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  1. /*
  2.  * snprintf.c - a portable implementation of snprintf
  3.  *
  4.  * AUTHOR
  5.  *   Mark Martinec <mark.martinec@ijs.si>, April 1999.
  6.  *
  7.  *   Copyright 1999, Mark Martinec. All rights reserved.
  8.  *
  9.  * TERMS AND CONDITIONS
  10.  *   This program is free software; you can redistribute it and/or modify
  11.  *   it under the terms of the "Frontier Artistic License" which comes
  12.  *   with this Kit.
  13.  *
  14.  *   This program is distributed in the hope that it will be useful,
  15.  *   but WITHOUT ANY WARRANTY; without even the implied warranty
  16.  *   of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  17.  *   See the Frontier Artistic License for more details.
  18.  *
  19.  *   You should have received a copy of the Frontier Artistic License
  20.  *   with this Kit in the file named LICENSE.txt .
  21.  *   If not, I'll be glad to provide one.
  22.  *
  23.  * FEATURES
  24.  * - careful adherence to specs regarding flags, field width and precision;
  25.  * - good performance for large string handling (large format, large
  26.  *   argument or large paddings). Performance is similar to system's sprintf
  27.  *   and in several cases significantly better (make sure you compile with
  28.  *   optimizations turned on, tell the compiler the code is strict ANSI
  29.  *   if necessary to give it more freedom for optimizations);
  30.  * - return value semantics per ISO/IEC 9899:1999 ("ISO C99");
  31.  * - written in standard ISO/ANSI C - requires an ANSI C compiler.
  32.  *
  33.  * SUPPORTED CONVERSION SPECIFIERS AND DATA TYPES
  34.  *
  35.  * This snprintf only supports the following conversion specifiers:
  36.  * s, c, d, u, o, x, X, p  (and synonyms: i, D, U, O - see below)
  37.  * with flags: '-', '+', ' ', '0' and '#'.
  38.  * An asterisk is supported for field width as well as precision.
  39.  *
  40.  * Length modifiers 'h' (short int), 'l' (long int),
  41.  * and 'll' (long long int) are supported.
  42.  * NOTE:
  43.  *   If macro SNPRINTF_LONGLONG_SUPPORT is not defined (default) the
  44.  *   length modifier 'll' is recognized but treated the same as 'l',
  45.  *   which may cause argument value truncation! Defining
  46.  *   SNPRINTF_LONGLONG_SUPPORT requires that your system's sprintf also
  47.  *   handles length modifier 'll'.  long long int is a language extension
  48.  *   which may not be portable.
  49.  *
  50.  * Conversion of numeric data (conversion specifiers d, u, o, x, X, p)
  51.  * with length modifiers (none or h, l, ll) is left to the system routine
  52.  * sprintf, but all handling of flags, field width and precision as well as
  53.  * c and s conversions is done very carefully by this portable routine.
  54.  * If a string precision (truncation) is specified (e.g. %.8s) it is
  55.  * guaranteed the string beyond the specified precision will not be referenced.
  56.  *
  57.  * Length modifiers h, l and ll are ignored for c and s conversions (data
  58.  * types wint_t and wchar_t are not supported).
  59.  *
  60.  * The following common synonyms for conversion characters are supported:
  61.  *   - i is a synonym for d
  62.  *   - D is a synonym for ld, explicit length modifiers are ignored
  63.  *   - U is a synonym for lu, explicit length modifiers are ignored
  64.  *   - O is a synonym for lo, explicit length modifiers are ignored
  65.  * The D, O and U conversion characters are nonstandard, they are supported
  66.  * for backward compatibility only, and should not be used for new code.
  67.  *
  68.  * The following is specifically NOT supported:
  69.  *   - flag ' (thousands' grouping character) is recognized but ignored
  70.  *   - numeric conversion specifiers: f, e, E, g, G and synonym F,
  71.  *     as well as the new a and A conversion specifiers
  72.  *   - length modifier 'L' (long double) and 'q' (quad - use 'll' instead)
  73.  *   - wide character/string conversions: lc, ls, and nonstandard
  74.  *     synonyms C and S
  75.  *   - writeback of converted string length: conversion character n
  76.  *   - the n$ specification for direct reference to n-th argument
  77.  *   - locales
  78.  *
  79.  * It is permitted for str_m to be zero, and it is permitted to specify NULL
  80.  * pointer for resulting string argument if str_m is zero (as per ISO C99).
  81.  *
  82.  * The return value is the number of characters which would be generated
  83.  * for the given input, excluding the trailing null. If this value
  84.  * is greater or equal to str_m, not all characters from the result
  85.  * have been stored in str, output bytes beyond the (str_m-1) -th character
  86.  * are discarded. If str_m is greater than zero it is guaranteed
  87.  * the resulting string will be null-terminated.
  88.  *
  89.  * NOTE that this matches the ISO C99, OpenBSD, and GNU C library 2.1,
  90.  * but is different from some older and vendor implementations,
  91.  * and is also different from XPG, XSH5, SUSv2 specifications.
  92.  * For historical discussion on changes in the semantics and standards
  93.  * of snprintf see printf(3) man page in the Linux programmers manual.
  94.  *
  95.  * Routines asprintf and vasprintf return a pointer (in the ptr argument)
  96.  * to a buffer sufficiently large to hold the resulting string. This pointer
  97.  * should be passed to free(3) to release the allocated storage when it is
  98.  * no longer needed. If sufficient space cannot be allocated, these functions
  99.  * will return -1 and set ptr to be a NULL pointer. These two routines are a
  100.  * GNU C library extensions (glibc).
  101.  *
  102.  * Routines asnprintf and vasnprintf are similar to asprintf and vasprintf,
  103.  * yet, like snprintf and vsnprintf counterparts, will write at most str_m-1
  104.  * characters into the allocated output string, the last character in the
  105.  * allocated buffer then gets the terminating null. If the formatted string
  106.  * length (the return value) is greater than or equal to the str_m argument,
  107.  * the resulting string was truncated and some of the formatted characters
  108.  * were discarded. These routines present a handy way to limit the amount
  109.  * of allocated memory to some sane value.
  110.  *
  111.  * AVAILABILITY
  112.  *   http://www.ijs.si/software/snprintf/
  113.  *
  114.  * REVISION HISTORY
  115.  * 1999-04      V0.9  Mark Martinec
  116.  *              - initial version, some modifications after comparing printf
  117.  *                man pages for Digital Unix 4.0, Solaris 2.6 and HPUX 10,
  118.  *                and checking how Perl handles sprintf (differently!);
  119.  * 1999-04-09   V1.0  Mark Martinec <mark.martinec@ijs.si>
  120.  *              - added main test program, fixed remaining inconsistencies,
  121.  *                added optional (long long int) support;
  122.  * 1999-04-12   V1.1  Mark Martinec <mark.martinec@ijs.si>
  123.  *              - support the 'p' conversion (pointer to void);
  124.  *              - if a string precision is specified
  125.  *                make sure the string beyond the specified precision
  126.  *                will not be referenced (e.g. by strlen);
  127.  * 1999-04-13   V1.2  Mark Martinec <mark.martinec@ijs.si>
  128.  *              - support synonyms %D=%ld, %U=%lu, %O=%lo;
  129.  *              - speed up the case of long format string with few conversions;
  130.  * 1999-06-30   V1.3  Mark Martinec <mark.martinec@ijs.si>
  131.  *              - fixed runaway loop (eventually crashing when str_l wraps
  132.  *                beyond 2^31) while copying format string without
  133.  *                conversion specifiers to a buffer that is too short
  134.  *                (thanks to Edwin Young <edwiny@autonomy.com> for
  135.  *                spotting the problem);
  136.  *              - added macros PORTABLE_SNPRINTF_VERSION_(MAJOR|MINOR)
  137.  *                to snprintf.h
  138.  * 2000-02-14   V2.0 (never released) Mark Martinec <mark.martinec@ijs.si>
  139.  *              - relaxed license terms: The Artistic License now applies.
  140.  *                You may still apply the GNU GENERAL PUBLIC LICENSE
  141.  *                as was distributed with previous versions, if you prefer;
  142.  *              - changed REVISION HISTORY dates to use ISO 8601 date format;
  143.  *              - added vsnprintf (patch also independently proposed by
  144.  *                Caolan McNamara 2000-05-04, and Keith M Willenson 2000-06-01)
  145.  * 2000-06-27   V2.1  Mark Martinec <mark.martinec@ijs.si>
  146.  *              - removed POSIX check for str_m<1; value 0 for str_m is
  147.  *                allowed by ISO C99 (and GNU C library 2.1) - (pointed out
  148.  *                on 2000-05-04 by Caolan McNamara, caolan@ csn dot ul dot ie).
  149.  *                Besides relaxed license this change in standards adherence
  150.  *                is the main reason to bump up the major version number;
  151.  *              - added nonstandard routines asnprintf, vasnprintf, asprintf,
  152.  *                vasprintf that dynamically allocate storage for the
  153.  *                resulting string; these routines are not compiled by default,
  154.  *                see comments where NEED_V?ASN?PRINTF macros are defined;
  155.  *              - autoconf contributed by Caolan McNamara
  156.  * 2000-10-06   V2.2  Mark Martinec <mark.martinec@ijs.si>
  157.  *              - BUG FIX: the %c conversion used a temporary variable
  158.  *                that was no longer in scope when referenced,
  159.  *                possibly causing incorrect resulting character;
  160.  *              - BUG FIX: make precision and minimal field width unsigned
  161.  *                to handle huge values (2^31 <= n < 2^32) correctly;
  162.  *                also be more careful in the use of signed/unsigned/size_t
  163.  *                internal variables - probably more careful than many
  164.  *                vendor implementations, but there may still be a case
  165.  *                where huge values of str_m, precision or minimal field
  166.  *                could cause incorrect behaviour;
  167.  *              - use separate variables for signed/unsigned arguments,
  168.  *                and for short/int, long, and long long argument lengths
  169.  *                to avoid possible incompatibilities on certain
  170.  *                computer architectures. Also use separate variable
  171.  *                arg_sign to hold sign of a numeric argument,
  172.  *                to make code more transparent;
  173.  *              - some fiddling with zero padding and "0x" to make it
  174.  *                Linux compatible;
  175.  *              - systematically use macros fast_memcpy and fast_memset
  176.  *                instead of case-by-case hand optimization; determine some
  177.  *                breakeven string lengths for different architectures;
  178.  *              - terminology change: 'format' -> 'conversion specifier',
  179.  *                'C9x' -> 'ISO/IEC 9899:1999 ("ISO C99")',
  180.  *                'alternative form' -> 'alternate form',
  181.  *                'data type modifier' -> 'length modifier';
  182.  *              - several comments rephrased and new ones added;
  183.  *              - make compiler not complain about 'credits' defined but
  184.  *                not used;
  185.  */
  186.  
  187.  
  188. /* Define HAVE_SNPRINTF if your system already has snprintf and vsnprintf.
  189.  *
  190.  * If HAVE_SNPRINTF is defined this module will not produce code for
  191.  * snprintf and vsnprintf, unless PREFER_PORTABLE_SNPRINTF is defined as well,
  192.  * causing this portable version of snprintf to be called portable_snprintf
  193.  * (and portable_vsnprintf).
  194.  */
  195. /* #define HAVE_SNPRINTF */
  196.  
  197. /* Define PREFER_PORTABLE_SNPRINTF if your system does have snprintf and
  198.  * vsnprintf but you would prefer to use the portable routine(s) instead.
  199.  * In this case the portable routine is declared as portable_snprintf
  200.  * (and portable_vsnprintf) and a macro 'snprintf' (and 'vsnprintf')
  201.  * is defined to expand to 'portable_v?snprintf' - see file snprintf.h .
  202.  * Defining this macro is only useful if HAVE_SNPRINTF is also defined,
  203.  * but does does no harm if defined nevertheless.
  204.  */
  205. /* #define PREFER_PORTABLE_SNPRINTF */
  206.  
  207. /* Define SNPRINTF_LONGLONG_SUPPORT if you want to support
  208.  * data type (long long int) and length modifier 'll' (e.g. %lld).
  209.  * If undefined, 'll' is recognized but treated as a single 'l'.
  210.  *
  211.  * If the system's sprintf does not handle 'll'
  212.  * the SNPRINTF_LONGLONG_SUPPORT must not be defined!
  213.  *
  214.  * This is off by default as (long long int) is a language extension.
  215.  */
  216. /* #define SNPRINTF_LONGLONG_SUPPORT */
  217.  
  218. /* Define NEED_SNPRINTF_ONLY if you only need snprintf, and not vsnprintf.
  219.  * If NEED_SNPRINTF_ONLY is defined, the snprintf will be defined directly,
  220.  * otherwise both snprintf and vsnprintf routines will be defined
  221.  * and snprintf will be a simple wrapper around vsnprintf, at the expense
  222.  * of an extra procedure call.
  223.  */
  224. /* #define NEED_SNPRINTF_ONLY */
  225.  
  226. /* Define NEED_V?ASN?PRINTF macros if you need library extension
  227.  * routines asprintf, vasprintf, asnprintf, vasnprintf respectively,
  228.  * and your system library does not provide them. They are all small
  229.  * wrapper routines around portable_vsnprintf. Defining any of the four
  230.  * NEED_V?ASN?PRINTF macros automatically turns off NEED_SNPRINTF_ONLY
  231.  * and turns on PREFER_PORTABLE_SNPRINTF.
  232.  *
  233.  * Watch for name conflicts with the system library if these routines
  234.  * are already present there.
  235.  *
  236.  * NOTE: vasprintf and vasnprintf routines need va_copy() from stdarg.h, as
  237.  * specified by C99, to be able to traverse the same list of arguments twice.
  238.  * I don't know of any other standard and portable way of achieving the same.
  239.  * With some versions of gcc you may use __va_copy(). You might even get away
  240.  * with "ap2 = ap", in this case you must not call va_end(ap2) !
  241.  *   #define va_copy(ap2,ap) ap2 = ap
  242.  */
  243. /* #define NEED_ASPRINTF   */
  244. /* #define NEED_ASNPRINTF  */
  245. /* #define NEED_VASPRINTF  */
  246. /* #define NEED_VASNPRINTF */
  247.  
  248.  
  249. /* Define the following macros if desired:
  250.  *   SOLARIS_COMPATIBLE, SOLARIS_BUG_COMPATIBLE,
  251.  *   HPUX_COMPATIBLE, HPUX_BUG_COMPATIBLE, LINUX_COMPATIBLE,
  252.  *   DIGITAL_UNIX_COMPATIBLE, DIGITAL_UNIX_BUG_COMPATIBLE,
  253.  *   PERL_COMPATIBLE, PERL_BUG_COMPATIBLE,
  254.  *
  255.  * - For portable applications it is best not to rely on peculiarities
  256.  *   of a given implementation so it may be best not to define any
  257.  *   of the macros that select compatibility and to avoid features
  258.  *   that vary among the systems.
  259.  *
  260.  * - Selecting compatibility with more than one operating system
  261.  *   is not strictly forbidden but is not recommended.
  262.  *
  263.  * - 'x'_BUG_COMPATIBLE implies 'x'_COMPATIBLE .
  264.  *
  265.  * - 'x'_COMPATIBLE refers to (and enables) a behaviour that is
  266.  *   documented in a sprintf man page on a given operating system
  267.  *   and actually adhered to by the system's sprintf (but not on
  268.  *   most other operating systems). It may also refer to and enable
  269.  *   a behaviour that is declared 'undefined' or 'implementation specific'
  270.  *   in the man page but a given implementation behaves predictably
  271.  *   in a certain way.
  272.  *
  273.  * - 'x'_BUG_COMPATIBLE refers to (and enables) a behaviour of system's sprintf
  274.  *   that contradicts the sprintf man page on the same operating system.
  275.  *
  276.  * - I do not claim that the 'x'_COMPATIBLE and 'x'_BUG_COMPATIBLE
  277.  *   conditionals take into account all idiosyncrasies of a particular
  278.  *   implementation, there may be other incompatibilities.
  279.  */
  280.  
  281.  
  283. /* ============================================= */
  284. /* NO USER SERVICABLE PARTS FOLLOWING THIS POINT */
  285. /* ============================================= */
  286.  
  287. #define PORTABLE_SNPRINTF_VERSION_MAJOR 2
  288. #define PORTABLE_SNPRINTF_VERSION_MINOR 2
  289.  
  290. #if defined(NEED_ASPRINTF) || defined(NEED_ASNPRINTF) || defined(NEED_VASPRINTF) || defined(NEED_VASNPRINTF)
  291. # if defined(NEED_SNPRINTF_ONLY)
  292. # undef NEED_SNPRINTF_ONLY
  293. # endif
  294. # if !defined(PREFER_PORTABLE_SNPRINTF)
  295. # define PREFER_PORTABLE_SNPRINTF
  296. # endif
  297. #endif
  298.  
  299. #if defined(SOLARIS_BUG_COMPATIBLE) && !defined(SOLARIS_COMPATIBLE)
  300. #define SOLARIS_COMPATIBLE
  301. #endif
  302.  
  303. #if defined(HPUX_BUG_COMPATIBLE) && !defined(HPUX_COMPATIBLE)
  304. #define HPUX_COMPATIBLE
  305. #endif
  306.  
  307. #if defined(DIGITAL_UNIX_BUG_COMPATIBLE) && !defined(DIGITAL_UNIX_COMPATIBLE)
  308. #define DIGITAL_UNIX_COMPATIBLE
  309. #endif
  310.  
  311. #if defined(PERL_BUG_COMPATIBLE) && !defined(PERL_COMPATIBLE)
  312. #define PERL_COMPATIBLE
  313. #endif
  314.  
  315. #if defined(LINUX_BUG_COMPATIBLE) && !defined(LINUX_COMPATIBLE)
  316. #define LINUX_COMPATIBLE
  317. #endif
  318.  
  319. #include <sys/types.h>
  320. #include <string.h>
  321. #include <stdlib.h>
  322. #include <stdio.h>
  323. #include <stdarg.h>
  324. #include <assert.h>
  325. #include <errno.h>
  326.  
  327. #ifdef isdigit
  328. #undef isdigit
  329. #endif
  330. #define isdigit(c) ((c) >= '0' && (c) <= '9')
  331.  
  332. /* For copying strings longer or equal to 'breakeven_point'
  333.  * it is more efficient to call memcpy() than to do it inline.
  334.  * The value depends mostly on the processor architecture,
  335.  * but also on the compiler and its optimization capabilities.
  336.  * The value is not critical, some small value greater than zero
  337.  * will be just fine if you don't care to squeeze every drop
  338.  * of performance out of the code.
  339.  *
  340.  * Small values favor memcpy, large values favor inline code.
  341.  */
  342. #if defined(__alpha__) || defined(__alpha)
  343. #  define breakeven_point   2   /* AXP (DEC Alpha)     - gcc or cc or egcs */
  344. #endif
  345. #if defined(__i386__)  || defined(__i386)
  346. #  define breakeven_point  12   /* Intel Pentium/Linux - gcc 2.96 */
  347. #endif
  348. #if defined(__hppa)
  349. #  define breakeven_point  10   /* HP-PA               - gcc */
  350. #endif
  351. #if defined(__sparc__) || defined(__sparc)
  352. #  define breakeven_point  33   /* Sun Sparc 5         - gcc 2.8.1 */
  353. #endif
  354.  
  355. /* some other values of possible interest: */
  356. /* #define breakeven_point  8 */  /* VAX 4000          - vaxc */
  357. /* #define breakeven_point 19 */  /* VAX 4000          - gcc 2.7.0 */
  358.  
  359. #ifndef breakeven_point
  360. #  define breakeven_point   6   /* some reasonable one-size-fits-all value */
  361. #endif
  362.  
  363. #define fast_memcpy(d,s,n) \
  364.   { register size_t nn = (size_t)(n); \
  365.     if (nn >= breakeven_point) memcpy((d), (s), nn); \
  366.     else if (nn > 0) { /* proc call overhead is worth only for large strings*/\
  367.       register char *dd; register const char *ss; \
  368.       for (ss=(s), dd=(d); nn>0; nn--) *dd++ = *ss++; } }
  369.  
  370. #define fast_memset(d,c,n) \
  371.   { register size_t nn = (size_t)(n); \
  372.     if (nn >= breakeven_point) memset((d), (int)(c), nn); \
  373.     else if (nn > 0) { /* proc call overhead is worth only for large strings*/\
  374.       register char *dd; register const int cc=(int)(c); \
  375.       for (dd=(d); nn>0; nn--) *dd++ = cc; } }
  376.  
  377. /* prototypes */
  378.  
  379. #if defined(NEED_ASPRINTF)
  380. int asprintf   (char **ptr, const char *fmt, /*args*/ ...);
  381. #endif
  382. #if defined(NEED_VASPRINTF)
  383. int vasprintf  (char **ptr, const char *fmt, va_list ap);
  384. #endif
  385. #if defined(NEED_ASNPRINTF)
  386. int asnprintf  (char **ptr, size_t str_m, const char *fmt, /*args*/ ...);
  387. #endif
  388. #if defined(NEED_VASNPRINTF)
  389. int vasnprintf (char **ptr, size_t str_m, const char *fmt, va_list ap);
  390. #endif
  391.  
  392. #if defined(HAVE_SNPRINTF)
  393. /* declare our portable snprintf  routine under name portable_snprintf  */
  394. /* declare our portable vsnprintf routine under name portable_vsnprintf */
  395. #else
  396. /* declare our portable routines under names snprintf and vsnprintf */
  397. #define portable_snprintf snprintf
  398. #if !defined(NEED_SNPRINTF_ONLY)
  399. #define portable_vsnprintf vsnprintf
  400. #endif
  401. #endif
  402.  
  403. #if !defined(HAVE_SNPRINTF) || defined(PREFER_PORTABLE_SNPRINTF)
  404. int portable_snprintf(char *str, size_t str_m, const char *fmt, /*args*/ ...);
  405. #if !defined(NEED_SNPRINTF_ONLY)
  406. int portable_vsnprintf(char *str, size_t str_m, const char *fmt, va_list ap);
  407. #endif
  408. #endif
  409.  
  410. /* declarations */
  411.  
  412. static char credits[] = "\n\
  413. @(#)snprintf.c, v2.2: Mark Martinec, <mark.martinec@ijs.si>\n\
  414. @(#)snprintf.c, v2.2: Copyright 1999, Mark Martinec. Frontier Artistic License applies.\n\
  415. @(#)snprintf.c, v2.2: http://www.ijs.si/software/snprintf/\n";
  416.  
  417. #if defined(NEED_ASPRINTF)
  418. int asprintf(char **ptr, const char *fmt, /*args*/ ...) {
  419.   va_list ap;
  420.   size_t str_m;
  421.   int str_l;
  422.  
  423.   *ptr = NULL;
  424.   va_start(ap, fmt);                            /* measure the required size */
  425.   str_l = portable_vsnprintf(NULL, (size_t)0, fmt, ap);
  426.   va_end(ap);
  427.   assert(str_l >= 0);        /* possible integer overflow if str_m > INT_MAX */
  428.   *ptr = (char *) malloc(str_m = (size_t)str_l + 1);
  429.   if (*ptr == NULL) { errno = ENOMEM; str_l = -1; }
  430.   else {
  431.     int str_l2;
  432.     va_start(ap, fmt);
  433.     str_l2 = portable_vsnprintf(*ptr, str_m, fmt, ap);
  434.     va_end(ap);
  435.     assert(str_l2 == str_l);
  436.   }
  437.   return str_l;
  438. }
  439. #endif
  440.  
  441. #if defined(NEED_VASPRINTF)
  442. int vasprintf(char **ptr, const char *fmt, va_list ap) {
  443.   size_t str_m;
  444.   int str_l;
  445.  
  446.   *ptr = NULL;
  447.   { va_list ap2;
  448.     va_copy(ap2, ap);  /* don't consume the original ap, we'll need it again */
  449.     str_l = portable_vsnprintf(NULL, (size_t)0, fmt, ap2);/*get required size*/
  450.     va_end(ap2);
  451.   }
  452.   assert(str_l >= 0);        /* possible integer overflow if str_m > INT_MAX */
  453.   *ptr = (char *) malloc(str_m = (size_t)str_l + 1);
  454.   if (*ptr == NULL) { errno = ENOMEM; str_l = -1; }
  455.   else {
  456.     int str_l2 = portable_vsnprintf(*ptr, str_m, fmt, ap);
  457.     assert(str_l2 == str_l);
  458.   }
  459.   return str_l;
  460. }
  461. #endif
  462.  
  463. #if defined(NEED_ASNPRINTF)
  464. int asnprintf (char **ptr, size_t str_m, const char *fmt, /*args*/ ...) {
  465.   va_list ap;
  466.   int str_l;
  467.  
  468.   *ptr = NULL;
  469.   va_start(ap, fmt);                            /* measure the required size */
  470.   str_l = portable_vsnprintf(NULL, (size_t)0, fmt, ap);
  471.   va_end(ap);
  472.   assert(str_l >= 0);        /* possible integer overflow if str_m > INT_MAX */
  473.   if ((size_t)str_l + 1 < str_m) str_m = (size_t)str_l + 1;      /* truncate */
  474.   /* if str_m is 0, no buffer is allocated, just set *ptr to NULL */
  475.   if (str_m == 0) {  /* not interested in resulting string, just return size */
  476.   } else {
  477.     *ptr = (char *) malloc(str_m);
  478.     if (*ptr == NULL) { errno = ENOMEM; str_l = -1; }
  479.     else {
  480.       int str_l2;
  481.       va_start(ap, fmt);
  482.       str_l2 = portable_vsnprintf(*ptr, str_m, fmt, ap);
  483.       va_end(ap);
  484.       assert(str_l2 == str_l);
  485.     }
  486.   }
  487.   return str_l;
  488. }
  489. #endif
  490.  
  491. #if defined(NEED_VASNPRINTF)
  492. int vasnprintf (char **ptr, size_t str_m, const char *fmt, va_list ap) {
  493.   int str_l;
  494.  
  495.   *ptr = NULL;
  496.   { va_list ap2;
  497.     va_copy(ap2, ap);  /* don't consume the original ap, we'll need it again */
  498.     str_l = portable_vsnprintf(NULL, (size_t)0, fmt, ap2);/*get required size*/
  499.     va_end(ap2);
  500.   }
  501.   assert(str_l >= 0);        /* possible integer overflow if str_m > INT_MAX */
  502.   if ((size_t)str_l + 1 < str_m) str_m = (size_t)str_l + 1;      /* truncate */
  503.   /* if str_m is 0, no buffer is allocated, just set *ptr to NULL */
  504.   if (str_m == 0) {  /* not interested in resulting string, just return size */
  505.   } else {
  506.     *ptr = (char *) malloc(str_m);
  507.     if (*ptr == NULL) { errno = ENOMEM; str_l = -1; }
  508.     else {
  509.       int str_l2 = portable_vsnprintf(*ptr, str_m, fmt, ap);
  510.       assert(str_l2 == str_l);
  511.     }
  512.   }
  513.   return str_l;
  514. }
  515. #endif
  516.  
  517. /*
  518.  * If the system does have snprintf and the portable routine is not
  519.  * specifically required, this module produces no code for snprintf/vsnprintf.
  520.  */
  521. #if !defined(HAVE_SNPRINTF) || defined(PREFER_PORTABLE_SNPRINTF)
  522.  
  523. #if !defined(NEED_SNPRINTF_ONLY)
  524. int portable_snprintf(char *str, size_t str_m, const char *fmt, /*args*/ ...) {
  525.   va_list ap;
  526.   int str_l;
  527.  
  528.   va_start(ap, fmt);
  529.   str_l = portable_vsnprintf(str, str_m, fmt, ap);
  530.   va_end(ap);
  531.   return str_l;
  532. }
  533. #endif
  534.  
  535. #if defined(NEED_SNPRINTF_ONLY)
  536. int portable_snprintf(char *str, size_t str_m, const char *fmt, /*args*/ ...) {
  537. #else
  538. int portable_vsnprintf(char *str, size_t str_m, const char *fmt, va_list ap) {
  539. #endif
  540.  
  541. #if defined(NEED_SNPRINTF_ONLY)
  542.   va_list ap;
  543. #endif
  544.   size_t str_l = 0;
  545.   const char *p = fmt;
  546.  
  547. /* In contrast with POSIX, the ISO C99 now says
  548.  * that str can be NULL and str_m can be 0.
  549.  * This is more useful than the old:  if (str_m < 1) return -1; */
  550.  
  551. #if defined(NEED_SNPRINTF_ONLY)
  552.   va_start(ap, fmt);
  553. #endif
  554.   if (!p) p = "";
  555.   while (*p) {
  556.     if (*p != '%') {
  557.    /* if (str_l < str_m) str[str_l++] = *p++;    -- this would be sufficient */
  558.    /* but the following code achieves better performance for cases
  559.     * where format string is long and contains few conversions */
  560.       const char *q = strchr(p+1,'%');
  561.       size_t n = !q ? strlen(p) : (q-p);
  562.       if (str_l < str_m) {
  563.         size_t avail = str_m-str_l;
  564.         fast_memcpy(str+str_l, p, (n>avail?avail:n));
  565.       }
  566.       p += n; str_l += n;
  567.     } else {
  568.       const char *starting_p;
  569.       size_t min_field_width = 0, precision = 0;
  570.       int zero_padding = 0, precision_specified = 0, justify_left = 0;
  571.       int alternate_form = 0, force_sign = 0;
  572.       int space_for_positive = 1; /* If both the ' ' and '+' flags appear,
  573.                                      the ' ' flag should be ignored. */
  574.       char length_modifier = '\0';            /* allowed values: \0, h, l, L */
  575.       char tmp[32];/* temporary buffer for simple numeric->string conversion */
  576.  
  577.       const char *str_arg;      /* string address in case of string argument */
  578.       size_t str_arg_l;         /* natural field width of arg without padding
  579.                                    and sign */
  580.       unsigned char uchar_arg;
  581.         /* unsigned char argument value - only defined for c conversion.
  582.            N.B. standard explicitly states the char argument for
  583.            the c conversion is unsigned */
  584.  
  585.       size_t number_of_zeros_to_pad = 0;
  586.         /* number of zeros to be inserted for numeric conversions
  587.            as required by the precision or minimal field width */
  588.  
  589.       size_t zero_padding_insertion_ind = 0;
  590.         /* index into tmp where zero padding is to be inserted */
  591.  
  592.       char fmt_spec = '\0';
  593.         /* current conversion specifier character */
  594.  
  595.       str_arg = credits;/* just to make compiler happy (defined but not used)*/
  596.       str_arg = NULL;
  597.       starting_p = p; p++;  /* skip '%' */
  598.    /* parse flags */
  599.       while (*p == '0' || *p == '-' || *p == '+' ||
  600.              *p == ' ' || *p == '#' || *p == '\'') {
  601.         switch (*p) {
  602.         case '0': zero_padding = 1; break;
  603.         case '-': justify_left = 1; break;
  604.         case '+': force_sign = 1; space_for_positive = 0; break;
  605.         case ' ': force_sign = 1;
  606.      /* If both the ' ' and '+' flags appear, the ' ' flag should be ignored */
  607. #ifdef PERL_COMPATIBLE
  608.      /* ... but in Perl the last of ' ' and '+' applies */
  609.                   space_for_positive = 1;
  610. #endif
  611.                   break;
  612.         case '#': alternate_form = 1; break;
  613.         case '\'': break;
  614.         }
  615.         p++;
  616.       }
  617.    /* If the '0' and '-' flags both appear, the '0' flag should be ignored. */
  618.  
  619.    /* parse field width */
  620.       if (*p == '*') {
  621.         int j;
  622.         p++; j = va_arg(ap, int);
  623.         if (j >= 0) min_field_width = j;
  624.         else { min_field_width = -j; justify_left = 1; }
  625.       } else if (isdigit((int)(*p))) {
  626.         /* size_t could be wider than unsigned int;
  627.            make sure we treat argument like common implementations do */
  628.         unsigned int uj = *p++ - '0';
  629.         while (isdigit((int)(*p))) uj = 10*uj + (unsigned int)(*p++ - '0');
  630.         min_field_width = uj;
  631.       }
  632.    /* parse precision */
  633.       if (*p == '.') {
  634.         p++; precision_specified = 1;
  635.         if (*p == '*') {
  636.           int j = va_arg(ap, int);
  637.           p++;
  638.           if (j >= 0) precision = j;
  639.           else {
  640.             precision_specified = 0; precision = 0;
  641.          /* NOTE:
  642.           *   Solaris 2.6 man page claims that in this case the precision
  643.           *   should be set to 0.  Digital Unix 4.0, HPUX 10 and BSD man page
  644.           *   claim that this case should be treated as unspecified precision,
  645.           *   which is what we do here.
  646.           */
  647.           }
  648.         } else if (isdigit((int)(*p))) {
  649.           /* size_t could be wider than unsigned int;
  650.              make sure we treat argument like common implementations do */
  651.           unsigned int uj = *p++ - '0';
  652.           while (isdigit((int)(*p))) uj = 10*uj + (unsigned int)(*p++ - '0');
  653.           precision = uj;
  654.         }
  655.       }
  656.    /* parse 'h', 'l' and 'll' length modifiers */
  657.       if (*p == 'h' || *p == 'l') {
  658.         length_modifier = *p; p++;
  659.         if (length_modifier == 'l' && *p == 'l') {   /* double l = long long */
  660. #ifdef SNPRINTF_LONGLONG_SUPPORT
  661.           length_modifier = '2';                  /* double l encoded as '2' */
  662. #else
  663.           length_modifier = 'l';                 /* treat it as a single 'l' */
  664. #endif
  665.           p++;
  666.         }
  667.       }
  668.       fmt_spec = *p;
  669.    /* common synonyms: */
  670.       switch (fmt_spec) {
  671.       case 'i': fmt_spec = 'd'; break;
  672.       case 'D': fmt_spec = 'd'; length_modifier = 'l'; break;
  673.       case 'U': fmt_spec = 'u'; length_modifier = 'l'; break;
  674.       case 'O': fmt_spec = 'o'; length_modifier = 'l'; break;
  675.       default: break;
  676.       }
  677.    /* get parameter value, do initial processing */
  678.       switch (fmt_spec) {
  679.       case '%': /* % behaves similar to 's' regarding flags and field widths */
  680.       case 'c': /* c behaves similar to 's' regarding flags and field widths */
  681.       case 's':
  682.         length_modifier = '\0';          /* wint_t and wchar_t not supported */
  683.      /* the result of zero padding flag with non-numeric conversion specifier*/
  684.      /* is undefined. Solaris and HPUX 10 does zero padding in this case,    */
  685.      /* Digital Unix and Linux does not. */
  686. #if !defined(SOLARIS_COMPATIBLE) && !defined(HPUX_COMPATIBLE)
  687.         zero_padding = 0;    /* turn zero padding off for string conversions */
  688. #endif
  689.         str_arg_l = 1;
  690.         switch (fmt_spec) {
  691.         case '%':
  692.           str_arg = p; break;
  693.         case 'c': {
  694.           int j = va_arg(ap, int);
  695.           uchar_arg = (unsigned char) j;   /* standard demands unsigned char */
  696.           str_arg = (const char *) &uchar_arg;
  697.           break;
  698.         }
  699.         case 's':
  700.           str_arg = va_arg(ap, const char *);
  701.           if (!str_arg) str_arg_l = 0;
  702.        /* make sure not to address string beyond the specified precision !!! */
  703.           else if (!precision_specified) str_arg_l = strlen(str_arg);
  704.        /* truncate string if necessary as requested by precision */
  705.           else if (precision == 0) str_arg_l = 0;
  706.           else {
  707.        /* memchr on HP does not like n > 2^31  !!! */
  708.             const char *q = memchr(str_arg, '\0',
  709.                              precision <= 0x7fffffff ? precision : 0x7fffffff);
  710.             str_arg_l = !q ? precision : (q-str_arg);
  711.           }
  712.           break;
  713.         default: break;
  714.         }
  715.         break;
  716.       case 'd': case 'u': case 'o': case 'x': case 'X': case 'p': {
  717.         /* NOTE: the u, o, x, X and p conversion specifiers imply
  718.                  the value is unsigned;  d implies a signed value */
  719.  
  720.         int arg_sign = 0;
  721.           /* 0 if numeric argument is zero (or if pointer is NULL for 'p'),
  722.             +1 if greater than zero (or nonzero for unsigned arguments),
  723.             -1 if negative (unsigned argument is never negative) */
  724.  
  725.         int int_arg = 0;  unsigned int uint_arg = 0;
  726.           /* only defined for length modifier h, or for no length modifiers */
  727.  
  728.         long int long_arg = 0;  unsigned long int ulong_arg = 0;
  729.           /* only defined for length modifier l */
  730.  
  731.         void *ptr_arg = NULL;
  732.           /* pointer argument value -only defined for p conversion */
  733.  
  734. #ifdef SNPRINTF_LONGLONG_SUPPORT
  735.         long long int long_long_arg = 0;
  736.         unsigned long long int ulong_long_arg = 0;
  737.           /* only defined for length modifier ll */
  738. #endif
  739.         if (fmt_spec == 'p') {
  740.         /* HPUX 10: An l, h, ll or L before any other conversion character
  741.          *   (other than d, i, u, o, x, or X) is ignored.
  742.          * Digital Unix:
  743.          *   not specified, but seems to behave as HPUX does.
  744.          * Solaris: If an h, l, or L appears before any other conversion
  745.          *   specifier (other than d, i, u, o, x, or X), the behavior
  746.          *   is undefined. (Actually %hp converts only 16-bits of address
  747.          *   and %llp treats address as 64-bit data which is incompatible
  748.          *   with (void *) argument on a 32-bit system).
  749.          */
  750. #ifdef SOLARIS_COMPATIBLE
  751. #  ifdef SOLARIS_BUG_COMPATIBLE
  752.           /* keep length modifiers even if it represents 'll' */
  753. #  else
  754.           if (length_modifier == '2') length_modifier = '\0';
  755. #  endif
  756. #else
  757.           length_modifier = '\0';
  758. #endif
  759.           ptr_arg = va_arg(ap, void *);
  760.           if (ptr_arg != NULL) arg_sign = 1;
  761.         } else if (fmt_spec == 'd') {  /* signed */
  762.           switch (length_modifier) {
  763.           case '\0':
  764.           case 'h':
  765.          /* It is non-portable to specify a second argument of char or short
  766.           * to va_arg, because arguments seen by the called function
  767.           * are not char or short.  C converts char and short arguments
  768.           * to int before passing them to a function.
  769.           */
  770.             int_arg = va_arg(ap, int);
  771.             if      (int_arg > 0) arg_sign =  1;
  772.             else if (int_arg < 0) arg_sign = -1;
  773.             break;
  774.           case 'l':
  775.             long_arg = va_arg(ap, long int);
  776.             if      (long_arg > 0) arg_sign =  1;
  777.             else if (long_arg < 0) arg_sign = -1;
  778.             break;
  779. #ifdef SNPRINTF_LONGLONG_SUPPORT
  780.           case '2':
  781.             long_long_arg = va_arg(ap, long long int);
  782.             if      (long_long_arg > 0) arg_sign =  1;
  783.             else if (long_long_arg < 0) arg_sign = -1;
  784.             break;
  785. #endif
  786.           }
  787.         } else {  /* unsigned */
  788.           switch (length_modifier) {
  789.           case '\0':
  790.           case 'h':
  791.             uint_arg = va_arg(ap, unsigned int);
  792.             if (uint_arg) arg_sign = 1;
  793.             break;
  794.           case 'l':
  795.             ulong_arg = va_arg(ap, unsigned long int);
  796.             if (ulong_arg) arg_sign = 1;
  797.             break;
  798. #ifdef SNPRINTF_LONGLONG_SUPPORT
  799.           case '2':
  800.             ulong_long_arg = va_arg(ap, unsigned long long int);
  801.             if (ulong_long_arg) arg_sign = 1;
  802.             break;
  803. #endif
  804.           }
  805.         }
  806.         str_arg = tmp; str_arg_l = 0;
  807.      /* NOTE:
  808.       *   For d, i, u, o, x, and X conversions, if precision is specified,
  809.       *   the '0' flag should be ignored. This is so with Solaris 2.6,
  810.       *   Digital UNIX 4.0, HPUX 10, Linux, FreeBSD, NetBSD; but not with Perl.
  811.       */
  812. #ifndef PERL_COMPATIBLE
  813.         if (precision_specified) zero_padding = 0;
  814. #endif
  815.         if (fmt_spec == 'd') {
  816.           if (force_sign && arg_sign >= 0)
  817.             tmp[str_arg_l++] = space_for_positive ? ' ' : '+';
  818.          /* leave negative numbers for sprintf to handle,
  819.             to avoid handling tricky cases like (short int)(-32768) */
  820. #ifdef LINUX_COMPATIBLE
  821.         } else if (fmt_spec == 'p' && force_sign && arg_sign > 0) {
  822.           tmp[str_arg_l++] = space_for_positive ? ' ' : '+';
  823. #endif
  824.         } else if (alternate_form) {
  825.           if (arg_sign != 0 && (fmt_spec == 'x' || fmt_spec == 'X') )
  826.             { tmp[str_arg_l++] = '0'; tmp[str_arg_l++] = fmt_spec; }
  827.          /* alternate form should have no effect for p conversion, but ... */
  828. #ifdef HPUX_COMPATIBLE
  829.           else if (fmt_spec == 'p'
  830.          /* HPUX 10: for an alternate form of p conversion,
  831.           *          a nonzero result is prefixed by 0x. */
  832. #ifndef HPUX_BUG_COMPATIBLE
  833.          /* Actually it uses 0x prefix even for a zero value. */
  834.                    && arg_sign != 0
  835. #endif
  836.                   ) { tmp[str_arg_l++] = '0'; tmp[str_arg_l++] = 'x'; }
  837. #endif
  838.         }
  839.         zero_padding_insertion_ind = str_arg_l;
  840.         if (!precision_specified) precision = 1;   /* default precision is 1 */
  841.         if (precision == 0 && arg_sign == 0
  842. #if defined(HPUX_BUG_COMPATIBLE) || defined(LINUX_COMPATIBLE)
  843.             && fmt_spec != 'p'
  844.          /* HPUX 10 man page claims: With conversion character p the result of
  845.           * converting a zero value with a precision of zero is a null string.
  846.           * Actually HP returns all zeroes, and Linux returns "(nil)". */
  847. #endif
  848.         ) {
  849.          /* converted to null string */
  850.          /* When zero value is formatted with an explicit precision 0,
  851.             the resulting formatted string is empty (d, i, u, o, x, X, p).   */
  852.         } else {
  853.           char f[5]; int f_l = 0;
  854.           f[f_l++] = '%';    /* construct a simple format string for sprintf */
  855.           if (!length_modifier) { }
  856.           else if (length_modifier=='2') { f[f_l++] = 'l'; f[f_l++] = 'l'; }
  857.           else f[f_l++] = length_modifier;
  858.           f[f_l++] = fmt_spec; f[f_l++] = '\0';
  859.           if (fmt_spec == 'p') str_arg_l += sprintf(tmp+str_arg_l, f, ptr_arg);
  860.           else if (fmt_spec == 'd') {  /* signed */
  861.             switch (length_modifier) {
  862.             case '\0':
  863.             case 'h': str_arg_l+=sprintf(tmp+str_arg_l, f, int_arg);  break;
  864.             case 'l': str_arg_l+=sprintf(tmp+str_arg_l, f, long_arg); break;
  865. #ifdef SNPRINTF_LONGLONG_SUPPORT
  866.             case '2': str_arg_l+=sprintf(tmp+str_arg_l,f,long_long_arg); break;
  867. #endif
  868.             }
  869.           } else {  /* unsigned */
  870.             switch (length_modifier) {
  871.             case '\0':
  872.             case 'h': str_arg_l+=sprintf(tmp+str_arg_l, f, uint_arg);  break;
  873.             case 'l': str_arg_l+=sprintf(tmp+str_arg_l, f, ulong_arg); break;
  874. #ifdef SNPRINTF_LONGLONG_SUPPORT
  875.             case '2': str_arg_l+=sprintf(tmp+str_arg_l,f,ulong_long_arg);break;
  876. #endif
  877.             }
  878.           }
  879.          /* include the optional minus sign and possible "0x"
  880.             in the region before the zero padding insertion point */
  881.           if (zero_padding_insertion_ind < str_arg_l &&
  882.               tmp[zero_padding_insertion_ind] == '-') {
  883.             zero_padding_insertion_ind++;
  884.           }
  885.           if (zero_padding_insertion_ind+1 < str_arg_l &&
  886.               tmp[zero_padding_insertion_ind]   == '0' &&
  887.              (tmp[zero_padding_insertion_ind+1] == 'x' ||
  888.               tmp[zero_padding_insertion_ind+1] == 'X') ) {
  889.             zero_padding_insertion_ind += 2;
  890.           }
  891.         }
  892.         { size_t num_of_digits = str_arg_l - zero_padding_insertion_ind;
  893.           if (alternate_form && fmt_spec == 'o'
  894. #ifdef HPUX_COMPATIBLE                                  /* ("%#.o",0) -> ""  */
  895.               && (str_arg_l > 0)
  896. #endif
  897. #ifdef DIGITAL_UNIX_BUG_COMPATIBLE                      /* ("%#o",0) -> "00" */
  898. #else
  899.               /* unless zero is already the first character */
  900.               && !(zero_padding_insertion_ind < str_arg_l
  901.                    && tmp[zero_padding_insertion_ind] == '0')
  902. #endif
  903.           ) {        /* assure leading zero for alternate-form octal numbers */
  904.             if (!precision_specified || precision < num_of_digits+1) {
  905.              /* precision is increased to force the first character to be zero,
  906.                 except if a zero value is formatted with an explicit precision
  907.                 of zero */
  908.               precision = num_of_digits+1; precision_specified = 1;
  909.             }
  910.           }
  911.        /* zero padding to specified precision? */
  912.           if (num_of_digits < precision)
  913.             number_of_zeros_to_pad = precision - num_of_digits;
  914.         }
  915.      /* zero padding to specified minimal field width? */
  916.         if (!justify_left && zero_padding) {
  917.           int n = min_field_width - (str_arg_l+number_of_zeros_to_pad);
  918.           if (n > 0) number_of_zeros_to_pad += n;
  919.         }
  920.         break;
  921.       }
  922.       default: /* unrecognized conversion specifier, keep format string as-is*/
  923.         zero_padding = 0;  /* turn zero padding off for non-numeric convers. */
  924. #ifndef DIGITAL_UNIX_COMPATIBLE
  925.         justify_left = 1; min_field_width = 0;                /* reset flags */
  926. #endif
  927. #if defined(PERL_COMPATIBLE) || defined(LINUX_COMPATIBLE)
  928.      /* keep the entire format string unchanged */
  929.         str_arg = starting_p; str_arg_l = p - starting_p;
  930.      /* well, not exactly so for Linux, which does something inbetween,
  931.       * and I don't feel an urge to imitate it: "%+++++hy" -> "%+y"  */
  932. #else
  933.      /* discard the unrecognized conversion, just keep *
  934.       * the unrecognized conversion character          */
  935.         str_arg = p; str_arg_l = 0;
  936. #endif
  937.         if (*p) str_arg_l++;  /* include invalid conversion specifier unchanged
  938.                                  if not at end-of-string */
  939.         break;
  940.       }
  941.       if (*p) p++;      /* step over the just processed conversion specifier */
  942.    /* insert padding to the left as requested by min_field_width;
  943.       this does not include the zero padding in case of numerical conversions*/
  944.       if (!justify_left) {                /* left padding with blank or zero */
  945.         int n = min_field_width - (str_arg_l+number_of_zeros_to_pad);
  946.         if (n > 0) {
  947.           if (str_l < str_m) {
  948.             size_t avail = str_m-str_l;
  949.             fast_memset(str+str_l, (zero_padding?'0':' '), (n>avail?avail:n));
  950.           }
  951.           str_l += n;
  952.         }
  953.       }
  954.    /* zero padding as requested by the precision or by the minimal field width
  955.     * for numeric conversions required? */
  956.       if (number_of_zeros_to_pad <= 0) {
  957.      /* will not copy first part of numeric right now, *
  958.       * force it to be copied later in its entirety    */
  959.         zero_padding_insertion_ind = 0;
  960.       } else {
  961.      /* insert first part of numerics (sign or '0x') before zero padding */
  962.         int n = zero_padding_insertion_ind;
  963.         if (n > 0) {
  964.           if (str_l < str_m) {
  965.             size_t avail = str_m-str_l;
  966.             fast_memcpy(str+str_l, str_arg, (n>avail?avail:n));
  967.           }
  968.           str_l += n;
  969.         }
  970.      /* insert zero padding as requested by the precision or min field width */
  971.         n = number_of_zeros_to_pad;
  972.         if (n > 0) {
  973.           if (str_l < str_m) {
  974.             size_t avail = str_m-str_l;
  975.             fast_memset(str+str_l, '0', (n>avail?avail:n));
  976.           }
  977.           str_l += n;
  978.         }
  979.       }
  980.    /* insert formatted string
  981.     * (or as-is conversion specifier for unknown conversions) */
  982.       { int n = str_arg_l - zero_padding_insertion_ind;
  983.         if (n > 0) {
  984.           if (str_l < str_m) {
  985.             size_t avail = str_m-str_l;
  986.             fast_memcpy(str+str_l, str_arg+zero_padding_insertion_ind,
  987.                         (n>avail?avail:n));
  988.           }
  989.           str_l += n;
  990.         }
  991.       }
  992.    /* insert right padding */
  993.       if (justify_left) {          /* right blank padding to the field width */
  994.         int n = min_field_width - (str_arg_l+number_of_zeros_to_pad);
  995.         if (n > 0) {
  996.           if (str_l < str_m) {
  997.             size_t avail = str_m-str_l;
  998.             fast_memset(str+str_l, ' ', (n>avail?avail:n));
  999.           }
  1000.           str_l += n;
  1001.         }
  1002.       }
  1003.     }
  1004.   }
  1005. #if defined(NEED_SNPRINTF_ONLY)
  1006.   va_end(ap);
  1007. #endif
  1008.   if (str_m > 0) { /* make sure the string is null-terminated
  1009.                       even at the expense of overwriting the last character
  1010.                       (shouldn't happen, but just in case) */
  1011.     str[str_l <= str_m-1 ? str_l : str_m-1] = '\0';
  1012.   }
  1013.   /* Return the number of characters formatted (excluding trailing null
  1014.    * character), that is, the number of characters that would have been
  1015.    * written to the buffer if it were large enough.
  1016.    *
  1017.    * The value of str_l should be returned, but str_l is of unsigned type
  1018.    * size_t, and snprintf is int, possibly leading to an undetected
  1019.    * integer overflow, resulting in a negative return value, which is illegal.
  1020.    * Both XSH5 and ISO C99 (at least the draft) are silent on this issue.
  1021.    * Should errno be set to EOVERFLOW and EOF returned in this case???
  1022.    */
  1023.   return (int) str_l;
  1024. }
  1025. #endif
  1026.