1 /*
2 ** $Id: lobject.c $
3 ** Some generic functions over Lua objects
4 ** See Copyright Notice in lua.h
5 */
6 
7 #define lobject_c
8 #define LUA_CORE
9 
10 #include "lprefix.h"
11 
12 
13 #include <locale.h>
14 #include <math.h>
15 #include <stdarg.h>
16 #include <stdio.h>
17 #include <stdlib.h>
18 #include <string.h>
19 
20 #include "lua.h"
21 
22 #include "lctype.h"
23 #include "ldebug.h"
24 #include "ldo.h"
25 #include "lmem.h"
26 #include "lobject.h"
27 #include "lstate.h"
28 #include "lstring.h"
29 #include "lvm.h"
30 
31 
32 /*
33 ** Computes ceil(log2(x))
34 */
luaO_ceillog2(unsigned int x)35 int luaO_ceillog2 (unsigned int x) {
36   static const lu_byte log_2[256] = {  /* log_2[i] = ceil(log2(i - 1)) */
37     0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
38     6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
39     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
40     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
41     8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
42     8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
43     8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
44     8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8
45   };
46   int l = 0;
47   x--;
48   while (x >= 256) { l += 8; x >>= 8; }
49   return l + log_2[x];
50 }
51 
52 
intarith(lua_State * L,int op,lua_Integer v1,lua_Integer v2)53 static lua_Integer intarith (lua_State *L, int op, lua_Integer v1,
54                                                    lua_Integer v2) {
55   switch (op) {
56     case LUA_OPADD: return intop(+, v1, v2);
57     case LUA_OPSUB:return intop(-, v1, v2);
58     case LUA_OPMUL:return intop(*, v1, v2);
59     case LUA_OPMOD: return luaV_mod(L, v1, v2);
60     case LUA_OPIDIV: return luaV_idiv(L, v1, v2);
61     case LUA_OPBAND: return intop(&, v1, v2);
62     case LUA_OPBOR: return intop(|, v1, v2);
63     case LUA_OPBXOR: return intop(^, v1, v2);
64     case LUA_OPSHL: return luaV_shiftl(v1, v2);
65     case LUA_OPSHR: return luaV_shiftl(v1, -v2);
66     case LUA_OPUNM: return intop(-, 0, v1);
67     case LUA_OPBNOT: return intop(^, ~l_castS2U(0), v1);
68     default: lua_assert(0); return 0;
69   }
70 }
71 
72 
numarith(lua_State * L,int op,lua_Number v1,lua_Number v2)73 static lua_Number numarith (lua_State *L, int op, lua_Number v1,
74                                                   lua_Number v2) {
75   switch (op) {
76     case LUA_OPADD: return luai_numadd(L, v1, v2);
77     case LUA_OPSUB: return luai_numsub(L, v1, v2);
78     case LUA_OPMUL: return luai_nummul(L, v1, v2);
79     case LUA_OPDIV: return luai_numdiv(L, v1, v2);
80     case LUA_OPPOW: return luai_numpow(L, v1, v2);
81     case LUA_OPIDIV: return luai_numidiv(L, v1, v2);
82     case LUA_OPUNM: return luai_numunm(L, v1);
83     case LUA_OPMOD: return luaV_modf(L, v1, v2);
84     default: lua_assert(0); return 0;
85   }
86 }
87 
88 
luaO_rawarith(lua_State * L,int op,const TValue * p1,const TValue * p2,TValue * res)89 int luaO_rawarith (lua_State *L, int op, const TValue *p1, const TValue *p2,
90                    TValue *res) {
91   switch (op) {
92     case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR:
93     case LUA_OPSHL: case LUA_OPSHR:
94     case LUA_OPBNOT: {  /* operate only on integers */
95       lua_Integer i1; lua_Integer i2;
96       if (tointegerns(p1, &i1) && tointegerns(p2, &i2)) {
97         setivalue(res, intarith(L, op, i1, i2));
98         return 1;
99       }
100       else return 0;  /* fail */
101     }
102     case LUA_OPDIV: case LUA_OPPOW: {  /* operate only on floats */
103       lua_Number n1; lua_Number n2;
104       if (tonumberns(p1, n1) && tonumberns(p2, n2)) {
105         setfltvalue(res, numarith(L, op, n1, n2));
106         return 1;
107       }
108       else return 0;  /* fail */
109     }
110     default: {  /* other operations */
111       lua_Number n1; lua_Number n2;
112       if (ttisinteger(p1) && ttisinteger(p2)) {
113         setivalue(res, intarith(L, op, ivalue(p1), ivalue(p2)));
114         return 1;
115       }
116       else if (tonumberns(p1, n1) && tonumberns(p2, n2)) {
117         setfltvalue(res, numarith(L, op, n1, n2));
118         return 1;
119       }
120       else return 0;  /* fail */
121     }
122   }
123 }
124 
125 
luaO_arith(lua_State * L,int op,const TValue * p1,const TValue * p2,StkId res)126 void luaO_arith (lua_State *L, int op, const TValue *p1, const TValue *p2,
127                  StkId res) {
128   if (!luaO_rawarith(L, op, p1, p2, s2v(res))) {
129     /* could not perform raw operation; try metamethod */
130     luaT_trybinTM(L, p1, p2, res, cast(TMS, (op - LUA_OPADD) + TM_ADD));
131   }
132 }
133 
134 
luaO_hexavalue(int c)135 int luaO_hexavalue (int c) {
136   if (lisdigit(c)) return c - '0';
137   else return (ltolower(c) - 'a') + 10;
138 }
139 
140 
isneg(const char ** s)141 static int isneg (const char **s) {
142   if (**s == '-') { (*s)++; return 1; }
143   else if (**s == '+') (*s)++;
144   return 0;
145 }
146 
147 
148 
149 /*
150 ** {==================================================================
151 ** Lua's implementation for 'lua_strx2number'
152 ** ===================================================================
153 */
154 
155 #if !defined(lua_strx2number)
156 
157 /* maximum number of significant digits to read (to avoid overflows
158    even with single floats) */
159 #define MAXSIGDIG	30
160 
161 /*
162 ** convert a hexadecimal numeric string to a number, following
163 ** C99 specification for 'strtod'
164 */
lua_strx2number(const char * s,char ** endptr)165 static lua_Number lua_strx2number (const char *s, char **endptr) {
166   int dot = lua_getlocaledecpoint();
167   lua_Number r = 0.0;  /* result (accumulator) */
168   int sigdig = 0;  /* number of significant digits */
169   int nosigdig = 0;  /* number of non-significant digits */
170   int e = 0;  /* exponent correction */
171   int neg;  /* 1 if number is negative */
172   int hasdot = 0;  /* true after seen a dot */
173   *endptr = cast_charp(s);  /* nothing is valid yet */
174   while (lisspace(cast_uchar(*s))) s++;  /* skip initial spaces */
175   neg = isneg(&s);  /* check sign */
176   if (!(*s == '0' && (*(s + 1) == 'x' || *(s + 1) == 'X')))  /* check '0x' */
177     return 0.0;  /* invalid format (no '0x') */
178   for (s += 2; ; s++) {  /* skip '0x' and read numeral */
179     if (*s == dot) {
180       if (hasdot) break;  /* second dot? stop loop */
181       else hasdot = 1;
182     }
183     else if (lisxdigit(cast_uchar(*s))) {
184       if (sigdig == 0 && *s == '0')  /* non-significant digit (zero)? */
185         nosigdig++;
186       else if (++sigdig <= MAXSIGDIG)  /* can read it without overflow? */
187           r = (r * cast_num(16.0)) + luaO_hexavalue(*s);
188       else e++; /* too many digits; ignore, but still count for exponent */
189       if (hasdot) e--;  /* decimal digit? correct exponent */
190     }
191     else break;  /* neither a dot nor a digit */
192   }
193   if (nosigdig + sigdig == 0)  /* no digits? */
194     return 0.0;  /* invalid format */
195   *endptr = cast_charp(s);  /* valid up to here */
196   e *= 4;  /* each digit multiplies/divides value by 2^4 */
197   if (*s == 'p' || *s == 'P') {  /* exponent part? */
198     int exp1 = 0;  /* exponent value */
199     int neg1;  /* exponent sign */
200     s++;  /* skip 'p' */
201     neg1 = isneg(&s);  /* sign */
202     if (!lisdigit(cast_uchar(*s)))
203       return 0.0;  /* invalid; must have at least one digit */
204     while (lisdigit(cast_uchar(*s)))  /* read exponent */
205       exp1 = exp1 * 10 + *(s++) - '0';
206     if (neg1) exp1 = -exp1;
207     e += exp1;
208     *endptr = cast_charp(s);  /* valid up to here */
209   }
210   if (neg) r = -r;
211   return l_mathop(ldexp)(r, e);
212 }
213 
214 #endif
215 /* }====================================================== */
216 
217 
218 /* maximum length of a numeral to be converted to a number */
219 #if !defined (L_MAXLENNUM)
220 #define L_MAXLENNUM	200
221 #endif
222 
223 /*
224 ** Convert string 's' to a Lua number (put in 'result'). Return NULL on
225 ** fail or the address of the ending '\0' on success. ('mode' == 'x')
226 ** means a hexadecimal numeral.
227 */
l_str2dloc(const char * s,lua_Number * result,int mode)228 static const char *l_str2dloc (const char *s, lua_Number *result, int mode) {
229   char *endptr;
230   *result = (mode == 'x') ? lua_strx2number(s, &endptr)  /* try to convert */
231                           : lua_str2number(s, &endptr);
232   if (endptr == s) return NULL;  /* nothing recognized? */
233   while (lisspace(cast_uchar(*endptr))) endptr++;  /* skip trailing spaces */
234   return (*endptr == '\0') ? endptr : NULL;  /* OK iff no trailing chars */
235 }
236 
237 
238 /*
239 ** Convert string 's' to a Lua number (put in 'result') handling the
240 ** current locale.
241 ** This function accepts both the current locale or a dot as the radix
242 ** mark. If the conversion fails, it may mean number has a dot but
243 ** locale accepts something else. In that case, the code copies 's'
244 ** to a buffer (because 's' is read-only), changes the dot to the
245 ** current locale radix mark, and tries to convert again.
246 ** The variable 'mode' checks for special characters in the string:
247 ** - 'n' means 'inf' or 'nan' (which should be rejected)
248 ** - 'x' means a hexadecimal numeral
249 ** - '.' just optimizes the search for the common case (no special chars)
250 */
l_str2d(const char * s,lua_Number * result)251 static const char *l_str2d (const char *s, lua_Number *result) {
252   const char *endptr;
253   const char *pmode = strpbrk(s, ".xXnN");  /* look for special chars */
254   int mode = pmode ? ltolower(cast_uchar(*pmode)) : 0;
255   if (mode == 'n')  /* reject 'inf' and 'nan' */
256     return NULL;
257   endptr = l_str2dloc(s, result, mode);  /* try to convert */
258   if (endptr == NULL) {  /* failed? may be a different locale */
259     char buff[L_MAXLENNUM + 1];
260     const char *pdot = strchr(s, '.');
261     if (pdot == NULL || strlen(s) > L_MAXLENNUM)
262       return NULL;  /* string too long or no dot; fail */
263     strcpy(buff, s);  /* copy string to buffer */
264     buff[pdot - s] = lua_getlocaledecpoint();  /* correct decimal point */
265     endptr = l_str2dloc(buff, result, mode);  /* try again */
266     if (endptr != NULL)
267       endptr = s + (endptr - buff);  /* make relative to 's' */
268   }
269   return endptr;
270 }
271 
272 
273 #define MAXBY10		cast(lua_Unsigned, LUA_MAXINTEGER / 10)
274 #define MAXLASTD	cast_int(LUA_MAXINTEGER % 10)
275 
l_str2int(const char * s,lua_Integer * result)276 static const char *l_str2int (const char *s, lua_Integer *result) {
277   lua_Unsigned a = 0;
278   int empty = 1;
279   int neg;
280   while (lisspace(cast_uchar(*s))) s++;  /* skip initial spaces */
281   neg = isneg(&s);
282   if (s[0] == '0' &&
283       (s[1] == 'x' || s[1] == 'X')) {  /* hex? */
284     s += 2;  /* skip '0x' */
285     for (; lisxdigit(cast_uchar(*s)); s++) {
286       a = a * 16 + luaO_hexavalue(*s);
287       empty = 0;
288     }
289   }
290   else {  /* decimal */
291     for (; lisdigit(cast_uchar(*s)); s++) {
292       int d = *s - '0';
293       if (a >= MAXBY10 && (a > MAXBY10 || d > MAXLASTD + neg))  /* overflow? */
294         return NULL;  /* do not accept it (as integer) */
295       a = a * 10 + d;
296       empty = 0;
297     }
298   }
299   while (lisspace(cast_uchar(*s))) s++;  /* skip trailing spaces */
300   if (empty || *s != '\0') return NULL;  /* something wrong in the numeral */
301   else {
302     *result = l_castU2S((neg) ? 0u - a : a);
303     return s;
304   }
305 }
306 
307 
luaO_str2num(const char * s,TValue * o)308 size_t luaO_str2num (const char *s, TValue *o) {
309   lua_Integer i; lua_Number n;
310   const char *e;
311   if ((e = l_str2int(s, &i)) != NULL) {  /* try as an integer */
312     setivalue(o, i);
313   }
314   else if ((e = l_str2d(s, &n)) != NULL) {  /* else try as a float */
315     setfltvalue(o, n);
316   }
317   else
318     return 0;  /* conversion failed */
319   return (e - s) + 1;  /* success; return string size */
320 }
321 
322 
luaO_utf8esc(char * buff,unsigned long x)323 int luaO_utf8esc (char *buff, unsigned long x) {
324   int n = 1;  /* number of bytes put in buffer (backwards) */
325   lua_assert(x <= 0x7FFFFFFFu);
326   if (x < 0x80)  /* ascii? */
327     buff[UTF8BUFFSZ - 1] = cast_char(x);
328   else {  /* need continuation bytes */
329     unsigned int mfb = 0x3f;  /* maximum that fits in first byte */
330     do {  /* add continuation bytes */
331       buff[UTF8BUFFSZ - (n++)] = cast_char(0x80 | (x & 0x3f));
332       x >>= 6;  /* remove added bits */
333       mfb >>= 1;  /* now there is one less bit available in first byte */
334     } while (x > mfb);  /* still needs continuation byte? */
335     buff[UTF8BUFFSZ - n] = cast_char((~mfb << 1) | x);  /* add first byte */
336   }
337   return n;
338 }
339 
340 
341 /*
342 ** Maximum length of the conversion of a number to a string. Must be
343 ** enough to accommodate both LUA_INTEGER_FMT and LUA_NUMBER_FMT.
344 ** (For a long long int, this is 19 digits plus a sign and a final '\0',
345 ** adding to 21. For a long double, it can go to a sign, 33 digits,
346 ** the dot, an exponent letter, an exponent sign, 5 exponent digits,
347 ** and a final '\0', adding to 43.)
348 */
349 #define MAXNUMBER2STR	44
350 
351 
352 /*
353 ** Convert a number object to a string, adding it to a buffer
354 */
tostringbuff(TValue * obj,char * buff)355 static int tostringbuff (TValue *obj, char *buff) {
356   int len;
357   lua_assert(ttisnumber(obj));
358   if (ttisinteger(obj))
359     len = lua_integer2str(buff, MAXNUMBER2STR, ivalue(obj));
360   else {
361     len = lua_number2str(buff, MAXNUMBER2STR, fltvalue(obj));
362     if (buff[strspn(buff, "-0123456789")] == '\0') {  /* looks like an int? */
363       buff[len++] = lua_getlocaledecpoint();
364       buff[len++] = '0';  /* adds '.0' to result */
365     }
366   }
367   return len;
368 }
369 
370 
371 /*
372 ** Convert a number object to a Lua string, replacing the value at 'obj'
373 */
luaO_tostring(lua_State * L,TValue * obj)374 void luaO_tostring (lua_State *L, TValue *obj) {
375   char buff[MAXNUMBER2STR];
376   int len = tostringbuff(obj, buff);
377   setsvalue(L, obj, luaS_newlstr(L, buff, len));
378 }
379 
380 
381 
382 
383 /*
384 ** {==================================================================
385 ** 'luaO_pushvfstring'
386 ** ===================================================================
387 */
388 
389 /* size for buffer space used by 'luaO_pushvfstring' */
390 #define BUFVFS		200
391 
392 /* buffer used by 'luaO_pushvfstring' */
393 typedef struct BuffFS {
394   lua_State *L;
395   int pushed;  /* number of string pieces already on the stack */
396   int blen;  /* length of partial string in 'space' */
397   char space[BUFVFS];  /* holds last part of the result */
398 } BuffFS;
399 
400 
401 /*
402 ** Push given string to the stack, as part of the buffer, and
403 ** join the partial strings in the stack into one.
404 */
pushstr(BuffFS * buff,const char * str,size_t l)405 static void pushstr (BuffFS *buff, const char *str, size_t l) {
406   lua_State *L = buff->L;
407   setsvalue2s(L, L->top, luaS_newlstr(L, str, l));
408   L->top++;  /* may use one extra slot */
409   buff->pushed++;
410   luaV_concat(L, buff->pushed);  /* join partial results into one */
411   buff->pushed = 1;
412 }
413 
414 
415 /*
416 ** empty the buffer space into the stack
417 */
clearbuff(BuffFS * buff)418 static void clearbuff (BuffFS *buff) {
419   pushstr(buff, buff->space, buff->blen);  /* push buffer contents */
420   buff->blen = 0;  /* space now is empty */
421 }
422 
423 
424 /*
425 ** Get a space of size 'sz' in the buffer. If buffer has not enough
426 ** space, empty it. 'sz' must fit in an empty buffer.
427 */
getbuff(BuffFS * buff,int sz)428 static char *getbuff (BuffFS *buff, int sz) {
429   lua_assert(buff->blen <= BUFVFS); lua_assert(sz <= BUFVFS);
430   if (sz > BUFVFS - buff->blen)  /* not enough space? */
431     clearbuff(buff);
432   return buff->space + buff->blen;
433 }
434 
435 
436 #define addsize(b,sz)	((b)->blen += (sz))
437 
438 
439 /*
440 ** Add 'str' to the buffer. If string is larger than the buffer space,
441 ** push the string directly to the stack.
442 */
addstr2buff(BuffFS * buff,const char * str,size_t slen)443 static void addstr2buff (BuffFS *buff, const char *str, size_t slen) {
444   if (slen <= BUFVFS) {  /* does string fit into buffer? */
445     char *bf = getbuff(buff, cast_int(slen));
446     memcpy(bf, str, slen);  /* add string to buffer */
447     addsize(buff, cast_int(slen));
448   }
449   else {  /* string larger than buffer */
450     clearbuff(buff);  /* string comes after buffer's content */
451     pushstr(buff, str, slen);  /* push string */
452   }
453 }
454 
455 
456 /*
457 ** Add a number to the buffer.
458 */
addnum2buff(BuffFS * buff,TValue * num)459 static void addnum2buff (BuffFS *buff, TValue *num) {
460   char *numbuff = getbuff(buff, MAXNUMBER2STR);
461   int len = tostringbuff(num, numbuff);  /* format number into 'numbuff' */
462   addsize(buff, len);
463 }
464 
465 
466 /*
467 ** this function handles only '%d', '%c', '%f', '%p', '%s', and '%%'
468    conventional formats, plus Lua-specific '%I' and '%U'
469 */
luaO_pushvfstring(lua_State * L,const char * fmt,va_list argp)470 const char *luaO_pushvfstring (lua_State *L, const char *fmt, va_list argp) {
471   BuffFS buff;  /* holds last part of the result */
472   const char *e;  /* points to next '%' */
473   buff.pushed = buff.blen = 0;
474   buff.L = L;
475   while ((e = strchr(fmt, '%')) != NULL) {
476     addstr2buff(&buff, fmt, e - fmt);  /* add 'fmt' up to '%' */
477     switch (*(e + 1)) {  /* conversion specifier */
478       case 's': {  /* zero-terminated string */
479         const char *s = va_arg(argp, char *);
480         if (s == NULL) s = "(null)";
481         addstr2buff(&buff, s, strlen(s));
482         break;
483       }
484       case 'c': {  /* an 'int' as a character */
485         char c = cast_uchar(va_arg(argp, int));
486         addstr2buff(&buff, &c, sizeof(char));
487         break;
488       }
489       case 'd': {  /* an 'int' */
490         TValue num;
491         setivalue(&num, va_arg(argp, int));
492         addnum2buff(&buff, &num);
493         break;
494       }
495       case 'I': {  /* a 'lua_Integer' */
496         TValue num;
497         setivalue(&num, cast(lua_Integer, va_arg(argp, l_uacInt)));
498         addnum2buff(&buff, &num);
499         break;
500       }
501       case 'f': {  /* a 'lua_Number' */
502         TValue num;
503         setfltvalue(&num, cast_num(va_arg(argp, l_uacNumber)));
504         addnum2buff(&buff, &num);
505         break;
506       }
507       case 'p': {  /* a pointer */
508         const int sz = 3 * sizeof(void*) + 8; /* enough space for '%p' */
509         char *bf = getbuff(&buff, sz);
510         void *p = va_arg(argp, void *);
511         int len = lua_pointer2str(bf, sz, p);
512         addsize(&buff, len);
513         break;
514       }
515       case 'U': {  /* a 'long' as a UTF-8 sequence */
516         char bf[UTF8BUFFSZ];
517         int len = luaO_utf8esc(bf, va_arg(argp, long));
518         addstr2buff(&buff, bf + UTF8BUFFSZ - len, len);
519         break;
520       }
521       case '%': {
522         addstr2buff(&buff, "%", 1);
523         break;
524       }
525       default: {
526         luaG_runerror(L, "invalid option '%%%c' to 'lua_pushfstring'",
527                          *(e + 1));
528       }
529     }
530     fmt = e + 2;  /* skip '%' and the specifier */
531   }
532   addstr2buff(&buff, fmt, strlen(fmt));  /* rest of 'fmt' */
533   clearbuff(&buff);  /* empty buffer into the stack */
534   lua_assert(buff.pushed == 1);
535   return svalue(s2v(L->top - 1));
536 }
537 
538 
luaO_pushfstring(lua_State * L,const char * fmt,...)539 const char *luaO_pushfstring (lua_State *L, const char *fmt, ...) {
540   const char *msg;
541   va_list argp;
542   va_start(argp, fmt);
543   msg = luaO_pushvfstring(L, fmt, argp);
544   va_end(argp);
545   return msg;
546 }
547 
548 /* }================================================================== */
549 
550 
551 #define RETS	"..."
552 #define PRE	"[string \""
553 #define POS	"\"]"
554 
555 #define addstr(a,b,l)	( memcpy(a,b,(l) * sizeof(char)), a += (l) )
556 
luaO_chunkid(char * out,const char * source,size_t srclen)557 void luaO_chunkid (char *out, const char *source, size_t srclen) {
558   size_t bufflen = LUA_IDSIZE;  /* free space in buffer */
559   if (*source == '=') {  /* 'literal' source */
560     if (srclen <= bufflen)  /* small enough? */
561       memcpy(out, source + 1, srclen * sizeof(char));
562     else {  /* truncate it */
563       addstr(out, source + 1, bufflen - 1);
564       *out = '\0';
565     }
566   }
567   else if (*source == '@') {  /* file name */
568     if (srclen <= bufflen)  /* small enough? */
569       memcpy(out, source + 1, srclen * sizeof(char));
570     else {  /* add '...' before rest of name */
571       addstr(out, RETS, LL(RETS));
572       bufflen -= LL(RETS);
573       memcpy(out, source + 1 + srclen - bufflen, bufflen * sizeof(char));
574     }
575   }
576   else {  /* string; format as [string "source"] */
577     const char *nl = strchr(source, '\n');  /* find first new line (if any) */
578     addstr(out, PRE, LL(PRE));  /* add prefix */
579     bufflen -= LL(PRE RETS POS) + 1;  /* save space for prefix+suffix+'\0' */
580     if (srclen < bufflen && nl == NULL) {  /* small one-line source? */
581       addstr(out, source, srclen);  /* keep it */
582     }
583     else {
584       if (nl != NULL) srclen = nl - source;  /* stop at first newline */
585       if (srclen > bufflen) srclen = bufflen;
586       addstr(out, source, srclen);
587       addstr(out, RETS, LL(RETS));
588     }
589     memcpy(out, POS, (LL(POS) + 1) * sizeof(char));
590   }
591 }
592 
593