diff options
| -rw-r--r-- | fs/unicode/Makefile | 2 | ||||
| -rw-r--r-- | fs/unicode/utf8-norm.c | 642 | ||||
| -rw-r--r-- | fs/unicode/utf8n.h | 112 |
3 files changed, 756 insertions, 0 deletions
diff --git a/fs/unicode/Makefile b/fs/unicode/Makefile index 764f8e5da4bb..16d43d180416 100644 --- a/fs/unicode/Makefile +++ b/fs/unicode/Makefile @@ -1,5 +1,7 @@ # SPDX-License-Identifier: GPL-2.0 +obj-$(CONFIG_UNICODE) += utf8-norm.o + # This rule is not invoked during the kernel compilation. It is used to # regenerate the utf8data.h header file. utf8data.h.new: *.txt $(objdir)/scripts/mkutf8data diff --git a/fs/unicode/utf8-norm.c b/fs/unicode/utf8-norm.c new file mode 100644 index 000000000000..aa2980f26527 --- /dev/null +++ b/fs/unicode/utf8-norm.c @@ -0,0 +1,642 @@ +/* + * Copyright (c) 2014 SGI. + * All rights reserved. + * + * This program 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. + * + * This program is distributed in the hope that it would 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. + * + */ + +#include "utf8n.h" + +struct utf8data { + unsigned int maxage; + unsigned int offset; +}; + +#define __INCLUDED_FROM_UTF8NORM_C__ +#include "utf8data.h" +#undef __INCLUDED_FROM_UTF8NORM_C__ + +int utf8version_is_supported(u8 maj, u8 min, u8 rev) +{ + int i = ARRAY_SIZE(utf8agetab) - 1; + unsigned int sb_utf8version = UNICODE_AGE(maj, min, rev); + + while (i >= 0 && utf8agetab[i] != 0) { + if (sb_utf8version == utf8agetab[i]) + return 1; + i--; + } + return 0; +} +EXPORT_SYMBOL(utf8version_is_supported); + +/* + * 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); +} + +/* + * 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. + * + * 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) + +/* + * 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 utf8data *data, const char *s, + size_t len) +{ + utf8trie_t *trie = NULL; + int offlen; + int offset; + int mask; + int node; + + if (!data) + return NULL; + if (len == 0) + return NULL; + + trie = utf8data + data->offset; + 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. */ + node = 0; + trie = NULL; + } + } else { + /* Left leg */ + if (offlen) { + /* Left node after this node. */ + node = (*trie & LEFTNODE); + trie += offlen + 1; + } else if (*trie & RIGHTPATH) { + /* No left node. */ + node = 0; + trie = NULL; + } else { + /* Left node after this node */ + node = (*trie & TRIENODE); + trie++; + } + } + } + return trie; +} + +/* + * Use trie to scan s. + * Returns the leaf if one exists, NULL otherwise. + * + * Forwards to utf8nlookup(). + */ +static utf8leaf_t *utf8lookup(const struct utf8data *data, const char *s) +{ + return utf8nlookup(data, s, (size_t)-1); +} + +/* + * Maximum age of any character in s. + * Return -1 if s is not valid UTF-8 unicode. + * Return 0 if only non-assigned code points are used. + */ +int utf8agemax(const struct utf8data *data, const char *s) +{ + utf8leaf_t *leaf; + int age = 0; + int leaf_age; + + if (!data) + return -1; + while (*s) { + leaf = utf8lookup(data, s); + if (!leaf) + return -1; + + leaf_age = utf8agetab[LEAF_GEN(leaf)]; + if (leaf_age <= data->maxage && leaf_age > age) + age = leaf_age; + s += utf8clen(s); + } + return age; +} +EXPORT_SYMBOL(utf8agemax); + +/* + * Minimum age of any character in s. + * Return -1 if s is not valid UTF-8 unicode. + * Return 0 if non-assigned code points are used. + */ +int utf8agemin(const struct utf8data *data, const char *s) +{ + utf8leaf_t *leaf; + int age; + int leaf_age; + + if (!data) + return -1; + age = data->maxage; + while (*s) { + leaf = utf8lookup(data, s); + if (!leaf) + return -1; + leaf_age = utf8agetab[LEAF_GEN(leaf)]; + if (leaf_age <= data->maxage && leaf_age < age) + age = leaf_age; + s += utf8clen(s); + } + return age; +} +EXPORT_SYMBOL(utf8agemin); + +/* + * Maximum age of any character in s, touch at most len bytes. + * Return -1 if s is not valid UTF-8 unicode. + */ +int utf8nagemax(const struct utf8data *data, const char *s, size_t len) +{ + utf8leaf_t *leaf; + int age = 0; + int leaf_age; + + if (!data) + return -1; + while (len && *s) { + leaf = utf8nlookup(data, s, len); + if (!leaf) + return -1; + leaf_age = utf8agetab[LEAF_GEN(leaf)]; + if (leaf_age <= data->maxage && leaf_age > age) + age = leaf_age; + len -= utf8clen(s); + s += utf8clen(s); + } + return age; +} +EXPORT_SYMBOL(utf8nagemax); + +/* + * Maximum age of any character in s, touch at most len bytes. + * Return -1 if s is not valid UTF-8 unicode. + */ +int utf8nagemin(const struct utf8data *data, const char *s, size_t len) +{ + utf8leaf_t *leaf; + int leaf_age; + int age; + + if (!data) + return -1; + age = data->maxage; + while (len && *s) { + leaf = utf8nlookup(data, s, len); + if (!leaf) + return -1; + leaf_age = utf8agetab[LEAF_GEN(leaf)]; + if (leaf_age <= data->maxage && leaf_age < age) + age = leaf_age; + len -= utf8clen(s); + s += utf8clen(s); + } + return age; +} +EXPORT_SYMBOL(utf8nagemin); + +/* + * Length of the normalization of s. + * Return -1 if s is not valid UTF-8 unicode. + * + * A string of Default_Ignorable_Code_Point has length 0. + */ +ssize_t utf8len(const struct utf8data *data, const char *s) +{ + utf8leaf_t *leaf; + size_t ret = 0; + + if (!data) + return -1; + while (*s) { + leaf = utf8lookup(data, s); + if (!leaf) + return -1; + if (utf8agetab[LEAF_GEN(leaf)] > data->maxage) + ret += utf8clen(s); + else if (LEAF_CCC(leaf) == DECOMPOSE) + ret += strlen(LEAF_STR(leaf)); + else + ret += utf8clen(s); + s += utf8clen(s); + } + return ret; +} +EXPORT_SYMBOL(utf8len); + +/* + * 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 utf8data *data, const char *s, size_t len) +{ + utf8leaf_t *leaf; + size_t ret = 0; + + if (!data) + return -1; + while (len && *s) { + leaf = utf8nlookup(data, s, len); + if (!leaf) + return -1; + if (utf8agetab[LEAF_GEN(leaf)] > data->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; +} +EXPORT_SYMBOL(utf8nlen); + +/* + * 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 utf8data *data, + const char *s, size_t len) +{ + if (!data) + return -1; + if (!s) + return -1; + u8c->data = data; + 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; +} +EXPORT_SYMBOL(utf8ncursor); + +/* + * Set up an utf8cursor for use by utf8byte(). + * + * u8c : pointer to cursor. + * data : const struct utf8data to use for normalization. + * s : NUL-terminated string. + * + * Returns -1 on error, 0 on success. + */ +int utf8cursor(struct utf8cursor *u8c, const struct utf8data *data, + const char *s) +{ + return utf8ncursor(u8c, data, s, (unsigned int)-1); +} +EXPORT_SYMBOL(utf8cursor); + +/* + * 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->data, u8c->s); + else + leaf = utf8nlookup(u8c->data, 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 (utf8agetab[LEAF_GEN(leaf)] > u8c->data->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->data, u8c->s); + } + + /* + * 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; + } + } +} +EXPORT_SYMBOL(utf8byte); + +const struct utf8data *utf8nfdi(unsigned int maxage) +{ + int i = ARRAY_SIZE(utf8nfdidata) - 1; + + while (maxage < utf8nfdidata[i].maxage) + i--; + if (maxage > utf8nfdidata[i].maxage) + return NULL; + return &utf8nfdidata[i]; +} +EXPORT_SYMBOL(utf8nfdi); + +const struct utf8data *utf8nfdicf(unsigned int maxage) +{ + int i = ARRAY_SIZE(utf8nfdicfdata) - 1; + + while (maxage < utf8nfdicfdata[i].maxage) + i--; + if (maxage > utf8nfdicfdata[i].maxage) + return NULL; + return &utf8nfdicfdata[i]; +} +EXPORT_SYMBOL(utf8nfdicf); diff --git a/fs/unicode/utf8n.h b/fs/unicode/utf8n.h new file mode 100644 index 000000000000..696e52124296 --- /dev/null +++ b/fs/unicode/utf8n.h @@ -0,0 +1,112 @@ +/* + * Copyright (c) 2014 SGI. + * All rights reserved. + * + * This program 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. + * + * This program is distributed in the hope that it would 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. + * + */ + +#ifndef UTF8NORM_H +#define UTF8NORM_H + +#include <linux/types.h> +#include <linux/export.h> +#include <linux/string.h> +#include <linux/module.h> + +/* Encoding a unicode version number as a single unsigned int. */ +#define UNICODE_MAJ_SHIFT (16) +#define UNICODE_MIN_SHIFT (8) + +#define UNICODE_AGE(MAJ, MIN, REV) \ + (((unsigned int)(MAJ) << UNICODE_MAJ_SHIFT) | \ + ((unsigned int)(MIN) << UNICODE_MIN_SHIFT) | \ + ((unsigned int)(REV))) + +/* Highest unicode version supported by the data tables. */ +extern int utf8version_is_supported(u8 maj, u8 min, u8 rev); + +/* + * Look for the correct const struct utf8data for a unicode version. + * Returns NULL if the version requested is too new. + * + * Two normalization forms are supported: nfdi and nfdicf. + * + * nfdi: + * - Apply unicode normalization form NFD. + * - Remove any Default_Ignorable_Code_Point. + * + * nfdicf: + * - Apply unicode normalization form NFD. + * - Remove any Default_Ignorable_Code_Point. + * - Apply a full casefold (C + F). + */ +extern const struct utf8data *utf8nfdi(unsigned int maxage); +extern const struct utf8data *utf8nfdicf(unsigned int maxage); + +/* + * Determine the maximum age of any unicode character in the string. + * Returns 0 if only unassigned code points are present. + * Returns -1 if the input is not valid UTF-8. + */ +extern int utf8agemax(const struct utf8data *data, const char *s); +extern int utf8nagemax(const struct utf8data *data, const char *s, size_t len); + +/* + * Determine the minimum age of any unicode character in the string. + * Returns 0 if any unassigned code points are present. + * Returns -1 if the input is not valid UTF-8. + */ +extern int utf8agemin(const struct utf8data *data, const char *s); +extern int utf8nagemin(const struct utf8data *data, const char *s, size_t len); + +/* + * Determine the length of the normalized from of the string, + * excluding any terminating NULL byte. + * Returns 0 if only ignorable code points are present. + * Returns -1 if the input is not valid UTF-8. + */ +extern ssize_t utf8len(const struct utf8data *data, const char *s); +extern ssize_t utf8nlen(const struct utf8data *data, const char *s, size_t len); + +/* + * Cursor structure used by the normalizer. + */ +struct utf8cursor { + const struct utf8data *data; + const char *s; + const char *p; + const char *ss; + const char *sp; + unsigned int len; + unsigned int slen; + short int ccc; + short int nccc; +}; + +/* + * Initialize a utf8cursor to normalize a string. + * Returns 0 on success. + * Returns -1 on failure. + */ +extern int utf8cursor(struct utf8cursor *u8c, const struct utf8data *data, + const char *s); +extern int utf8ncursor(struct utf8cursor *u8c, const struct utf8data *data, + const char *s, size_t len); + +/* + * Get the next byte in the normalization. + * Returns a value > 0 && < 256 on success. + * Returns 0 when the end of the normalization is reached. + * Returns -1 if the string being normalized is not valid UTF-8. + */ +extern int utf8byte(struct utf8cursor *u8c); + +#endif /* UTF8NORM_H */ |