attrib.c

上一个上传的有问题,这个是好的。visopsys包括系统内核和GUI的全部SOURCE code ,还包括一些基本的docs文档。里面src子目录对应所有SOURCE code.对于想研究操作系统的朋

/**
 * attrib.c - Attribute handling code. Part of the Linux-NTFS project.
 *
 * Copyright (c) 2000-2005 Anton Altaparmakov
 * Copyright (c) 2002-2005 Richard Russon
 * Copyright (c) 2004-2006 Yura Pakhuchiy
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Modified 01/2007 by Andy McLaughlin for Visopsys port.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif

#include "compat.h"
#include "attrib.h"
#include "attrlist.h"
#include "device.h"
#include "mft.h"
#include "debug.h"
#include "mst.h"
#include "volume.h"
#include "types.h"
#include "layout.h"
#include "inode.h"
#include "runlist.h"
#include "lcnalloc.h"
#include "dir.h"
#include "compress.h"
#include "bitmap.h"
#include "logging.h"

ntfschar AT_UNNAMED[] = { const_cpu_to_le16('\0') };

/**
 * ntfs_get_attribute_value_length - Find the length of an attribute
 * @a:
 *
 * Description...
 *
 * Returns:
 */
s64 ntfs_get_attribute_value_length(const ATTR_RECORD *a)
{
	if (!a) {
		errno = EINVAL;
		return 0;
	}
	errno = 0;
	if (a->non_resident)
		return sle64_to_cpu(a->data_size);
	else
		return (s64)le32_to_cpu(a->value_length);
	errno = EINVAL;
	return 0;
}

/**
 * ntfs_get_attribute_value - Get a copy of an attribute
 * @vol:	
 * @a:	
 * @b:	
 *
 * Description...
 *
 * Returns:
 */
s64 ntfs_get_attribute_value(const ntfs_volume *vol,
		const ATTR_RECORD *a, u8 *b)
{
	runlist *rl;
	s64 total, r;
	int i;

	/* Sanity checks. */
	if (!vol || !a || !b) {
		errno = EINVAL;
		return 0;
	}
	/* Complex attribute? */
	/*
	 * Ignore the flags in case they are not zero for an attribute list
	 * attribute.  Windows does not complain about invalid flags and chkdsk
	 * does not detect or fix them so we need to cope with it, too.
	 */
	if (a->type != AT_ATTRIBUTE_LIST && a->flags) {
		ntfs_log_error("Non-zero (%04x) attribute flags. Cannot handle "
			       "this yet.\n", le16_to_cpu(a->flags));
		errno = EOPNOTSUPP;
		return 0;
	}
	if (!a->non_resident) {
		/* Attribute is resident. */

		/* Sanity check. */
		if (le32_to_cpu(a->value_length) + le16_to_cpu(a->value_offset)
				> le32_to_cpu(a->length)) {
			return 0;
		}

		memcpy(b, (const char*)a + le16_to_cpu(a->value_offset),
				le32_to_cpu(a->value_length));
		errno = 0;
		return (s64)le32_to_cpu(a->value_length);
	}

	/* Attribute is not resident. */

	/* If no data, return 0. */
	if (!(a->data_size)) {
		errno = 0;
		return 0;
	}
	/*
	 * FIXME: What about attribute lists?!? (AIA)
	 */
	/* Decompress the mapping pairs array into a runlist. */
	rl = ntfs_mapping_pairs_decompress(vol, a, NULL);
	if (!rl) {
		errno = EINVAL;
		return 0;
	}
	/*
	 * FIXED: We were overflowing here in a nasty fashion when we
	 * reach the last cluster in the runlist as the buffer will
	 * only be big enough to hold data_size bytes while we are
	 * reading in allocated_size bytes which is usually larger
	 * than data_size, since the actual data is unlikely to have a
	 * size equal to a multiple of the cluster size!
	 * FIXED2:  We were also overflowing here in the same fashion
	 * when the data_size was more than one run smaller than the
	 * allocated size which happens with Windows XP sometimes.
	 */
	/* Now load all clusters in the runlist into b. */
	for (i = 0, total = 0; rl[i].length; i++) {
		if (total + (rl[i].length << vol->cluster_size_bits) >=
				sle64_to_cpu(a->data_size)) {
			unsigned char *intbuf = NULL;
			/*
			 * We have reached the last run so we were going to
			 * overflow when executing the ntfs_pread() which is
			 * BAAAAAAAD!
			 * Temporary fix:
			 *	Allocate a new buffer with size:
			 *	rl[i].length << vol->cluster_size_bits, do the
			 *	read into our buffer, then memcpy the correct
			 *	amount of data into the caller supplied buffer,
			 *	free our buffer, and continue.
			 * We have reached the end of data size so we were
			 * going to overflow in the same fashion.
			 * Temporary fix:  same as above.
			 */
			intbuf = malloc(rl[i].length << vol->cluster_size_bits);
			if (!intbuf) {
				int eo = errno;
				ntfs_log_perror("Couldn't allocate memory for "
						"internal buffer.");
				free(rl);
				errno = eo;
				return 0;
			}
			/*
			 * FIXME: If compressed file: Only read if lcn != -1.
			 * Otherwise, we are dealing with a sparse run and we
			 * just memset the user buffer to 0 for the length of
			 * the run, which should be 16 (= compression unit
			 * size).
			 * FIXME: Really only when file is compressed, or can
			 * we have sparse runs in uncompressed files as well?
			 * - Yes we can, in sparse files! But not necessarily
			 * size of 16, just run length.
			 */
			r = ntfs_pread(vol->dev, rl[i].lcn <<
					vol->cluster_size_bits, rl[i].length <<
					vol->cluster_size_bits, intbuf);
			if (r != rl[i].length << vol->cluster_size_bits) {
#define ESTR "Error reading attribute value"
				if (r == -1) {
					int eo = errno;
					ntfs_log_perror(ESTR);
					errno = eo;
				} else if (r < rl[i].length <<
						vol->cluster_size_bits) {
					ntfs_log_debug(ESTR ": Ran out of input data.\n");
					errno = EIO;
				} else {
					ntfs_log_debug(ESTR ": unknown error\n");
					errno = EIO;
				}
#undef ESTR
				free(rl);
				free(intbuf);
				return 0;
			}
			memcpy(b + total, intbuf, sle64_to_cpu(a->data_size) -
					total);
			free(intbuf);
			total = sle64_to_cpu(a->data_size);
			break;
		}
		/*
		 * FIXME: If compressed file: Only read if lcn != -1.
		 * Otherwise, we are dealing with a sparse run and we just
		 * memset the user buffer to 0 for the length of the run, which
		 * should be 16 (= compression unit size).
		 * FIXME: Really only when file is compressed, or can
		 * we have sparse runs in uncompressed files as well?
		 * - Yes we can, in sparse files! But not necessarily size of
		 * 16, just run length.
		 */
		r = ntfs_pread(vol->dev, rl[i].lcn << vol->cluster_size_bits,
				rl[i].length << vol->cluster_size_bits,
				b + total);
		if (r != rl[i].length << vol->cluster_size_bits) {
#define ESTR "Error reading attribute value"
			if (r == -1) {
				int eo = errno;
				ntfs_log_perror(ESTR);
				errno = eo;
			} else if (r < rl[i].length << vol->cluster_size_bits) {
				ntfs_log_debug(ESTR ": Ran out of input data.\n");
				errno = EIO;
			} else {
				ntfs_log_debug(ESTR ": unknown error\n");
				errno = EIO;
			}
#undef ESTR
			return 0;
		}
		total += r;
	}
	free(rl);
	return total;
}

/* Already cleaned up code below, but still look for FIXME:... */

/**
 * __ntfs_attr_init - primary initialization of an ntfs attribute structure
 * @na:		ntfs attribute to initialize
 * @ni:		ntfs inode with which to initialize the ntfs attribute
 * @type:	attribute type
 * @name:	attribute name in little endian Unicode or NULL
 * @name_len:	length of attribute @name in Unicode characters (if @name given)
 *
 * Initialize the ntfs attribute @na with @ni, @type, @name, and @name_len.
 */
static __inline__ void __ntfs_attr_init(ntfs_attr *na, ntfs_inode *ni,
		const ATTR_TYPES type, ntfschar *name, const u32 name_len)
{
	na->rl = NULL;
	na->ni = ni;
	na->type = type;
	na->name = name;
	if (name)
		na->name_len = name_len;
	else
		na->name_len = 0;
}

/**
 * ntfs_attr_init - initialize an ntfs_attr with data sizes and status
 * @na:
 * @non_resident:
 * @compressed:
 * @encrypted:
 * @sparse:
 * @allocated_size:
 * @data_size:
 * @initialized_size:
 * @compressed_size:
 * @compression_unit:
 *
 * Final initialization for an ntfs attribute.
 */
void ntfs_attr_init(ntfs_attr *na, const BOOL non_resident,
		const BOOL compressed, const BOOL encrypted, const BOOL sparse,
		const s64 allocated_size, const s64 data_size,
		const s64 initialized_size, const s64 compressed_size,
		const u8 compression_unit)
{
	if (!NAttrInitialized(na)) {
		if (non_resident)
			NAttrSetNonResident(na);
		if (compressed)
			NAttrSetCompressed(na);
		if (encrypted)
			NAttrSetEncrypted(na);
		if (sparse)
			NAttrSetSparse(na);
		na->allocated_size = allocated_size;
		na->data_size = data_size;
		na->initialized_size = initialized_size;
		if (compressed || sparse) {
			ntfs_volume *vol = na->ni->vol;

			na->compressed_size = compressed_size;
			na->compression_block_clusters = 1 << compression_unit;
			na->compression_block_size = 1 << (compression_unit +
					vol->cluster_size_bits);
			na->compression_block_size_bits = ffs(
					na->compression_block_size) - 1;
		}
		NAttrSetInitialized(na);
	}
}

/**
 * ntfs_attr_open - open an ntfs attribute for access
 * @ni:		open ntfs inode in which the ntfs attribute resides
 * @type:	attribute type
 * @name:	attribute name in little endian Unicode or AT_UNNAMED or NULL
 * @name_len:	length of attribute @name in Unicode characters (if @name given)
 *
 * Allocate a new ntfs attribute structure, initialize it with @ni, @type,
 * @name, and @name_len, then return it. Return NULL on error with
 * errno set to the error code.
 *
 * If @name is AT_UNNAMED look specifically for an unnamed attribute.  If you
 * do not care whether the attribute is named or not set @name to NULL.  In
 * both those cases @name_len is not used at all.
 */
ntfs_attr *ntfs_attr_open(ntfs_inode *ni, const ATTR_TYPES type,
		ntfschar *name, u32 name_len)
{
	ntfs_attr_search_ctx *ctx;
	ntfs_attr *na;
	ATTR_RECORD *a;
	int err;
	BOOL cs;

	ntfs_log_trace("Entering for inode 0x%llx, attr 0x%x.\n",
		(unsigned long long)ni->mft_no, type);
	if (!ni || !ni->vol || !ni->mrec) {
		errno = EINVAL;
		return NULL;
	}
	na = calloc(sizeof(ntfs_attr), 1);
	if (!na)
		return NULL;
	if (name && name != AT_UNNAMED && name != NTFS_INDEX_I30) {
		name = ntfs_ucsndup(name, name_len);
		if (!name) {
			err = errno;
			free(na);
			errno = err;
			return NULL;
		}
	}

	ctx = ntfs_attr_get_search_ctx(ni, NULL);
	if (!ctx) {
		err = errno;
		goto err_out;
	}
	if (ntfs_attr_lookup(type, name, name_len, 0, 0, NULL, 0, ctx)) {
		err = errno;
		goto put_err_out;
	}

	a = ctx->attr;
	/*
	 * Wipe the flags in case they are not zero for an attribute list
	 * attribute.  Windows does not complain about invalid flags and chkdsk
	 * does not detect or fix them so we need to cope with it, too.
	 */
	if (type == AT_ATTRIBUTE_LIST)
		a->flags = 0;
	cs = a->flags & (ATTR_IS_COMPRESSED | ATTR_IS_SPARSE);
	if (!name) {
		if (a->name_length) {
			name = ntfs_ucsndup((ntfschar*)((u8*)a + le16_to_cpu(
					a->name_offset)), a->name_length);
			if (!name) {
				err = errno;
				goto put_err_out;
			}
			name_len = a->name_length;
		} else {
			name = AT_UNNAMED;
			name_len = 0;
		}
	}
	__ntfs_attr_init(na, ni, type, name, name_len);
	if (a->non_resident) {
		ntfs_attr_init(na, TRUE, a->flags & ATTR_IS_COMPRESSED,
				a->flags & ATTR_IS_ENCRYPTED,
				a->flags & ATTR_IS_SPARSE,
				sle64_to_cpu(a->allocated_size),
				sle64_to_cpu(a->data_size),
				sle64_to_cpu(a->initialized_size),
				cs ? sle64_to_cpu(a->compressed_size) : 0,
				cs ? a->compression_unit : 0);
	} else {
		s64 l = le32_to_cpu(a->value_length);
		ntfs_attr_init(na, FALSE, a->flags & ATTR_IS_COMPRESSED,
				a->flags & ATTR_IS_ENCRYPTED,
				a->flags & ATTR_IS_SPARSE, (l + 7) & ~7, l, l,
				cs ? (l + 7) & ~7 : 0, 0);
	}
	ntfs_attr_put_search_ctx(ctx);
	return na;