1 /*
2 ** $Id: lutf8lib.c,v 1.16.1.1 2017/04/19 17:29:57 roberto Exp $
3 ** Standard library for UTF-8 manipulation
4 ** See Copyright Notice in lua.h
5 */
6 
7 #define lutf8lib_c
8 #define LUA_LIB
9 
10 #include "lprefix.h"
11 
12 
13 #include <assert.h>
14 #include <limits.h>
15 #include <stdlib.h>
16 #include <string.h>
17 
18 #include "lua.h"
19 
20 #include "lauxlib.h"
21 #include "lualib.h"
22 
23 #define MAXUNICODE	0x10FFFF
24 
25 #define iscont(p)	((*(p) & 0xC0) == 0x80)
26 
27 
28 /* from strlib */
29 /* translate a relative string position: negative means back from end */
u_posrelat(lua_Integer pos,size_t len)30 static lua_Integer u_posrelat (lua_Integer pos, size_t len) {
31   if (pos >= 0) return pos;
32   else if (0u - (size_t)pos > len) return 0;
33   else return (lua_Integer)len + pos + 1;
34 }
35 
36 
37 /*
38 ** Decode one UTF-8 sequence, returning NULL if byte sequence is invalid.
39 */
utf8_decode(const char * o,int * val)40 static const char *utf8_decode (const char *o, int *val) {
41   static const unsigned int limits[] = {0xFF, 0x7F, 0x7FF, 0xFFFF};
42   const unsigned char *s = (const unsigned char *)o;
43   unsigned int c = s[0];
44   unsigned int res = 0;  /* final result */
45   if (c < 0x80)  /* ascii? */
46     res = c;
47   else {
48     int count = 0;  /* to count number of continuation bytes */
49     while (c & 0x40) {  /* still have continuation bytes? */
50       int cc = s[++count];  /* read next byte */
51       if ((cc & 0xC0) != 0x80)  /* not a continuation byte? */
52         return NULL;  /* invalid byte sequence */
53       res = (res << 6) | (cc & 0x3F);  /* add lower 6 bits from cont. byte */
54       c <<= 1;  /* to test next bit */
55     }
56     res |= ((c & 0x7F) << (count * 5));  /* add first byte */
57     if (count > 3 || res > MAXUNICODE || res <= limits[count])
58       return NULL;  /* invalid byte sequence */
59     s += count;  /* skip continuation bytes read */
60   }
61   if (val) *val = res;
62   return (const char *)s + 1;  /* +1 to include first byte */
63 }
64 
65 
66 /*
67 ** utf8len(s [, i [, j]]) --> number of characters that start in the
68 ** range [i,j], or nil + current position if 's' is not well formed in
69 ** that interval
70 */
utflen(lua_State * L)71 static int utflen (lua_State *L) {
72   int n = 0;
73   size_t len;
74   const char *s = luaL_checklstring(L, 1, &len);
75   lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
76   lua_Integer posj = u_posrelat(luaL_optinteger(L, 3, -1), len);
77   luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 2,
78                    "initial position out of string");
79   luaL_argcheck(L, --posj < (lua_Integer)len, 3,
80                    "final position out of string");
81   while (posi <= posj) {
82     const char *s1 = utf8_decode(s + posi, NULL);
83     if (s1 == NULL) {  /* conversion error? */
84       lua_pushnil(L);  /* return nil ... */
85       lua_pushinteger(L, posi + 1);  /* ... and current position */
86       return 2;
87     }
88     posi = s1 - s;
89     n++;
90   }
91   lua_pushinteger(L, n);
92   return 1;
93 }
94 
95 
96 /*
97 ** codepoint(s, [i, [j]])  -> returns codepoints for all characters
98 ** that start in the range [i,j]
99 */
codepoint(lua_State * L)100 static int codepoint (lua_State *L) {
101   size_t len;
102   const char *s = luaL_checklstring(L, 1, &len);
103   lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
104   lua_Integer pose = u_posrelat(luaL_optinteger(L, 3, posi), len);
105   int n;
106   const char *se;
107   luaL_argcheck(L, posi >= 1, 2, "out of range");
108   luaL_argcheck(L, pose <= (lua_Integer)len, 3, "out of range");
109   if (posi > pose) return 0;  /* empty interval; return no values */
110   if (pose - posi >= INT_MAX)  /* (lua_Integer -> int) overflow? */
111     return luaL_error(L, "string slice too long");
112   n = (int)(pose -  posi) + 1;
113   luaL_checkstack(L, n, "string slice too long");
114   n = 0;
115   se = s + pose;
116   for (s += posi - 1; s < se;) {
117     int code;
118     s = utf8_decode(s, &code);
119     if (s == NULL)
120       return luaL_error(L, "invalid UTF-8 code");
121     lua_pushinteger(L, code);
122     n++;
123   }
124   return n;
125 }
126 
127 
pushutfchar(lua_State * L,int arg)128 static void pushutfchar (lua_State *L, int arg) {
129   lua_Integer code = luaL_checkinteger(L, arg);
130   luaL_argcheck(L, 0 <= code && code <= MAXUNICODE, arg, "value out of range");
131   lua_pushfstring(L, "%U", (long)code);
132 }
133 
134 
135 /*
136 ** utfchar(n1, n2, ...)  -> char(n1)..char(n2)...
137 */
utfchar(lua_State * L)138 static int utfchar (lua_State *L) {
139   int n = lua_gettop(L);  /* number of arguments */
140   if (n == 1)  /* optimize common case of single char */
141     pushutfchar(L, 1);
142   else {
143     int i;
144     luaL_Buffer b;
145     luaL_buffinit(L, &b);
146     for (i = 1; i <= n; i++) {
147       pushutfchar(L, i);
148       luaL_addvalue(&b);
149     }
150     luaL_pushresult(&b);
151   }
152   return 1;
153 }
154 
155 
156 /*
157 ** offset(s, n, [i])  -> index where n-th character counting from
158 **   position 'i' starts; 0 means character at 'i'.
159 */
byteoffset(lua_State * L)160 static int byteoffset (lua_State *L) {
161   size_t len;
162   const char *s = luaL_checklstring(L, 1, &len);
163   lua_Integer n  = luaL_checkinteger(L, 2);
164   lua_Integer posi = (n >= 0) ? 1 : len + 1;
165   posi = u_posrelat(luaL_optinteger(L, 3, posi), len);
166   luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 3,
167                    "position out of range");
168   if (n == 0) {
169     /* find beginning of current byte sequence */
170     while (posi > 0 && iscont(s + posi)) posi--;
171   }
172   else {
173     if (iscont(s + posi))
174       return luaL_error(L, "initial position is a continuation byte");
175     if (n < 0) {
176        while (n < 0 && posi > 0) {  /* move back */
177          do {  /* find beginning of previous character */
178            posi--;
179          } while (posi > 0 && iscont(s + posi));
180          n++;
181        }
182      }
183      else {
184        n--;  /* do not move for 1st character */
185        while (n > 0 && posi < (lua_Integer)len) {
186          do {  /* find beginning of next character */
187            posi++;
188          } while (iscont(s + posi));  /* (cannot pass final '\0') */
189          n--;
190        }
191      }
192   }
193   if (n == 0)  /* did it find given character? */
194     lua_pushinteger(L, posi + 1);
195   else  /* no such character */
196     lua_pushnil(L);
197   return 1;
198 }
199 
200 
iter_aux(lua_State * L)201 static int iter_aux (lua_State *L) {
202   size_t len;
203   const char *s = luaL_checklstring(L, 1, &len);
204   lua_Integer n = lua_tointeger(L, 2) - 1;
205   if (n < 0)  /* first iteration? */
206     n = 0;  /* start from here */
207   else if (n < (lua_Integer)len) {
208     n++;  /* skip current byte */
209     while (iscont(s + n)) n++;  /* and its continuations */
210   }
211   if (n >= (lua_Integer)len)
212     return 0;  /* no more codepoints */
213   else {
214     int code;
215     const char *next = utf8_decode(s + n, &code);
216     if (next == NULL || iscont(next))
217       return luaL_error(L, "invalid UTF-8 code");
218     lua_pushinteger(L, n + 1);
219     lua_pushinteger(L, code);
220     return 2;
221   }
222 }
223 
224 
iter_codes(lua_State * L)225 static int iter_codes (lua_State *L) {
226   luaL_checkstring(L, 1);
227   lua_pushcfunction(L, iter_aux);
228   lua_pushvalue(L, 1);
229   lua_pushinteger(L, 0);
230   return 3;
231 }
232 
233 
234 /* pattern to match a single UTF-8 character */
235 #define UTF8PATT	"[\0-\x7F\xC2-\xF4][\x80-\xBF]*"
236 
237 
238 static const luaL_Reg funcs[] = {
239   {"offset", byteoffset},
240   {"codepoint", codepoint},
241   {"char", utfchar},
242   {"len", utflen},
243   {"codes", iter_codes},
244   /* placeholders */
245   {"charpattern", NULL},
246   {NULL, NULL}
247 };
248 
249 
luaopen_utf8(lua_State * L)250 LUAMOD_API int luaopen_utf8 (lua_State *L) {
251   luaL_newlib(L, funcs);
252   lua_pushlstring(L, UTF8PATT, sizeof(UTF8PATT)/sizeof(char) - 1);
253   lua_setfield(L, -2, "charpattern");
254   return 1;
255 }
256 
257