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vsnprintf_ss.c revision 1.7 
      1 /*	$NetBSD: vsnprintf_ss.c,v 1.7 2009/10/24 15:20:15 dsl Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Chris Torek.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 #include <sys/cdefs.h>
     36 #if defined(LIBC_SCCS) && !defined(lint)
     37 #if 0
     38 static char sccsid[] = "@(#)vsnprintf.c	8.1 (Berkeley) 6/4/93";
     39 #else
     40 __RCSID("$NetBSD: vsnprintf_ss.c,v 1.7 2009/10/24 15:20:15 dsl Exp $");
     41 #endif
     42 #endif /* LIBC_SCCS and not lint */
     43 
     44 #include "namespace.h"
     45 
     46 #include <sys/types.h>
     47 #include <inttypes.h>
     48 #include <assert.h>
     49 #include <stdio.h>
     50 #include <errno.h>
     51 #include <stdarg.h>
     52 #include <string.h>
     53 #include "reentrant.h"
     54 #include "extern.h"
     55 #include "local.h"
     56 
     57 #ifdef __weak_alias
     58 __weak_alias(vsnprintf_ss,_vsnprintf_ss)
     59 #endif
     60 
     61 /*
     62  * vsnprintf_ss: scaled down version of printf(3).
     63  *
     64  * this version based on vfprintf() from libc which was derived from
     65  * software contributed to Berkeley by Chris Torek.
     66  *
     67  */
     68 
     69 /*
     70  * macros for converting digits to letters and vice versa
     71  */
     72 #define	to_digit(c)	((c) - '0')
     73 #define is_digit(c)	((unsigned)to_digit(c) <= 9)
     74 #define	to_char(n)	(char)((n) + '0')
     75 
     76 /*
     77  * flags used during conversion.
     78  */
     79 #define	ALT		0x001		/* alternate form */
     80 #define	HEXPREFIX	0x002		/* add 0x or 0X prefix */
     81 #define	LADJUST		0x004		/* left adjustment */
     82 #define	LONGDBL		0x008		/* long double; unimplemented */
     83 #define	LONGINT		0x010		/* long integer */
     84 #define	QUADINT		0x020		/* quad integer */
     85 #define	SHORTINT	0x040		/* short integer */
     86 #define	MAXINT		0x080		/* intmax_t */
     87 #define	PTRINT		0x100		/* intptr_t */
     88 #define	SIZEINT		0x200		/* size_t */
     89 #define	ZEROPAD		0x400		/* zero (as opposed to blank) pad */
     90 #define FPT		0x800		/* Floating point number */
     91 
     92 	/*
     93 	 * To extend shorts properly, we need both signed and unsigned
     94 	 * argument extraction methods.
     95 	 */
     96 #define	SARG() \
     97 	(flags&MAXINT ? va_arg(ap, intmax_t) : \
     98 	    flags&PTRINT ? va_arg(ap, intptr_t) : \
     99 	    flags&SIZEINT ? va_arg(ap, ssize_t) : /* XXX */ \
    100 	    flags&QUADINT ? va_arg(ap, quad_t) : \
    101 	    flags&LONGINT ? va_arg(ap, long) : \
    102 	    flags&SHORTINT ? (long)(short)va_arg(ap, int) : \
    103 	    (long)va_arg(ap, int))
    104 #define	UARG() \
    105 	(flags&MAXINT ? va_arg(ap, uintmax_t) : \
    106 	    flags&PTRINT ? va_arg(ap, uintptr_t) : \
    107 	    flags&SIZEINT ? va_arg(ap, size_t) : \
    108 	    flags&QUADINT ? va_arg(ap, u_quad_t) : \
    109 	    flags&LONGINT ? va_arg(ap, u_long) : \
    110 	    flags&SHORTINT ? (u_long)(u_short)va_arg(ap, int) : \
    111 	    (u_long)va_arg(ap, u_int))
    112 
    113 #define PUTCHAR(C) do {					\
    114 	if (sbuf < tailp)				\
    115 		*sbuf++ = (C);				\
    116 } while (/*CONSTCOND*/0)
    117 
    118 int
    119 vsnprintf_ss(char *sbuf, size_t slen, const char *fmt0, _BSD_VA_LIST_ ap)
    120 {
    121 	const char *fmt;	/* format string */
    122 	int ch;			/* character from fmt */
    123 	int n;			/* handy integer (short term usage) */
    124 	char *cp;		/* handy char pointer (short term usage) */
    125 	int flags;		/* flags as above */
    126 	int ret;		/* return value accumulator */
    127 	int width;		/* width from format (%8d), or 0 */
    128 	int prec;		/* precision from format (%.3d), or -1 */
    129 	char sign;		/* sign prefix (' ', '+', '-', or \0) */
    130 
    131 	u_quad_t _uquad;	/* integer arguments %[diouxX] */
    132 	enum { OCT, DEC, HEX } base;/* base for [diouxX] conversion */
    133 	int dprec;		/* a copy of prec if [diouxX], 0 otherwise */
    134 	int realsz;		/* field size expanded by dprec */
    135 	int size;		/* size of converted field or string */
    136 	const char *xdigs;	/* digits for [xX] conversion */
    137 	char bf[128]; 		/* space for %c, %[diouxX] */
    138 	char *tailp;		/* tail pointer for snprintf */
    139 
    140 	static const char xdigs_lower[16] = "0123456789abcdef";
    141 	static const char xdigs_upper[16] = "0123456789ABCDEF";
    142 
    143 	_DIAGASSERT(slen == 0 || sbuf != NULL);
    144 	_DIAGASSERT(fmt0 != NULL);
    145 
    146 	if ((int)slen < 0) {
    147 		errno = EINVAL;
    148 		return (-1);
    149 	}
    150 
    151 	tailp = sbuf + slen;
    152 
    153 	cp = NULL;	/* XXX: shutup gcc */
    154 	size = 0;	/* XXX: shutup gcc */
    155 
    156 	fmt = fmt0;
    157 	ret = 0;
    158 
    159 	xdigs = NULL;		/* XXX: shut up gcc warning */
    160 
    161 	/*
    162 	 * Scan the format for conversions (`%' character).
    163 	 */
    164 	for (;;) {
    165 		while (*fmt != '%' && *fmt) {
    166 			ret++;
    167 			PUTCHAR(*fmt++);
    168 		}
    169 		if (*fmt == 0)
    170 			goto done;
    171 
    172 		fmt++;		/* skip over '%' */
    173 
    174 		flags = 0;
    175 		dprec = 0;
    176 		width = 0;
    177 		prec = -1;
    178 		sign = '\0';
    179 
    180 rflag:		ch = *fmt++;
    181 reswitch:	switch (ch) {
    182 		case ' ':
    183 			/*
    184 			 * ``If the space and + flags both appear, the space
    185 			 * flag will be ignored.''
    186 			 *	-- ANSI X3J11
    187 			 */
    188 			if (!sign)
    189 				sign = ' ';
    190 			goto rflag;
    191 		case '#':
    192 			flags |= ALT;
    193 			goto rflag;
    194 		case '*':
    195 			/*
    196 			 * ``A negative field width argument is taken as a
    197 			 * - flag followed by a positive field width.''
    198 			 *	-- ANSI X3J11
    199 			 * They don't exclude field widths read from args.
    200 			 */
    201 			if ((width = va_arg(ap, int)) >= 0)
    202 				goto rflag;
    203 			width = -width;
    204 			/* FALLTHROUGH */
    205 		case '-':
    206 			flags |= LADJUST;
    207 			goto rflag;
    208 		case '+':
    209 			sign = '+';
    210 			goto rflag;
    211 		case '.':
    212 			if ((ch = *fmt++) == '*') {
    213 				n = va_arg(ap, int);
    214 				prec = n < 0 ? -1 : n;
    215 				goto rflag;
    216 			}
    217 			n = 0;
    218 			while (is_digit(ch)) {
    219 				n = 10 * n + to_digit(ch);
    220 				ch = *fmt++;
    221 			}
    222 			prec = n < 0 ? -1 : n;
    223 			goto reswitch;
    224 		case '0':
    225 			/*
    226 			 * ``Note that 0 is taken as a flag, not as the
    227 			 * beginning of a field width.''
    228 			 *	-- ANSI X3J11
    229 			 */
    230 			flags |= ZEROPAD;
    231 			goto rflag;
    232 		case '1': case '2': case '3': case '4':
    233 		case '5': case '6': case '7': case '8': case '9':
    234 			n = 0;
    235 			do {
    236 				n = 10 * n + to_digit(ch);
    237 				ch = *fmt++;
    238 			} while (is_digit(ch));
    239 			width = n;
    240 			goto reswitch;
    241 		case 'h':
    242 			flags |= SHORTINT;
    243 			goto rflag;
    244 		case 'j':
    245 			flags |= MAXINT;
    246 			goto rflag;
    247 		case 'l':
    248 			if (*fmt == 'l') {
    249 				fmt++;
    250 				flags |= QUADINT;
    251 			} else {
    252 				flags |= LONGINT;
    253 			}
    254 			goto rflag;
    255 		case 'q':
    256 			flags |= QUADINT;
    257 			goto rflag;
    258 		case 't':
    259 			flags |= PTRINT;
    260 			goto rflag;
    261 		case 'z':
    262 			flags |= SIZEINT;
    263 			goto rflag;
    264 		case 'c':
    265 			*(cp = bf) = va_arg(ap, int);
    266 			size = 1;
    267 			sign = '\0';
    268 			break;
    269 		case 'D':
    270 			flags |= LONGINT;
    271 			/*FALLTHROUGH*/
    272 		case 'd':
    273 		case 'i':
    274 			_uquad = SARG();
    275 			if ((quad_t)_uquad < 0) {
    276 				_uquad = -_uquad;
    277 				sign = '-';
    278 			}
    279 			base = DEC;
    280 			goto number;
    281 		case 'n':
    282 			if (flags & MAXINT)
    283 				*va_arg(ap, intmax_t *) = ret;
    284 			else if (flags & PTRINT)
    285 				*va_arg(ap, intptr_t *) = ret;
    286 			else if (flags & SIZEINT)
    287 				*va_arg(ap, ssize_t *) = ret;
    288 			else if (flags & QUADINT)
    289 				*va_arg(ap, quad_t *) = ret;
    290 			else if (flags & LONGINT)
    291 				*va_arg(ap, long *) = ret;
    292 			else if (flags & SHORTINT)
    293 				*va_arg(ap, short *) = ret;
    294 			else
    295 				*va_arg(ap, int *) = ret;
    296 			continue;	/* no output */
    297 		case 'O':
    298 			flags |= LONGINT;
    299 			/*FALLTHROUGH*/
    300 		case 'o':
    301 			_uquad = UARG();
    302 			base = OCT;
    303 			goto nosign;
    304 		case 'p':
    305 			/*
    306 			 * ``The argument shall be a pointer to void.  The
    307 			 * value of the pointer is converted to a sequence
    308 			 * of printable characters, in an implementation-
    309 			 * defined manner.''
    310 			 *	-- ANSI X3J11
    311 			 */
    312 			/* NOSTRICT */
    313 			_uquad = (u_long)va_arg(ap, void *);
    314 			base = HEX;
    315 			xdigs = xdigs_lower;
    316 			flags |= HEXPREFIX;
    317 			ch = 'x';
    318 			goto nosign;
    319 		case 's':
    320 			if ((cp = va_arg(ap, char *)) == NULL)
    321 				/*XXXUNCONST*/
    322 				cp = __UNCONST("(null)");
    323 			if (prec >= 0) {
    324 				/*
    325 				 * can't use strlen; can only look for the
    326 				 * NUL in the first `prec' characters, and
    327 				 * strlen() will go further.
    328 				 */
    329 				char *p = memchr(cp, 0, prec);
    330 
    331 				if (p != NULL) {
    332 					size = p - cp;
    333 					if (size > prec)
    334 						size = prec;
    335 				} else
    336 					size = prec;
    337 			} else
    338 				size = strlen(cp);
    339 			sign = '\0';
    340 			break;
    341 		case 'U':
    342 			flags |= LONGINT;
    343 			/*FALLTHROUGH*/
    344 		case 'u':
    345 			_uquad = UARG();
    346 			base = DEC;
    347 			goto nosign;
    348 		case 'X':
    349 			xdigs = xdigs_upper;
    350 			goto hex;
    351 		case 'x':
    352 			xdigs = xdigs_lower;
    353 hex:			_uquad = UARG();
    354 			base = HEX;
    355 			/* leading 0x/X only if non-zero */
    356 			if (flags & ALT && _uquad != 0)
    357 				flags |= HEXPREFIX;
    358 
    359 			/* unsigned conversions */
    360 nosign:			sign = '\0';
    361 			/*
    362 			 * ``... diouXx conversions ... if a precision is
    363 			 * specified, the 0 flag will be ignored.''
    364 			 *	-- ANSI X3J11
    365 			 */
    366 number:			if ((dprec = prec) >= 0)
    367 				flags &= ~ZEROPAD;
    368 
    369 			/*
    370 			 * ``The result of converting a zero value with an
    371 			 * explicit precision of zero is no characters.''
    372 			 *	-- ANSI X3J11
    373 			 */
    374 			cp = bf + sizeof(bf);
    375 			if (_uquad != 0 || prec != 0) {
    376 				/*
    377 				 * Unsigned mod is hard, and unsigned mod
    378 				 * by a constant is easier than that by
    379 				 * a variable; hence this switch.
    380 				 */
    381 				switch (base) {
    382 				case OCT:
    383 					do {
    384 						*--cp = to_char(_uquad & 7);
    385 						_uquad >>= 3;
    386 					} while (_uquad);
    387 					/* handle octal leading 0 */
    388 					if (flags & ALT && *cp != '0')
    389 						*--cp = '0';
    390 					break;
    391 
    392 				case DEC:
    393 					/* many numbers are 1 digit */
    394 					while (_uquad >= 10) {
    395 						*--cp = to_char(_uquad % 10);
    396 						_uquad /= 10;
    397 					}
    398 					*--cp = to_char(_uquad);
    399 					break;
    400 
    401 				case HEX:
    402 					do {
    403 						*--cp = xdigs[_uquad & 15];
    404 						_uquad >>= 4;
    405 					} while (_uquad);
    406 					break;
    407 
    408 				default:
    409 					/*XXXUNCONST*/
    410 					cp = __UNCONST("bug bad base");
    411 					size = strlen(cp);
    412 					goto skipsize;
    413 				}
    414 			}
    415 			size = bf + sizeof(bf) - cp;
    416 		skipsize:
    417 			break;
    418 		default:	/* "%?" prints ?, unless ? is NUL */
    419 			if (ch == '\0')
    420 				goto done;
    421 			/* pretend it was %c with argument ch */
    422 			cp = bf;
    423 			*cp = ch;
    424 			size = 1;
    425 			sign = '\0';
    426 			break;
    427 		}
    428 
    429 		/*
    430 		 * All reasonable formats wind up here.  At this point, `cp'
    431 		 * points to a string which (if not flags&LADJUST) should be
    432 		 * padded out to `width' places.  If flags&ZEROPAD, it should
    433 		 * first be prefixed by any sign or other prefix; otherwise,
    434 		 * it should be blank padded before the prefix is emitted.
    435 		 * After any left-hand padding and prefixing, emit zeroes
    436 		 * required by a decimal [diouxX] precision, then print the
    437 		 * string proper, then emit zeroes required by any leftover
    438 		 * floating precision; finally, if LADJUST, pad with blanks.
    439 		 *
    440 		 * Compute actual size, so we know how much to pad.
    441 		 * size excludes decimal prec; realsz includes it.
    442 		 */
    443 		realsz = dprec > size ? dprec : size;
    444 		if (sign)
    445 			realsz++;
    446 		else if (flags & HEXPREFIX)
    447 			realsz+= 2;
    448 
    449 		/* adjust ret */
    450 		ret += width > realsz ? width : realsz;
    451 
    452 		/* right-adjusting blank padding */
    453 		if ((flags & (LADJUST|ZEROPAD)) == 0) {
    454 			n = width - realsz;
    455 			while (n-- > 0)
    456 				PUTCHAR(' ');
    457 		}
    458 
    459 		/* prefix */
    460 		if (sign) {
    461 			PUTCHAR(sign);
    462 		} else if (flags & HEXPREFIX) {
    463 			PUTCHAR('0');
    464 			PUTCHAR(ch);
    465 		}
    466 
    467 		/* right-adjusting zero padding */
    468 		if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD) {
    469 			n = width - realsz;
    470 			while (n-- > 0)
    471 				PUTCHAR('0');
    472 		}
    473 
    474 		/* leading zeroes from decimal precision */
    475 		n = dprec - size;
    476 		while (n-- > 0)
    477 			PUTCHAR('0');
    478 
    479 		/* the string or number proper */
    480 		while (size--)
    481 			PUTCHAR(*cp++);
    482 		/* left-adjusting padding (always blank) */
    483 		if (flags & LADJUST) {
    484 			n = width - realsz;
    485 			while (n-- > 0)
    486 				PUTCHAR(' ');
    487 		}
    488 	}
    489 
    490 done:
    491 	if (sbuf == tailp)
    492 		sbuf[-1] = '\0';
    493 	else
    494 		*sbuf = '\0';
    495 	return (ret);
    496 	/* NOTREACHED */
    497 }
    498