libc/stdio/vfprintf.cpp

/*	$OpenBSD: vfprintf.c,v 1.71 2016/01/04 15:47:47 schwarze Exp $	*/
/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#define CHAR_TYPE char

#include <sys/mman.h>
#include <sys/types.h>

#include <errno.h>
#include <float.h>
#include <langinfo.h>
#include <limits.h>
#include <locale.h>
#include <math.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <wchar.h>

#include "fvwrite.h"
#include "gdtoa.h"
#include "local.h"

union arg {
  int intarg;
  unsigned int uintarg;
  long longarg;
  unsigned long ulongarg;
  long long longlongarg;
  unsigned long long ulonglongarg;
  ptrdiff_t ptrdiffarg;
  size_t sizearg;
  ssize_t ssizearg;
  intmax_t intmaxarg;
  uintmax_t uintmaxarg;
  void* pvoidarg;
  char* pchararg;
  signed char* pschararg;
  short* pshortarg;
  int* pintarg;
  long* plongarg;
  long long* plonglongarg;
  ptrdiff_t* pptrdiffarg;
  ssize_t* pssizearg;
  intmax_t* pintmaxarg;
  double doublearg;
  long double longdoublearg;
  wint_t wintarg;
  wchar_t* pwchararg;
};

static int __find_arguments(const CHAR_TYPE* fmt0, va_list ap, union arg** argtable, size_t* argtablesiz);
static int __grow_type_table(unsigned char** typetable, int* tablesize);

/*
 * Flush out all the vectors defined by the given uio,
 * then reset it so that it can be reused.
 */
static int __sprint(FILE* fp, struct __suio* uio) {
  int err;

  if (uio->uio_resid == 0) {
    uio->uio_iovcnt = 0;
    return (0);
  }
  err = __sfvwrite(fp, uio);
  uio->uio_resid = 0;
  uio->uio_iovcnt = 0;
  return (err);
}

/*
 * Helper function for `fprintf to unbuffered unix file': creates a
 * temporary buffer.  We only work on write-only files; this avoids
 * worries about ungetc buffers and so forth.
 */
static int __sbprintf(FILE* fp, const char* fmt, va_list ap) {
  int ret;
  FILE fake;
  struct __sfileext fakeext;
  unsigned char buf[BUFSIZ];

  _FILEEXT_SETUP(&fake, &fakeext);
  /* copy the important variables */
  fake._flags = fp->_flags & ~__SNBF;
  fake._file = fp->_file;
  fake._cookie = fp->_cookie;
  fake._write = fp->_write;

  /* set up the buffer */
  fake._bf._base = fake._p = buf;
  fake._bf._size = fake._w = sizeof(buf);
  fake._lbfsize = 0; /* not actually used, but Just In Case */

  /* do the work, then copy any error status */
  ret = __vfprintf(&fake, fmt, ap);
  if (ret >= 0 && __sflush(&fake)) ret = EOF;
  if (fake._flags & __SERR) fp->_flags |= __SERR;
  return (ret);
}

/*
 * Convert a wide character string argument for the %ls format to a multibyte
 * string representation. If not -1, prec specifies the maximum number of
 * bytes to output, and also means that we can't assume that the wide char
 * string is null-terminated.
 */
static char* __wcsconv(wchar_t* wcsarg, int prec) {
  mbstate_t mbs;
  char buf[MB_LEN_MAX];
  wchar_t* p;
  char* convbuf;
  size_t clen, nbytes;

  /* Allocate space for the maximum number of bytes we could output. */
  if (prec < 0) {
    memset(&mbs, 0, sizeof(mbs));
    p = wcsarg;
    nbytes = wcsrtombs(NULL, (const wchar_t**)&p, 0, &mbs);
    if (nbytes == (size_t)-1) return (NULL);
  } else {
    /*
     * Optimisation: if the output precision is small enough,
     * just allocate enough memory for the maximum instead of
     * scanning the string.
     */
    if (prec < 128)
      nbytes = prec;
    else {
      nbytes = 0;
      p = wcsarg;
      memset(&mbs, 0, sizeof(mbs));
      for (;;) {
        clen = wcrtomb(buf, *p++, &mbs);
        if (clen == 0 || clen == (size_t)-1 || nbytes + clen > (size_t)prec) break;
        nbytes += clen;
      }
      if (clen == (size_t)-1) return (NULL);
    }
  }
  if ((convbuf = static_cast<char*>(malloc(nbytes + 1))) == NULL) return NULL;

  /* Fill the output buffer. */
  p = wcsarg;
  memset(&mbs, 0, sizeof(mbs));
  if ((nbytes = wcsrtombs(convbuf, (const wchar_t**)&p, nbytes, &mbs)) == (size_t)-1) {
    free(convbuf);
    return (NULL);
  }
  convbuf[nbytes] = '\0';
  return (convbuf);
}

#define DEFPREC 6

#define to_digit(c) ((c) - '0')
#define is_digit(c) ((unsigned)to_digit(c) <= 9)
#define to_char(n) ((CHAR_TYPE)((n) + '0'))

template <typename CharT>
static int exponent(CharT* p0, int exp, int fmtch) {
  CharT* p = p0;
  *p++ = fmtch;
  if (exp < 0) {
    exp = -exp;
    *p++ = '-';
  } else {
    *p++ = '+';
  }

  CharT expbuf[MAXEXPDIG];
  CharT* t = expbuf + MAXEXPDIG;
  if (exp > 9) {
    do {
      *--t = to_char(exp % 10);
    } while ((exp /= 10) > 9);
    *--t = to_char(exp);
    for (; t < expbuf + MAXEXPDIG; *p++ = *t++) /* nothing */;
  } else {
    /*
     * Exponents for decimal floating point conversions
     * (%[eEgG]) must be at least two characters long,
     * whereas exponents for hexadecimal conversions can
     * be only one character long.
     */
    if (fmtch == 'e' || fmtch == 'E') *p++ = '0';
    *p++ = to_char(exp);
  }
  return (p - p0);
}

/*
 * The size of the buffer we use as scratch space for integer
 * conversions, among other things.  Technically, we would need the
 * most space for base 10 conversions with thousands' grouping
 * characters between each pair of digits.  100 bytes is a
 * conservative overestimate even for a 128-bit uintmax_t.
 */
#define BUF 100

#define STATIC_ARG_TBL_SIZE 8 /* Size of static argument table. */

/*
 * Flags used during conversion.
 */
#define ALT 0x0001      /* alternate form */
#define LADJUST 0x0004  /* left adjustment */
#define LONGDBL 0x0008  /* long double */
#define LONGINT 0x0010  /* long integer */
#define LLONGINT 0x0020 /* long long integer */
#define SHORTINT 0x0040 /* short integer */
#define ZEROPAD 0x0080  /* zero (as opposed to blank) pad */
#define FPT 0x0100      /* Floating point number */
#define PTRINT 0x0200   /* (unsigned) ptrdiff_t */
#define SIZEINT 0x0400  /* (signed) size_t */
#define CHARINT 0x0800  /* 8 bit integer */
#define MAXINT 0x1000   /* largest integer size (intmax_t) */

int __vfprintf(FILE* fp, const char* fmt0, __va_list ap) {
  char* fmt;           /* format string */
  int ch;              /* character from fmt */
  int n, n2;           /* handy integers (short term usage) */
  char* cp;            /* handy char pointer (short term usage) */
  struct __siov* iovp; /* for PRINT macro */
  int flags;           /* flags as above */
  int ret;             /* return value accumulator */
  int width;           /* width from format (%8d), or 0 */
  int prec;            /* precision from format; <0 for N/A */
  char sign;           /* sign prefix (' ', '+', '-', or \0) */
  wchar_t wc;
  mbstate_t ps;
  /*
   * We can decompose the printed representation of floating
   * point numbers into several parts, some of which may be empty:
   *
   * [+|-| ] [0x|0X] MMM . NNN [e|E|p|P] [+|-] ZZ
   *    A       B     ---C---      D       E   F
   *
   * A:	'sign' holds this value if present; '\0' otherwise
   * B:	ox[1] holds the 'x' or 'X'; '\0' if not hexadecimal
   * C:	cp points to the string MMMNNN.  Leading and trailing
   *	zeros are not in the string and must be added.
   * D:	expchar holds this character; '\0' if no exponent, e.g. %f
   * F:	at least two digits for decimal, at least one digit for hex
   */
  char* decimal_point = NULL;
  int signflag; /* true if float is negative */
  union {       /* floating point arguments %[aAeEfFgG] */
    double dbl;
    long double ldbl;
  } fparg;
  int expt;                   /* integer value of exponent */
  char expchar;               /* exponent character: [eEpP\0] */
  char* dtoaend;              /* pointer to end of converted digits */
  int expsize;                /* character count for expstr */
  int lead;                   /* sig figs before decimal or group sep */
  int ndig;                   /* actual number of digits returned by dtoa */
  char expstr[MAXEXPDIG + 2]; /* buffer for exponent string: e+ZZZ */
  char* dtoaresult = NULL;

  uintmax_t _umax;             /* integer arguments %[diouxX] */
  enum { OCT, DEC, HEX } base; /* base for %[diouxX] conversion */
  int dprec;                   /* a copy of prec if %[diouxX], 0 otherwise */
  int realsz;                  /* field size expanded by dprec */
  int size;                    /* size of converted field or string */
  const char* xdigs;           /* digits for %[xX] conversion */
#define NIOV 8
  struct __suio uio;       /* output information: summary */
  struct __siov iov[NIOV]; /* ... and individual io vectors */
  char buf[BUF];           /* buffer with space for digits of uintmax_t */
  char ox[2];              /* space for 0x; ox[1] is either x, X, or \0 */
  union arg* argtable;     /* args, built due to positional arg */
  union arg statargtable[STATIC_ARG_TBL_SIZE];
  size_t argtablesiz;
  int nextarg;   /* 1-based argument index */
  va_list orgap; /* original argument pointer */
  char* convbuf; /* buffer for wide to multi-byte conversion */

  /*
   * Choose PADSIZE to trade efficiency vs. size.  If larger printf
   * fields occur frequently, increase PADSIZE and make the initialisers
   * below longer.
   */
#define PADSIZE 16 /* pad chunk size */
  static char blanks[PADSIZE] = { ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
                                  ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ' };
  static char zeroes[PADSIZE] = { '0', '0', '0', '0', '0', '0', '0', '0',
                                  '0', '0', '0', '0', '0', '0', '0', '0' };

  static const char xdigs_lower[] = "0123456789abcdef";
  static const char xdigs_upper[] = "0123456789ABCDEF";

  /*
   * BEWARE, these `goto error' on error, and PAD uses `n'.
   */
#define PRINT(ptr, len)                   \
  do {                                    \
    iovp->iov_base = (ptr);               \
    iovp->iov_len = (len);                \
    uio.uio_resid += (len);               \
    iovp++;                               \
    if (++uio.uio_iovcnt >= NIOV) {       \
      if (__sprint(fp, &uio)) goto error; \
      iovp = iov;                         \
    }                                     \
  } while (0)
#define PAD(howmany, with)     \
  do {                         \
    if ((n = (howmany)) > 0) { \
      while (n > PADSIZE) {    \
        PRINT(with, PADSIZE);  \
        n -= PADSIZE;          \
      }                        \
      PRINT(with, n);          \
    }                          \
  } while (0)
#define PRINTANDPAD(p, ep, len, with)       \
  do {                                      \
    n2 = (ep) - (p);                        \
    if (n2 > (len)) n2 = (len);             \
    if (n2 > 0) PRINT((p), n2);             \
    PAD((len) - (n2 > 0 ? n2 : 0), (with)); \
  } while (0)
#define FLUSH()                                          \
  do {                                                   \
    if (uio.uio_resid && __sprint(fp, &uio)) goto error; \
    uio.uio_iovcnt = 0;                                  \
    iovp = iov;                                          \
  } while (0)

  /*
   * To extend shorts properly, we need both signed and unsigned
   * argument extraction methods.
   */
#define SARG()                                                                               \
  ((intmax_t)(flags & MAXINT                                                                 \
                  ? GETARG(intmax_t)                                                         \
                  : flags & LLONGINT                                                         \
                        ? GETARG(long long)                                                  \
                        : flags & LONGINT                                                    \
                              ? GETARG(long)                                                 \
                              : flags & PTRINT                                               \
                                    ? GETARG(ptrdiff_t)                                      \
                                    : flags & SIZEINT                                        \
                                          ? GETARG(ssize_t)                                  \
                                          : flags & SHORTINT                                 \
                                                ? (short)GETARG(int)                         \
                                                : flags & CHARINT ? (signed char)GETARG(int) \
                                                                  : GETARG(int)))
#define UARG()                                                                                \
  ((uintmax_t)(flags & MAXINT                                                                 \
                   ? GETARG(uintmax_t)                                                        \
                   : flags & LLONGINT                                                         \
                         ? GETARG(unsigned long long)                                         \
                         : flags & LONGINT                                                    \
                               ? GETARG(unsigned long)                                        \
                               : flags & PTRINT ? (uintptr_t)GETARG(ptrdiff_t) : /* XXX */    \
                                     flags & SIZEINT                                          \
                                         ? GETARG(size_t)                                     \
                                         : flags & SHORTINT                                   \
                                               ? (unsigned short)GETARG(int)                  \
                                               : flags & CHARINT ? (unsigned char)GETARG(int) \
                                                                 : GETARG(unsigned int)))

  /*
   * Append a digit to a value and check for overflow.
   */
#define APPEND_DIGIT(val, dig)                            \
  do {                                                    \
    if ((val) > INT_MAX / 10) goto overflow;              \
    (val) *= 10;                                          \
    if ((val) > INT_MAX - to_digit((dig))) goto overflow; \
    (val) += to_digit((dig));                             \
  } while (0)

  /*
   * Get * arguments, including the form *nn$.  Preserve the nextarg
   * that the argument can be gotten once the type is determined.
   */
#define GETASTER(val)                                                     \
  n2 = 0;                                                                 \
  cp = fmt;                                                               \
  while (is_digit(*cp)) {                                                 \
    APPEND_DIGIT(n2, *cp);                                                \
    cp++;                                                                 \
  }                                                                       \
  if (*cp == '$') {                                                       \
    int hold = nextarg;                                                   \
    if (argtable == NULL) {                                               \
      argtable = statargtable;                                            \
      if (__find_arguments(fmt0, orgap, &argtable, &argtablesiz) == -1) { \
        ret = -1;                                                         \
        goto error;                                                       \
      }                                                                   \
    }                                                                     \
    nextarg = n2;                                                         \
    val = GETARG(int);                                                    \
    nextarg = hold;                                                       \
    fmt = ++cp;                                                           \
  } else {                                                                \
    val = GETARG(int);                                                    \
  }

/*
 * Get the argument indexed by nextarg.   If the argument table is
 * built, use it to get the argument.  If its not, get the next
 * argument (and arguments must be gotten sequentially).
 */
#define GETARG(type) \
  ((argtable != NULL) ? *((type*)(&argtable[nextarg++])) : (nextarg++, va_arg(ap, type)))

  _SET_ORIENTATION(fp, -1);
  /* sorry, fprintf(read_only_file, "") returns EOF, not 0 */
  if (cantwrite(fp)) {
    errno = EBADF;
    return (EOF);
  }

  /* optimise fprintf(stderr) (and other unbuffered Unix files) */
  if ((fp->_flags & (__SNBF | __SWR | __SRW)) == (__SNBF | __SWR) && fp->_file >= 0)
    return (__sbprintf(fp, fmt0, ap));

  fmt = (char*)fmt0;
  argtable = NULL;
  nextarg = 1;
  va_copy(orgap, ap);
  uio.uio_iov = iovp = iov;
  uio.uio_resid = 0;
  uio.uio_iovcnt = 0;
  ret = 0;
  convbuf = NULL;

  memset(&ps, 0, sizeof(ps));
  /*
   * Scan the format for conversions (`%' character).
   */
  for (;;) {
    cp = fmt;
    while ((n = mbrtowc(&wc, fmt, MB_CUR_MAX, &ps)) > 0) {
      fmt += n;
      if (wc == '%') {
        fmt--;
        break;
      }
    }
    if (n < 0) {
      ret = -1;
      goto error;
    }
    if (fmt != cp) {
      ptrdiff_t m = fmt - cp;
      if (m < 0 || m > INT_MAX - ret) goto overflow;
      PRINT(cp, m);
      ret += m;
    }
    if (n == 0) goto done;
    fmt++; /* skip over '%' */

    flags = 0;
    dprec = 0;
    width = 0;
    prec = -1;
    sign = '\0';
    ox[1] = '\0';

  rflag:
    ch = *fmt++;
  reswitch:
    switch (ch) {
      case ' ':
        /*
         * ``If the space and + flags both appear, the space
         * flag will be ignored.''
         *	-- ANSI X3J11
         */
        if (!sign) sign = ' ';
        goto rflag;
      case '#':
        flags |= ALT;
        goto rflag;
      case '\'':
        /* grouping not implemented */
        goto rflag;
      case '*':
        /*
         * ``A negative field width argument is taken as a
         * - flag followed by a positive field width.''
         *	-- ANSI X3J11
         * They don't exclude field widths read from args.
         */
        GETASTER(width);
        if (width >= 0) goto rflag;
        if (width == INT_MIN) goto overflow;
        width = -width;
        /* FALLTHROUGH */
      case '-':
        flags |= LADJUST;
        goto rflag;
      case '+':
        sign = '+';
        goto rflag;
      case '.':
        if ((ch = *fmt++) == '*') {
          GETASTER(n);
          prec = n < 0 ? -1 : n;
          goto rflag;
        }
        n = 0;
        while (is_digit(ch)) {
          APPEND_DIGIT(n, ch);
          ch = *fmt++;
        }
        if (ch == '$') {
          nextarg = n;
          if (argtable == NULL) {
            argtable = statargtable;
            if (__find_arguments(fmt0, orgap, &argtable, &argtablesiz) == -1) {
              ret = -1;
              goto error;
            }
          }
          goto rflag;
        }
        prec = n;
        goto reswitch;
      case '0':
        /*
         * ``Note that 0 is taken as a flag, not as the
         * beginning of a field width.''
         *	-- ANSI X3J11
         */
        flags |= ZEROPAD;
        goto rflag;
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
        n = 0;
        do {
          APPEND_DIGIT(n, ch);
          ch = *fmt++;
        } while (is_digit(ch));
        if (ch == '$') {
          nextarg = n;
          if (argtable == NULL) {
            argtable = statargtable;
            if (__find_arguments(fmt0, orgap, &argtable, &argtablesiz) == -1) {
              ret = -1;
              goto error;
            }
          }
          goto rflag;
        }
        width = n;
        goto reswitch;
      case 'L':
        flags |= LONGDBL;
        goto rflag;
      case 'h':
        if (*fmt == 'h') {
          fmt++;
          flags |= CHARINT;
        } else {
          flags |= SHORTINT;
        }
        goto rflag;
      case 'j':
        flags |= MAXINT;
        goto rflag;
      case 'l':
        if (*fmt == 'l') {
          fmt++;
          flags |= LLONGINT;
        } else {
          flags |= LONGINT;
        }
        goto rflag;
      case 'q':
        flags |= LLONGINT;
        goto rflag;
      case 't':
        flags |= PTRINT;
        goto rflag;
      case 'z':
        flags |= SIZEINT;
        goto rflag;
      case 'C':
        flags |= LONGINT;
        /*FALLTHROUGH*/
      case 'c':
        if (flags & LONGINT) {
          mbstate_t mbs;
          size_t mbseqlen;

          memset(&mbs, 0, sizeof(mbs));
          mbseqlen = wcrtomb(buf, (wchar_t)GETARG(wint_t), &mbs);
          if (mbseqlen == (size_t)-1) {
            ret = -1;
            goto error;
          }
          cp = buf;
          size = (int)mbseqlen;
        } else {
          *(cp = buf) = GETARG(int);
          size = 1;
        }
        sign = '\0';
        break;
      case 'D':
        flags |= LONGINT;
        /*FALLTHROUGH*/
      case 'd':
      case 'i':
        _umax = SARG();
        if ((intmax_t)_umax < 0) {
          _umax = -_umax;
          sign = '-';
        }
        base = DEC;
        goto number;
      case 'a':
      case 'A':
        if (ch == 'a') {
          ox[1] = 'x';
          xdigs = xdigs_lower;
          expchar = 'p';
        } else {
          ox[1] = 'X';
          xdigs = xdigs_upper;
          expchar = 'P';
        }
        if (prec >= 0) prec++;
        if (dtoaresult) __freedtoa(dtoaresult);
        if (flags & LONGDBL) {
          fparg.ldbl = GETARG(long double);
          dtoaresult = cp = __hldtoa(fparg.ldbl, xdigs, prec, &expt, &signflag, &dtoaend);
          if (dtoaresult == NULL) {
            errno = ENOMEM;
            goto error;
          }
        } else {
          fparg.dbl = GETARG(double);
          dtoaresult = cp = __hdtoa(fparg.dbl, xdigs, prec, &expt, &signflag, &dtoaend);
          if (dtoaresult == NULL) {
            errno = ENOMEM;
            goto error;
          }
        }
        if (prec < 0) prec = dtoaend - cp;
        if (expt == INT_MAX) ox[1] = '\0';
        goto fp_common;
      case 'e':
      case 'E':
        expchar = ch;
        if (prec < 0) /* account for digit before decpt */
          prec = DEFPREC + 1;
        else
          prec++;
        goto fp_begin;
      case 'f':
      case 'F':
        expchar = '\0';
        goto fp_begin;
      case 'g':
      case 'G':
        expchar = ch - ('g' - 'e');
        if (prec == 0) prec = 1;
      fp_begin:
        if (prec < 0) prec = DEFPREC;
        if (dtoaresult) __freedtoa(dtoaresult);
        if (flags & LONGDBL) {
          fparg.ldbl = GETARG(long double);
          dtoaresult = cp = __ldtoa(&fparg.ldbl, expchar ? 2 : 3, prec, &expt, &signflag, &dtoaend);
          if (dtoaresult == NULL) {
            errno = ENOMEM;
            goto error;
          }
        } else {
          fparg.dbl = GETARG(double);
          dtoaresult = cp = __dtoa(fparg.dbl, expchar ? 2 : 3, prec, &expt, &signflag, &dtoaend);
          if (dtoaresult == NULL) {
            errno = ENOMEM;
            goto error;
          }
          if (expt == 9999) expt = INT_MAX;
        }
      fp_common:
        if (signflag) sign = '-';
        if (expt == INT_MAX) { /* inf or nan */
          if (*cp == 'N') {
            cp = const_cast<char*>((ch >= 'a') ? "nan" : "NAN");
          } else {
            cp = const_cast<char*>((ch >= 'a') ? "inf" : "INF");
          }
          size = 3;
          flags &= ~ZEROPAD;
          break;
        }
        flags |= FPT;
        ndig = dtoaend - cp;
        if (ch == 'g' || ch == 'G') {
          if (expt > -4 && expt <= prec) {
            /* Make %[gG] smell like %[fF] */
            expchar = '\0';
            if (flags & ALT)
              prec -= expt;
            else
              prec = ndig - expt;
            if (prec < 0) prec = 0;
          } else {
            /*
             * Make %[gG] smell like %[eE], but
             * trim trailing zeroes if no # flag.
             */
            if (!(flags & ALT)) prec = ndig;
          }
        }
        if (expchar) {
          expsize = exponent(expstr, expt - 1, expchar);
          size = expsize + prec;
          if (prec > 1 || flags & ALT) ++size;
        } else {
          /* space for digits before decimal point */
          if (expt > 0)
            size = expt;
          else /* "0" */
            size = 1;
          /* space for decimal pt and following digits */
          if (prec || flags & ALT) size += prec + 1;
          lead = expt;
        }
        break;
#ifndef NO_PRINTF_PERCENT_N
      case 'n':
        if (flags & LLONGINT)
          *GETARG(long long*) = ret;
        else if (flags & LONGINT)
          *GETARG(long*) = ret;
        else if (flags & SHORTINT)
          *GETARG(short*) = ret;
        else if (flags & CHARINT)
          *GETARG(signed char*) = ret;
        else if (flags & PTRINT)
          *GETARG(ptrdiff_t*) = ret;
        else if (flags & SIZEINT)
          *GETARG(ssize_t*) = ret;
        else if (flags & MAXINT)
          *GETARG(intmax_t*) = ret;
        else
          *GETARG(int*) = ret;
        continue; /* no output */
#endif            /* NO_PRINTF_PERCENT_N */
      case 'O':
        flags |= LONGINT;
        /*FALLTHROUGH*/
      case 'o':
        _umax = UARG();
        base = OCT;
        goto nosign;
      case 'p':
        /*
         * ``The argument shall be a pointer to void.  The
         * value of the pointer is converted to a sequence
         * of printable characters, in an implementation-
         * defined manner.''
         *	-- ANSI X3J11
         */
        _umax = (u_long)GETARG(void*);
        base = HEX;
        xdigs = xdigs_lower;
        ox[1] = 'x';
        goto nosign;
      case 'S':
        flags |= LONGINT;
        /*FALLTHROUGH*/
      case 's':
        if (flags & LONGINT) {
          wchar_t* wcp;

          free(convbuf);
          convbuf = NULL;
          if ((wcp = GETARG(wchar_t*)) == NULL) {
            cp = const_cast<char*>("(null)");
          } else {
            convbuf = __wcsconv(wcp, prec);
            if (convbuf == NULL) {
              ret = -1;
              goto error;
            }
            cp = convbuf;
          }
        } else if ((cp = GETARG(char*)) == NULL) {
          cp = const_cast<char*>("(null)");
        }
        if (prec >= 0) {
          size = strnlen(cp, prec);
        } else {
          size_t len;

          if ((len = strlen(cp)) > INT_MAX) goto overflow;
          size = (int)len;
        }
        sign = '\0';
        break;
      case 'U':
        flags |= LONGINT;
        /*FALLTHROUGH*/
      case 'u':
        _umax = UARG();
        base = DEC;
        goto nosign;
      case 'X':
        xdigs = xdigs_upper;
        goto hex;
      case 'x':
        xdigs = xdigs_lower;
      hex:
        _umax = UARG();
        base = HEX;
        /* leading 0x/X only if non-zero */
        if (flags & ALT && _umax != 0) ox[1] = ch;

        /* unsigned conversions */
      nosign:
        sign = '\0';
        /*
         * ``... diouXx conversions ... if a precision is
         * specified, the 0 flag will be ignored.''
         *	-- ANSI X3J11
         */
      number:
        if ((dprec = prec) >= 0) flags &= ~ZEROPAD;

        /*
         * ``The result of converting a zero value with an
         * explicit precision of zero is no characters.''
         *	-- ANSI X3J11
         */
        cp = buf + BUF;
        if (_umax != 0 || prec != 0) {
          /*
           * Unsigned mod is hard, and unsigned mod
           * by a constant is easier than that by
           * a variable; hence this switch.
           */
          switch (base) {
            case OCT:
              do {
                *--cp = to_char(_umax & 7);
                _umax >>= 3;
              } while (_umax);
              /* handle octal leading 0 */
              if (flags & ALT && *cp != '0') *--cp = '0';
              break;

            case DEC:
              /* many numbers are 1 digit */
              while (_umax >= 10) {
                *--cp = to_char(_umax % 10);
                _umax /= 10;
              }
              *--cp = to_char(_umax);
              break;

            case HEX:
              do {
                *--cp = xdigs[_umax & 15];
                _umax >>= 4;
              } while (_umax);
              break;

            default:
              abort();
          }
        }
        size = buf + BUF - cp;
        if (size > BUF) abort(); /* should never happen */
        break;
      default: /* "%?" prints ?, unless ? is NUL */
        if (ch == '\0') goto done;
        /* pretend it was %c with argument ch */
        cp = buf;
        *cp = ch;
        size = 1;
        sign = '\0';
        break;
    }

    /*
     * All reasonable formats wind up here.  At this point, `cp'
     * points to a string which (if not flags&LADJUST) should be
     * padded out to `width' places.  If flags&ZEROPAD, it should
     * first be prefixed by any sign or other prefix; otherwise,
     * it should be blank padded before the prefix is emitted.
     * After any left-hand padding and prefixing, emit zeroes
     * required by a decimal %[diouxX] precision, then print the
     * string proper, then emit zeroes required by any leftover
     * floating precision; finally, if LADJUST, pad with blanks.
     *
     * Compute actual size, so we know how much to pad.
     * size excludes decimal prec; realsz includes it.
     */
    realsz = dprec > size ? dprec : size;
    if (sign) realsz++;
    if (ox[1]) realsz += 2;

    /* right-adjusting blank padding */
    if ((flags & (LADJUST | ZEROPAD)) == 0) PAD(width - realsz, blanks);

    /* prefix */
    if (sign) PRINT(&sign, 1);
    if (ox[1]) { /* ox[1] is either x, X, or \0 */
      ox[0] = '0';
      PRINT(ox, 2);
    }

    /* right-adjusting zero padding */
    if ((flags & (LADJUST | ZEROPAD)) == ZEROPAD) PAD(width - realsz, zeroes);

    /* leading zeroes from decimal precision */
    PAD(dprec - size, zeroes);

    /* the string or number proper */
    if ((flags & FPT) == 0) {
      PRINT(cp, size);
    } else { /* glue together f_p fragments */
      if (decimal_point == NULL) decimal_point = nl_langinfo(RADIXCHAR);
      if (!expchar) { /* %[fF] or sufficiently short %[gG] */
        if (expt <= 0) {
          PRINT(zeroes, 1);
          if (prec || flags & ALT) PRINT(decimal_point, 1);
          PAD(-expt, zeroes);
          /* already handled initial 0's */
          prec += expt;
        } else {
          PRINTANDPAD(cp, dtoaend, lead, zeroes);
          cp += lead;
          if (prec || flags & ALT) PRINT(decimal_point, 1);
        }
        PRINTANDPAD(cp, dtoaend, prec, zeroes);
      } else { /* %[eE] or sufficiently long %[gG] */
        if (prec > 1 || flags & ALT) {
          buf[0] = *cp++;
          buf[1] = *decimal_point;
          PRINT(buf, 2);
          PRINT(cp, ndig - 1);
          PAD(prec - ndig, zeroes);
        } else { /* XeYYY */
          PRINT(cp, 1);
        }
        PRINT(expstr, expsize);
      }
    }
    /* left-adjusting padding (always blank) */
    if (flags & LADJUST) PAD(width - realsz, blanks);

    /* finally, adjust ret */
    if (width < realsz) width = realsz;
    if (width > INT_MAX - ret) goto overflow;
    ret += width;

    FLUSH(); /* copy out the I/O vectors */
  }
done:
  FLUSH();
error:
  va_end(orgap);
  if (__sferror(fp)) ret = -1;
  goto finish;

overflow:
  errno = ENOMEM;
  ret = -1;

finish:
  free(convbuf);
  if (dtoaresult) __freedtoa(dtoaresult);
  if (argtable != NULL && argtable != statargtable) {
    munmap(argtable, argtablesiz);
    argtable = NULL;
  }
  return (ret);
}

/*
 * Type ids for argument type table.
 */
#define T_UNUSED 0
#define T_SHORT 1
#define T_U_SHORT 2
#define TP_SHORT 3
#define T_INT 4
#define T_U_INT 5
#define TP_INT 6
#define T_LONG 7
#define T_U_LONG 8
#define TP_LONG 9
#define T_LLONG 10
#define T_U_LLONG 11
#define TP_LLONG 12
#define T_DOUBLE 13
#define T_LONG_DOUBLE 14
#define TP_CHAR 15
#define TP_VOID 16
#define T_PTRINT 17
#define TP_PTRINT 18
#define T_SIZEINT 19
#define T_SSIZEINT 20
#define TP_SSIZEINT 21
#define T_MAXINT 22
#define T_MAXUINT 23
#define TP_MAXINT 24
#define T_CHAR 25
#define T_U_CHAR 26
#define T_WINT 27
#define TP_WCHAR 28

/*
 * Find all arguments when a positional parameter is encountered.  Returns a
 * table, indexed by argument number, of pointers to each arguments.  The
 * initial argument table should be an array of STATIC_ARG_TBL_SIZE entries.
 * It will be replaced with a mmap-ed one if it overflows (malloc cannot be
 * used since we are attempting to make snprintf thread safe, and alloca is
 * problematic since we have nested functions..)
 */
static int __find_arguments(const char* fmt0, va_list ap, union arg** argtable,
                            size_t* argtablesiz) {
  char* fmt;                /* format string */
  int ch;                   /* character from fmt */
  int n, n2;                /* handy integer (short term usage) */
  char* cp;                 /* handy char pointer (short term usage) */
  int flags;                /* flags as above */
  unsigned char* typetable; /* table of types */
  unsigned char stattypetable[STATIC_ARG_TBL_SIZE];
  int tablesize; /* current size of type table */
  int tablemax;  /* largest used index in table */
  int nextarg;   /* 1-based argument index */
  int ret = 0;   /* return value */
  wchar_t wc;
  mbstate_t ps;

  /*
   * Add an argument type to the table, expanding if necessary.
   */
#define ADDTYPE(type)                                                      \
  ((nextarg >= tablesize) ? __grow_type_table(&typetable, &tablesize) : 0, \
   (nextarg > tablemax) ? tablemax = nextarg : 0, typetable[nextarg++] = type)

#define ADDSARG()                                                                             \
  ((flags & MAXINT)                                                                           \
       ? ADDTYPE(T_MAXINT)                                                                    \
       : ((flags & PTRINT) ? ADDTYPE(T_PTRINT)                                                \
                           : ((flags & SIZEINT)                                               \
                                  ? ADDTYPE(T_SSIZEINT)                                       \
                                  : ((flags & LLONGINT)                                       \
                                         ? ADDTYPE(T_LLONG)                                   \
                                         : ((flags & LONGINT)                                 \
                                                ? ADDTYPE(T_LONG)                             \
                                                : ((flags & SHORTINT)                         \
                                                       ? ADDTYPE(T_SHORT)                     \
                                                       : ((flags & CHARINT) ? ADDTYPE(T_CHAR) \
                                                                            : ADDTYPE(T_INT))))))))

#define ADDUARG()                                                                  \
  ((flags & MAXINT)                                                                \
       ? ADDTYPE(T_MAXUINT)                                                        \
       : ((flags & PTRINT)                                                         \
              ? ADDTYPE(T_PTRINT)                                                  \
              : ((flags & SIZEINT)                                                 \
                     ? ADDTYPE(T_SIZEINT)                                          \
                     : ((flags & LLONGINT)                                         \
                            ? ADDTYPE(T_U_LLONG)                                   \
                            : ((flags & LONGINT)                                   \
                                   ? ADDTYPE(T_U_LONG)                             \
                                   : ((flags & SHORTINT)                           \
                                          ? ADDTYPE(T_U_SHORT)                     \
                                          : ((flags & CHARINT) ? ADDTYPE(T_U_CHAR) \
                                                               : ADDTYPE(T_U_INT))))))))

  /*
   * Add * arguments to the type array.
   */
#define ADDASTER()         \
  n2 = 0;                  \
  cp = fmt;                \
  while (is_digit(*cp)) {  \
    APPEND_DIGIT(n2, *cp); \
    cp++;                  \
  }                        \
  if (*cp == '$') {        \
    int hold = nextarg;    \
    nextarg = n2;          \
    ADDTYPE(T_INT);        \
    nextarg = hold;        \
    fmt = ++cp;            \
  } else {                 \
    ADDTYPE(T_INT);        \
  }
  fmt = (char*)fmt0;
  typetable = stattypetable;
  tablesize = STATIC_ARG_TBL_SIZE;
  tablemax = 0;
  nextarg = 1;
  memset(typetable, T_UNUSED, STATIC_ARG_TBL_SIZE);
  memset(&ps, 0, sizeof(ps));

  /*
   * Scan the format for conversions (`%' character).
   */
  for (;;) {
    cp = fmt;
    while ((n = mbrtowc(&wc, fmt, MB_CUR_MAX, &ps)) > 0) {
      fmt += n;
      if (wc == '%') {
        fmt--;
        break;
      }
    }
    if (n < 0) return (-1);
    if (n == 0) goto done;
    fmt++; /* skip over '%' */

    flags = 0;

  rflag:
    ch = *fmt++;
  reswitch:
    switch (ch) {
      case ' ':
      case '#':
      case '\'':
        goto rflag;
      case '*':
        ADDASTER();
        goto rflag;
      case '-':
      case '+':
        goto rflag;
      case '.':
        if ((ch = *fmt++) == '*') {
          ADDASTER();
          goto rflag;
        }
        while (is_digit(ch)) {
          ch = *fmt++;
        }
        goto reswitch;
      case '0':
        goto rflag;
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
        n = 0;
        do {
          APPEND_DIGIT(n, ch);
          ch = *fmt++;
        } while (is_digit(ch));
        if (ch == '$') {
          nextarg = n;
          goto rflag;
        }
        goto reswitch;
      case 'L':
        flags |= LONGDBL;
        goto rflag;
      case 'h':
        if (*fmt == 'h') {
          fmt++;
          flags |= CHARINT;
        } else {
          flags |= SHORTINT;
        }
        goto rflag;
      case 'j':
        flags |= MAXINT;
        goto rflag;
      case 'l':
        if (*fmt == 'l') {
          fmt++;
          flags |= LLONGINT;
        } else {
          flags |= LONGINT;
        }
        goto rflag;
      case 'q':
        flags |= LLONGINT;
        goto rflag;
      case 't':
        flags |= PTRINT;
        goto rflag;
      case 'z':
        flags |= SIZEINT;
        goto rflag;
      case 'C':
        flags |= LONGINT;
        /*FALLTHROUGH*/
      case 'c':
        if (flags & LONGINT)
          ADDTYPE(T_WINT);
        else
          ADDTYPE(T_INT);
        break;
      case 'D':
        flags |= LONGINT;
        /*FALLTHROUGH*/
      case 'd':
      case 'i':
        ADDSARG();
        break;
      case 'a':
      case 'A':
      case 'e':
      case 'E':
      case 'f':
      case 'F':
      case 'g':
      case 'G':
        if (flags & LONGDBL)
          ADDTYPE(T_LONG_DOUBLE);
        else
          ADDTYPE(T_DOUBLE);
        break;
#ifndef NO_PRINTF_PERCENT_N
      case 'n':
        if (flags & LLONGINT)
          ADDTYPE(TP_LLONG);
        else if (flags & LONGINT)
          ADDTYPE(TP_LONG);
        else if (flags & SHORTINT)
          ADDTYPE(TP_SHORT);
        else if (flags & PTRINT)
          ADDTYPE(TP_PTRINT);
        else if (flags & SIZEINT)
          ADDTYPE(TP_SSIZEINT);
        else if (flags & MAXINT)
          ADDTYPE(TP_MAXINT);
        else
          ADDTYPE(TP_INT);
        continue; /* no output */
#endif            /* NO_PRINTF_PERCENT_N */
      case 'O':
        flags |= LONGINT;
        /*FALLTHROUGH*/
      case 'o':
        ADDUARG();
        break;
      case 'p':
        ADDTYPE(TP_VOID);
        break;
      case 'S':
        flags |= LONGINT;
        /*FALLTHROUGH*/
      case 's':
        if (flags & LONGINT)
          ADDTYPE(TP_WCHAR);
        else
          ADDTYPE(TP_CHAR);
        break;
      case 'U':
        flags |= LONGINT;
        /*FALLTHROUGH*/
      case 'u':
      case 'X':
      case 'x':
        ADDUARG();
        break;
      default: /* "%?" prints ?, unless ? is NUL */
        if (ch == '\0') goto done;
        break;
    }
  }
done:
  /*
   * Build the argument table.
   */
  if (tablemax >= STATIC_ARG_TBL_SIZE) {
    *argtablesiz = sizeof(union arg) * (tablemax + 1);
    *argtable = static_cast<arg*>(mmap(NULL, *argtablesiz,
                                       PROT_WRITE | PROT_READ,
                                       MAP_ANON | MAP_PRIVATE, -1, 0));
    if (*argtable == MAP_FAILED) return -1;
  }

#if 0
	/* XXX is this required? */
	(*argtable)[0].intarg = 0;
#endif
  for (n = 1; n <= tablemax; n++) {
    switch (typetable[n]) {
      case T_UNUSED:
      case T_CHAR:
      case T_U_CHAR:
      case T_SHORT:
      case T_U_SHORT:
      case T_INT:
        (*argtable)[n].intarg = va_arg(ap, int);
        break;
      case TP_SHORT:
        (*argtable)[n].pshortarg = va_arg(ap, short*);
        break;
      case T_U_INT:
        (*argtable)[n].uintarg = va_arg(ap, unsigned int);
        break;
      case TP_INT:
        (*argtable)[n].pintarg = va_arg(ap, int*);
        break;
      case T_LONG:
        (*argtable)[n].longarg = va_arg(ap, long);
        break;
      case T_U_LONG:
        (*argtable)[n].ulongarg = va_arg(ap, unsigned long);
        break;
      case TP_LONG:
        (*argtable)[n].plongarg = va_arg(ap, long*);
        break;
      case T_LLONG:
        (*argtable)[n].longlongarg = va_arg(ap, long long);
        break;
      case T_U_LLONG:
        (*argtable)[n].ulonglongarg = va_arg(ap, unsigned long long);
        break;
      case TP_LLONG:
        (*argtable)[n].plonglongarg = va_arg(ap, long long*);
        break;
      case T_DOUBLE:
        (*argtable)[n].doublearg = va_arg(ap, double);
        break;
      case T_LONG_DOUBLE:
        (*argtable)[n].longdoublearg = va_arg(ap, long double);
        break;
      case TP_CHAR:
        (*argtable)[n].pchararg = va_arg(ap, char*);
        break;
      case TP_VOID:
        (*argtable)[n].pvoidarg = va_arg(ap, void*);
        break;
      case T_PTRINT:
        (*argtable)[n].ptrdiffarg = va_arg(ap, ptrdiff_t);
        break;
      case TP_PTRINT:
        (*argtable)[n].pptrdiffarg = va_arg(ap, ptrdiff_t*);
        break;
      case T_SIZEINT:
        (*argtable)[n].sizearg = va_arg(ap, size_t);
        break;
      case T_SSIZEINT:
        (*argtable)[n].ssizearg = va_arg(ap, ssize_t);
        break;
      case TP_SSIZEINT:
        (*argtable)[n].pssizearg = va_arg(ap, ssize_t*);
        break;
      case T_MAXINT:
        (*argtable)[n].intmaxarg = va_arg(ap, intmax_t);
        break;
      case T_MAXUINT:
        (*argtable)[n].uintmaxarg = va_arg(ap, uintmax_t);
        break;
      case TP_MAXINT:
        (*argtable)[n].pintmaxarg = va_arg(ap, intmax_t*);
        break;
      case T_WINT:
        (*argtable)[n].wintarg = va_arg(ap, wint_t);
        break;
      case TP_WCHAR:
        (*argtable)[n].pwchararg = va_arg(ap, wchar_t*);
        break;
    }
  }
  goto finish;

overflow:
  errno = ENOMEM;
  ret = -1;

finish:
  if (typetable != NULL && typetable != stattypetable) {
    munmap(typetable, *argtablesiz);
    typetable = NULL;
  }
  return (ret);
}

/*
 * Increase the size of the type table.
 */
static int __grow_type_table(unsigned char** typetable, int* tablesize) {
  unsigned char* old_table = *typetable;
  int new_size = *tablesize * 2;

  if (new_size < getpagesize()) new_size = getpagesize();

  if (*tablesize == STATIC_ARG_TBL_SIZE) {
    *typetable = static_cast<unsigned char*>(mmap(NULL, new_size,
                                                  PROT_WRITE | PROT_READ,
                                                  MAP_ANON | MAP_PRIVATE, -1, 0));
    if (*typetable == MAP_FAILED) return -1;
    bcopy(old_table, *typetable, *tablesize);
  } else {
    unsigned char* new_table = static_cast<unsigned char*>(mmap(NULL, new_size,
                                                                PROT_WRITE | PROT_READ,
                                                                MAP_ANON | MAP_PRIVATE, -1, 0));
    if (new_table == MAP_FAILED) return -1;
    memmove(new_table, *typetable, *tablesize);
    munmap(*typetable, *tablesize);
    *typetable = new_table;
  }
  memset(*typetable + *tablesize, T_UNUSED, (new_size - *tablesize));

  *tablesize = new_size;
  return 0;
}