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lobject.c (24000B)


      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 <float.h>
     14 #include <locale.h>
     15 #include <math.h>
     16 #include <stdarg.h>
     17 #include <stdio.h>
     18 #include <stdlib.h>
     19 #include <string.h>
     20 
     21 #include "lua.h"
     22 
     23 #include "lctype.h"
     24 #include "ldebug.h"
     25 #include "ldo.h"
     26 #include "lmem.h"
     27 #include "lobject.h"
     28 #include "lstate.h"
     29 #include "lstring.h"
     30 #include "lvm.h"
     31 
     32 
     33 /*
     34 ** Computes ceil(log2(x))
     35 */
     36 lu_byte luaO_ceillog2 (unsigned int x) {
     37   static const lu_byte log_2[256] = {  /* log_2[i - 1] = ceil(log2(i)) */
     38     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,
     39     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,
     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     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,
     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     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
     46   };
     47   int l = 0;
     48   x--;
     49   while (x >= 256) { l += 8; x >>= 8; }
     50   return cast_byte(l + log_2[x]);
     51 }
     52 
     53 /*
     54 ** Encodes 'p'% as a floating-point byte, represented as (eeeexxxx).
     55 ** The exponent is represented using excess-7. Mimicking IEEE 754, the
     56 ** representation normalizes the number when possible, assuming an extra
     57 ** 1 before the mantissa (xxxx) and adding one to the exponent (eeee)
     58 ** to signal that. So, the real value is (1xxxx) * 2^(eeee - 7 - 1) if
     59 ** eeee != 0, and (xxxx) * 2^-7 otherwise (subnormal numbers).
     60 */
     61 lu_byte luaO_codeparam (unsigned int p) {
     62   if (p >= (cast(lu_mem, 0x1F) << (0xF - 7 - 1)) * 100u)  /* overflow? */
     63     return 0xFF;  /* return maximum value */
     64   else {
     65     p = (cast(l_uint32, p) * 128 + 99) / 100;  /* round up the division */
     66     if (p < 0x10) {  /* subnormal number? */
     67       /* exponent bits are already zero; nothing else to do */
     68       return cast_byte(p);
     69     }
     70     else {  /* p >= 0x10 implies ceil(log2(p + 1)) >= 5 */
     71       /* preserve 5 bits in 'p' */
     72       unsigned log = luaO_ceillog2(p + 1) - 5u;
     73       return cast_byte(((p >> log) - 0x10) | ((log + 1) << 4));
     74     }
     75   }
     76 }
     77 
     78 
     79 /*
     80 ** Computes 'p' times 'x', where 'p' is a floating-point byte. Roughly,
     81 ** we have to multiply 'x' by the mantissa and then shift accordingly to
     82 ** the exponent.  If the exponent is positive, both the multiplication
     83 ** and the shift increase 'x', so we have to care only about overflows.
     84 ** For negative exponents, however, multiplying before the shift keeps
     85 ** more significant bits, as long as the multiplication does not
     86 ** overflow, so we check which order is best.
     87 */
     88 l_mem luaO_applyparam (lu_byte p, l_mem x) {
     89   unsigned int m = p & 0xF;  /* mantissa */
     90   int e = (p >> 4);  /* exponent */
     91   if (e > 0) {  /* normalized? */
     92     e--;  /* correct exponent */
     93     m += 0x10;  /* correct mantissa; maximum value is 0x1F */
     94   }
     95   e -= 7;  /* correct excess-7 */
     96   if (e >= 0) {
     97     if (x < (MAX_LMEM / 0x1F) >> e)  /* no overflow? */
     98       return (x * m) << e;  /* order doesn't matter here */
     99     else  /* real overflow */
    100       return MAX_LMEM;
    101   }
    102   else {  /* negative exponent */
    103     e = -e;
    104     if (x < MAX_LMEM / 0x1F)  /* multiplication cannot overflow? */
    105       return (x * m) >> e;  /* multiplying first gives more precision */
    106     else if ((x >> e) <  MAX_LMEM / 0x1F)  /* cannot overflow after shift? */
    107       return (x >> e) * m;
    108     else  /* real overflow */
    109       return MAX_LMEM;
    110   }
    111 }
    112 
    113 
    114 static lua_Integer intarith (lua_State *L, int op, lua_Integer v1,
    115                                                    lua_Integer v2) {
    116   switch (op) {
    117     case LUA_OPADD: return intop(+, v1, v2);
    118     case LUA_OPSUB:return intop(-, v1, v2);
    119     case LUA_OPMUL:return intop(*, v1, v2);
    120     case LUA_OPMOD: return luaV_mod(L, v1, v2);
    121     case LUA_OPIDIV: return luaV_idiv(L, v1, v2);
    122     case LUA_OPBAND: return intop(&, v1, v2);
    123     case LUA_OPBOR: return intop(|, v1, v2);
    124     case LUA_OPBXOR: return intop(^, v1, v2);
    125     case LUA_OPSHL: return luaV_shiftl(v1, v2);
    126     case LUA_OPSHR: return luaV_shiftr(v1, v2);
    127     case LUA_OPUNM: return intop(-, 0, v1);
    128     case LUA_OPBNOT: return intop(^, ~l_castS2U(0), v1);
    129     default: lua_assert(0); return 0;
    130   }
    131 }
    132 
    133 
    134 static lua_Number numarith (lua_State *L, int op, lua_Number v1,
    135                                                   lua_Number v2) {
    136   switch (op) {
    137     case LUA_OPADD: return luai_numadd(L, v1, v2);
    138     case LUA_OPSUB: return luai_numsub(L, v1, v2);
    139     case LUA_OPMUL: return luai_nummul(L, v1, v2);
    140     case LUA_OPDIV: return luai_numdiv(L, v1, v2);
    141     case LUA_OPPOW: return luai_numpow(L, v1, v2);
    142     case LUA_OPIDIV: return luai_numidiv(L, v1, v2);
    143     case LUA_OPUNM: return luai_numunm(L, v1);
    144     case LUA_OPMOD: return luaV_modf(L, v1, v2);
    145     default: lua_assert(0); return 0;
    146   }
    147 }
    148 
    149 
    150 int luaO_rawarith (lua_State *L, int op, const TValue *p1, const TValue *p2,
    151                    TValue *res) {
    152   switch (op) {
    153     case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR:
    154     case LUA_OPSHL: case LUA_OPSHR:
    155     case LUA_OPBNOT: {  /* operate only on integers */
    156       lua_Integer i1; lua_Integer i2;
    157       if (tointegerns(p1, &i1) && tointegerns(p2, &i2)) {
    158         setivalue(res, intarith(L, op, i1, i2));
    159         return 1;
    160       }
    161       else return 0;  /* fail */
    162     }
    163     case LUA_OPDIV: case LUA_OPPOW: {  /* operate only on floats */
    164       lua_Number n1; lua_Number n2;
    165       if (tonumberns(p1, n1) && tonumberns(p2, n2)) {
    166         setfltvalue(res, numarith(L, op, n1, n2));
    167         return 1;
    168       }
    169       else return 0;  /* fail */
    170     }
    171     default: {  /* other operations */
    172       lua_Number n1; lua_Number n2;
    173       if (ttisinteger(p1) && ttisinteger(p2)) {
    174         setivalue(res, intarith(L, op, ivalue(p1), ivalue(p2)));
    175         return 1;
    176       }
    177       else if (tonumberns(p1, n1) && tonumberns(p2, n2)) {
    178         setfltvalue(res, numarith(L, op, n1, n2));
    179         return 1;
    180       }
    181       else return 0;  /* fail */
    182     }
    183   }
    184 }
    185 
    186 
    187 void luaO_arith (lua_State *L, int op, const TValue *p1, const TValue *p2,
    188                  StkId res) {
    189   if (!luaO_rawarith(L, op, p1, p2, s2v(res))) {
    190     /* could not perform raw operation; try metamethod */
    191     luaT_trybinTM(L, p1, p2, res, cast(TMS, (op - LUA_OPADD) + TM_ADD));
    192   }
    193 }
    194 
    195 
    196 lu_byte luaO_hexavalue (int c) {
    197   lua_assert(lisxdigit(c));
    198   if (lisdigit(c)) return cast_byte(c - '0');
    199   else return cast_byte((ltolower(c) - 'a') + 10);
    200 }
    201 
    202 
    203 static int isneg (const char **s) {
    204   if (**s == '-') { (*s)++; return 1; }
    205   else if (**s == '+') (*s)++;
    206   return 0;
    207 }
    208 
    209 
    210 
    211 /*
    212 ** {==================================================================
    213 ** Lua's implementation for 'lua_strx2number'
    214 ** ===================================================================
    215 */
    216 
    217 #if !defined(lua_strx2number)
    218 
    219 /* maximum number of significant digits to read (to avoid overflows
    220    even with single floats) */
    221 #define MAXSIGDIG	30
    222 
    223 /*
    224 ** convert a hexadecimal numeric string to a number, following
    225 ** C99 specification for 'strtod'
    226 */
    227 static lua_Number lua_strx2number (const char *s, char **endptr) {
    228   int dot = lua_getlocaledecpoint();
    229   lua_Number r = l_mathop(0.0);  /* result (accumulator) */
    230   int sigdig = 0;  /* number of significant digits */
    231   int nosigdig = 0;  /* number of non-significant digits */
    232   int e = 0;  /* exponent correction */
    233   int neg;  /* 1 if number is negative */
    234   int hasdot = 0;  /* true after seen a dot */
    235   *endptr = cast_charp(s);  /* nothing is valid yet */
    236   while (lisspace(cast_uchar(*s))) s++;  /* skip initial spaces */
    237   neg = isneg(&s);  /* check sign */
    238   if (!(*s == '0' && (*(s + 1) == 'x' || *(s + 1) == 'X')))  /* check '0x' */
    239     return l_mathop(0.0);  /* invalid format (no '0x') */
    240   for (s += 2; ; s++) {  /* skip '0x' and read numeral */
    241     if (*s == dot) {
    242       if (hasdot) break;  /* second dot? stop loop */
    243       else hasdot = 1;
    244     }
    245     else if (lisxdigit(cast_uchar(*s))) {
    246       if (sigdig == 0 && *s == '0')  /* non-significant digit (zero)? */
    247         nosigdig++;
    248       else if (++sigdig <= MAXSIGDIG)  /* can read it without overflow? */
    249           r = (r * l_mathop(16.0)) + luaO_hexavalue(*s);
    250       else e++;  /* too many digits; ignore, but still count for exponent */
    251       if (hasdot) e--;  /* decimal digit? correct exponent */
    252     }
    253     else break;  /* neither a dot nor a digit */
    254   }
    255   if (nosigdig + sigdig == 0)  /* no digits? */
    256     return l_mathop(0.0);  /* invalid format */
    257   *endptr = cast_charp(s);  /* valid up to here */
    258   e *= 4;  /* each digit multiplies/divides value by 2^4 */
    259   if (*s == 'p' || *s == 'P') {  /* exponent part? */
    260     int exp1 = 0;  /* exponent value */
    261     int neg1;  /* exponent sign */
    262     s++;  /* skip 'p' */
    263     neg1 = isneg(&s);  /* sign */
    264     if (!lisdigit(cast_uchar(*s)))
    265       return l_mathop(0.0);  /* invalid; must have at least one digit */
    266     while (lisdigit(cast_uchar(*s)))  /* read exponent */
    267       exp1 = exp1 * 10 + *(s++) - '0';
    268     if (neg1) exp1 = -exp1;
    269     e += exp1;
    270     *endptr = cast_charp(s);  /* valid up to here */
    271   }
    272   if (neg) r = -r;
    273   return l_mathop(ldexp)(r, e);
    274 }
    275 
    276 #endif
    277 /* }====================================================== */
    278 
    279 
    280 /* maximum length of a numeral to be converted to a number */
    281 #if !defined (L_MAXLENNUM)
    282 #define L_MAXLENNUM	200
    283 #endif
    284 
    285 /*
    286 ** Convert string 's' to a Lua number (put in 'result'). Return NULL on
    287 ** fail or the address of the ending '\0' on success. ('mode' == 'x')
    288 ** means a hexadecimal numeral.
    289 */
    290 static const char *l_str2dloc (const char *s, lua_Number *result, int mode) {
    291   char *endptr;
    292   *result = (mode == 'x') ? lua_strx2number(s, &endptr)  /* try to convert */
    293                           : lua_str2number(s, &endptr);
    294   if (endptr == s) return NULL;  /* nothing recognized? */
    295   while (lisspace(cast_uchar(*endptr))) endptr++;  /* skip trailing spaces */
    296   return (*endptr == '\0') ? endptr : NULL;  /* OK iff no trailing chars */
    297 }
    298 
    299 
    300 /*
    301 ** Convert string 's' to a Lua number (put in 'result') handling the
    302 ** current locale.
    303 ** This function accepts both the current locale or a dot as the radix
    304 ** mark. If the conversion fails, it may mean number has a dot but
    305 ** locale accepts something else. In that case, the code copies 's'
    306 ** to a buffer (because 's' is read-only), changes the dot to the
    307 ** current locale radix mark, and tries to convert again.
    308 ** The variable 'mode' checks for special characters in the string:
    309 ** - 'n' means 'inf' or 'nan' (which should be rejected)
    310 ** - 'x' means a hexadecimal numeral
    311 ** - '.' just optimizes the search for the common case (no special chars)
    312 */
    313 static const char *l_str2d (const char *s, lua_Number *result) {
    314   const char *endptr;
    315   const char *pmode = strpbrk(s, ".xXnN");  /* look for special chars */
    316   int mode = pmode ? ltolower(cast_uchar(*pmode)) : 0;
    317   if (mode == 'n')  /* reject 'inf' and 'nan' */
    318     return NULL;
    319   endptr = l_str2dloc(s, result, mode);  /* try to convert */
    320   if (endptr == NULL) {  /* failed? may be a different locale */
    321     char buff[L_MAXLENNUM + 1];
    322     const char *pdot = strchr(s, '.');
    323     if (pdot == NULL || strlen(s) > L_MAXLENNUM)
    324       return NULL;  /* string too long or no dot; fail */
    325     strcpy(buff, s);  /* copy string to buffer */
    326     buff[pdot - s] = lua_getlocaledecpoint();  /* correct decimal point */
    327     endptr = l_str2dloc(buff, result, mode);  /* try again */
    328     if (endptr != NULL)
    329       endptr = s + (endptr - buff);  /* make relative to 's' */
    330   }
    331   return endptr;
    332 }
    333 
    334 
    335 #define MAXBY10		cast(lua_Unsigned, LUA_MAXINTEGER / 10)
    336 #define MAXLASTD	cast_int(LUA_MAXINTEGER % 10)
    337 
    338 static const char *l_str2int (const char *s, lua_Integer *result) {
    339   lua_Unsigned a = 0;
    340   int empty = 1;
    341   int neg;
    342   while (lisspace(cast_uchar(*s))) s++;  /* skip initial spaces */
    343   neg = isneg(&s);
    344   if (s[0] == '0' &&
    345       (s[1] == 'x' || s[1] == 'X')) {  /* hex? */
    346     s += 2;  /* skip '0x' */
    347     for (; lisxdigit(cast_uchar(*s)); s++) {
    348       a = a * 16 + luaO_hexavalue(*s);
    349       empty = 0;
    350     }
    351   }
    352   else {  /* decimal */
    353     for (; lisdigit(cast_uchar(*s)); s++) {
    354       int d = *s - '0';
    355       if (a >= MAXBY10 && (a > MAXBY10 || d > MAXLASTD + neg))  /* overflow? */
    356         return NULL;  /* do not accept it (as integer) */
    357       a = a * 10 + cast_uint(d);
    358       empty = 0;
    359     }
    360   }
    361   while (lisspace(cast_uchar(*s))) s++;  /* skip trailing spaces */
    362   if (empty || *s != '\0') return NULL;  /* something wrong in the numeral */
    363   else {
    364     *result = l_castU2S((neg) ? 0u - a : a);
    365     return s;
    366   }
    367 }
    368 
    369 
    370 size_t luaO_str2num (const char *s, TValue *o) {
    371   lua_Integer i; lua_Number n;
    372   const char *e;
    373   if ((e = l_str2int(s, &i)) != NULL) {  /* try as an integer */
    374     setivalue(o, i);
    375   }
    376   else if ((e = l_str2d(s, &n)) != NULL) {  /* else try as a float */
    377     setfltvalue(o, n);
    378   }
    379   else
    380     return 0;  /* conversion failed */
    381   return ct_diff2sz(e - s) + 1;  /* success; return string size */
    382 }
    383 
    384 
    385 int luaO_utf8esc (char *buff, unsigned long x) {
    386   int n = 1;  /* number of bytes put in buffer (backwards) */
    387   lua_assert(x <= 0x7FFFFFFFu);
    388   if (x < 0x80)  /* ascii? */
    389     buff[UTF8BUFFSZ - 1] = cast_char(x);
    390   else {  /* need continuation bytes */
    391     unsigned int mfb = 0x3f;  /* maximum that fits in first byte */
    392     do {  /* add continuation bytes */
    393       buff[UTF8BUFFSZ - (n++)] = cast_char(0x80 | (x & 0x3f));
    394       x >>= 6;  /* remove added bits */
    395       mfb >>= 1;  /* now there is one less bit available in first byte */
    396     } while (x > mfb);  /* still needs continuation byte? */
    397     buff[UTF8BUFFSZ - n] = cast_char((~mfb << 1) | x);  /* add first byte */
    398   }
    399   return n;
    400 }
    401 
    402 
    403 /*
    404 ** The size of the buffer for the conversion of a number to a string
    405 ** 'LUA_N2SBUFFSZ' must be enough to accommodate both LUA_INTEGER_FMT
    406 ** and LUA_NUMBER_FMT.  For a long long int, this is 19 digits plus a
    407 ** sign and a final '\0', adding to 21. For a long double, it can go to
    408 ** a sign, the dot, an exponent letter, an exponent sign, 4 exponent
    409 ** digits, the final '\0', plus the significant digits, which are
    410 ** approximately the *_DIG attribute.
    411 */
    412 #if LUA_N2SBUFFSZ < (20 + l_floatatt(DIG))
    413 #error "invalid value for LUA_N2SBUFFSZ"
    414 #endif
    415 
    416 
    417 /*
    418 ** Convert a float to a string, adding it to a buffer. First try with
    419 ** a not too large number of digits, to avoid noise (for instance,
    420 ** 1.1 going to "1.1000000000000001"). If that lose precision, so
    421 ** that reading the result back gives a different number, then do the
    422 ** conversion again with extra precision. Moreover, if the numeral looks
    423 ** like an integer (without a decimal point or an exponent), add ".0" to
    424 ** its end.
    425 */
    426 static int tostringbuffFloat (lua_Number n, char *buff) {
    427   /* first conversion */
    428   int len = l_sprintf(buff, LUA_N2SBUFFSZ, LUA_NUMBER_FMT,
    429                             (LUAI_UACNUMBER)n);
    430   lua_Number check = lua_str2number(buff, NULL);  /* read it back */
    431   if (check != n) {  /* not enough precision? */
    432     /* convert again with more precision */
    433     len = l_sprintf(buff, LUA_N2SBUFFSZ, LUA_NUMBER_FMT_N,
    434                           (LUAI_UACNUMBER)n);
    435   }
    436   /* looks like an integer? */
    437   if (buff[strspn(buff, "-0123456789")] == '\0') {
    438     buff[len++] = lua_getlocaledecpoint();
    439     buff[len++] = '0';  /* adds '.0' to result */
    440   }
    441   return len;
    442 }
    443 
    444 
    445 /*
    446 ** Convert a number object to a string, adding it to a buffer.
    447 */
    448 unsigned luaO_tostringbuff (const TValue *obj, char *buff) {
    449   int len;
    450   lua_assert(ttisnumber(obj));
    451   if (ttisinteger(obj))
    452     len = lua_integer2str(buff, LUA_N2SBUFFSZ, ivalue(obj));
    453   else
    454     len = tostringbuffFloat(fltvalue(obj), buff);
    455   lua_assert(len < LUA_N2SBUFFSZ);
    456   return cast_uint(len);
    457 }
    458 
    459 
    460 /*
    461 ** Convert a number object to a Lua string, replacing the value at 'obj'
    462 */
    463 void luaO_tostring (lua_State *L, TValue *obj) {
    464   char buff[LUA_N2SBUFFSZ];
    465   unsigned len = luaO_tostringbuff(obj, buff);
    466   setsvalue(L, obj, luaS_newlstr(L, buff, len));
    467 }
    468 
    469 
    470 
    471 
    472 /*
    473 ** {==================================================================
    474 ** 'luaO_pushvfstring'
    475 ** ===================================================================
    476 */
    477 
    478 /*
    479 ** Size for buffer space used by 'luaO_pushvfstring'. It should be
    480 ** (LUA_IDSIZE + LUA_N2SBUFFSZ) + a minimal space for basic messages,
    481 ** so that 'luaG_addinfo' can work directly on the static buffer.
    482 */
    483 #define BUFVFS		cast_uint(LUA_IDSIZE + LUA_N2SBUFFSZ + 95)
    484 
    485 /*
    486 ** Buffer used by 'luaO_pushvfstring'. 'err' signals an error while
    487 ** building result (memory error [1] or buffer overflow [2]).
    488 */
    489 typedef struct BuffFS {
    490   lua_State *L;
    491   char *b;
    492   size_t buffsize;
    493   size_t blen;  /* length of string in 'buff' */
    494   int err;
    495   char space[BUFVFS];  /* initial buffer */
    496 } BuffFS;
    497 
    498 
    499 static void initbuff (lua_State *L, BuffFS *buff) {
    500   buff->L = L;
    501   buff->b = buff->space;
    502   buff->buffsize = sizeof(buff->space);
    503   buff->blen = 0;
    504   buff->err = 0;
    505 }
    506 
    507 
    508 /*
    509 ** Push final result from 'luaO_pushvfstring'. This function may raise
    510 ** errors explicitly or through memory errors, so it must run protected.
    511 */
    512 static void pushbuff (lua_State *L, void *ud) {
    513   BuffFS *buff = cast(BuffFS*, ud);
    514   switch (buff->err) {
    515     case 1:  /* memory error */
    516       luaD_throw(L, LUA_ERRMEM);
    517       break;
    518     case 2:  /* length overflow: Add "..." at the end of result */
    519       if (buff->buffsize - buff->blen < 3)
    520         strcpy(buff->b + buff->blen - 3, "...");  /* 'blen' must be > 3 */
    521       else {  /* there is enough space left for the "..." */
    522         strcpy(buff->b + buff->blen, "...");
    523         buff->blen += 3;
    524       }
    525       /* FALLTHROUGH */
    526     default: {  /* no errors, but it can raise one creating the new string */
    527       TString *ts = luaS_newlstr(L, buff->b, buff->blen);
    528       setsvalue2s(L, L->top.p, ts);
    529       L->top.p++;
    530     }
    531   }
    532 }
    533 
    534 
    535 static const char *clearbuff (BuffFS *buff) {
    536   lua_State *L = buff->L;
    537   const char *res;
    538   if (luaD_rawrunprotected(L, pushbuff, buff) != LUA_OK)  /* errors? */
    539     res = NULL;  /* error message is on the top of the stack */
    540   else
    541     res = getstr(tsvalue(s2v(L->top.p - 1)));
    542   if (buff->b != buff->space)  /* using dynamic buffer? */
    543     luaM_freearray(L, buff->b, buff->buffsize);  /* free it */
    544   return res;
    545 }
    546 
    547 
    548 static void addstr2buff (BuffFS *buff, const char *str, size_t slen) {
    549   size_t left = buff->buffsize - buff->blen;  /* space left in the buffer */
    550   if (buff->err)  /* do nothing else after an error */
    551     return;
    552   if (slen > left) {  /* new string doesn't fit into current buffer? */
    553     if (slen > ((MAX_SIZE/2) - buff->blen)) {  /* overflow? */
    554       memcpy(buff->b + buff->blen, str, left);  /* copy what it can */
    555       buff->blen = buff->buffsize;
    556       buff->err = 2;  /* doesn't add anything else */
    557       return;
    558     }
    559     else {
    560       size_t newsize = buff->buffsize + slen;  /* limited to MAX_SIZE/2 */
    561       char *newb =
    562         (buff->b == buff->space)  /* still using static space? */
    563         ? luaM_reallocvector(buff->L, NULL, 0, newsize, char)
    564         : luaM_reallocvector(buff->L, buff->b, buff->buffsize, newsize,
    565                                                                char);
    566       if (newb == NULL) {  /* allocation error? */
    567         buff->err = 1;  /* signal a memory error */
    568         return;
    569       }
    570       if (buff->b == buff->space)  /* new buffer (not reallocated)? */
    571         memcpy(newb, buff->b, buff->blen);  /* copy previous content */
    572       buff->b = newb;  /* set new (larger) buffer... */
    573       buff->buffsize = newsize;  /* ...and its new size */
    574     }
    575   }
    576   memcpy(buff->b + buff->blen, str, slen);  /* copy new content */
    577   buff->blen += slen;
    578 }
    579 
    580 
    581 /*
    582 ** Add a numeral to the buffer.
    583 */
    584 static void addnum2buff (BuffFS *buff, TValue *num) {
    585   char numbuff[LUA_N2SBUFFSZ];
    586   unsigned len = luaO_tostringbuff(num, numbuff);
    587   addstr2buff(buff, numbuff, len);
    588 }
    589 
    590 
    591 /*
    592 ** this function handles only '%d', '%c', '%f', '%p', '%s', and '%%'
    593    conventional formats, plus Lua-specific '%I' and '%U'
    594 */
    595 const char *luaO_pushvfstring (lua_State *L, const char *fmt, va_list argp) {
    596   BuffFS buff;  /* holds last part of the result */
    597   const char *e;  /* points to next '%' */
    598   initbuff(L, &buff);
    599   while ((e = strchr(fmt, '%')) != NULL) {
    600     addstr2buff(&buff, fmt, ct_diff2sz(e - fmt));  /* add 'fmt' up to '%' */
    601     switch (*(e + 1)) {  /* conversion specifier */
    602       case 's': {  /* zero-terminated string */
    603         const char *s = va_arg(argp, char *);
    604         if (s == NULL) s = "(null)";
    605         addstr2buff(&buff, s, strlen(s));
    606         break;
    607       }
    608       case 'c': {  /* an 'int' as a character */
    609         char c = cast_char(va_arg(argp, int));
    610         addstr2buff(&buff, &c, sizeof(char));
    611         break;
    612       }
    613       case 'd': {  /* an 'int' */
    614         TValue num;
    615         setivalue(&num, va_arg(argp, int));
    616         addnum2buff(&buff, &num);
    617         break;
    618       }
    619       case 'I': {  /* a 'lua_Integer' */
    620         TValue num;
    621         setivalue(&num, cast(lua_Integer, va_arg(argp, l_uacInt)));
    622         addnum2buff(&buff, &num);
    623         break;
    624       }
    625       case 'f': {  /* a 'lua_Number' */
    626         TValue num;
    627         setfltvalue(&num, cast_num(va_arg(argp, l_uacNumber)));
    628         addnum2buff(&buff, &num);
    629         break;
    630       }
    631       case 'p': {  /* a pointer */
    632         char bf[LUA_N2SBUFFSZ];  /* enough space for '%p' */
    633         void *p = va_arg(argp, void *);
    634         int len = lua_pointer2str(bf, LUA_N2SBUFFSZ, p);
    635         addstr2buff(&buff, bf, cast_uint(len));
    636         break;
    637       }
    638       case 'U': {  /* an 'unsigned long' as a UTF-8 sequence */
    639         char bf[UTF8BUFFSZ];
    640         int len = luaO_utf8esc(bf, va_arg(argp, unsigned long));
    641         addstr2buff(&buff, bf + UTF8BUFFSZ - len, cast_uint(len));
    642         break;
    643       }
    644       case '%': {
    645         addstr2buff(&buff, "%", 1);
    646         break;
    647       }
    648       default: {
    649         addstr2buff(&buff, e, 2);  /* keep unknown format in the result */
    650         break;
    651       }
    652     }
    653     fmt = e + 2;  /* skip '%' and the specifier */
    654   }
    655   addstr2buff(&buff, fmt, strlen(fmt));  /* rest of 'fmt' */
    656   return clearbuff(&buff);  /* empty buffer into a new string */
    657 }
    658 
    659 
    660 const char *luaO_pushfstring (lua_State *L, const char *fmt, ...) {
    661   const char *msg;
    662   va_list argp;
    663   va_start(argp, fmt);
    664   msg = luaO_pushvfstring(L, fmt, argp);
    665   va_end(argp);
    666   if (msg == NULL)  /* error? */
    667     luaD_throw(L, LUA_ERRMEM);
    668   return msg;
    669 }
    670 
    671 /* }================================================================== */
    672 
    673 
    674 #define RETS	"..."
    675 #define PRE	"[string \""
    676 #define POS	"\"]"
    677 
    678 #define addstr(a,b,l)	( memcpy(a,b,(l) * sizeof(char)), a += (l) )
    679 
    680 void luaO_chunkid (char *out, const char *source, size_t srclen) {
    681   size_t bufflen = LUA_IDSIZE;  /* free space in buffer */
    682   if (*source == '=') {  /* 'literal' source */
    683     if (srclen <= bufflen)  /* small enough? */
    684       memcpy(out, source + 1, srclen * sizeof(char));
    685     else {  /* truncate it */
    686       addstr(out, source + 1, bufflen - 1);
    687       *out = '\0';
    688     }
    689   }
    690   else if (*source == '@') {  /* file name */
    691     if (srclen <= bufflen)  /* small enough? */
    692       memcpy(out, source + 1, srclen * sizeof(char));
    693     else {  /* add '...' before rest of name */
    694       addstr(out, RETS, LL(RETS));
    695       bufflen -= LL(RETS);
    696       memcpy(out, source + 1 + srclen - bufflen, bufflen * sizeof(char));
    697     }
    698   }
    699   else {  /* string; format as [string "source"] */
    700     const char *nl = strchr(source, '\n');  /* find first new line (if any) */
    701     addstr(out, PRE, LL(PRE));  /* add prefix */
    702     bufflen -= LL(PRE RETS POS) + 1;  /* save space for prefix+suffix+'\0' */
    703     if (srclen < bufflen && nl == NULL) {  /* small one-line source? */
    704       addstr(out, source, srclen);  /* keep it */
    705     }
    706     else {
    707       if (nl != NULL)
    708         srclen = ct_diff2sz(nl - source);  /* stop at first newline */
    709       if (srclen > bufflen) srclen = bufflen;
    710       addstr(out, source, srclen);
    711       addstr(out, RETS, LL(RETS));
    712     }
    713     memcpy(out, POS, (LL(POS) + 1) * sizeof(char));
    714   }
    715 }
    716