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linux/linux-5.18.11/fs/unicode/utf8-norm.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2014 SGI.
* All rights reserved.
*/
#include "utf8n.h"
int utf8version_is_supported(const struct unicode_map *um, unsigned int version)
{
int i = um->tables->utf8agetab_size - 1;
while (i >= 0 && um->tables->utf8agetab[i] != 0) {
if (version == um->tables->utf8agetab[i])
return 1;
i--;
}
return 0;
}
/*
* UTF-8 valid ranges.
*
* The UTF-8 encoding spreads the bits of a 32bit word over several
* bytes. This table gives the ranges that can be held and how they'd
* be represented.
*
* 0x00000000 0x0000007F: 0xxxxxxx
* 0x00000000 0x000007FF: 110xxxxx 10xxxxxx
* 0x00000000 0x0000FFFF: 1110xxxx 10xxxxxx 10xxxxxx
* 0x00000000 0x001FFFFF: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
* 0x00000000 0x03FFFFFF: 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
* 0x00000000 0x7FFFFFFF: 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
*
* There is an additional requirement on UTF-8, in that only the
* shortest representation of a 32bit value is to be used. A decoder
* must not decode sequences that do not satisfy this requirement.
* Thus the allowed ranges have a lower bound.
*
* 0x00000000 0x0000007F: 0xxxxxxx
* 0x00000080 0x000007FF: 110xxxxx 10xxxxxx
* 0x00000800 0x0000FFFF: 1110xxxx 10xxxxxx 10xxxxxx
* 0x00010000 0x001FFFFF: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
* 0x00200000 0x03FFFFFF: 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
* 0x04000000 0x7FFFFFFF: 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
*
* Actual unicode characters are limited to the range 0x0 - 0x10FFFF,
* 17 planes of 65536 values. This limits the sequences actually seen
* even more, to just the following.
*
* 0 - 0x7F: 0 - 0x7F
* 0x80 - 0x7FF: 0xC2 0x80 - 0xDF 0xBF
* 0x800 - 0xFFFF: 0xE0 0xA0 0x80 - 0xEF 0xBF 0xBF
* 0x10000 - 0x10FFFF: 0xF0 0x90 0x80 0x80 - 0xF4 0x8F 0xBF 0xBF
*
* Within those ranges the surrogates 0xD800 - 0xDFFF are not allowed.
*
* Note that the longest sequence seen with valid usage is 4 bytes,
* the same a single UTF-32 character. This makes the UTF-8
* representation of Unicode strictly smaller than UTF-32.
*
* The shortest sequence requirement was introduced by:
* Corrigendum #1: UTF-8 Shortest Form
* It can be found here:
* http://www.unicode.org/versions/corrigendum1.html
*
*/
/*
* Return the number of bytes used by the current UTF-8 sequence.
* Assumes the input points to the first byte of a valid UTF-8
* sequence.
*/
static inline int utf8clen(const char *s)
{
unsigned char c = *s;
return 1 + (c >= 0xC0) + (c >= 0xE0) + (c >= 0xF0);
}
/*
* Decode a 3-byte UTF-8 sequence.
*/
static unsigned int
utf8decode3(const char *str)
{
unsigned int uc;
uc = *str++ & 0x0F;
uc <<= 6;
uc |= *str++ & 0x3F;
uc <<= 6;
uc |= *str++ & 0x3F;
return uc;
}
/*
* Encode a 3-byte UTF-8 sequence.
*/
static int
utf8encode3(char *str, unsigned int val)
{
str[2] = (val & 0x3F) | 0x80;
val >>= 6;
str[1] = (val & 0x3F) | 0x80;
val >>= 6;
str[0] = val | 0xE0;
return 3;
}
/*
* utf8trie_t
*
* A compact binary tree, used to decode UTF-8 characters.
*
* Internal nodes are one byte for the node itself, and up to three
* bytes for an offset into the tree. The first byte contains the
* following information:
* NEXTBYTE - flag - advance to next byte if set
* BITNUM - 3 bit field - the bit number to tested
* OFFLEN - 2 bit field - number of bytes in the offset
* if offlen == 0 (non-branching node)
* RIGHTPATH - 1 bit field - set if the following node is for the
* right-hand path (tested bit is set)
* TRIENODE - 1 bit field - set if the following node is an internal
* node, otherwise it is a leaf node
* if offlen != 0 (branching node)
* LEFTNODE - 1 bit field - set if the left-hand node is internal
* RIGHTNODE - 1 bit field - set if the right-hand node is internal
*
* Due to the way utf8 works, there cannot be branching nodes with
* NEXTBYTE set, and moreover those nodes always have a righthand
* descendant.
*/
typedef const unsigned char utf8trie_t;
#define BITNUM 0x07
#define NEXTBYTE 0x08
#define OFFLEN 0x30
#define OFFLEN_SHIFT 4
#define RIGHTPATH 0x40
#define TRIENODE 0x80
#define RIGHTNODE 0x40
#define LEFTNODE 0x80
/*
* utf8leaf_t
*
* The leaves of the trie are embedded in the trie, and so the same
* underlying datatype: unsigned char.
*
* leaf[0]: The unicode version, stored as a generation number that is
* an index into ->utf8agetab[]. With this we can filter code
* points based on the unicode version in which they were
* defined. The CCC of a non-defined code point is 0.
* leaf[1]: Canonical Combining Class. During normalization, we need
* to do a stable sort into ascending order of all characters
* with a non-zero CCC that occur between two characters with
* a CCC of 0, or at the begin or end of a string.
* The unicode standard guarantees that all CCC values are
* between 0 and 254 inclusive, which leaves 255 available as
* a special value.
* Code points with CCC 0 are known as stoppers.
* leaf[2]: Decomposition. If leaf[1] == 255, then leaf[2] is the
* start of a NUL-terminated string that is the decomposition
* of the character.
* The CCC of a decomposable character is the same as the CCC
* of the first character of its decomposition.
* Some characters decompose as the empty string: these are
* characters with the Default_Ignorable_Code_Point property.
* These do affect normalization, as they all have CCC 0.
*
* The decompositions in the trie have been fully expanded, with the
* exception of Hangul syllables, which are decomposed algorithmically.
*
* Casefolding, if applicable, is also done using decompositions.
*
* The trie is constructed in such a way that leaves exist for all
* UTF-8 sequences that match the criteria from the "UTF-8 valid
* ranges" comment above, and only for those sequences. Therefore a
* lookup in the trie can be used to validate the UTF-8 input.
*/
typedef const unsigned char utf8leaf_t;
#define LEAF_GEN(LEAF) ((LEAF)[0])
#define LEAF_CCC(LEAF) ((LEAF)[1])
#define LEAF_STR(LEAF) ((const char *)((LEAF) + 2))
#define MINCCC (0)
#define MAXCCC (254)
#define STOPPER (0)
#define DECOMPOSE (255)
/* Marker for hangul syllable decomposition. */
#define HANGUL ((char)(255))
/* Size of the synthesized leaf used for Hangul syllable decomposition. */
#define UTF8HANGULLEAF (12)
/*
* Hangul decomposition (algorithm from Section 3.12 of Unicode 6.3.0)
*
* AC00;<Hangul Syllable, First>;Lo;0;L;;;;;N;;;;;
* D7A3;<Hangul Syllable, Last>;Lo;0;L;;;;;N;;;;;
*
* SBase = 0xAC00
* LBase = 0x1100
* VBase = 0x1161
* TBase = 0x11A7
* LCount = 19
* VCount = 21
* TCount = 28
* NCount = 588 (VCount * TCount)
* SCount = 11172 (LCount * NCount)
*
* Decomposition:
* SIndex = s - SBase
*
* LV (Canonical/Full)
* LIndex = SIndex / NCount
* VIndex = (Sindex % NCount) / TCount
* LPart = LBase + LIndex
* VPart = VBase + VIndex
*
* LVT (Canonical)
* LVIndex = (SIndex / TCount) * TCount
* TIndex = (Sindex % TCount)
* LVPart = SBase + LVIndex
* TPart = TBase + TIndex
*
* LVT (Full)
* LIndex = SIndex / NCount
* VIndex = (Sindex % NCount) / TCount
* TIndex = (Sindex % TCount)
* LPart = LBase + LIndex
* VPart = VBase + VIndex
* if (TIndex == 0) {
* d = <LPart, VPart>
* } else {
* TPart = TBase + TIndex
* d = <LPart, TPart, VPart>
* }
*/
/* Constants */
#define SB (0xAC00)
#define LB (0x1100)
#define VB (0x1161)
#define TB (0x11A7)
#define LC (19)
#define VC (21)
#define TC (28)
#define NC (VC * TC)
#define SC (LC * NC)
/* Algorithmic decomposition of hangul syllable. */
static utf8leaf_t *
utf8hangul(const char *str, unsigned char *hangul)
{
unsigned int si;
unsigned int li;
unsigned int vi;
unsigned int ti;
unsigned char *h;
/* Calculate the SI, LI, VI, and TI values. */
si = utf8decode3(str) - SB;
li = si / NC;
vi = (si % NC) / TC;
ti = si % TC;
/* Fill in base of leaf. */
h = hangul;
LEAF_GEN(h) = 2;
LEAF_CCC(h) = DECOMPOSE;
h += 2;
/* Add LPart, a 3-byte UTF-8 sequence. */
h += utf8encode3((char *)h, li + LB);
/* Add VPart, a 3-byte UTF-8 sequence. */
h += utf8encode3((char *)h, vi + VB);
/* Add TPart if required, also a 3-byte UTF-8 sequence. */
if (ti)
h += utf8encode3((char *)h, ti + TB);
/* Terminate string. */
h[0] = '\0';
return hangul;
}
/*
* Use trie to scan s, touching at most len bytes.
* Returns the leaf if one exists, NULL otherwise.
*
* A non-NULL return guarantees that the UTF-8 sequence starting at s
* is well-formed and corresponds to a known unicode code point. The
* shorthand for this will be "is valid UTF-8 unicode".
*/
static utf8leaf_t *utf8nlookup(const struct unicode_map *um,
enum utf8_normalization n, unsigned char *hangul, const char *s,
size_t len)
{
utf8trie_t *trie = um->tables->utf8data + um->ntab[n]->offset;
int offlen;
int offset;
int mask;
int node;
if (len == 0)
return NULL;
node = 1;
while (node) {
offlen = (*trie & OFFLEN) >> OFFLEN_SHIFT;
if (*trie & NEXTBYTE) {
if (--len == 0)
return NULL;
s++;
}
mask = 1 << (*trie & BITNUM);
if (*s & mask) {
/* Right leg */
if (offlen) {
/* Right node at offset of trie */
node = (*trie & RIGHTNODE);
offset = trie[offlen];
while (--offlen) {
offset <<= 8;
offset |= trie[offlen];
}
trie += offset;
} else if (*trie & RIGHTPATH) {
/* Right node after this node */
node = (*trie & TRIENODE);
trie++;
} else {
/* No right node. */
return NULL;
}
} else {
/* Left leg */
if (offlen) {
/* Left node after this node. */
node = (*trie & LEFTNODE);
trie += offlen + 1;
} else if (*trie & RIGHTPATH) {
/* No left node. */
return NULL;
} else {
/* Left node after this node */
node = (*trie & TRIENODE);
trie++;
}
}
}
/*
* Hangul decomposition is done algorithmically. These are the
* codepoints >= 0xAC00 and <= 0xD7A3. Their UTF-8 encoding is
* always 3 bytes long, so s has been advanced twice, and the
* start of the sequence is at s-2.
*/
if (LEAF_CCC(trie) == DECOMPOSE && LEAF_STR(trie)[0] == HANGUL)
trie = utf8hangul(s - 2, hangul);
return trie;
}
/*
* Use trie to scan s.
* Returns the leaf if one exists, NULL otherwise.
*
* Forwards to utf8nlookup().
*/
static utf8leaf_t *utf8lookup(const struct unicode_map *um,
enum utf8_normalization n, unsigned char *hangul, const char *s)
{
return utf8nlookup(um, n, hangul, s, (size_t)-1);
}
/*
* Length of the normalization of s, touch at most len bytes.
* Return -1 if s is not valid UTF-8 unicode.
*/
ssize_t utf8nlen(const struct unicode_map *um, enum utf8_normalization n,
const char *s, size_t len)
{
utf8leaf_t *leaf;
size_t ret = 0;
unsigned char hangul[UTF8HANGULLEAF];
while (len && *s) {
leaf = utf8nlookup(um, n, hangul, s, len);
if (!leaf)
return -1;
if (um->tables->utf8agetab[LEAF_GEN(leaf)] >
um->ntab[n]->maxage)
ret += utf8clen(s);
else if (LEAF_CCC(leaf) == DECOMPOSE)
ret += strlen(LEAF_STR(leaf));
else
ret += utf8clen(s);
len -= utf8clen(s);
s += utf8clen(s);
}
return ret;
}
/*
* Set up an utf8cursor for use by utf8byte().
*
* u8c : pointer to cursor.
* data : const struct utf8data to use for normalization.
* s : string.
* len : length of s.
*
* Returns -1 on error, 0 on success.
*/
int utf8ncursor(struct utf8cursor *u8c, const struct unicode_map *um,
enum utf8_normalization n, const char *s, size_t len)
{
if (!s)
return -1;
u8c->um = um;
u8c->n = n;
u8c->s = s;
u8c->p = NULL;
u8c->ss = NULL;
u8c->sp = NULL;
u8c->len = len;
u8c->slen = 0;
u8c->ccc = STOPPER;
u8c->nccc = STOPPER;
/* Check we didn't clobber the maximum length. */
if (u8c->len != len)
return -1;
/* The first byte of s may not be an utf8 continuation. */
if (len > 0 && (*s & 0xC0) == 0x80)
return -1;
return 0;
}
/*
* Get one byte from the normalized form of the string described by u8c.
*
* Returns the byte cast to an unsigned char on succes, and -1 on failure.
*
* The cursor keeps track of the location in the string in u8c->s.
* When a character is decomposed, the current location is stored in
* u8c->p, and u8c->s is set to the start of the decomposition. Note
* that bytes from a decomposition do not count against u8c->len.
*
* Characters are emitted if they match the current CCC in u8c->ccc.
* Hitting end-of-string while u8c->ccc == STOPPER means we're done,
* and the function returns 0 in that case.
*
* Sorting by CCC is done by repeatedly scanning the string. The
* values of u8c->s and u8c->p are stored in u8c->ss and u8c->sp at
* the start of the scan. The first pass finds the lowest CCC to be
* emitted and stores it in u8c->nccc, the second pass emits the
* characters with this CCC and finds the next lowest CCC. This limits
* the number of passes to 1 + the number of different CCCs in the
* sequence being scanned.
*
* Therefore:
* u8c->p != NULL -> a decomposition is being scanned.
* u8c->ss != NULL -> this is a repeating scan.
* u8c->ccc == -1 -> this is the first scan of a repeating scan.
*/
int utf8byte(struct utf8cursor *u8c)
{
utf8leaf_t *leaf;
int ccc;
for (;;) {
/* Check for the end of a decomposed character. */
if (u8c->p && *u8c->s == '\0') {
u8c->s = u8c->p;
u8c->p = NULL;
}
/* Check for end-of-string. */
if (!u8c->p && (u8c->len == 0 || *u8c->s == '\0')) {
/* There is no next byte. */
if (u8c->ccc == STOPPER)
return 0;
/* End-of-string during a scan counts as a stopper. */
ccc = STOPPER;
goto ccc_mismatch;
} else if ((*u8c->s & 0xC0) == 0x80) {
/* This is a continuation of the current character. */
if (!u8c->p)
u8c->len--;
return (unsigned char)*u8c->s++;
}
/* Look up the data for the current character. */
if (u8c->p) {
leaf = utf8lookup(u8c->um, u8c->n, u8c->hangul, u8c->s);
} else {
leaf = utf8nlookup(u8c->um, u8c->n, u8c->hangul,
u8c->s, u8c->len);
}
/* No leaf found implies that the input is a binary blob. */
if (!leaf)
return -1;
ccc = LEAF_CCC(leaf);
/* Characters that are too new have CCC 0. */
if (u8c->um->tables->utf8agetab[LEAF_GEN(leaf)] >
u8c->um->ntab[u8c->n]->maxage) {
ccc = STOPPER;
} else if (ccc == DECOMPOSE) {
u8c->len -= utf8clen(u8c->s);
u8c->p = u8c->s + utf8clen(u8c->s);
u8c->s = LEAF_STR(leaf);
/* Empty decomposition implies CCC 0. */
if (*u8c->s == '\0') {
if (u8c->ccc == STOPPER)
continue;
ccc = STOPPER;
goto ccc_mismatch;
}
leaf = utf8lookup(u8c->um, u8c->n, u8c->hangul, u8c->s);
if (!leaf)
return -1;
ccc = LEAF_CCC(leaf);
}
/*
* If this is not a stopper, then see if it updates
* the next canonical class to be emitted.
*/
if (ccc != STOPPER && u8c->ccc < ccc && ccc < u8c->nccc)
u8c->nccc = ccc;
/*
* Return the current byte if this is the current
* combining class.
*/
if (ccc == u8c->ccc) {
if (!u8c->p)
u8c->len--;
return (unsigned char)*u8c->s++;
}
/* Current combining class mismatch. */
ccc_mismatch:
if (u8c->nccc == STOPPER) {
/*
* Scan forward for the first canonical class
* to be emitted. Save the position from
* which to restart.
*/
u8c->ccc = MINCCC - 1;
u8c->nccc = ccc;
u8c->sp = u8c->p;
u8c->ss = u8c->s;
u8c->slen = u8c->len;
if (!u8c->p)
u8c->len -= utf8clen(u8c->s);
u8c->s += utf8clen(u8c->s);
} else if (ccc != STOPPER) {
/* Not a stopper, and not the ccc we're emitting. */
if (!u8c->p)
u8c->len -= utf8clen(u8c->s);
u8c->s += utf8clen(u8c->s);
} else if (u8c->nccc != MAXCCC + 1) {
/* At a stopper, restart for next ccc. */
u8c->ccc = u8c->nccc;
u8c->nccc = MAXCCC + 1;
u8c->s = u8c->ss;
u8c->p = u8c->sp;
u8c->len = u8c->slen;
} else {
/* All done, proceed from here. */
u8c->ccc = STOPPER;
u8c->nccc = STOPPER;
u8c->sp = NULL;
u8c->ss = NULL;
u8c->slen = 0;
}
}
}
#ifdef CONFIG_UNICODE_NORMALIZATION_SELFTEST_MODULE
EXPORT_SYMBOL_GPL(utf8version_is_supported);
EXPORT_SYMBOL_GPL(utf8nlen);
EXPORT_SYMBOL_GPL(utf8ncursor);
EXPORT_SYMBOL_GPL(utf8byte);
#endif