1/*	$NetBSD: lutf8lib.c,v 1.11 2023/06/08 21:12:08 nikita Exp $	*/
2
3/*
4** Id: lutf8lib.c
5** Standard library for UTF-8 manipulation
6** See Copyright Notice in lua.h
7*/
8
9#define lutf8lib_c
10#define LUA_LIB
11
12#include "lprefix.h"
13
14
15#ifndef _KERNEL
16#include <assert.h>
17#include <limits.h>
18#include <stdlib.h>
19#include <string.h>
20#endif /* _KERNEL */
21
22#include "lua.h"
23
24#include "lauxlib.h"
25#include "lualib.h"
26
27
28#define MAXUNICODE	0x10FFFFu
29
30#define MAXUTF		0x7FFFFFFFu
31
32
33#define MSGInvalid	"invalid UTF-8 code"
34
35/*
36** Integer type for decoded UTF-8 values; MAXUTF needs 31 bits.
37*/
38#if (UINT_MAX >> 30) >= 1
39typedef unsigned int utfint;
40#else
41typedef unsigned long utfint;
42#endif
43
44
45#define iscont(c)	(((c) & 0xC0) == 0x80)
46#define iscontp(p)	iscont(*(p))
47
48
49/* from strlib */
50/* translate a relative string position: negative means back from end */
51static lua_Integer u_posrelat (lua_Integer pos, size_t len) {
52  if (pos >= 0) return pos;
53  else if (0u - (size_t)pos > len) return 0;
54  else return (lua_Integer)len + pos + 1;
55}
56
57
58/*
59** Decode one UTF-8 sequence, returning NULL if byte sequence is
60** invalid.  The array 'limits' stores the minimum value for each
61** sequence length, to check for overlong representations. Its first
62** entry forces an error for non-ascii bytes with no continuation
63** bytes (count == 0).
64*/
65static const char *utf8_decode (const char *s, utfint *val, int strict) {
66  static const utfint limits[] =
67        {~(utfint)0, 0x80, 0x800, 0x10000u, 0x200000u, 0x4000000u};
68  unsigned int c = (unsigned char)s[0];
69  utfint res = 0;  /* final result */
70  if (c < 0x80)  /* ascii? */
71    res = c;
72  else {
73    int count = 0;  /* to count number of continuation bytes */
74    for (; c & 0x40; c <<= 1) {  /* while it needs continuation bytes... */
75      unsigned int cc = (unsigned char)s[++count];  /* read next byte */
76      if (!iscont(cc))  /* not a continuation byte? */
77        return NULL;  /* invalid byte sequence */
78      res = (res << 6) | (cc & 0x3F);  /* add lower 6 bits from cont. byte */
79    }
80    res |= ((utfint)(c & 0x7F) << (count * 5));  /* add first byte */
81    if (count > 5 || res > MAXUTF || res < limits[count])
82      return NULL;  /* invalid byte sequence */
83    s += count;  /* skip continuation bytes read */
84  }
85  if (strict) {
86    /* check for invalid code points; too large or surrogates */
87    if (res > MAXUNICODE || (0xD800u <= res && res <= 0xDFFFu))
88      return NULL;
89  }
90  if (val) *val = res;
91  return s + 1;  /* +1 to include first byte */
92}
93
94
95/*
96** utf8len(s [, i [, j [, lax]]]) --> number of characters that
97** start in the range [i,j], or nil + current position if 's' is not
98** well formed in that interval
99*/
100static int utflen (lua_State *L) {
101  lua_Integer n = 0;  /* counter for the number of characters */
102  size_t len;  /* string length in bytes */
103  const char *s = luaL_checklstring(L, 1, &len);
104  lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
105  lua_Integer posj = u_posrelat(luaL_optinteger(L, 3, -1), len);
106  int lax = lua_toboolean(L, 4);
107  luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 2,
108                   "initial position out of bounds");
109  luaL_argcheck(L, --posj < (lua_Integer)len, 3,
110                   "final position out of bounds");
111  while (posi <= posj) {
112    const char *s1 = utf8_decode(s + posi, NULL, !lax);
113    if (s1 == NULL) {  /* conversion error? */
114      luaL_pushfail(L);  /* return fail ... */
115      lua_pushinteger(L, posi + 1);  /* ... and current position */
116      return 2;
117    }
118    posi = s1 - s;
119    n++;
120  }
121  lua_pushinteger(L, n);
122  return 1;
123}
124
125
126/*
127** codepoint(s, [i, [j [, lax]]]) -> returns codepoints for all
128** characters that start in the range [i,j]
129*/
130static int codepoint (lua_State *L) {
131  size_t len;
132  const char *s = luaL_checklstring(L, 1, &len);
133  lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
134  lua_Integer pose = u_posrelat(luaL_optinteger(L, 3, posi), len);
135  int lax = lua_toboolean(L, 4);
136  int n;
137  const char *se;
138  luaL_argcheck(L, posi >= 1, 2, "out of bounds");
139  luaL_argcheck(L, pose <= (lua_Integer)len, 3, "out of bounds");
140  if (posi > pose) return 0;  /* empty interval; return no values */
141  if (pose - posi >= INT_MAX)  /* (lua_Integer -> int) overflow? */
142    return luaL_error(L, "string slice too long");
143  n = (int)(pose -  posi) + 1;  /* upper bound for number of returns */
144  luaL_checkstack(L, n, "string slice too long");
145  n = 0;  /* count the number of returns */
146  se = s + pose;  /* string end */
147  for (s += posi - 1; s < se;) {
148    utfint code;
149    s = utf8_decode(s, &code, !lax);
150    if (s == NULL)
151      return luaL_error(L, MSGInvalid);
152    lua_pushinteger(L, code);
153    n++;
154  }
155  return n;
156}
157
158
159static void pushutfchar (lua_State *L, int arg) {
160  lua_Unsigned code = (lua_Unsigned)luaL_checkinteger(L, arg);
161  luaL_argcheck(L, code <= MAXUTF, arg, "value out of range");
162  lua_pushfstring(L, "%U", (long)code);
163}
164
165
166/*
167** utfchar(n1, n2, ...)  -> char(n1)..char(n2)...
168*/
169static int utfchar (lua_State *L) {
170  int n = lua_gettop(L);  /* number of arguments */
171  if (n == 1)  /* optimize common case of single char */
172    pushutfchar(L, 1);
173  else {
174    int i;
175    luaL_Buffer b;
176    luaL_buffinit(L, &b);
177    for (i = 1; i <= n; i++) {
178      pushutfchar(L, i);
179      luaL_addvalue(&b);
180    }
181    luaL_pushresult(&b);
182  }
183  return 1;
184}
185
186
187/*
188** offset(s, n, [i])  -> index where n-th character counting from
189**   position 'i' starts; 0 means character at 'i'.
190*/
191static int byteoffset (lua_State *L) {
192  size_t len;
193  const char *s = luaL_checklstring(L, 1, &len);
194  lua_Integer n  = luaL_checkinteger(L, 2);
195  lua_Integer posi = (n >= 0) ? 1 : len + 1;
196  posi = u_posrelat(luaL_optinteger(L, 3, posi), len);
197  luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 3,
198                   "position out of bounds");
199  if (n == 0) {
200    /* find beginning of current byte sequence */
201    while (posi > 0 && iscontp(s + posi)) posi--;
202  }
203  else {
204    if (iscontp(s + posi))
205      return luaL_error(L, "initial position is a continuation byte");
206    if (n < 0) {
207       while (n < 0 && posi > 0) {  /* move back */
208         do {  /* find beginning of previous character */
209           posi--;
210         } while (posi > 0 && iscontp(s + posi));
211         n++;
212       }
213     }
214     else {
215       n--;  /* do not move for 1st character */
216       while (n > 0 && posi < (lua_Integer)len) {
217         do {  /* find beginning of next character */
218           posi++;
219         } while (iscontp(s + posi));  /* (cannot pass final '\0') */
220         n--;
221       }
222     }
223  }
224  if (n == 0)  /* did it find given character? */
225    lua_pushinteger(L, posi + 1);
226  else  /* no such character */
227    luaL_pushfail(L);
228  return 1;
229}
230
231
232static int iter_aux (lua_State *L, int strict) {
233  size_t len;
234  const char *s = luaL_checklstring(L, 1, &len);
235  lua_Unsigned n = (lua_Unsigned)lua_tointeger(L, 2);
236  if (n < len) {
237    while (iscontp(s + n)) n++;  /* go to next character */
238  }
239  if (n >= len)  /* (also handles original 'n' being negative) */
240    return 0;  /* no more codepoints */
241  else {
242    utfint code;
243    const char *next = utf8_decode(s + n, &code, strict);
244    if (next == NULL || iscontp(next))
245      return luaL_error(L, MSGInvalid);
246    lua_pushinteger(L, n + 1);
247    lua_pushinteger(L, code);
248    return 2;
249  }
250}
251
252
253static int iter_auxstrict (lua_State *L) {
254  return iter_aux(L, 1);
255}
256
257static int iter_auxlax (lua_State *L) {
258  return iter_aux(L, 0);
259}
260
261
262static int iter_codes (lua_State *L) {
263  int lax = lua_toboolean(L, 2);
264  const char *s = luaL_checkstring(L, 1);
265  luaL_argcheck(L, !iscontp(s), 1, MSGInvalid);
266  lua_pushcfunction(L, lax ? iter_auxlax : iter_auxstrict);
267  lua_pushvalue(L, 1);
268  lua_pushinteger(L, 0);
269  return 3;
270}
271
272
273/* pattern to match a single UTF-8 character */
274#define UTF8PATT	"[\0-\x7F\xC2-\xFD][\x80-\xBF]*"
275
276
277static const luaL_Reg funcs[] = {
278  {"offset", byteoffset},
279  {"codepoint", codepoint},
280  {"char", utfchar},
281  {"len", utflen},
282  {"codes", iter_codes},
283  /* placeholders */
284  {"charpattern", NULL},
285  {NULL, NULL}
286};
287
288
289LUAMOD_API int luaopen_utf8 (lua_State *L) {
290  luaL_newlib(L, funcs);
291  lua_pushlstring(L, UTF8PATT, sizeof(UTF8PATT)/sizeof(char) - 1);
292  lua_setfield(L, -2, "charpattern");
293  return 1;
294}
295
296