/*
* snprintf.c - a portable implementation of snprintf
*
* AUTHOR
* Mark Martinec <mark.martinec@ijs.si>, 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 <mark.martinec@ijs.si>
* - added main test program, fixed remaining inconsistencies,
* added optional (long long int) support;
* 1999-04-12 V1.1 Mark Martinec <mark.martinec@ijs.si>
* - 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 <mark.martinec@ijs.si>
* - 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 <mark.martinec@ijs.si>
* - 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 <edwiny@autonomy.com> for
* spotting the problem);
* - added macros PORTABLE_SNPRINTF_VERSION_(MAJOR|MINOR)
* to snprintf.h
* 2000-02-14 V2.0 (never released) Mark Martinec <mark.martinec@ijs.si>
* - 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 <mark.martinec@ijs.si>
* - 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 a