lua

lobject.c (24000B)

---

 /*
 ** $Id: lobject.c $
 ** Some generic functions over Lua objects
 ** See Copyright Notice in lua.h
 */
 
 #define lobject_c
 #define LUA_CORE
 
 #include "lprefix.h"
 
 
 #include <float.h>
 #include <locale.h>
 #include <math.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "lua.h"
 
 #include "lctype.h"
 #include "ldebug.h"
 #include "ldo.h"
 #include "lmem.h"
 #include "lobject.h"
 #include "lstate.h"
 #include "lstring.h"
 #include "lvm.h"
 
 
 /*
 ** Computes ceil(log2(x))
 */
 lu_byte luaO_ceillog2 (unsigned int x) {
   static const lu_byte log_2[256] = {  /* log_2[i - 1] = ceil(log2(i)) */
     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,
     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,
     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,
     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,
     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,
     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,
     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,
     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
   };
   int l = 0;
   x--;
   while (x >= 256) { l += 8; x >>= 8; }
   return cast_byte(l + log_2[x]);
 }
 
 /*
 ** Encodes 'p'% as a floating-point byte, represented as (eeeexxxx).
 ** The exponent is represented using excess-7. Mimicking IEEE 754, the
 ** representation normalizes the number when possible, assuming an extra
 ** 1 before the mantissa (xxxx) and adding one to the exponent (eeee)
 ** to signal that. So, the real value is (1xxxx) * 2^(eeee - 7 - 1) if
 ** eeee != 0, and (xxxx) * 2^-7 otherwise (subnormal numbers).
 */
 lu_byte luaO_codeparam (unsigned int p) {
   if (p >= (cast(lu_mem, 0x1F) << (0xF - 7 - 1)) * 100u)  /* overflow? */
     return 0xFF;  /* return maximum value */
   else {
     p = (cast(l_uint32, p) * 128 + 99) / 100;  /* round up the division */
     if (p < 0x10) {  /* subnormal number? */
       /* exponent bits are already zero; nothing else to do */
       return cast_byte(p);
     }
     else {  /* p >= 0x10 implies ceil(log2(p + 1)) >= 5 */
       /* preserve 5 bits in 'p' */
       unsigned log = luaO_ceillog2(p + 1) - 5u;
       return cast_byte(((p >> log) - 0x10) | ((log + 1) << 4));
     }
   }
 }
 
 
 /*
 ** Computes 'p' times 'x', where 'p' is a floating-point byte. Roughly,
 ** we have to multiply 'x' by the mantissa and then shift accordingly to
 ** the exponent.  If the exponent is positive, both the multiplication
 ** and the shift increase 'x', so we have to care only about overflows.
 ** For negative exponents, however, multiplying before the shift keeps
 ** more significant bits, as long as the multiplication does not
 ** overflow, so we check which order is best.
 */
 l_mem luaO_applyparam (lu_byte p, l_mem x) {
   unsigned int m = p & 0xF;  /* mantissa */
   int e = (p >> 4);  /* exponent */
   if (e > 0) {  /* normalized? */
     e--;  /* correct exponent */
     m += 0x10;  /* correct mantissa; maximum value is 0x1F */
   }
   e -= 7;  /* correct excess-7 */
   if (e >= 0) {
     if (x < (MAX_LMEM / 0x1F) >> e)  /* no overflow? */
       return (x * m) << e;  /* order doesn't matter here */
     else  /* real overflow */
       return MAX_LMEM;
   }
   else {  /* negative exponent */
     e = -e;
     if (x < MAX_LMEM / 0x1F)  /* multiplication cannot overflow? */
       return (x * m) >> e;  /* multiplying first gives more precision */
     else if ((x >> e) <  MAX_LMEM / 0x1F)  /* cannot overflow after shift? */
       return (x >> e) * m;
     else  /* real overflow */
       return MAX_LMEM;
   }
 }
 
 
 static lua_Integer intarith (lua_State *L, int op, lua_Integer v1,
                                                    lua_Integer v2) {
   switch (op) {
     case LUA_OPADD: return intop(+, v1, v2);
     case LUA_OPSUB:return intop(-, v1, v2);
     case LUA_OPMUL:return intop(*, v1, v2);
     case LUA_OPMOD: return luaV_mod(L, v1, v2);
     case LUA_OPIDIV: return luaV_idiv(L, v1, v2);
     case LUA_OPBAND: return intop(&, v1, v2);
     case LUA_OPBOR: return intop(|, v1, v2);
     case LUA_OPBXOR: return intop(^, v1, v2);
     case LUA_OPSHL: return luaV_shiftl(v1, v2);
     case LUA_OPSHR: return luaV_shiftr(v1, v2);
     case LUA_OPUNM: return intop(-, 0, v1);
     case LUA_OPBNOT: return intop(^, ~l_castS2U(0), v1);
     default: lua_assert(0); return 0;
   }
 }
 
 
 static lua_Number numarith (lua_State *L, int op, lua_Number v1,
                                                   lua_Number v2) {
   switch (op) {
     case LUA_OPADD: return luai_numadd(L, v1, v2);
     case LUA_OPSUB: return luai_numsub(L, v1, v2);
     case LUA_OPMUL: return luai_nummul(L, v1, v2);
     case LUA_OPDIV: return luai_numdiv(L, v1, v2);
     case LUA_OPPOW: return luai_numpow(L, v1, v2);
     case LUA_OPIDIV: return luai_numidiv(L, v1, v2);
     case LUA_OPUNM: return luai_numunm(L, v1);
     case LUA_OPMOD: return luaV_modf(L, v1, v2);
     default: lua_assert(0); return 0;
   }
 }
 
 
 int luaO_rawarith (lua_State *L, int op, const TValue *p1, const TValue *p2,
                    TValue *res) {
   switch (op) {
     case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR:
     case LUA_OPSHL: case LUA_OPSHR:
     case LUA_OPBNOT: {  /* operate only on integers */
       lua_Integer i1; lua_Integer i2;
       if (tointegerns(p1, &i1) && tointegerns(p2, &i2)) {
         setivalue(res, intarith(L, op, i1, i2));
         return 1;
       }
       else return 0;  /* fail */
     }
     case LUA_OPDIV: case LUA_OPPOW: {  /* operate only on floats */
       lua_Number n1; lua_Number n2;
       if (tonumberns(p1, n1) && tonumberns(p2, n2)) {
         setfltvalue(res, numarith(L, op, n1, n2));
         return 1;
       }
       else return 0;  /* fail */
     }
     default: {  /* other operations */
       lua_Number n1; lua_Number n2;
       if (ttisinteger(p1) && ttisinteger(p2)) {
         setivalue(res, intarith(L, op, ivalue(p1), ivalue(p2)));
         return 1;
       }
       else if (tonumberns(p1, n1) && tonumberns(p2, n2)) {
         setfltvalue(res, numarith(L, op, n1, n2));
         return 1;
       }
       else return 0;  /* fail */
     }
   }
 }
 
 
 void luaO_arith (lua_State *L, int op, const TValue *p1, const TValue *p2,
                  StkId res) {
   if (!luaO_rawarith(L, op, p1, p2, s2v(res))) {
     /* could not perform raw operation; try metamethod */
     luaT_trybinTM(L, p1, p2, res, cast(TMS, (op - LUA_OPADD) + TM_ADD));
   }
 }
 
 
 lu_byte luaO_hexavalue (int c) {
   lua_assert(lisxdigit(c));
   if (lisdigit(c)) return cast_byte(c - '0');
   else return cast_byte((ltolower(c) - 'a') + 10);
 }
 
 
 static int isneg (const char **s) {
   if (**s == '-') { (*s)++; return 1; }
   else if (**s == '+') (*s)++;
   return 0;
 }
 
 
 
 /*
 ** {==================================================================
 ** Lua's implementation for 'lua_strx2number'
 ** ===================================================================
 */
 
 #if !defined(lua_strx2number)
 
 /* maximum number of significant digits to read (to avoid overflows
    even with single floats) */
 #define MAXSIGDIG	30
 
 /*
 ** convert a hexadecimal numeric string to a number, following
 ** C99 specification for 'strtod'
 */
 static lua_Number lua_strx2number (const char *s, char **endptr) {
   int dot = lua_getlocaledecpoint();
   lua_Number r = l_mathop(0.0);  /* result (accumulator) */
   int sigdig = 0;  /* number of significant digits */
   int nosigdig = 0;  /* number of non-significant digits */
   int e = 0;  /* exponent correction */
   int neg;  /* 1 if number is negative */
   int hasdot = 0;  /* true after seen a dot */
   *endptr = cast_charp(s);  /* nothing is valid yet */
   while (lisspace(cast_uchar(*s))) s++;  /* skip initial spaces */
   neg = isneg(&s);  /* check sign */
   if (!(*s == '0' && (*(s + 1) == 'x' || *(s + 1) == 'X')))  /* check '0x' */
     return l_mathop(0.0);  /* invalid format (no '0x') */
   for (s += 2; ; s++) {  /* skip '0x' and read numeral */
     if (*s == dot) {
       if (hasdot) break;  /* second dot? stop loop */
       else hasdot = 1;
     }
     else if (lisxdigit(cast_uchar(*s))) {
       if (sigdig == 0 && *s == '0')  /* non-significant digit (zero)? */
         nosigdig++;
       else if (++sigdig <= MAXSIGDIG)  /* can read it without overflow? */
           r = (r * l_mathop(16.0)) + luaO_hexavalue(*s);
       else e++;  /* too many digits; ignore, but still count for exponent */
       if (hasdot) e--;  /* decimal digit? correct exponent */
     }
     else break;  /* neither a dot nor a digit */
   }
   if (nosigdig + sigdig == 0)  /* no digits? */
     return l_mathop(0.0);  /* invalid format */
   *endptr = cast_charp(s);  /* valid up to here */
   e *= 4;  /* each digit multiplies/divides value by 2^4 */
   if (*s == 'p' || *s == 'P') {  /* exponent part? */
     int exp1 = 0;  /* exponent value */
     int neg1;  /* exponent sign */
     s++;  /* skip 'p' */
     neg1 = isneg(&s);  /* sign */
     if (!lisdigit(cast_uchar(*s)))
       return l_mathop(0.0);  /* invalid; must have at least one digit */
     while (lisdigit(cast_uchar(*s)))  /* read exponent */
       exp1 = exp1 * 10 + *(s++) - '0';
     if (neg1) exp1 = -exp1;
     e += exp1;
     *endptr = cast_charp(s);  /* valid up to here */
   }
   if (neg) r = -r;
   return l_mathop(ldexp)(r, e);
 }
 
 #endif
 /* }====================================================== */
 
 
 /* maximum length of a numeral to be converted to a number */
 #if !defined (L_MAXLENNUM)
 #define L_MAXLENNUM	200
 #endif
 
 /*
 ** Convert string 's' to a Lua number (put in 'result'). Return NULL on
 ** fail or the address of the ending '\0' on success. ('mode' == 'x')
 ** means a hexadecimal numeral.
 */
 static const char *l_str2dloc (const char *s, lua_Number *result, int mode) {
   char *endptr;
   *result = (mode == 'x') ? lua_strx2number(s, &endptr)  /* try to convert */
                           : lua_str2number(s, &endptr);
   if (endptr == s) return NULL;  /* nothing recognized? */
   while (lisspace(cast_uchar(*endptr))) endptr++;  /* skip trailing spaces */
   return (*endptr == '\0') ? endptr : NULL;  /* OK iff no trailing chars */
 }
 
 
 /*
 ** Convert string 's' to a Lua number (put in 'result') handling the
 ** current locale.
 ** This function accepts both the current locale or a dot as the radix
 ** mark. If the conversion fails, it may mean number has a dot but
 ** locale accepts something else. In that case, the code copies 's'
 ** to a buffer (because 's' is read-only), changes the dot to the
 ** current locale radix mark, and tries to convert again.
 ** The variable 'mode' checks for special characters in the string:
 ** - 'n' means 'inf' or 'nan' (which should be rejected)
 ** - 'x' means a hexadecimal numeral
 ** - '.' just optimizes the search for the common case (no special chars)
 */
 static const char *l_str2d (const char *s, lua_Number *result) {
   const char *endptr;
   const char *pmode = strpbrk(s, ".xXnN");  /* look for special chars */
   int mode = pmode ? ltolower(cast_uchar(*pmode)) : 0;
   if (mode == 'n')  /* reject 'inf' and 'nan' */
     return NULL;
   endptr = l_str2dloc(s, result, mode);  /* try to convert */
   if (endptr == NULL) {  /* failed? may be a different locale */
     char buff[L_MAXLENNUM + 1];
     const char *pdot = strchr(s, '.');
     if (pdot == NULL || strlen(s) > L_MAXLENNUM)
       return NULL;  /* string too long or no dot; fail */
     strcpy(buff, s);  /* copy string to buffer */
     buff[pdot - s] = lua_getlocaledecpoint();  /* correct decimal point */
     endptr = l_str2dloc(buff, result, mode);  /* try again */
     if (endptr != NULL)
       endptr = s + (endptr - buff);  /* make relative to 's' */
   }
   return endptr;
 }
 
 
 #define MAXBY10		cast(lua_Unsigned, LUA_MAXINTEGER / 10)
 #define MAXLASTD	cast_int(LUA_MAXINTEGER % 10)
 
 static const char *l_str2int (const char *s, lua_Integer *result) {
   lua_Unsigned a = 0;
   int empty = 1;
   int neg;
   while (lisspace(cast_uchar(*s))) s++;  /* skip initial spaces */
   neg = isneg(&s);
   if (s[0] == '0' &&
       (s[1] == 'x' || s[1] == 'X')) {  /* hex? */
     s += 2;  /* skip '0x' */
     for (; lisxdigit(cast_uchar(*s)); s++) {
       a = a * 16 + luaO_hexavalue(*s);
       empty = 0;
     }
   }
   else {  /* decimal */
     for (; lisdigit(cast_uchar(*s)); s++) {
       int d = *s - '0';
       if (a >= MAXBY10 && (a > MAXBY10 || d > MAXLASTD + neg))  /* overflow? */
         return NULL;  /* do not accept it (as integer) */
       a = a * 10 + cast_uint(d);
       empty = 0;
     }
   }
   while (lisspace(cast_uchar(*s))) s++;  /* skip trailing spaces */
   if (empty || *s != '\0') return NULL;  /* something wrong in the numeral */
   else {
     *result = l_castU2S((neg) ? 0u - a : a);
     return s;
   }
 }
 
 
 size_t luaO_str2num (const char *s, TValue *o) {
   lua_Integer i; lua_Number n;
   const char *e;
   if ((e = l_str2int(s, &i)) != NULL) {  /* try as an integer */
     setivalue(o, i);
   }
   else if ((e = l_str2d(s, &n)) != NULL) {  /* else try as a float */
     setfltvalue(o, n);
   }
   else
     return 0;  /* conversion failed */
   return ct_diff2sz(e - s) + 1;  /* success; return string size */
 }
 
 
 int luaO_utf8esc (char *buff, unsigned long x) {
   int n = 1;  /* number of bytes put in buffer (backwards) */
   lua_assert(x <= 0x7FFFFFFFu);
   if (x < 0x80)  /* ascii? */
     buff[UTF8BUFFSZ - 1] = cast_char(x);
   else {  /* need continuation bytes */
     unsigned int mfb = 0x3f;  /* maximum that fits in first byte */
     do {  /* add continuation bytes */
       buff[UTF8BUFFSZ - (n++)] = cast_char(0x80 | (x & 0x3f));
       x >>= 6;  /* remove added bits */
       mfb >>= 1;  /* now there is one less bit available in first byte */
     } while (x > mfb);  /* still needs continuation byte? */
     buff[UTF8BUFFSZ - n] = cast_char((~mfb << 1) | x);  /* add first byte */
   }
   return n;
 }
 
 
 /*
 ** The size of the buffer for the conversion of a number to a string
 ** 'LUA_N2SBUFFSZ' must be enough to accommodate both LUA_INTEGER_FMT
 ** and LUA_NUMBER_FMT.  For a long long int, this is 19 digits plus a
 ** sign and a final '\0', adding to 21. For a long double, it can go to
 ** a sign, the dot, an exponent letter, an exponent sign, 4 exponent
 ** digits, the final '\0', plus the significant digits, which are
 ** approximately the *_DIG attribute.
 */
 #if LUA_N2SBUFFSZ < (20 + l_floatatt(DIG))
 #error "invalid value for LUA_N2SBUFFSZ"
 #endif
 
 
 /*
 ** Convert a float to a string, adding it to a buffer. First try with
 ** a not too large number of digits, to avoid noise (for instance,
 ** 1.1 going to "1.1000000000000001"). If that lose precision, so
 ** that reading the result back gives a different number, then do the
 ** conversion again with extra precision. Moreover, if the numeral looks
 ** like an integer (without a decimal point or an exponent), add ".0" to
 ** its end.
 */
 static int tostringbuffFloat (lua_Number n, char *buff) {
   /* first conversion */
   int len = l_sprintf(buff, LUA_N2SBUFFSZ, LUA_NUMBER_FMT,
                             (LUAI_UACNUMBER)n);
   lua_Number check = lua_str2number(buff, NULL);  /* read it back */
   if (check != n) {  /* not enough precision? */
     /* convert again with more precision */
     len = l_sprintf(buff, LUA_N2SBUFFSZ, LUA_NUMBER_FMT_N,
                           (LUAI_UACNUMBER)n);
   }
   /* looks like an integer? */
   if (buff[strspn(buff, "-0123456789")] == '\0') {
     buff[len++] = lua_getlocaledecpoint();
     buff[len++] = '0';  /* adds '.0' to result */
   }
   return len;
 }
 
 
 /*
 ** Convert a number object to a string, adding it to a buffer.
 */
 unsigned luaO_tostringbuff (const TValue *obj, char *buff) {
   int len;
   lua_assert(ttisnumber(obj));
   if (ttisinteger(obj))
     len = lua_integer2str(buff, LUA_N2SBUFFSZ, ivalue(obj));
   else
     len = tostringbuffFloat(fltvalue(obj), buff);
   lua_assert(len < LUA_N2SBUFFSZ);
   return cast_uint(len);
 }
 
 
 /*
 ** Convert a number object to a Lua string, replacing the value at 'obj'
 */
 void luaO_tostring (lua_State *L, TValue *obj) {
   char buff[LUA_N2SBUFFSZ];
   unsigned len = luaO_tostringbuff(obj, buff);
   setsvalue(L, obj, luaS_newlstr(L, buff, len));
 }
 
 
 
 
 /*
 ** {==================================================================
 ** 'luaO_pushvfstring'
 ** ===================================================================
 */
 
 /*
 ** Size for buffer space used by 'luaO_pushvfstring'. It should be
 ** (LUA_IDSIZE + LUA_N2SBUFFSZ) + a minimal space for basic messages,
 ** so that 'luaG_addinfo' can work directly on the static buffer.
 */
 #define BUFVFS		cast_uint(LUA_IDSIZE + LUA_N2SBUFFSZ + 95)
 
 /*
 ** Buffer used by 'luaO_pushvfstring'. 'err' signals an error while
 ** building result (memory error [1] or buffer overflow [2]).
 */
 typedef struct BuffFS {
   lua_State *L;
   char *b;
   size_t buffsize;
   size_t blen;  /* length of string in 'buff' */
   int err;
   char space[BUFVFS];  /* initial buffer */
 } BuffFS;
 
 
 static void initbuff (lua_State *L, BuffFS *buff) {
   buff->L = L;
   buff->b = buff->space;
   buff->buffsize = sizeof(buff->space);
   buff->blen = 0;
   buff->err = 0;
 }
 
 
 /*
 ** Push final result from 'luaO_pushvfstring'. This function may raise
 ** errors explicitly or through memory errors, so it must run protected.
 */
 static void pushbuff (lua_State *L, void *ud) {
   BuffFS *buff = cast(BuffFS*, ud);
   switch (buff->err) {
     case 1:  /* memory error */
       luaD_throw(L, LUA_ERRMEM);
       break;
     case 2:  /* length overflow: Add "..." at the end of result */
       if (buff->buffsize - buff->blen < 3)
         strcpy(buff->b + buff->blen - 3, "...");  /* 'blen' must be > 3 */
       else {  /* there is enough space left for the "..." */
         strcpy(buff->b + buff->blen, "...");
         buff->blen += 3;
       }
       /* FALLTHROUGH */
     default: {  /* no errors, but it can raise one creating the new string */
       TString *ts = luaS_newlstr(L, buff->b, buff->blen);
       setsvalue2s(L, L->top.p, ts);
       L->top.p++;
     }
   }
 }
 
 
 static const char *clearbuff (BuffFS *buff) {
   lua_State *L = buff->L;
   const char *res;
   if (luaD_rawrunprotected(L, pushbuff, buff) != LUA_OK)  /* errors? */
     res = NULL;  /* error message is on the top of the stack */
   else
     res = getstr(tsvalue(s2v(L->top.p - 1)));
   if (buff->b != buff->space)  /* using dynamic buffer? */
     luaM_freearray(L, buff->b, buff->buffsize);  /* free it */
   return res;
 }
 
 
 static void addstr2buff (BuffFS *buff, const char *str, size_t slen) {
   size_t left = buff->buffsize - buff->blen;  /* space left in the buffer */
   if (buff->err)  /* do nothing else after an error */
     return;
   if (slen > left) {  /* new string doesn't fit into current buffer? */
     if (slen > ((MAX_SIZE/2) - buff->blen)) {  /* overflow? */
       memcpy(buff->b + buff->blen, str, left);  /* copy what it can */
       buff->blen = buff->buffsize;
       buff->err = 2;  /* doesn't add anything else */
       return;
     }
     else {
       size_t newsize = buff->buffsize + slen;  /* limited to MAX_SIZE/2 */
       char *newb =
         (buff->b == buff->space)  /* still using static space? */
         ? luaM_reallocvector(buff->L, NULL, 0, newsize, char)
         : luaM_reallocvector(buff->L, buff->b, buff->buffsize, newsize,
                                                                char);
       if (newb == NULL) {  /* allocation error? */
         buff->err = 1;  /* signal a memory error */
         return;
       }
       if (buff->b == buff->space)  /* new buffer (not reallocated)? */
         memcpy(newb, buff->b, buff->blen);  /* copy previous content */
       buff->b = newb;  /* set new (larger) buffer... */
       buff->buffsize = newsize;  /* ...and its new size */
     }
   }
   memcpy(buff->b + buff->blen, str, slen);  /* copy new content */
   buff->blen += slen;
 }
 
 
 /*
 ** Add a numeral to the buffer.
 */
 static void addnum2buff (BuffFS *buff, TValue *num) {
   char numbuff[LUA_N2SBUFFSZ];
   unsigned len = luaO_tostringbuff(num, numbuff);
   addstr2buff(buff, numbuff, len);
 }
 
 
 /*
 ** this function handles only '%d', '%c', '%f', '%p', '%s', and '%%'
    conventional formats, plus Lua-specific '%I' and '%U'
 */
 const char *luaO_pushvfstring (lua_State *L, const char *fmt, va_list argp) {
   BuffFS buff;  /* holds last part of the result */
   const char *e;  /* points to next '%' */
   initbuff(L, &buff);
   while ((e = strchr(fmt, '%')) != NULL) {
     addstr2buff(&buff, fmt, ct_diff2sz(e - fmt));  /* add 'fmt' up to '%' */
     switch (*(e + 1)) {  /* conversion specifier */
       case 's': {  /* zero-terminated string */
         const char *s = va_arg(argp, char *);
         if (s == NULL) s = "(null)";
         addstr2buff(&buff, s, strlen(s));
         break;
       }
       case 'c': {  /* an 'int' as a character */
         char c = cast_char(va_arg(argp, int));
         addstr2buff(&buff, &c, sizeof(char));
         break;
       }
       case 'd': {  /* an 'int' */
         TValue num;
         setivalue(&num, va_arg(argp, int));
         addnum2buff(&buff, &num);
         break;
       }
       case 'I': {  /* a 'lua_Integer' */
         TValue num;
         setivalue(&num, cast(lua_Integer, va_arg(argp, l_uacInt)));
         addnum2buff(&buff, &num);
         break;
       }
       case 'f': {  /* a 'lua_Number' */
         TValue num;
         setfltvalue(&num, cast_num(va_arg(argp, l_uacNumber)));
         addnum2buff(&buff, &num);
         break;
       }
       case 'p': {  /* a pointer */
         char bf[LUA_N2SBUFFSZ];  /* enough space for '%p' */
         void *p = va_arg(argp, void *);
         int len = lua_pointer2str(bf, LUA_N2SBUFFSZ, p);
         addstr2buff(&buff, bf, cast_uint(len));
         break;
       }
       case 'U': {  /* an 'unsigned long' as a UTF-8 sequence */
         char bf[UTF8BUFFSZ];
         int len = luaO_utf8esc(bf, va_arg(argp, unsigned long));
         addstr2buff(&buff, bf + UTF8BUFFSZ - len, cast_uint(len));
         break;
       }
       case '%': {
         addstr2buff(&buff, "%", 1);
         break;
       }
       default: {
         addstr2buff(&buff, e, 2);  /* keep unknown format in the result */
         break;
       }
     }
     fmt = e + 2;  /* skip '%' and the specifier */
   }
   addstr2buff(&buff, fmt, strlen(fmt));  /* rest of 'fmt' */
   return clearbuff(&buff);  /* empty buffer into a new string */
 }
 
 
 const char *luaO_pushfstring (lua_State *L, const char *fmt, ...) {
   const char *msg;
   va_list argp;
   va_start(argp, fmt);
   msg = luaO_pushvfstring(L, fmt, argp);
   va_end(argp);
   if (msg == NULL)  /* error? */
     luaD_throw(L, LUA_ERRMEM);
   return msg;
 }
 
 /* }================================================================== */
 
 
 #define RETS	"..."
 #define PRE	"[string \""
 #define POS	"\"]"
 
 #define addstr(a,b,l)	( memcpy(a,b,(l) * sizeof(char)), a += (l) )
 
 void luaO_chunkid (char *out, const char *source, size_t srclen) {
   size_t bufflen = LUA_IDSIZE;  /* free space in buffer */
   if (*source == '=') {  /* 'literal' source */
     if (srclen <= bufflen)  /* small enough? */
       memcpy(out, source + 1, srclen * sizeof(char));
     else {  /* truncate it */
       addstr(out, source + 1, bufflen - 1);
       *out = '\0';
     }
   }
   else if (*source == '@') {  /* file name */
     if (srclen <= bufflen)  /* small enough? */
       memcpy(out, source + 1, srclen * sizeof(char));
     else {  /* add '...' before rest of name */
       addstr(out, RETS, LL(RETS));
       bufflen -= LL(RETS);
       memcpy(out, source + 1 + srclen - bufflen, bufflen * sizeof(char));
     }
   }
   else {  /* string; format as [string "source"] */
     const char *nl = strchr(source, '\n');  /* find first new line (if any) */
     addstr(out, PRE, LL(PRE));  /* add prefix */
     bufflen -= LL(PRE RETS POS) + 1;  /* save space for prefix+suffix+'\0' */
     if (srclen < bufflen && nl == NULL) {  /* small one-line source? */
       addstr(out, source, srclen);  /* keep it */
     }
     else {
       if (nl != NULL)
         srclen = ct_diff2sz(nl - source);  /* stop at first newline */
       if (srclen > bufflen) srclen = bufflen;
       addstr(out, source, srclen);
       addstr(out, RETS, LL(RETS));
     }
     memcpy(out, POS, (LL(POS) + 1) * sizeof(char));
   }
 }