unistr.c

linux 内核源代码

/*
 * unistr.c - NTFS Unicode string handling. Part of the Linux-NTFS project.
 *
 * Copyright (c) 2001-2006 Anton Altaparmakov
 *
 * 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
 */

#include <linux/slab.h>

#include "types.h"
#include "debug.h"
#include "ntfs.h"

/*
 * IMPORTANT
 * =========
 *
 * All these routines assume that the Unicode characters are in little endian
 * encoding inside the strings!!!
 */

/*
 * This is used by the name collation functions to quickly determine what
 * characters are (in)valid.
 */
static const u8 legal_ansi_char_array[0x40] = {
	0x00, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,
	0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,

	0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,
	0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,

	0x17, 0x07, 0x18, 0x17, 0x17, 0x17, 0x17, 0x17,
	0x17, 0x17, 0x18, 0x16, 0x16, 0x17, 0x07, 0x00,

	0x17, 0x17, 0x17, 0x17, 0x17, 0x17, 0x17, 0x17,
	0x17, 0x17, 0x04, 0x16, 0x18, 0x16, 0x18, 0x18,
};

/**
 * ntfs_are_names_equal - compare two Unicode names for equality
 * @s1:			name to compare to @s2
 * @s1_len:		length in Unicode characters of @s1
 * @s2:			name to compare to @s1
 * @s2_len:		length in Unicode characters of @s2
 * @ic:			ignore case bool
 * @upcase:		upcase table (only if @ic == IGNORE_CASE)
 * @upcase_size:	length in Unicode characters of @upcase (if present)
 *
 * Compare the names @s1 and @s2 and return 'true' (1) if the names are
 * identical, or 'false' (0) if they are not identical. If @ic is IGNORE_CASE,
 * the @upcase table is used to performa a case insensitive comparison.
 */
bool ntfs_are_names_equal(const ntfschar *s1, size_t s1_len,
		const ntfschar *s2, size_t s2_len, const IGNORE_CASE_BOOL ic,
		const ntfschar *upcase, const u32 upcase_size)
{
	if (s1_len != s2_len)
		return false;
	if (ic == CASE_SENSITIVE)
		return !ntfs_ucsncmp(s1, s2, s1_len);
	return !ntfs_ucsncasecmp(s1, s2, s1_len, upcase, upcase_size);
}

/**
 * ntfs_collate_names - collate two Unicode names
 * @name1:	first Unicode name to compare
 * @name2:	second Unicode name to compare
 * @err_val:	if @name1 contains an invalid character return this value
 * @ic:		either CASE_SENSITIVE or IGNORE_CASE
 * @upcase:	upcase table (ignored if @ic is CASE_SENSITIVE)
 * @upcase_len:	upcase table size (ignored if @ic is CASE_SENSITIVE)
 *
 * ntfs_collate_names collates two Unicode names and returns:
 *
 *  -1 if the first name collates before the second one,
 *   0 if the names match,
 *   1 if the second name collates before the first one, or
 * @err_val if an invalid character is found in @name1 during the comparison.
 *
 * The following characters are considered invalid: '"', '*', '<', '>' and '?'.
 */
int ntfs_collate_names(const ntfschar *name1, const u32 name1_len,
		const ntfschar *name2, const u32 name2_len,
		const int err_val, const IGNORE_CASE_BOOL ic,
		const ntfschar *upcase, const u32 upcase_len)
{
	u32 cnt, min_len;
	u16 c1, c2;

	min_len = name1_len;
	if (name1_len > name2_len)
		min_len = name2_len;
	for (cnt = 0; cnt < min_len; ++cnt) {
		c1 = le16_to_cpu(*name1++);
		c2 = le16_to_cpu(*name2++);
		if (ic) {
			if (c1 < upcase_len)
				c1 = le16_to_cpu(upcase[c1]);
			if (c2 < upcase_len)
				c2 = le16_to_cpu(upcase[c2]);
		}
		if (c1 < 64 && legal_ansi_char_array[c1] & 8)
			return err_val;
		if (c1 < c2)
			return -1;
		if (c1 > c2)
			return 1;
	}
	if (name1_len < name2_len)
		return -1;
	if (name1_len == name2_len)
		return 0;
	/* name1_len > name2_len */
	c1 = le16_to_cpu(*name1);
	if (c1 < 64 && legal_ansi_char_array[c1] & 8)
		return err_val;
	return 1;
}

/**
 * ntfs_ucsncmp - compare two little endian Unicode strings
 * @s1:		first string
 * @s2:		second string
 * @n:		maximum unicode characters to compare
 *
 * Compare the first @n characters of the Unicode strings @s1 and @s2,
 * The strings in little endian format and appropriate le16_to_cpu()
 * conversion is performed on non-little endian machines.
 *
 * The function returns an integer less than, equal to, or greater than zero
 * if @s1 (or the first @n Unicode characters thereof) is found, respectively,
 * to be less than, to match, or be greater than @s2.
 */
int ntfs_ucsncmp(const ntfschar *s1, const ntfschar *s2, size_t n)
{
	u16 c1, c2;
	size_t i;

	for (i = 0; i < n; ++i) {
		c1 = le16_to_cpu(s1[i]);
		c2 = le16_to_cpu(s2[i]);
		if (c1 < c2)
			return -1;
		if (c1 > c2)
			return 1;
		if (!c1)
			break;
	}
	return 0;
}

/**
 * ntfs_ucsncasecmp - compare two little endian Unicode strings, ignoring case
 * @s1:			first string
 * @s2:			second string
 * @n:			maximum unicode characters to compare
 * @upcase:		upcase table
 * @upcase_size:	upcase table size in Unicode characters
 *
 * Compare the first @n characters of the Unicode strings @s1 and @s2,
 * ignoring case. The strings in little endian format and appropriate
 * le16_to_cpu() conversion is performed on non-little endian machines.
 *
 * Each character is uppercased using the @upcase table before the comparison.
 *
 * The function returns an integer less than, equal to, or greater than zero
 * if @s1 (or the first @n Unicode characters thereof) is found, respectively,
 * to be less than, to match, or be greater than @s2.
 */
int ntfs_ucsncasecmp(const ntfschar *s1, const ntfschar *s2, size_t n,
		const ntfschar *upcase, const u32 upcase_size)
{
	size_t i;
	u16 c1, c2;

	for (i = 0; i < n; ++i) {
		if ((c1 = le16_to_cpu(s1[i])) < upcase_size)
			c1 = le16_to_cpu(upcase[c1]);
		if ((c2 = le16_to_cpu(s2[i])) < upcase_size)
			c2 = le16_to_cpu(upcase[c2]);
		if (c1 < c2)
			return -1;
		if (c1 > c2)
			return 1;
		if (!c1)
			break;
	}
	return 0;
}

void ntfs_upcase_name(ntfschar *name, u32 name_len, const ntfschar *upcase,
		const u32 upcase_len)
{
	u32 i;
	u16 u;

	for (i = 0; i < name_len; i++)
		if ((u = le16_to_cpu(name[i])) < upcase_len)
			name[i] = upcase[u];
}

void ntfs_file_upcase_value(FILE_NAME_ATTR *file_name_attr,
		const ntfschar *upcase, const u32 upcase_len)
{
	ntfs_upcase_name((ntfschar*)&file_name_attr->file_name,
			file_name_attr->file_name_length, upcase, upcase_len);
}

int ntfs_file_compare_values(FILE_NAME_ATTR *file_name_attr1,
		FILE_NAME_ATTR *file_name_attr2,
		const int err_val, const IGNORE_CASE_BOOL ic,
		const ntfschar *upcase, const u32 upcase_len)
{
	return ntfs_collate_names((ntfschar*)&file_name_attr1->file_name,
			file_name_attr1->file_name_length,
			(ntfschar*)&file_name_attr2->file_name,
			file_name_attr2->file_name_length,
			err_val, ic, upcase, upcase_len);
}

/**
 * ntfs_nlstoucs - convert NLS string to little endian Unicode string
 * @vol:	ntfs volume which we are working with
 * @ins:	input NLS string buffer
 * @ins_len:	length of input string in bytes
 * @outs:	on return contains the allocated output Unicode string buffer
 *
 * Convert the input string @ins, which is in whatever format the loaded NLS
 * map dictates, into a little endian, 2-byte Unicode string.
 *
 * This function allocates the string and the caller is responsible for
 * calling kmem_cache_free(ntfs_name_cache, *@outs); when finished with it.
 *
 * On success the function returns the number of Unicode characters written to
 * the output string *@outs (>= 0), not counting the terminating Unicode NULL
 * character. *@outs is set to the allocated output string buffer.
 *
 * On error, a negative number corresponding to the error code is returned. In
 * that case the output string is not allocated. Both *@outs and *@outs_len
 * are then undefined.
 *
 * This might look a bit odd due to fast path optimization...
 */
int ntfs_nlstoucs(const ntfs_volume *vol, const char *ins,
		const int ins_len, ntfschar **outs)
{
	struct nls_table *nls = vol->nls_map;
	ntfschar *ucs;
	wchar_t wc;
	int i, o, wc_len;

	/* We do not trust outside sources. */
	if (likely(ins)) {
		ucs = kmem_cache_alloc(ntfs_name_cache, GFP_NOFS);
		if (likely(ucs)) {
			for (i = o = 0; i < ins_len; i += wc_len) {
				wc_len = nls->char2uni(ins + i, ins_len - i,
						&wc);
				if (likely(wc_len >= 0 &&
						o < NTFS_MAX_NAME_LEN)) {
					if (likely(wc)) {
						ucs[o++] = cpu_to_le16(wc);
						continue;
					} /* else if (!wc) */
					break;
				} /* else if (wc_len < 0 ||
						o >= NTFS_MAX_NAME_LEN) */
				goto name_err;
			}
			ucs[o] = 0;
			*outs = ucs;
			return o;
		} /* else if (!ucs) */
		ntfs_error(vol->sb, "Failed to allocate buffer for converted "
				"name from ntfs_name_cache.");
		return -ENOMEM;
	} /* else if (!ins) */
	ntfs_error(vol->sb, "Received NULL pointer.");
	return -EINVAL;
name_err:
	kmem_cache_free(ntfs_name_cache, ucs);
	if (wc_len < 0) {
		ntfs_error(vol->sb, "Name using character set %s contains "
				"characters that cannot be converted to "
				"Unicode.", nls->charset);
		i = -EILSEQ;
	} else /* if (o >= NTFS_MAX_NAME_LEN) */ {
		ntfs_error(vol->sb, "Name is too long (maximum length for a "
				"name on NTFS is %d Unicode characters.",
				NTFS_MAX_NAME_LEN);
		i = -ENAMETOOLONG;
	}
	return i;
}

/**
 * ntfs_ucstonls - convert little endian Unicode string to NLS string
 * @vol:	ntfs volume which we are working with
 * @ins:	input Unicode string buffer
 * @ins_len:	length of input string in Unicode characters
 * @outs:	on return contains the (allocated) output NLS string buffer
 * @outs_len:	length of output string buffer in bytes
 *
 * Convert the input little endian, 2-byte Unicode string @ins, of length
 * @ins_len into the string format dictated by the loaded NLS.
 *
 * If *@outs is NULL, this function allocates the string and the caller is
 * responsible for calling kfree(*@outs); when finished with it. In this case
 * @outs_len is ignored and can be 0.
 *
 * On success the function returns the number of bytes written to the output
 * string *@outs (>= 0), not counting the terminating NULL byte. If the output
 * string buffer was allocated, *@outs is set to it.
 *
 * On error, a negative number corresponding to the error code is returned. In
 * that case the output string is not allocated. The contents of *@outs are
 * then undefined.
 *
 * This might look a bit odd due to fast path optimization...
 */
int ntfs_ucstonls(const ntfs_volume *vol, const ntfschar *ins,
		const int ins_len, unsigned char **outs, int outs_len)
{
	struct nls_table *nls = vol->nls_map;
	unsigned char *ns;
	int i, o, ns_len, wc;

	/* We don't trust outside sources. */
	if (ins) {
		ns = *outs;
		ns_len = outs_len;
		if (ns && !ns_len) {
			wc = -ENAMETOOLONG;
			goto conversion_err;
		}
		if (!ns) {
			ns_len = ins_len * NLS_MAX_CHARSET_SIZE;
			ns = kmalloc(ns_len + 1, GFP_NOFS);
			if (!ns)
				goto mem_err_out;
		}
		for (i = o = 0; i < ins_len; i++) {
retry:			wc = nls->uni2char(le16_to_cpu(ins[i]), ns + o,
					ns_len - o);
			if (wc > 0) {
				o += wc;
				continue;
			} else if (!wc)
				break;
			else if (wc == -ENAMETOOLONG && ns != *outs) {
				unsigned char *tc;
				/* Grow in multiples of 64 bytes. */
				tc = kmalloc((ns_len + 64) &
						~63, GFP_NOFS);
				if (tc) {
					memcpy(tc, ns, ns_len);
					ns_len = ((ns_len + 64) & ~63) - 1;
					kfree(ns);
					ns = tc;
					goto retry;
				} /* No memory so goto conversion_error; */
			} /* wc < 0, real error. */
			goto conversion_err;
		}
		ns[o] = 0;
		*outs = ns;
		return o;
	} /* else (!ins) */
	ntfs_error(vol->sb, "Received NULL pointer.");
	return -EINVAL;
conversion_err:
	ntfs_error(vol->sb, "Unicode name contains characters that cannot be "
			"converted to character set %s.  You might want to "
			"try to use the mount option nls=utf8.", nls->charset);
	if (ns != *outs)
		kfree(ns);
	if (wc != -ENAMETOOLONG)
		wc = -EILSEQ;
	return wc;
mem_err_out:
	ntfs_error(vol->sb, "Failed to allocate name!");
	return -ENOMEM;
}