * PURPOSE
 *      Inode name handling routines for the OSTA-UDF(tm) filesystem.
 *
 * 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) 1998-2004 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/smp_lock.h>
#include <linux/buffer_head.h>
#include <linux/sched.h>

static inline int udf_match(int len1, const char *name1, int len2,
			    const char *name2)
{
	if (len1 != len2)
		return 0;

	return !memcmp(name1, name2, len1);
}

int udf_write_fi(struct inode *inode, struct fileIdentDesc *cfi,
		 struct fileIdentDesc *sfi, struct udf_fileident_bh *fibh,
		 uint8_t * impuse, uint8_t * fileident)
{
	uint16_t crclen = fibh->eoffset - fibh->soffset - sizeof(tag);
	uint16_t crc;
	uint8_t checksum = 0;
	int i;
	int offset;
	uint16_t liu = le16_to_cpu(cfi->lengthOfImpUse);
	uint8_t lfi = cfi->lengthFileIdent;
	int padlen = fibh->eoffset - fibh->soffset - liu - lfi -
		sizeof(struct fileIdentDesc);
	int adinicb = 0;

	if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB)
		adinicb = 1;

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

	if (impuse) {
		if (adinicb || (offset + liu < 0)) {
			memcpy((uint8_t *)sfi->impUse, impuse, liu);
		} else if (offset >= 0) {
			memcpy(fibh->ebh->b_data + offset, impuse, liu);
		} else {
			memcpy((uint8_t *)sfi->impUse, impuse, -offset);
			memcpy(fibh->ebh->b_data, impuse - offset, liu + offset);
		}
	}

	offset += liu;

	if (fileident) {
		if (adinicb || (offset + lfi < 0)) {
			memcpy((uint8_t *)sfi->fileIdent + liu, fileident, lfi);
		} else if (offset >= 0) {
			memcpy(fibh->ebh->b_data + offset, fileident, lfi);
		} else {
			memcpy((uint8_t *)sfi->fileIdent + liu, fileident, -offset);
			memcpy(fibh->ebh->b_data, fileident - offset, lfi + offset);
		}
	}

	offset += lfi;

	if (adinicb || (offset + padlen < 0)) {
		memset((uint8_t *)sfi->padding + liu + lfi, 0x00, padlen);
	} else if (offset >= 0) {
		memset(fibh->ebh->b_data + offset, 0x00, padlen);
	} else {
		memset((uint8_t *)sfi->padding + liu + lfi, 0x00, -offset);
		memset(fibh->ebh->b_data, 0x00, padlen + offset);
	}

	crc = udf_crc((uint8_t *)cfi + sizeof(tag),
		      sizeof(struct fileIdentDesc) - sizeof(tag), 0);

	if (fibh->sbh == fibh->ebh) {
		crc = udf_crc((uint8_t *)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_t *)sfi->impUse,
			      -fibh->soffset - sizeof(struct fileIdentDesc), crc);
		crc = udf_crc(fibh->ebh->b_data, fibh->eoffset, crc);
	}

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

	for (i = 0; i < 16; i++) {
		if (i != 4)
			checksum += ((uint8_t *)&cfi->descTag)[i];
	}

	cfi->descTag.tagChecksum = checksum;
	if (adinicb || (sizeof(struct fileIdentDesc) <= -fibh->soffset)) {
		memcpy((uint8_t *)sfi, (uint8_t *)cfi, sizeof(struct fileIdentDesc));
	} else {
		memcpy((uint8_t *)sfi, (uint8_t *)cfi, -fibh->soffset);
		memcpy(fibh->ebh->b_data, (uint8_t *)cfi - fibh->soffset,
		       sizeof(struct fileIdentDesc) + fibh->soffset);
	}

	if (adinicb) {
		mark_inode_dirty(inode);
	} else {
		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[UDF_NAME_LEN];
	char *nameptr;
	uint8_t lfi;
	uint16_t liu;
	loff_t size;
	kernel_lb_addr eloc;
	uint32_t elen;
	sector_t offset;
	struct extent_position epos = {};

	size = (udf_ext0_offset(dir) + dir->i_size) >> 2;
	f_pos = (udf_ext0_offset(dir) >> 2);

	fibh->soffset = fibh->eoffset = (f_pos & ((dir->i_sb->s_blocksize - 1) >> 2)) << 2;
	if (UDF_I_ALLOCTYPE(dir) == ICBTAG_FLAG_AD_IN_ICB) {
		fibh->sbh = fibh->ebh = NULL;
	} else if (inode_bmap(dir, f_pos >> (dir->i_sb->s_blocksize_bits - 2),
			      &epos, &eloc, &elen, &offset) == (EXT_RECORDED_ALLOCATED >> 30)) {
		block = udf_get_lb_pblock(dir->i_sb, eloc, offset);
		if ((++offset << dir->i_sb->s_blocksize_bits) < elen) {
			if (UDF_I_ALLOCTYPE(dir) == ICBTAG_FLAG_AD_SHORT)
				epos.offset -= sizeof(short_ad);
			else if (UDF_I_ALLOCTYPE(dir) == ICBTAG_FLAG_AD_LONG)
				epos.offset -= sizeof(long_ad);
		} else {
			offset = 0;
		}

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

	while ((f_pos < size)) {
		fi = udf_fileident_read(dir, &f_pos, fibh, cfi, &epos, &eloc,
					&elen, &offset);
		if (!fi) {
			if (fibh->sbh != fibh->ebh)
				brelse(fibh->ebh);
			brelse(fibh->sbh);
			brelse(epos.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_t *)(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 & FID_FILE_CHAR_DELETED) != 0) {
			if (!UDF_QUERY_FLAG(dir->i_sb, UDF_FLAG_UNDELETE))
				continue;
		}

		if ((cfi->fileCharacteristics & FID_FILE_CHAR_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.len, dentry->d_name.name)) {
				brelse(epos.bh);
				return fi;
			}
		}
	}

	if (fibh->sbh != fibh->ebh)
		brelse(fibh->ebh);
	brelse(fibh->sbh);
	brelse(epos.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.
 *	nd			Pointer to lookup nameidata
 *
 * 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 nameidata *nd)
{
	struct inode *inode = NULL;
	struct fileIdentDesc cfi;
	struct udf_fileident_bh fibh;

	if (dentry->d_name.len > UDF_NAME_LEN - 2)
		return ERR_PTR(-ENAMETOOLONG);

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

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

		inode = udf_iget(dir->i_sb, lelb_to_cpu(cfi.icb.extLocation));
		if (!inode) {
			unlock_kernel();
			return ERR_PTR(-EACCES);
		}
	}
	unlock_kernel();
	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;
	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_t lfi;
	uint16_t liu;
	int block;
	kernel_lb_addr eloc;
	uint32_t elen;
	sector_t offset;
	struct extent_position epos = {};

	sb = dir->i_sb;

	if (dentry) {
		if (!dentry->d_name.len) {
			*err = -EINVAL;
			return NULL;
		}
		if (!(namelen = udf_put_filename(sb, dentry->d_name.name, name,
						 dentry->d_name.len))) {
			*err = -ENAMETOOLONG;
			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 (UDF_I_ALLOCTYPE(dir) == ICBTAG_FLAG_AD_IN_ICB) {
		fibh->sbh = fibh->ebh = NULL;
	} else if (inode_bmap(dir, f_pos >> (dir->i_sb->s_blocksize_bits - 2),
			      &epos, &eloc, &elen, &offset) == (EXT_RECORDED_ALLOCATED >> 30)) {
		block = udf_get_lb_pblock(dir->i_sb, eloc, offset);
		if ((++offset << dir->i_sb->s_blocksize_bits) < elen) {
			if (UDF_I_ALLOCTYPE(dir) == ICBTAG_FLAG_AD_SHORT)
				epos.offset -= sizeof(short_ad);
			else if (UDF_I_ALLOCTYPE(dir) == ICBTAG_FLAG_AD_LONG)
				epos.offset -= sizeof(long_ad);
		} else {
			offset = 0;
		}

		if (!(fibh->sbh = fibh->ebh = udf_tread(dir->i_sb, block))) {
			brelse(epos.bh);
			*err = -EIO;
			return NULL;
		}

		block = UDF_I_LOCATION(dir).logicalBlockNum;

	} else {
		block = udf_get_lb_pblock(dir->i_sb, UDF_I_LOCATION(dir), 0);
		fibh->sbh = fibh->ebh = NULL;
		fibh->soffset = fibh->eoffset = sb->s_blocksize;
		goto add;
	}

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

		if (!fi) {
			if (fibh->sbh != fibh->ebh)
				brelse(fibh->ebh);
			brelse(fibh->sbh);
			brelse(epos.bh);
			*err = -EIO;
			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 */