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/*

 * snprintf.c - a portable implementation of snprintf

 *

 * AUTHOR

 *   Mark Martinec , April 1999.

 *

 *   Copyright 1999, Mark Martinec. All rights reserved.

 *

 * TERMS AND CONDITIONS

 *   This program is free software; you can redistribute it and/or modify

 *   it under the terms of the "Frontier Artistic License" which comes

 *   with this Kit.

 *

 *   This program is distributed in the hope that it will be useful,

 *   but WITHOUT ANY WARRANTY; without even the implied warranty

 *   of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

 *   See the Frontier Artistic License for more details.

 *

 *   You should have received a copy of the Frontier Artistic License

 *   with this Kit in the file named LICENSE.txt .

 *   If not, I'll be glad to provide one.

 *

 * FEATURES

 * - careful adherence to specs regarding flags, field width and precision;

 * - good performance for large string handling (large format, large

 *   argument or large paddings). Performance is similar to system's sprintf

 *   and in several cases significantly better (make sure you compile with

 *   optimizations turned on, tell the compiler the code is strict ANSI

 *   if necessary to give it more freedom for optimizations);

 * - return value semantics per ISO/IEC 9899:1999 ("ISO C99");

 * - written in standard ISO/ANSI C - requires an ANSI C compiler.

 *

 * SUPPORTED CONVERSION SPECIFIERS AND DATA TYPES

 *

 * This snprintf only supports the following conversion specifiers:

 * s, c, d, u, o, x, X, p  (and synonyms: i, D, U, O - see below)

 * with flags: '-', '+', ' ', '0' and '#'.

 * An asterisk is supported for field width as well as precision.

 *

 * Length modifiers 'h' (short int), 'l' (long int),

 * and 'll' (long long int) are supported.

 * NOTE:

 *   If macro SNPRINTF_LONGLONG_SUPPORT is not defined (default) the

 *   length modifier 'll' is recognized but treated the same as 'l',

 *   which may cause argument value truncation! Defining

 *   SNPRINTF_LONGLONG_SUPPORT requires that your system's sprintf also

 *   handles length modifier 'll'.  long long int is a language extension

 *   which may not be portable.

 *

 * Conversion of numeric data (conversion specifiers d, u, o, x, X, p)

 * with length modifiers (none or h, l, ll) is left to the system routine

 * sprintf, but all handling of flags, field width and precision as well as

 * c and s conversions is done very carefully by this portable routine.

 * If a string precision (truncation) is specified (e.g. %.8s) it is

 * guaranteed the string beyond the specified precision will not be referenced.

 *

 * Length modifiers h, l and ll are ignored for c and s conversions (data

 * types wint_t and wchar_t are not supported).

 *

 * The following common synonyms for conversion characters are supported:

 *   - i is a synonym for d

 *   - D is a synonym for ld, explicit length modifiers are ignored

 *   - U is a synonym for lu, explicit length modifiers are ignored

 *   - O is a synonym for lo, explicit length modifiers are ignored

 * The D, O and U conversion characters are nonstandard, they are supported

 * for backward compatibility only, and should not be used for new code.

 *

 * The following is specifically NOT supported:

 *   - flag ' (thousands' grouping character) is recognized but ignored

 *   - numeric conversion specifiers: f, e, E, g, G and synonym F,

 *     as well as the new a and A conversion specifiers

 *   - length modifier 'L' (long double) and 'q' (quad - use 'll' instead)

 *   - wide character/string conversions: lc, ls, and nonstandard

 *     synonyms C and S

 *   - writeback of converted string length: conversion character n

 *   - the n$ specification for direct reference to n-th argument

 *   - locales

 *

 * It is permitted for str_m to be zero, and it is permitted to specify NULL

 * pointer for resulting string argument if str_m is zero (as per ISO C99).

 *

 * The return value is the number of characters which would be generated

 * for the given input, excluding the trailing null. If this value

 * is greater or equal to str_m, not all characters from the result

 * have been stored in str, output bytes beyond the (str_m-1) -th character

 * are discarded. If str_m is greater than zero it is guaranteed

 * the resulting string will be null-terminated.

 *

 * NOTE that this matches the ISO C99, OpenBSD, and GNU C library 2.1,

 * but is different from some older and vendor implementations,

 * and is also different from XPG, XSH5, SUSv2 specifications.

 * For historical discussion on changes in the semantics and standards

 * of snprintf see printf(3) man page in the Linux programmers manual.

 *

 * Routines asprintf and vasprintf return a pointer (in the ptr argument)

 * to a buffer sufficiently large to hold the resulting string. This pointer

 * should be passed to free(3) to release the allocated storage when it is

 * no longer needed. If sufficient space cannot be allocated, these functions

 * will return -1 and set ptr to be a NULL pointer. These two routines are a

 * GNU C library extensions (glibc).

 *

 * Routines asnprintf and vasnprintf are similar to asprintf and vasprintf,

 * yet, like snprintf and vsnprintf counterparts, will write at most str_m-1

 * characters into the allocated output string, the last character in the

 * allocated buffer then gets the terminating null. If the formatted string

 * length (the return value) is greater than or equal to the str_m argument,

 * the resulting string was truncated and some of the formatted characters

 * were discarded. These routines present a handy way to limit the amount

 * of allocated memory to some sane value.

 *

 * AVAILABILITY

 *   http://www.ijs.si/software/snprintf/

 *

 * REVISION HISTORY

 * 1999-04	V0.9  Mark Martinec

 *		- initial version, some modifications after comparing printf

 *		  man pages for Digital Unix 4.0, Solaris 2.6 and HPUX 10,

 *		  and checking how Perl handles sprintf (differently!);

 * 1999-04-09	V1.0  Mark Martinec 

 *		- added main test program, fixed remaining inconsistencies,

 *		  added optional (long long int) support;

 * 1999-04-12	V1.1  Mark Martinec 

 *		- support the 'p' conversion (pointer to void);

 *		- if a string precision is specified

 *		  make sure the string beyond the specified precision

 *		  will not be referenced (e.g. by strlen);

 * 1999-04-13	V1.2  Mark Martinec 

 *		- support synonyms %D=%ld, %U=%lu, %O=%lo;

 *		- speed up the case of long format string with few conversions;

 * 1999-06-30	V1.3  Mark Martinec 

 *		- fixed runaway loop (eventually crashing when str_l wraps

 *		  beyond 2^31) while copying format string without

 *		  conversion specifiers to a buffer that is too short

 *		  (thanks to Edwin Young  for

 *		  spotting the problem);

 *		- added macros PORTABLE_SNPRINTF_VERSION_(MAJOR|MINOR)

 *		  to snprintf.h

 * 2000-02-14	V2.0 (never released) Mark Martinec 

 *		- relaxed license terms: The Artistic License now applies.

 *		  You may still apply the GNU GENERAL PUBLIC LICENSE

 *		  as was distributed with previous versions, if you prefer;

 *		- changed REVISION HISTORY dates to use ISO 8601 date format;

 *		- added vsnprintf (patch also independently proposed by

 *		  Caolan McNamara 2000-05-04, and Keith M Willenson 2000-06-01)

 * 2000-06-27	V2.1  Mark Martinec 

 *		- removed POSIX check for str_m<1; value 0 for str_m is

 *		  allowed by ISO C99 (and GNU C library 2.1) - (pointed out

 *		  on 2000-05-04 by Caolan McNamara, caolan@ csn dot ul dot ie).

 *		  Besides relaxed license this change in standards adherence

 *		  is the main reason to bump up the major version number;

 *		- added nonstandard routines asnprintf, vasnprintf, asprintf,

 *		  vasprintf that dynamically allocate storage for the

 *		  resulting string; these routines are not compiled by default,

 *		  see comments where NEED_V?ASN?PRINTF macros are defined;

 *		- autoconf contributed by Caolan McNamara

 * 2000-10-06	V2.2  Mark Martinec 

 *		- BUG FIX: the %c conversion used a temporary variable

 *		  that was no longer in scope when referenced,

 *		  possibly causing incorrect resulting character;

 *		- BUG FIX: make precision and minimal field width unsigned

 *		  to handle huge values (2^31 <= n < 2^32) correctly;

 *		  also be more careful in the use of signed/unsigned/size_t

 *		  internal variables - probably more careful than many

 *		  vendor implementations, but there may still be a case

 *		  where huge values of str_m, precision or minimal field

 *		  could cause incorrect behaviour;

 *		- use separate variables for signed/unsigned arguments,

 *		  and for short/int, long, and long long argument lengths

 *		  to avoid possible incompatibilities on certain

 *		  computer architectures. Also use separate variable

 *		  arg_sign to hold sign of a numeric argument,

 *		  to make code more transparent;

 *		- some fiddling with zero padding and "0x" to make it

 *		  Linux compatible;

 *		- systematically use macros fast_memcpy and fast_memset

 *		  instead of case-by-case hand optimization; determine some

 *		  breakeven string lengths for different architectures;

 *		- terminology change: 'format' -> 'conversion specifier',

 *		  'C9x' -> 'ISO/IEC 9899:1999 ("ISO C99")',

 *		  'alternative form' -> 'alternate form',

 *		  'data type modifier' -> 'length modifier';

 *		- several comments rephrased and new ones added;

 *		- make compiler not complain about 'credits' defined but

 *		  not used;

 */

/* Define HAVE_SNPRINTF if your system already has snprintf and vsnprintf.

 *

 * If HAVE_SNPRINTF is defined this module will not produce code for

 * snprintf and vsnprintf, unless PREFER_PORTABLE_SNPRINTF is defined as well,

 * causing this portable version of snprintf to be called portable_snprintf

 * (and portable_vsnprintf).

 */

/* #define HAVE_SNPRINTF */

/* Define PREFER_PORTABLE_SNPRINTF if your system does have snprintf and

 * vsnprintf but you would prefer to use the portable routine(s) instead.

 * In this case the portable routine is declared as portable_snprintf

 * (and portable_vsnprintf) and a macro 'snprintf' (and 'vsnprintf')

 * is defined to expand to 'portable_v?snprintf' - see file snprintf.h .

 * Defining this macro is only useful if HAVE_SNPRINTF is also defined,

 * but does does no harm if defined nevertheless.

 */

/* #define PREFER_PORTABLE_SNPRINTF */

/* Define SNPRINTF_LONGLONG_SUPPORT if you want to support

 * data type (long long int) and length modifier 'll' (e.g. %lld).

 * If undefined, 'll' is recognized but treated as a single 'l'.

 *

 * If the system's sprintf does not handle 'll'

 * the SNPRINTF_LONGLONG_SUPPORT must not be defined!

 *

 * This is off by default as (long long int) is a language extension.

 */

/* #define SNPRINTF_LONGLONG_SUPPORT */

/* Define NEED_SNPRINTF_ONLY if you only need snprintf, and not vsnprintf.

 * If NEED_SNPRINTF_ONLY is defined, the snprintf will be defined directly,

 * otherwise both snprintf and vsnprintf routines will be defined

 * and snprintf will be a simple wrapper around vsnprintf, at the expense

 * of an extra procedure call.

 */

/* #define NEED_SNPRINTF_ONLY */

/* Define NEED_V?ASN?PRINTF macros if you need library extension

 * routines asprintf, vasprintf, asnprintf, vasnprintf respectively,

 * and your system library does not provide them. They are all small

 * wrapper routines around portable_vsnprintf. Defining any of the four

 * NEED_V?ASN?PRINTF macros automatically turns off NEED_SNPRINTF_ONLY

 * and turns on PREFER_PORTABLE_SNPRINTF.

 *

 * Watch for name conflicts with the system library if these routines

 * are already present there.

 *

 * NOTE: vasprintf and vasnprintf routines need va_copy() from stdarg.h, as

 * specified by C99, to be able to traverse the same list of arguments twice.

 * I don't know of any other standard and portable way of achieving the same.

 * With some versions of gcc you may use __va_copy(). You might even get away

 * with "ap2 = ap", in this case you must not call va_end(ap2) !

 *   #define va_copy(ap2,ap) ap2 = ap

 */

/* #define NEED_ASPRINTF   */

/* #define NEED_ASNPRINTF  */

/* #define NEED_VASPRINTF  */

/* #define NEED_VASNPRINTF */

/* Define the following macros if desired:

 *   SOLARIS_COMPATIBLE, SOLARIS_BUG_COMPATIBLE,

 *   HPUX_COMPATIBLE, HPUX_BUG_COMPATIBLE, LINUX_COMPATIBLE,

 *   DIGITAL_UNIX_COMPATIBLE, DIGITAL_UNIX_BUG_COMPATIBLE,

 *   PERL_COMPATIBLE, PERL_BUG_COMPATIBLE,

 *

 * - For portable applications it is best not to rely on peculiarities

 *   of a given implementation so it may be best not to define any

 *   of the macros that select compatibility and to avoid features

 *   that vary among the systems.

 *

 * - Selecting compatibility with more than one operating system

 *   is not strictly forbidden but is not recommended.

 *

 * - 'x'_BUG_COMPATIBLE implies 'x'_COMPATIBLE .

 *

 * - 'x'_COMPATIBLE refers to (and enables) a behaviour that is

 *   documented in a sprintf man page on a given operating system

 *   and actually adhered to by the system's sprintf (but not on

 *   most other operating systems). It may also refer to and enable

 *   a behaviour that is declared 'undefined' or 'implementation specific'

 *   in the man page but a given implementation behaves predictably

 *   in a certain way.

 *

 * - 'x'_BUG_COMPATIBLE refers to (and enables) a behaviour of system's sprintf

 *   that contradicts the sprintf man page on the same operating system.

 *

 * - I do not claim that the 'x'_COMPATIBLE and 'x'_BUG_COMPATIBLE

 *   conditionals take into account all idiosyncrasies of a particular

 *   implementation, there may be other incompatibilities.

 */

/* ============================================= */

/* NO USER SERVICABLE PARTS FOLLOWING THIS POINT */

/* ============================================= */

#define PORTABLE_SNPRINTF_VERSION_MAJOR 2

#define PORTABLE_SNPRINTF_VERSION_MINOR 2

#if defined(NEED_ASPRINTF) || defined(NEED_ASNPRINTF) || defined(NEED_VASPRINTF) || defined(NEED_VASNPRINTF)

# if defined(NEED_SNPRINTF_ONLY)

# undef NEED_SNPRINTF_ONLY

# endif

# if !defined(PREFER_PORTABLE_SNPRINTF)

# define PREFER_PORTABLE_SNPRINTF

# endif

#endif

#if defined(SOLARIS_BUG_COMPATIBLE) && !defined(SOLARIS_COMPATIBLE)

#define SOLARIS_COMPATIBLE

#endif

#if defined(HPUX_BUG_COMPATIBLE) && !defined(HPUX_COMPATIBLE)

#define HPUX_COMPATIBLE

#endif

#if defined(DIGITAL_UNIX_BUG_COMPATIBLE) && !defined(DIGITAL_UNIX_COMPATIBLE)

#define DIGITAL_UNIX_COMPATIBLE

#endif

#if defined(PERL_BUG_COMPATIBLE) && !defined(PERL_COMPATIBLE)

#define PERL_COMPATIBLE

#endif

#if defined(LINUX_BUG_COMPATIBLE) && !defined(LINUX_COMPATIBLE)

#define LINUX_COMPATIBLE

#endif

#include 

#include 

#include 

#include 

#include 

#include 

#include 

#ifdef isdigit

#undef isdigit

#endif

#define isdigit(c) ((c) >= '0' && (c) <= '9')

/* For copying strings longer or equal to 'breakeven_point'

 * it is more efficient to call memcpy() than to do it inline.

 * The value depends mostly on the processor architecture,

 * but also on the compiler and its optimization capabilities.

 * The value is not critical, some small value greater than zero

 * will be just fine if you don't care to squeeze every drop

 * of performance out of the code.

 *

 * Small values favor memcpy, large values favor inline code.

 */

#if defined(__alpha__) || defined(__alpha)

#  define breakeven_point   2	/* AXP (DEC Alpha)     - gcc or cc or egcs */

#endif

#if defined(__i386__)  || defined(__i386)

#  define breakeven_point  12	/* Intel Pentium/Linux - gcc 2.96 */

#endif

#if defined(__hppa)

#  define breakeven_point  10	/* HP-PA               - gcc */

#endif

#if defined(__sparc__) || defined(__sparc)

#  define breakeven_point  33	/* Sun Sparc 5         - gcc 2.8.1 */

#endif

/* some other values of possible interest: */

/* #define breakeven_point  8 */  /* VAX 4000          - vaxc */

/* #define breakeven_point 19 */  /* VAX 4000          - gcc 2.7.0 */

#ifndef breakeven_point

#  define breakeven_point   6	/* some reasonable one-size-fits-all value */

#endif

#define fast_memcpy(d,s,n) \

  { register size_t nn = (size_t)(n); \

    if (nn >= breakeven_point) memcpy((d), (s), nn); \

    else if (nn > 0) { /* proc call overhead is worth only for large strings*/\

      register char *dd; register const char *ss; \

      for (ss=(s), dd=(d); nn>0; nn--) *dd++ = *ss++; } }

#define fast_memset(d,c,n) \

  { register size_t nn = (size_t)(n); \

    if (nn >= breakeven_point) memset((d), (int)(c), nn); \

    else if (nn > 0) { /* proc call overhead is worth only for large strings*/\

      register char *dd; register const int cc=(int)(c); \

      for (dd=(d); nn>0; nn--) *dd++ = cc; } }

/* prototypes */

#if defined(NEED_ASPRINTF)

int asprintf   (char **ptr, const char *fmt, /*args*/ ...);

#endif

#if defined(NEED_VASPRINTF)

int vasprintf  (char **ptr, const char *fmt, va_list ap);

#endif

#if defined(NEED_ASNPRINTF)

int asnprintf  (char **ptr, size_t str_m, const char *fmt, /*args*/ ...);

#endif

#if defined(NEED_VASNPRINTF)

int vasnprintf (char **ptr, size_t str_m, const char *fmt, va_list ap);

#endif

#if defined(HAVE_SNPRINTF)

/* declare our portable snprintf  routine under name portable_snprintf  */

/* declare our portable vsnprintf routine under name portable_vsnprintf */

#else

/* declare our portable routines under names snprintf and vsnprintf */

#define portable_snprintf snprintf

#if !defined(NEED_SNPRINTF_ONLY)

#define portable_vsnprintf vsnprintf

#endif

#endif

#if !defined(HAVE_SNPRINTF) || defined(PREFER_PORTABLE_SNPRINTF)

int portable_snprintf(char *str, size_t str_m, const char *fmt, /*args*/ ...);

#if !defined(NEED_SNPRINTF_ONLY)

int portable_vsnprintf(char *str, size_t str_m, const char *fmt, va_list ap);

#endif

#endif

/* declarations */

static char credits[] = "\n\

@(#)snprintf.c, v2.2: Mark Martinec, \n\

@(#)snprintf.c, v2.2: Copyright 1999, Mark Martinec. Frontier Artistic License applies.\n\

@(#)snprintf.c, v2.2: http://www.ijs.si/software/snprintf/\n";

#if defined(NEED_ASPRINTF)

int asprintf(char **ptr, const char *fmt, /*args*/ ...) {

  va_list ap;

  size_t str_m;

  int str_l;

  *ptr = NULL;

  va_start(ap, fmt);                            /* measure the required size */

  str_l = portable_vsnprintf(NULL, (size_t)0, fmt, ap);

  va_end(ap);

  assert(str_l >= 0);        /* possible integer overflow if str_m > INT_MAX */

  *ptr = (char *) malloc(str_m = (size_t)str_l + 1);

  if (*ptr == NULL) { errno = ENOMEM; str_l = -1; }

  else {

    int str_l2;

    va_start(ap, fmt);

    str_l2 = portable_vsnprintf(*ptr, str_m, fmt, ap);

    va_end(ap);

    assert(str_l2 == str_l);

  }

  return str_l;

}

#endif

#if defined(NEED_VASPRINTF)

int vasprintf(char **ptr, const char *fmt, va_list ap) {

  size_t str_m;

  int str_l;

  *ptr = NULL;

  { va_list ap2;

    va_copy(ap2, ap);  /* don't consume the original ap, we'll need it again */

    str_l = portable_vsnprintf(NULL, (size_t)0, fmt, ap2);/*get required size*/

    va_end(ap2);

  }

  assert(str_l >= 0);        /* possible integer overflow if str_m > INT_MAX */

  *ptr = (char *) malloc(str_m = (size_t)str_l + 1);

  if (*ptr == NULL) { errno = ENOMEM; str_l = -1; }

  else {

    int str_l2 = portable_vsnprintf(*ptr, str_m, fmt, ap);

    assert(str_l2 == str_l);

  }

  return str_l;

}

#endif

#if defined(NEED_ASNPRINTF)

int asnprintf (char **ptr, size_t str_m, const char *fmt, /*args*/ ...) {

  va_list ap;

  int str_l;

  *ptr = NULL;

  va_start(ap, fmt);                            /* measure the required size */

  str_l = portable_vsnprintf(NULL, (size_t)0, fmt, ap);

  va_end(ap);

  assert(str_l >= 0);        /* possible integer overflow if str_m > INT_MAX */

  if ((size_t)str_l + 1 < str_m) str_m = (size_t)str_l + 1;      /* truncate */

  /* if str_m is 0, no buffer is allocated, just set *ptr to NULL */

  if (str_m == 0) {  /* not interested in resulting string, just return size */

  } else {

    *ptr = (char *) malloc(str_m);

    if (*ptr == NULL) { errno = ENOMEM; str_l = -1; }

    else {

      int str_l2;

      va_start(ap, fmt);

      str_l2 = portable_vsnprintf(*ptr, str_m, fmt, ap);

      va_end(ap);

      assert(str_l2 == str_l);

    }

  }

  return str_l;

}

#endif

#if defined(NEED_VASNPRINTF)

int vasnprintf (char **ptr, size_t str_m, const char *fmt, va_list ap) {

  int str_l;

  *ptr = NULL;

  { va_list ap2;

    va_copy(ap2, ap);  /* don't consume the original ap, we'll need it again */

    str_l = portable_vsnprintf(NULL, (size_t)0, fmt, ap2);/*get required size*/

    va_end(ap2);

  }

  assert(str_l >= 0);        /* possible integer overflow if str_m > INT_MAX */

  if ((size_t)str_l + 1 < str_m) str_m = (size_t)str_l + 1;      /* truncate */

  /* if str_m is 0, no buffer is allocated, just set *ptr to NULL */

  if (str_m == 0) {  /* not interested in resulting string, just return size */

  } else {

    *ptr = (char *) malloc(str_m);

    if (*ptr == NULL) { errno = ENOMEM; str_l = -1; }

    else {

      int str_l2 = portable_vsnprintf(*ptr, str_m, fmt, ap);

      assert(str_l2 == str_l);

    }

  }

  return str_l;

}

#endif

/*

 * If the system does have snprintf and the portable routine is not

 * specifically required, this module produces no code for snprintf/vsnprintf.

 */

#if !defined(HAVE_SNPRINTF) || defined(PREFER_PORTABLE_SNPRINTF)

#if !defined(NEED_SNPRINTF_ONLY)

int portable_snprintf(char *str, size_t str_m, const char *fmt, /*args*/ ...) {

  va_list ap;

  int str_l;

  va_start(ap, fmt);

  str_l = portable_vsnprintf(str, str_m, fmt, ap);

  va_end(ap);

  return str_l;

}

#endif

#if defined(NEED_SNPRINTF_ONLY)

int portable_snprintf(char *str, size_t str_m, const char *fmt, /*args*/ ...) {

#else

int portable_vsnprintf(char *str, size_t str_m, const char *fmt, va_list ap) {

#endif

#if defined(NEED_SNPRINTF_ONLY)

  va_list ap;

#endif

  size_t str_l = 0;

  const char *p = fmt;

/* In contrast with POSIX, the ISO C99 now says

 * that str can be NULL and str_m can be 0.

 * This is more useful than the old:  if (str_m < 1) return -1; */

#if defined(NEED_SNPRINTF_ONLY)

  va_start(ap, fmt);

#endif

  if (!p) p = "";

  while (*p) {

    if (*p != '%') {

   /* if (str_l < str_m) str[str_l++] = *p++;    -- this would be sufficient */

   /* but the following code achieves better performance for cases

    * where format string is long and contains few conversions */

      const char *q = strchr(p+1,'%');

      size_t n = !q ? strlen(p) : (q-p);

      if (str_l < str_m) {

        size_t avail = str_m-str_l;

        fast_memcpy(str+str_l, p, (n>avail?avail:n));

      }

      p += n; str_l += n;

    } else {

      const char *starting_p;

      size_t min_field_width = 0, precision = 0;

      int zero_padding = 0, precision_specified = 0, justify_left = 0;

      int alternate_form = 0, force_sign = 0;

      int space_for_positive = 1; /* If both the ' ' and '+' flags appear,

                                     the ' ' flag should be ignored. */

      char length_modifier = '\0';            /* allowed values: \0, h, l, L */

      char tmp[32];/* temporary buffer for simple numeric->string conversion */

      const char *str_arg;      /* string address in case of string argument */

      size_t str_arg_l;         /* natural field width of arg without padding

                                   and sign */

      unsigned char uchar_arg;

        /* unsigned char argument value - only defined for c conversion.

           N.B. standard explicitly states the char argument for

           the c conversion is unsigned */

      size_t number_of_zeros_to_pad = 0;

        /* number of zeros to be inserted for numeric conversions

           as required by the precision or minimal field width */

      size_t zero_padding_insertion_ind = 0;

        /* index into tmp where zero padding is to be inserted */

      char fmt_spec = '\0';

        /* current conversion specifier character */

      str_arg = credits;/* just to make compiler happy (defined but not used)*/

      str_arg = NULL;

      starting_p = p; p++;  /* skip '%' */

   /* parse flags */

      while (*p == '0' || *p == '-' || *p == '+' ||

             *p == ' ' || *p == '#' || *p == '\'') {

        switch (*p) {

        case '0': zero_padding = 1; break;

        case '-': justify_left = 1; break;

        case '+': force_sign = 1; space_for_positive = 0; break;

        case ' ': force_sign = 1;

     /* If both the ' ' and '+' flags appear, the ' ' flag should be ignored */

#ifdef PERL_COMPATIBLE

     /* ... but in Perl the last of ' ' and '+' applies */

                  space_for_positive = 1;

#endif

                  break;

        case '#': alternate_form = 1; break;

        case '\'': break;

        }

        p++;

      }

   /* If the '0' and '-' flags both appear, the '0' flag should be ignored. */

   /* parse field width */

      if (*p == '*') {

        int j;

        p++; j = va_arg(ap, int);

        if (j >= 0) min_field_width = j;

        else { min_field_width = -j; justify_left = 1; }

      } else if (isdigit((int)(*p))) {

        /* size_t could be wider than unsigned int;

           make sure we treat argument like common implementations do */

        unsigned int uj = *p++ - '0';

        while (isdigit((int)(*p))) uj = 10*uj + (unsigned int)(*p++ - '0');

        min_field_width = uj;

      }

   /* parse precision */

      if (*p == '.') {

        p++; precision_specified = 1;

        if (*p == '*') {

          int j = va_arg(ap, int);

          p++;

          if (j >= 0) precision = j;

          else {

            precision_specified = 0; precision = 0;

         /* NOTE:

          *   Solaris 2.6 man page claims that in this case the precision

          *   should be set to 0.  Digital Unix 4.0, HPUX 10 and BSD man page

          *   claim that this case should be treated as unspecified precision,

          *   which is what we do here.

          */

          }

        } else if (isdigit((int)(*p))) {

          /* size_t could be wider than unsigned int;

             make sure we treat argument like common implementations do */

          unsigned int uj = *p++ - '0';

          while (isdigit((int)(*p))) uj = 10*uj + (unsigned int)(*p++ - '0');

          precision = uj;

        }

      }

   /* parse 'h', 'l' and 'll' length modifiers */

      if (*p == 'h' || *p == 'l') {

        length_modifier = *p; p++;

        if (length_modifier == 'l' && *p == 'l') {   /* double l = long long */

#ifdef SNPRINTF_LONGLONG_SUPPORT

          length_modifier = '2';                  /* double l encoded as '2' */

#else

          length_modifier = 'l';                 /* treat it as a single 'l' */

#endif

          p++;

        }

      }

      fmt_spec = *p;

   /* common synonyms: */

      switch (fmt_spec) {

      case 'i': fmt_spec = 'd'; break;

      case 'D': fmt_spec = 'd'; length_modifier = 'l'; break;

      case 'U': fmt_spec = 'u'; length_modifier = 'l'; break;

      case 'O': fmt_spec = 'o'; length_modifier = 'l'; break;

      default: break;

      }

   /* get parameter value, do initial processing */

      switch (fmt_spec) {

      case '%': /* % behaves similar to 's' regarding flags and field widths */

      case 'c': /* c behaves similar to 's' regarding flags and field widths */

      case 's':

        length_modifier = '\0';          /* wint_t and wchar_t not supported */

     /* the result of zero padding flag with non-numeric conversion specifier*/

     /* is undefined. Solaris and HPUX 10 does zero padding in this case,    */

     /* Digital Unix and Linux does not. */

#if !defined(SOLARIS_COMPATIBLE) && !defined(HPUX_COMPATIBLE)

        zero_padding = 0;    /* turn zero padding off for string conversions */

#endif

        str_arg_l = 1;

        switch (fmt_spec) {

        case '%':

          str_arg = p; break;

        case 'c': {

          int j = va_arg(ap, int);

          uchar_arg = (unsigned char) j;   /* standard demands unsigned char */

          str_arg = (const char *) &uchar_arg;

          break;

        }

        case 's':

          str_arg = va_arg(ap, const char *);

          if (!str_arg) str_arg_l = 0;

       /* make sure not to address string beyond the specified precision !!! */

          else if (!precision_specified) str_arg_l = strlen(str_arg);

       /* truncate string if necessary as requested by precision */

          else if (precision == 0) str_arg_l = 0;

          else {

       /* memchr on HP does not like n > 2^31  !!! */

            const char *q = memchr(str_arg, '\0',

                             precision <= 0x7fffffff ? precision : 0x7fffffff);

            str_arg_l = !q ? precision : (q-str_arg);

          }

          break;

        default: break;

        }

        break;

      case 'd': case 'u': case 'o': case 'x': case 'X': case 'p': {

        /* NOTE: the u, o, x, X and p conversion specifiers imply

                 the value is unsigned;  d implies a signed value */

        int arg_sign = 0;

          /* 0 if numeric argument is zero (or if pointer is NULL for 'p'),

            +1 if greater than zero (or nonzero for unsigned arguments),

            -1 if negative (unsigned argument is never negative) */

        int int_arg = 0;  unsigned int uint_arg = 0;

          /* only defined for length modifier h, or for no length modifiers */

        long int long_arg = 0;  unsigned long int ulong_arg = 0;

          /* only defined for length modifier l */

        void *ptr_arg = NULL;

          /* pointer argument value -only defined for p conversion */

#ifdef SNPRINTF_LONGLONG_SUPPORT

        long long int long_long_arg = 0;

        unsigned long long int ulong_long_arg = 0;

          /* only defined for length modifier ll */

#endif

        if (fmt_spec == 'p') {

        /* HPUX 10: An l, h, ll or L before any other conversion character

         *   (other than d, i, u, o, x, or X) is ignored.

         * Digital Unix:

         *   not specified, but seems to behave as HPUX does.

         * Solaris: If an h, l, or L appears before any other conversion

         *   specifier (other than d, i, u, o, x, or X), the behavior

         *   is undefined. (Actually %hp converts only 16-bits of address

         *   and %llp treats address as 64-bit data which is incompatible

         *   with (void *) argument on a 32-bit system).

         */

#ifdef SOLARIS_COMPATIBLE

#  ifdef SOLARIS_BUG_COMPATIBLE

          /* keep length modifiers even if it represents 'll' */

#  else

          if (length_modifier == '2') length_modifier = '\0';

#  endif

#else

          length_modifier = '\0';

#endif

          ptr_arg = va_arg(ap, void *);

          if (ptr_arg != NULL) arg_sign = 1;

        } else if (fmt_spec == 'd') {  /* signed */

          switch (length_modifier) {

          case '\0':

          case 'h':

         /* It is non-portable to specify a second argument of char or short

          * to va_arg, because arguments seen by the called function

          * are not char or short.  C converts char and short arguments

          * to int before passing them to a function.

          */

            int_arg = va_arg(ap, int);

            if      (int_arg > 0) arg_sign =  1;

            else if (int_arg < 0) arg_sign = -1;

            break;

          case 'l':

            long_arg = va_arg(ap, long int);

            if      (long_arg > 0) arg_sign =  1;

            else if (long_arg < 0) arg_sign = -1;

            break;

#ifdef SNPRINTF_LONGLONG_SUPPORT

          case '2':

            long_long_arg = va_arg(ap, long long int);

            if      (long_long_arg > 0) arg_sign =  1;

            else if (long_long_arg < 0) arg_sign = -1;

            break;

#endif

          }

        } else {  /* unsigned */

          switch (length_modifier) {

          case '\0':

          case 'h':

            uint_arg = va_arg(ap, unsigned int);

            if (uint_arg) arg_sign = 1;

            break;

          case 'l':

            ulong_arg = va_arg(ap, unsigned long int);

            if (ulong_arg) arg_sign = 1;

            break;

#ifdef SNPRINTF_LONGLONG_SUPPORT

          case '2':

            ulong_long_arg = va_arg(ap, unsigned long long int);

            if (ulong_long_arg) arg_sign = 1;

            break;

#endif

          }

        }

        str_arg = tmp; str_arg_l = 0;

     /* NOTE:

      *   For d, i, u, o, x, and X conversions, if precision is specified,

      *   the '0' flag should be ignored. This is so with Solaris 2.6,

      *   Digital UNIX 4.0, HPUX 10, Linux, FreeBSD, NetBSD; but not with Perl.

      */

#ifndef PERL_COMPATIBLE

        if (precision_specified) zero_padding = 0;

#endif

        if (fmt_spec == 'd') {

          if (force_sign && arg_sign >= 0)

            tmp[str_arg_l++] = space_for_positive ? ' ' : '+';

         /* leave negative numbers for sprintf to handle,

            to avoid handling tricky cases like (short int)(-32768) */

#ifdef LINUX_COMPATIBLE

        } else if (fmt_spec == 'p' && force_sign && arg_sign > 0) {

          tmp[str_arg_l++] = space_for_positive ? ' ' : '+';

#endif

        } else if (alternate_form) {

          if (arg_sign != 0 && (fmt_spec == 'x' || fmt_spec == 'X') )

            { tmp[str_arg_l++] = '0'; tmp[str_arg_l++] = fmt_spec; }

         /* alternate form should have no effect for p conversion, but ... */

#ifdef HPUX_COMPATIBLE

          else if (fmt_spec == 'p'

         /* HPUX 10: for an alternate form of p conversion,

          *          a nonzero result is prefixed by 0x. */

#ifndef HPUX_BUG_COMPATIBLE

         /* Actually it uses 0x prefix even for a zero value. */

                   && arg_sign != 0

#endif

                  ) { tmp[str_arg_l++] = '0'; tmp[str_arg_l++] = 'x'; }

#endif

        }

        zero_padding_insertion_ind = str_arg_l;

        if (!precision_specified) precision = 1;   /* default precision is 1 */

        if (precision == 0 && arg_sign == 0

#if defined(HPUX_BUG_COMPATIBLE) || defined(LINUX_COMPATIBLE)

            && fmt_spec != 'p'

         /* HPUX 10 man page claims: With conversion character p the result of

          * converting a zero value with a precision of zero is a null string.

          * Actually HP returns all zeroes, and Linux returns "(nil)". */

#endif

        ) {

         /* converted to null string */

         /* When zero value is formatted with an explicit precision 0,

            the resulting formatted string is empty (d, i, u, o, x, X, p).   */

        } else {

          char f[5]; int f_l = 0;

          f[f_l++] = '%';    /* construct a simple format string for sprintf */

          if (!length_modifier) { }

          else if (length_modifier=='2') { f[f_l++] = 'l'; f[f_l++] = 'l'; }

          else f[f_l++] = length_modifier;

          f[f_l++] = fmt_spec; f[f_l++] = '\0';

          if (fmt_spec == 'p') str_arg_l += sprintf(tmp+str_arg_l, f, ptr_arg);

          else if (fmt_spec == 'd') {  /* signed */

            switch (length_modifier) {

            case '\0':

            case 'h': str_arg_l+=sprintf(tmp+str_arg_l, f, int_arg);  break;

            case 'l': str_arg_l+=sprintf(tmp+str_arg_l, f, long_arg); break;

#ifdef SNPRINTF_LONGLONG_SUPPORT

            case '2': str_arg_l+=sprintf(tmp+str_arg_l,f,long_long_arg); break;

#endif

            }

          } else {  /* unsigned */

            switch (length_modifier) {

            case '\0':

            case 'h': str_arg_l+=sprintf(tmp+str_arg_l, f, uint_arg);  break;

            case 'l': str_arg_l+=sprintf(tmp+str_arg_l, f, ulong_arg); break;

#ifdef SNPRINTF_LONGLONG_SUPPORT

            case '2': str_arg_l+=sprintf(tmp+str_arg_l,f,ulong_long_arg);break;

#endif

            }

          }

         /* include the optional minus sign and possible "0x"

            in the region before the zero padding insertion point */

          if (zero_padding_insertion_ind < str_arg_l &&

              tmp[zero_padding_insertion_ind] == '-') {

            zero_padding_insertion_ind++;

          }

          if (zero_padding_insertion_ind+1 < str_arg_l &&

              tmp[zero_padding_insertion_ind]   == '0' &&

             (tmp[zero_padding_insertion_ind+1] == 'x' ||

              tmp[zero_padding_insertion_ind+1] == 'X') ) {

            zero_padding_insertion_ind += 2;

          }

        }

        { size_t num_of_digits = str_arg_l - zero_padding_insertion_ind;

          if (alternate_form && fmt_spec == 'o'

#ifdef HPUX_COMPATIBLE                                  /* ("%#.o",0) -> ""  */

              && (str_arg_l > 0)

#endif

#ifdef DIGITAL_UNIX_BUG_COMPATIBLE                      /* ("%#o",0) -> "00" */

#else

              /* unless zero is already the first character */

              && !(zero_padding_insertion_ind < str_arg_l

                   && tmp[zero_padding_insertion_ind] == '0')

#endif

          ) {        /* assure leading zero for alternate-form octal numbers */

            if (!precision_specified || precision < num_of_digits+1) {

             /* precision is increased to force the first character to be zero,

                except if a zero value is formatted with an explicit precision

                of zero */

              precision = num_of_digits+1; precision_specified = 1;

            }

          }

       /* zero padding to specified precision? */

          if (num_of_digits < precision)

            number_of_zeros_to_pad = precision - num_of_digits;

        }

     /* zero padding to specified minimal field width? */

        if (!justify_left && zero_padding) {

          int n = min_field_width - (str_arg_l+number_of_zeros_to_pad);

          if (n > 0) number_of_zeros_to_pad += n;

        }

        break;

      }

      default: /* unrecognized conversion specifier, keep format string as-is*/

        zero_padding = 0;  /* turn zero padding off for non-numeric convers. */

#ifndef DIGITAL_UNIX_COMPATIBLE

        justify_left = 1; min_field_width = 0;                /* reset flags */

#endif

#if defined(PERL_COMPATIBLE) || defined(LINUX_COMPATIBLE)

     /* keep the entire format string unchanged */

        str_arg = starting_p; str_arg_l = p - starting_p;

     /* well, not exactly so for Linux, which does something inbetween,

      * and I don't feel an urge to imitate it: "%+++++hy" -> "%+y"  */

#else

     /* discard the unrecognized conversion, just keep *

      * the unrecognized conversion character          */

        str_arg = p; str_arg_l = 0;

#endif

        if (*p) str_arg_l++;  /* include invalid conversion specifier unchanged

                                 if not at end-of-string */

        break;

      }

      if (*p) p++;      /* step over the just processed conversion specifier */

   /* insert padding to the left as requested by min_field_width;

      this does not include the zero padding in case of numerical conversions*/

      if (!justify_left) {                /* left padding with blank or zero */

        int n = min_field_width - (str_arg_l+number_of_zeros_to_pad);

        if (n > 0) {

          if (str_l < str_m) {

            size_t avail = str_m-str_l;

            fast_memset(str+str_l, (zero_padding?'0':' '), (n>avail?avail:n));

          }

          str_l += n;

        }

      }

   /* zero padding as requested by the precision or by the minimal field width

    * for numeric conversions required? */

      if (number_of_zeros_to_pad <= 0) {

     /* will not copy first part of numeric right now, *

      * force it to be copied later in its entirety    */

        zero_padding_insertion_ind = 0;

      } else {

     /* insert first part of numerics (sign or '0x') before zero padding */

        int n = zero_padding_insertion_ind;

        if (n > 0) {

          if (str_l < str_m) {

            size_t avail = str_m-str_l;

            fast_memcpy(str+str_l, str_arg, (n>avail?avail:n));

          }

          str_l += n;

        }

     /* insert zero padding as requested by the precision or min field width */

        n = number_of_zeros_to_pad;

        if (n > 0) {

          if (str_l < str_m) {

            size_t avail = str_m-str_l;

            fast_memset(str+str_l, '0', (n>avail?avail:n));

          }

          str_l += n;

        }

      }

   /* insert formatted string

    * (or as-is conversion specifier for unknown conversions) */

      { int n = str_arg_l - zero_padding_insertion_ind;

        if (n > 0) {

          if (str_l < str_m) {

            size_t avail = str_m-str_l;

            fast_memcpy(str+str_l, str_arg+zero_padding_insertion_ind,

                        (n>avail?avail:n));

          }

          str_l += n;

        }

      }

   /* insert right padding */

      if (justify_left) {          /* right blank padding to the field width */

        int n = min_field_width - (str_arg_l+number_of_zeros_to_pad);

        if (n > 0) {

          if (str_l < str_m) {

            size_t avail = str_m-str_l;

            fast_memset(str+str_l, ' ', (n>avail?avail:n));

          }

          str_l += n;

        }

      }

    }

  }

#if defined(NEED_SNPRINTF_ONLY)

  va_end(ap);

#endif

  if (str_m > 0) { /* make sure the string is null-terminated

                      even at the expense of overwriting the last character

                      (shouldn't happen, but just in case) */

    str[str_l <= str_m-1 ? str_l : str_m-1] = '\0';

  }

  /* Return the number of characters formatted (excluding trailing null

   * character), that is, the number of characters that would have been

   * written to the buffer if it were large enough.

   *

   * The value of str_l should be returned, but str_l is of unsigned type

   * size_t, and snprintf is int, possibly leading to an undetected

   * integer overflow, resulting in a negative return value, which is illegal.

   * Both XSH5 and ISO C99 (at least the draft) are silent on this issue.

   * Should errno be set to EOVERFLOW and EOF returned in this case???

   */

  return (int) str_l;

}

#endif