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/* * 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