xref: /openbsd-src/lib/libc/stdio/vfprintf.c (revision 675c2d3ef6ea3055d4205b4545e7b240efa755c8)
1 /*	$OpenBSD: vfprintf.c,v 1.56 2009/10/22 01:23:16 guenther Exp $	*/
2 /*-
3  * Copyright (c) 1990 The Regents of the University of California.
4  * All rights reserved.
5  *
6  * This code is derived from software contributed to Berkeley by
7  * Chris Torek.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 /*
35  * Actual printf innards.
36  *
37  * This code is large and complicated...
38  */
39 
40 #include <sys/types.h>
41 #include <sys/mman.h>
42 
43 #include <errno.h>
44 #include <limits.h>
45 #include <stdarg.h>
46 #include <stddef.h>
47 #include <stdio.h>
48 #include <stdint.h>
49 #include <stdlib.h>
50 #include <string.h>
51 #include <unistd.h>
52 
53 #include "local.h"
54 #include "fvwrite.h"
55 
56 union arg {
57 	int			intarg;
58 	unsigned int		uintarg;
59 	long			longarg;
60 	unsigned long		ulongarg;
61 	long long		longlongarg;
62 	unsigned long long	ulonglongarg;
63 	ptrdiff_t		ptrdiffarg;
64 	size_t			sizearg;
65 	size_t			ssizearg;
66 	intmax_t		intmaxarg;
67 	uintmax_t		uintmaxarg;
68 	void			*pvoidarg;
69 	char			*pchararg;
70 	signed char		*pschararg;
71 	short			*pshortarg;
72 	int			*pintarg;
73 	long			*plongarg;
74 	long long		*plonglongarg;
75 	ptrdiff_t		*pptrdiffarg;
76 	ssize_t			*pssizearg;
77 	intmax_t		*pintmaxarg;
78 #ifdef FLOATING_POINT
79 	double			doublearg;
80 	long double		longdoublearg;
81 #endif
82 };
83 
84 static int __find_arguments(const char *fmt0, va_list ap, union arg **argtable,
85     size_t *argtablesiz);
86 static int __grow_type_table(unsigned char **typetable, int *tablesize);
87 
88 /*
89  * Flush out all the vectors defined by the given uio,
90  * then reset it so that it can be reused.
91  */
92 static int
93 __sprint(FILE *fp, struct __suio *uio)
94 {
95 	int err;
96 
97 	if (uio->uio_resid == 0) {
98 		uio->uio_iovcnt = 0;
99 		return (0);
100 	}
101 	err = __sfvwrite(fp, uio);
102 	uio->uio_resid = 0;
103 	uio->uio_iovcnt = 0;
104 	return (err);
105 }
106 
107 /*
108  * Helper function for `fprintf to unbuffered unix file': creates a
109  * temporary buffer.  We only work on write-only files; this avoids
110  * worries about ungetc buffers and so forth.
111  */
112 static int
113 __sbprintf(FILE *fp, const char *fmt, va_list ap)
114 {
115 	int ret;
116 	FILE fake;
117 	struct __sfileext fakeext;
118 	unsigned char buf[BUFSIZ];
119 
120 	_FILEEXT_SETUP(&fake, &fakeext);
121 	/* copy the important variables */
122 	fake._flags = fp->_flags & ~__SNBF;
123 	fake._file = fp->_file;
124 	fake._cookie = fp->_cookie;
125 	fake._write = fp->_write;
126 
127 	/* set up the buffer */
128 	fake._bf._base = fake._p = buf;
129 	fake._bf._size = fake._w = sizeof(buf);
130 	fake._lbfsize = 0;	/* not actually used, but Just In Case */
131 
132 	/* do the work, then copy any error status */
133 	ret = vfprintf(&fake, fmt, ap);
134 	if (ret >= 0 && fflush(&fake))
135 		ret = EOF;
136 	if (fake._flags & __SERR)
137 		fp->_flags |= __SERR;
138 	return (ret);
139 }
140 
141 
142 #ifdef FLOATING_POINT
143 #include <float.h>
144 #include <locale.h>
145 #include <math.h>
146 #include "floatio.h"
147 
148 #define	DEFPREC		6
149 
150 extern char *__dtoa(double, int, int, int *, int *, char **);
151 extern void  __freedtoa(char *);
152 static int exponent(char *, int, int);
153 #endif /* FLOATING_POINT */
154 
155 /*
156  * The size of the buffer we use as scratch space for integer
157  * conversions, among other things.  Technically, we would need the
158  * most space for base 10 conversions with thousands' grouping
159  * characters between each pair of digits.  100 bytes is a
160  * conservative overestimate even for a 128-bit uintmax_t.
161  */
162 #define BUF	100
163 
164 #define STATIC_ARG_TBL_SIZE 8	/* Size of static argument table. */
165 
166 
167 /*
168  * Macros for converting digits to letters and vice versa
169  */
170 #define	to_digit(c)	((c) - '0')
171 #define is_digit(c)	((unsigned)to_digit(c) <= 9)
172 #define	to_char(n)	((n) + '0')
173 
174 /*
175  * Flags used during conversion.
176  */
177 #define	ALT		0x0001		/* alternate form */
178 #define	LADJUST		0x0004		/* left adjustment */
179 #define	LONGDBL		0x0008		/* long double; unimplemented */
180 #define	LONGINT		0x0010		/* long integer */
181 #define	LLONGINT	0x0020		/* long long integer */
182 #define	SHORTINT	0x0040		/* short integer */
183 #define	ZEROPAD		0x0080		/* zero (as opposed to blank) pad */
184 #define FPT		0x0100		/* Floating point number */
185 #define PTRINT		0x0200		/* (unsigned) ptrdiff_t */
186 #define SIZEINT		0x0400		/* (signed) size_t */
187 #define CHARINT		0x0800		/* 8 bit integer */
188 #define MAXINT		0x1000		/* largest integer size (intmax_t) */
189 
190 int
191 vfprintf(FILE *fp, const char *fmt0, __va_list ap)
192 {
193 	char *fmt;		/* format string */
194 	int ch;			/* character from fmt */
195 	int n, n2;		/* handy integers (short term usage) */
196 	char *cp;		/* handy char pointer (short term usage) */
197 	struct __siov *iovp;	/* for PRINT macro */
198 	int flags;		/* flags as above */
199 	int ret;		/* return value accumulator */
200 	int width;		/* width from format (%8d), or 0 */
201 	int prec;		/* precision from format; <0 for N/A */
202 	char sign;		/* sign prefix (' ', '+', '-', or \0) */
203 	wchar_t wc;
204 	mbstate_t ps;
205 #ifdef FLOATING_POINT
206 	/*
207 	 * We can decompose the printed representation of floating
208 	 * point numbers into several parts, some of which may be empty:
209 	 *
210 	 * [+|-| ] [0x|0X] MMM . NNN [e|E|p|P] [+|-] ZZ
211 	 *    A       B     ---C---      D       E   F
212 	 *
213 	 * A:	'sign' holds this value if present; '\0' otherwise
214 	 * B:	ox[1] holds the 'x' or 'X'; '\0' if not hexadecimal
215 	 * C:	cp points to the string MMMNNN.  Leading and trailing
216 	 *	zeros are not in the string and must be added.
217 	 * D:	expchar holds this character; '\0' if no exponent, e.g. %f
218 	 * F:	at least two digits for decimal, at least one digit for hex
219 	 */
220 	char *decimal_point = localeconv()->decimal_point;
221 	int signflag;		/* true if float is negative */
222 	union {			/* floating point arguments %[aAeEfFgG] */
223 		double dbl;
224 		long double ldbl;
225 	} fparg;
226 	int expt;		/* integer value of exponent */
227 	char expchar;		/* exponent character: [eEpP\0] */
228 	char *dtoaend;		/* pointer to end of converted digits */
229 	int expsize;		/* character count for expstr */
230 	int lead;		/* sig figs before decimal or group sep */
231 	int ndig;		/* actual number of digits returned by dtoa */
232 	char expstr[MAXEXPDIG+2];	/* buffer for exponent string: e+ZZZ */
233 	char *dtoaresult = NULL;
234 #endif
235 
236 	uintmax_t _umax;	/* integer arguments %[diouxX] */
237 	enum { OCT, DEC, HEX } base;	/* base for %[diouxX] conversion */
238 	int dprec;		/* a copy of prec if %[diouxX], 0 otherwise */
239 	int realsz;		/* field size expanded by dprec */
240 	int size;		/* size of converted field or string */
241 	const char *xdigs;	/* digits for %[xX] conversion */
242 #define NIOV 8
243 	struct __suio uio;	/* output information: summary */
244 	struct __siov iov[NIOV];/* ... and individual io vectors */
245 	char buf[BUF];		/* buffer with space for digits of uintmax_t */
246 	char ox[2];		/* space for 0x; ox[1] is either x, X, or \0 */
247 	union arg *argtable;	/* args, built due to positional arg */
248 	union arg statargtable[STATIC_ARG_TBL_SIZE];
249 	size_t argtablesiz;
250 	int nextarg;		/* 1-based argument index */
251 	va_list orgap;		/* original argument pointer */
252 
253 	/*
254 	 * Choose PADSIZE to trade efficiency vs. size.  If larger printf
255 	 * fields occur frequently, increase PADSIZE and make the initialisers
256 	 * below longer.
257 	 */
258 #define	PADSIZE	16		/* pad chunk size */
259 	static char blanks[PADSIZE] =
260 	 {' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' '};
261 	static char zeroes[PADSIZE] =
262 	 {'0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'};
263 
264 	static const char xdigs_lower[16] = "0123456789abcdef";
265 	static const char xdigs_upper[16] = "0123456789ABCDEF";
266 
267 	/*
268 	 * BEWARE, these `goto error' on error, and PAD uses `n'.
269 	 */
270 #define	PRINT(ptr, len) do { \
271 	iovp->iov_base = (ptr); \
272 	iovp->iov_len = (len); \
273 	uio.uio_resid += (len); \
274 	iovp++; \
275 	if (++uio.uio_iovcnt >= NIOV) { \
276 		if (__sprint(fp, &uio)) \
277 			goto error; \
278 		iovp = iov; \
279 	} \
280 } while (0)
281 #define	PAD(howmany, with) do { \
282 	if ((n = (howmany)) > 0) { \
283 		while (n > PADSIZE) { \
284 			PRINT(with, PADSIZE); \
285 			n -= PADSIZE; \
286 		} \
287 		PRINT(with, n); \
288 	} \
289 } while (0)
290 #define	PRINTANDPAD(p, ep, len, with) do {	\
291 	n2 = (ep) - (p);       			\
292 	if (n2 > (len))				\
293 		n2 = (len);			\
294 	if (n2 > 0)				\
295 		PRINT((p), n2);			\
296 	PAD((len) - (n2 > 0 ? n2 : 0), (with));	\
297 } while(0)
298 #define	FLUSH() do { \
299 	if (uio.uio_resid && __sprint(fp, &uio)) \
300 		goto error; \
301 	uio.uio_iovcnt = 0; \
302 	iovp = iov; \
303 } while (0)
304 
305 	/*
306 	 * To extend shorts properly, we need both signed and unsigned
307 	 * argument extraction methods.
308 	 */
309 #define	SARG() \
310 	((intmax_t)(flags&MAXINT ? GETARG(intmax_t) : \
311 	    flags&LLONGINT ? GETARG(long long) : \
312 	    flags&LONGINT ? GETARG(long) : \
313 	    flags&PTRINT ? GETARG(ptrdiff_t) : \
314 	    flags&SIZEINT ? GETARG(ssize_t) : \
315 	    flags&SHORTINT ? (short)GETARG(int) : \
316 	    flags&CHARINT ? (__signed char)GETARG(int) : \
317 	    GETARG(int)))
318 #define	UARG() \
319 	((uintmax_t)(flags&MAXINT ? GETARG(uintmax_t) : \
320 	    flags&LLONGINT ? GETARG(unsigned long long) : \
321 	    flags&LONGINT ? GETARG(unsigned long) : \
322 	    flags&PTRINT ? (uintptr_t)GETARG(ptrdiff_t) : /* XXX */ \
323 	    flags&SIZEINT ? GETARG(size_t) : \
324 	    flags&SHORTINT ? (unsigned short)GETARG(int) : \
325 	    flags&CHARINT ? (unsigned char)GETARG(int) : \
326 	    GETARG(unsigned int)))
327 
328 	/*
329 	 * Append a digit to a value and check for overflow.
330 	 */
331 #define APPEND_DIGIT(val, dig) do { \
332 	if ((val) > INT_MAX / 10) \
333 		goto overflow; \
334 	(val) *= 10; \
335 	if ((val) > INT_MAX - to_digit((dig))) \
336 		goto overflow; \
337 	(val) += to_digit((dig)); \
338 } while (0)
339 
340 	 /*
341 	  * Get * arguments, including the form *nn$.  Preserve the nextarg
342 	  * that the argument can be gotten once the type is determined.
343 	  */
344 #define GETASTER(val) \
345 	n2 = 0; \
346 	cp = fmt; \
347 	while (is_digit(*cp)) { \
348 		APPEND_DIGIT(n2, *cp); \
349 		cp++; \
350 	} \
351 	if (*cp == '$') { \
352 		int hold = nextarg; \
353 		if (argtable == NULL) { \
354 			argtable = statargtable; \
355 			__find_arguments(fmt0, orgap, &argtable, &argtablesiz); \
356 		} \
357 		nextarg = n2; \
358 		val = GETARG(int); \
359 		nextarg = hold; \
360 		fmt = ++cp; \
361 	} else { \
362 		val = GETARG(int); \
363 	}
364 
365 /*
366 * Get the argument indexed by nextarg.   If the argument table is
367 * built, use it to get the argument.  If its not, get the next
368 * argument (and arguments must be gotten sequentially).
369 */
370 #define GETARG(type) \
371 	((argtable != NULL) ? *((type*)(&argtable[nextarg++])) : \
372 		(nextarg++, va_arg(ap, type)))
373 
374 	_SET_ORIENTATION(fp, -1);
375 	/* sorry, fprintf(read_only_file, "") returns EOF, not 0 */
376 	if (cantwrite(fp)) {
377 		errno = EBADF;
378 		return (EOF);
379 	}
380 
381 	/* optimise fprintf(stderr) (and other unbuffered Unix files) */
382 	if ((fp->_flags & (__SNBF|__SWR|__SRW)) == (__SNBF|__SWR) &&
383 	    fp->_file >= 0)
384 		return (__sbprintf(fp, fmt0, ap));
385 
386 	fmt = (char *)fmt0;
387 	argtable = NULL;
388 	nextarg = 1;
389 	va_copy(orgap, ap);
390 	uio.uio_iov = iovp = iov;
391 	uio.uio_resid = 0;
392 	uio.uio_iovcnt = 0;
393 	ret = 0;
394 
395 	memset(&ps, 0, sizeof(ps));
396 	/*
397 	 * Scan the format for conversions (`%' character).
398 	 */
399 	for (;;) {
400 		cp = fmt;
401 		while ((n = mbrtowc(&wc, fmt, MB_CUR_MAX, &ps)) > 0) {
402 			fmt += n;
403 			if (wc == '%') {
404 				fmt--;
405 				break;
406 			}
407 		}
408 		if (fmt != cp) {
409 			ptrdiff_t m = fmt - cp;
410 			if (m < 0 || m > INT_MAX - ret)
411 				goto overflow;
412 			PRINT(cp, m);
413 			ret += m;
414 		}
415 		if (n <= 0)
416 			goto done;
417 		fmt++;		/* skip over '%' */
418 
419 		flags = 0;
420 		dprec = 0;
421 		width = 0;
422 		prec = -1;
423 		sign = '\0';
424 		ox[1] = '\0';
425 
426 rflag:		ch = *fmt++;
427 reswitch:	switch (ch) {
428 		case ' ':
429 			/*
430 			 * ``If the space and + flags both appear, the space
431 			 * flag will be ignored.''
432 			 *	-- ANSI X3J11
433 			 */
434 			if (!sign)
435 				sign = ' ';
436 			goto rflag;
437 		case '#':
438 			flags |= ALT;
439 			goto rflag;
440 		case '*':
441 			/*
442 			 * ``A negative field width argument is taken as a
443 			 * - flag followed by a positive field width.''
444 			 *	-- ANSI X3J11
445 			 * They don't exclude field widths read from args.
446 			 */
447 			GETASTER(width);
448 			if (width >= 0)
449 				goto rflag;
450 			if (width == INT_MIN)
451 				goto overflow;
452 			width = -width;
453 			/* FALLTHROUGH */
454 		case '-':
455 			flags |= LADJUST;
456 			goto rflag;
457 		case '+':
458 			sign = '+';
459 			goto rflag;
460 		case '.':
461 			if ((ch = *fmt++) == '*') {
462 				GETASTER(n);
463 				prec = n < 0 ? -1 : n;
464 				goto rflag;
465 			}
466 			n = 0;
467 			while (is_digit(ch)) {
468 				APPEND_DIGIT(n, ch);
469 				ch = *fmt++;
470 			}
471 			if (ch == '$') {
472 				nextarg = n;
473 				if (argtable == NULL) {
474 					argtable = statargtable;
475 					__find_arguments(fmt0, orgap,
476 					    &argtable, &argtablesiz);
477 				}
478 				goto rflag;
479 			}
480 			prec = n;
481 			goto reswitch;
482 		case '0':
483 			/*
484 			 * ``Note that 0 is taken as a flag, not as the
485 			 * beginning of a field width.''
486 			 *	-- ANSI X3J11
487 			 */
488 			flags |= ZEROPAD;
489 			goto rflag;
490 		case '1': case '2': case '3': case '4':
491 		case '5': case '6': case '7': case '8': case '9':
492 			n = 0;
493 			do {
494 				APPEND_DIGIT(n, ch);
495 				ch = *fmt++;
496 			} while (is_digit(ch));
497 			if (ch == '$') {
498 				nextarg = n;
499 				if (argtable == NULL) {
500 					argtable = statargtable;
501 					__find_arguments(fmt0, orgap,
502 					    &argtable, &argtablesiz);
503 				}
504 				goto rflag;
505 			}
506 			width = n;
507 			goto reswitch;
508 #ifdef FLOATING_POINT
509 		case 'L':
510 			flags |= LONGDBL;
511 			goto rflag;
512 #endif
513 		case 'h':
514 			if (*fmt == 'h') {
515 				fmt++;
516 				flags |= CHARINT;
517 			} else {
518 				flags |= SHORTINT;
519 			}
520 			goto rflag;
521 		case 'j':
522 			flags |= MAXINT;
523 			goto rflag;
524 		case 'l':
525 			if (*fmt == 'l') {
526 				fmt++;
527 				flags |= LLONGINT;
528 			} else {
529 				flags |= LONGINT;
530 			}
531 			goto rflag;
532 		case 'q':
533 			flags |= LLONGINT;
534 			goto rflag;
535 		case 't':
536 			flags |= PTRINT;
537 			goto rflag;
538 		case 'z':
539 			flags |= SIZEINT;
540 			goto rflag;
541 		case 'c':
542 			*(cp = buf) = GETARG(int);
543 			size = 1;
544 			sign = '\0';
545 			break;
546 		case 'D':
547 			flags |= LONGINT;
548 			/*FALLTHROUGH*/
549 		case 'd':
550 		case 'i':
551 			_umax = SARG();
552 			if ((intmax_t)_umax < 0) {
553 				_umax = -_umax;
554 				sign = '-';
555 			}
556 			base = DEC;
557 			goto number;
558 #ifdef FLOATING_POINT
559 		case 'a':
560 		case 'A':
561 			if (ch == 'a') {
562 				ox[1] = 'x';
563 				xdigs = xdigs_lower;
564 				expchar = 'p';
565 			} else {
566 				ox[1] = 'X';
567 				xdigs = xdigs_upper;
568 				expchar = 'P';
569 			}
570 			if (prec >= 0)
571 				prec++;
572 			if (dtoaresult)
573 				__freedtoa(dtoaresult);
574 			if (flags & LONGDBL) {
575 				fparg.ldbl = GETARG(long double);
576 				dtoaresult = cp =
577 				    __hldtoa(fparg.ldbl, xdigs, prec,
578 				    &expt, &signflag, &dtoaend);
579 				if (dtoaresult == NULL) {
580 					errno = ENOMEM;
581 					goto error;
582 				}
583 			} else {
584 				fparg.dbl = GETARG(double);
585 				dtoaresult = cp =
586 				    __hdtoa(fparg.dbl, xdigs, prec,
587 				    &expt, &signflag, &dtoaend);
588 				if (dtoaresult == NULL) {
589 					errno = ENOMEM;
590 					goto error;
591 				}
592 			}
593 			if (prec < 0)
594 				prec = dtoaend - cp;
595 			if (expt == INT_MAX)
596 				ox[1] = '\0';
597 			goto fp_common;
598 		case 'e':
599 		case 'E':
600 			expchar = ch;
601 			if (prec < 0)	/* account for digit before decpt */
602 				prec = DEFPREC + 1;
603 			else
604 				prec++;
605 			goto fp_begin;
606 		case 'f':
607 		case 'F':
608 			expchar = '\0';
609 			goto fp_begin;
610 		case 'g':
611 		case 'G':
612 			expchar = ch - ('g' - 'e');
613  			if (prec == 0)
614  				prec = 1;
615 fp_begin:
616 			if (prec < 0)
617 				prec = DEFPREC;
618 			if (dtoaresult)
619 				__freedtoa(dtoaresult);
620 			if (flags & LONGDBL) {
621 				fparg.ldbl = GETARG(long double);
622 				dtoaresult = cp =
623 				    __ldtoa(&fparg.ldbl, expchar ? 2 : 3, prec,
624 				    &expt, &signflag, &dtoaend);
625 				if (dtoaresult == NULL) {
626 					errno = ENOMEM;
627 					goto error;
628 				}
629 			} else {
630 				fparg.dbl = GETARG(double);
631 				dtoaresult = cp =
632 				    __dtoa(fparg.dbl, expchar ? 2 : 3, prec,
633 				    &expt, &signflag, &dtoaend);
634 				if (dtoaresult == NULL) {
635 					errno = ENOMEM;
636 					goto error;
637 				}
638 				if (expt == 9999)
639 					expt = INT_MAX;
640  			}
641 fp_common:
642 			if (signflag)
643 				sign = '-';
644 			if (expt == INT_MAX) {	/* inf or nan */
645 				if (*cp == 'N') {
646 					cp = (ch >= 'a') ? "nan" : "NAN";
647 					sign = '\0';
648 				} else
649 					cp = (ch >= 'a') ? "inf" : "INF";
650  				size = 3;
651 				flags &= ~ZEROPAD;
652  				break;
653  			}
654 			flags |= FPT;
655 			ndig = dtoaend - cp;
656  			if (ch == 'g' || ch == 'G') {
657 				if (expt > -4 && expt <= prec) {
658 					/* Make %[gG] smell like %[fF] */
659 					expchar = '\0';
660 					if (flags & ALT)
661 						prec -= expt;
662 					else
663 						prec = ndig - expt;
664 					if (prec < 0)
665 						prec = 0;
666 				} else {
667 					/*
668 					 * Make %[gG] smell like %[eE], but
669 					 * trim trailing zeroes if no # flag.
670 					 */
671 					if (!(flags & ALT))
672 						prec = ndig;
673 				}
674  			}
675 			if (expchar) {
676 				expsize = exponent(expstr, expt - 1, expchar);
677 				size = expsize + prec;
678 				if (prec > 1 || flags & ALT)
679  					++size;
680 			} else {
681 				/* space for digits before decimal point */
682 				if (expt > 0)
683 					size = expt;
684 				else	/* "0" */
685 					size = 1;
686 				/* space for decimal pt and following digits */
687 				if (prec || flags & ALT)
688 					size += prec + 1;
689 				lead = expt;
690 			}
691 			break;
692 #endif /* FLOATING_POINT */
693 		case 'n':
694 			if (flags & LLONGINT)
695 				*GETARG(long long *) = ret;
696 			else if (flags & LONGINT)
697 				*GETARG(long *) = ret;
698 			else if (flags & SHORTINT)
699 				*GETARG(short *) = ret;
700 			else if (flags & CHARINT)
701 				*GETARG(__signed char *) = ret;
702 			else if (flags & PTRINT)
703 				*GETARG(ptrdiff_t *) = ret;
704 			else if (flags & SIZEINT)
705 				*GETARG(ssize_t *) = ret;
706 			else if (flags & MAXINT)
707 				*GETARG(intmax_t *) = ret;
708 			else
709 				*GETARG(int *) = ret;
710 			continue;	/* no output */
711 		case 'O':
712 			flags |= LONGINT;
713 			/*FALLTHROUGH*/
714 		case 'o':
715 			_umax = UARG();
716 			base = OCT;
717 			goto nosign;
718 		case 'p':
719 			/*
720 			 * ``The argument shall be a pointer to void.  The
721 			 * value of the pointer is converted to a sequence
722 			 * of printable characters, in an implementation-
723 			 * defined manner.''
724 			 *	-- ANSI X3J11
725 			 */
726 			/* NOSTRICT */
727 			_umax = (u_long)GETARG(void *);
728 			base = HEX;
729 			xdigs = xdigs_lower;
730 			ox[1] = 'x';
731 			goto nosign;
732 		case 's':
733 			if ((cp = GETARG(char *)) == NULL)
734 				cp = "(null)";
735 			if (prec >= 0) {
736 				/*
737 				 * can't use strlen; can only look for the
738 				 * NUL in the first `prec' characters, and
739 				 * strlen() will go further.
740 				 */
741 				char *p = memchr(cp, 0, prec);
742 
743 				size = p ? (p - cp) : prec;
744 			} else {
745 				size_t len;
746 
747 				if ((len = strlen(cp)) > INT_MAX)
748 					goto overflow;
749 				size = (int)len;
750 			}
751 			sign = '\0';
752 			break;
753 		case 'U':
754 			flags |= LONGINT;
755 			/*FALLTHROUGH*/
756 		case 'u':
757 			_umax = UARG();
758 			base = DEC;
759 			goto nosign;
760 		case 'X':
761 			xdigs = xdigs_upper;
762 			goto hex;
763 		case 'x':
764 			xdigs = xdigs_lower;
765 hex:			_umax = UARG();
766 			base = HEX;
767 			/* leading 0x/X only if non-zero */
768 			if (flags & ALT && _umax != 0)
769 				ox[1] = ch;
770 
771 			/* unsigned conversions */
772 nosign:			sign = '\0';
773 			/*
774 			 * ``... diouXx conversions ... if a precision is
775 			 * specified, the 0 flag will be ignored.''
776 			 *	-- ANSI X3J11
777 			 */
778 number:			if ((dprec = prec) >= 0)
779 				flags &= ~ZEROPAD;
780 
781 			/*
782 			 * ``The result of converting a zero value with an
783 			 * explicit precision of zero is no characters.''
784 			 *	-- ANSI X3J11
785 			 */
786 			cp = buf + BUF;
787 			if (_umax != 0 || prec != 0) {
788 				/*
789 				 * Unsigned mod is hard, and unsigned mod
790 				 * by a constant is easier than that by
791 				 * a variable; hence this switch.
792 				 */
793 				switch (base) {
794 				case OCT:
795 					do {
796 						*--cp = to_char(_umax & 7);
797 						_umax >>= 3;
798 					} while (_umax);
799 					/* handle octal leading 0 */
800 					if (flags & ALT && *cp != '0')
801 						*--cp = '0';
802 					break;
803 
804 				case DEC:
805 					/* many numbers are 1 digit */
806 					while (_umax >= 10) {
807 						*--cp = to_char(_umax % 10);
808 						_umax /= 10;
809 					}
810 					*--cp = to_char(_umax);
811 					break;
812 
813 				case HEX:
814 					do {
815 						*--cp = xdigs[_umax & 15];
816 						_umax >>= 4;
817 					} while (_umax);
818 					break;
819 
820 				default:
821 					cp = "bug in vfprintf: bad base";
822 					size = strlen(cp);
823 					goto skipsize;
824 				}
825 			}
826 			size = buf + BUF - cp;
827 			if (size > BUF)	/* should never happen */
828 				abort();
829 		skipsize:
830 			break;
831 		default:	/* "%?" prints ?, unless ? is NUL */
832 			if (ch == '\0')
833 				goto done;
834 			/* pretend it was %c with argument ch */
835 			cp = buf;
836 			*cp = ch;
837 			size = 1;
838 			sign = '\0';
839 			break;
840 		}
841 
842 		/*
843 		 * All reasonable formats wind up here.  At this point, `cp'
844 		 * points to a string which (if not flags&LADJUST) should be
845 		 * padded out to `width' places.  If flags&ZEROPAD, it should
846 		 * first be prefixed by any sign or other prefix; otherwise,
847 		 * it should be blank padded before the prefix is emitted.
848 		 * After any left-hand padding and prefixing, emit zeroes
849 		 * required by a decimal %[diouxX] precision, then print the
850 		 * string proper, then emit zeroes required by any leftover
851 		 * floating precision; finally, if LADJUST, pad with blanks.
852 		 *
853 		 * Compute actual size, so we know how much to pad.
854 		 * size excludes decimal prec; realsz includes it.
855 		 */
856 		realsz = dprec > size ? dprec : size;
857 		if (sign)
858 			realsz++;
859 		if (ox[1])
860 			realsz+= 2;
861 
862 		/* right-adjusting blank padding */
863 		if ((flags & (LADJUST|ZEROPAD)) == 0)
864 			PAD(width - realsz, blanks);
865 
866 		/* prefix */
867 		if (sign)
868 			PRINT(&sign, 1);
869 		if (ox[1]) {	/* ox[1] is either x, X, or \0 */
870 			ox[0] = '0';
871 			PRINT(ox, 2);
872 		}
873 
874 		/* right-adjusting zero padding */
875 		if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD)
876 			PAD(width - realsz, zeroes);
877 
878 		/* leading zeroes from decimal precision */
879 		PAD(dprec - size, zeroes);
880 
881 		/* the string or number proper */
882 #ifdef FLOATING_POINT
883 		if ((flags & FPT) == 0) {
884 			PRINT(cp, size);
885 		} else {	/* glue together f_p fragments */
886 			if (!expchar) {	/* %[fF] or sufficiently short %[gG] */
887 				if (expt <= 0) {
888 					PRINT(zeroes, 1);
889 					if (prec || flags & ALT)
890 						PRINT(decimal_point, 1);
891 					PAD(-expt, zeroes);
892 					/* already handled initial 0's */
893 					prec += expt;
894  				} else {
895 					PRINTANDPAD(cp, dtoaend, lead, zeroes);
896 					cp += lead;
897 					if (prec || flags & ALT)
898 						PRINT(decimal_point, 1);
899 				}
900 				PRINTANDPAD(cp, dtoaend, prec, zeroes);
901 			} else {	/* %[eE] or sufficiently long %[gG] */
902 				if (prec > 1 || flags & ALT) {
903 					buf[0] = *cp++;
904 					buf[1] = *decimal_point;
905 					PRINT(buf, 2);
906 					PRINT(cp, ndig-1);
907 					PAD(prec - ndig, zeroes);
908 				} else { /* XeYYY */
909 					PRINT(cp, 1);
910 				}
911 				PRINT(expstr, expsize);
912 			}
913 		}
914 #else
915 		PRINT(cp, size);
916 #endif
917 		/* left-adjusting padding (always blank) */
918 		if (flags & LADJUST)
919 			PAD(width - realsz, blanks);
920 
921 		/* finally, adjust ret */
922 		if (width < realsz)
923 			width = realsz;
924 		if (width > INT_MAX - ret)
925 			goto overflow;
926 		ret += width;
927 
928 		FLUSH();	/* copy out the I/O vectors */
929 	}
930 done:
931 	FLUSH();
932 error:
933 	va_end(orgap);
934 	if (__sferror(fp))
935 		ret = -1;
936 	goto finish;
937 
938 overflow:
939 	errno = ENOMEM;
940 	ret = -1;
941 
942 finish:
943 #ifdef FLOATING_POINT
944 	if (dtoaresult)
945 		__freedtoa(dtoaresult);
946 #endif
947 	if (argtable != NULL && argtable != statargtable) {
948 		munmap(argtable, argtablesiz);
949 		argtable = NULL;
950 	}
951 	return (ret);
952 }
953 
954 /*
955  * Type ids for argument type table.
956  */
957 #define T_UNUSED	0
958 #define T_SHORT		1
959 #define T_U_SHORT	2
960 #define TP_SHORT	3
961 #define T_INT		4
962 #define T_U_INT		5
963 #define TP_INT		6
964 #define T_LONG		7
965 #define T_U_LONG	8
966 #define TP_LONG		9
967 #define T_LLONG		10
968 #define T_U_LLONG	11
969 #define TP_LLONG	12
970 #define T_DOUBLE	13
971 #define T_LONG_DOUBLE	14
972 #define TP_CHAR		15
973 #define TP_VOID		16
974 #define T_PTRINT	17
975 #define TP_PTRINT	18
976 #define T_SIZEINT	19
977 #define T_SSIZEINT	20
978 #define TP_SSIZEINT	21
979 #define T_MAXINT	22
980 #define T_MAXUINT	23
981 #define TP_MAXINT	24
982 #define T_CHAR		25
983 #define T_U_CHAR	26
984 
985 /*
986  * Find all arguments when a positional parameter is encountered.  Returns a
987  * table, indexed by argument number, of pointers to each arguments.  The
988  * initial argument table should be an array of STATIC_ARG_TBL_SIZE entries.
989  * It will be replaced with a mmap-ed one if it overflows (malloc cannot be
990  * used since we are attempting to make snprintf thread safe, and alloca is
991  * problematic since we have nested functions..)
992  */
993 static int
994 __find_arguments(const char *fmt0, va_list ap, union arg **argtable,
995     size_t *argtablesiz)
996 {
997 	char *fmt;		/* format string */
998 	int ch;			/* character from fmt */
999 	int n, n2;		/* handy integer (short term usage) */
1000 	char *cp;		/* handy char pointer (short term usage) */
1001 	int flags;		/* flags as above */
1002 	unsigned char *typetable; /* table of types */
1003 	unsigned char stattypetable[STATIC_ARG_TBL_SIZE];
1004 	int tablesize;		/* current size of type table */
1005 	int tablemax;		/* largest used index in table */
1006 	int nextarg;		/* 1-based argument index */
1007 	int ret = 0;		/* return value */
1008 	wchar_t wc;
1009 	mbstate_t ps;
1010 
1011 	/*
1012 	 * Add an argument type to the table, expanding if necessary.
1013 	 */
1014 #define ADDTYPE(type) \
1015 	((nextarg >= tablesize) ? \
1016 		__grow_type_table(&typetable, &tablesize) : 0, \
1017 	(nextarg > tablemax) ? tablemax = nextarg : 0, \
1018 	typetable[nextarg++] = type)
1019 
1020 #define	ADDSARG() \
1021         ((flags&MAXINT) ? ADDTYPE(T_MAXINT) : \
1022 	    ((flags&PTRINT) ? ADDTYPE(T_PTRINT) : \
1023 	    ((flags&SIZEINT) ? ADDTYPE(T_SSIZEINT) : \
1024 	    ((flags&LLONGINT) ? ADDTYPE(T_LLONG) : \
1025 	    ((flags&LONGINT) ? ADDTYPE(T_LONG) : \
1026 	    ((flags&SHORTINT) ? ADDTYPE(T_SHORT) : \
1027 	    ((flags&CHARINT) ? ADDTYPE(T_CHAR) : ADDTYPE(T_INT))))))))
1028 
1029 #define	ADDUARG() \
1030         ((flags&MAXINT) ? ADDTYPE(T_MAXUINT) : \
1031 	    ((flags&PTRINT) ? ADDTYPE(T_PTRINT) : \
1032 	    ((flags&SIZEINT) ? ADDTYPE(T_SIZEINT) : \
1033 	    ((flags&LLONGINT) ? ADDTYPE(T_U_LLONG) : \
1034 	    ((flags&LONGINT) ? ADDTYPE(T_U_LONG) : \
1035 	    ((flags&SHORTINT) ? ADDTYPE(T_U_SHORT) : \
1036 	    ((flags&CHARINT) ? ADDTYPE(T_U_CHAR) : ADDTYPE(T_U_INT))))))))
1037 
1038 	/*
1039 	 * Add * arguments to the type array.
1040 	 */
1041 #define ADDASTER() \
1042 	n2 = 0; \
1043 	cp = fmt; \
1044 	while (is_digit(*cp)) { \
1045 		APPEND_DIGIT(n2, *cp); \
1046 		cp++; \
1047 	} \
1048 	if (*cp == '$') { \
1049 		int hold = nextarg; \
1050 		nextarg = n2; \
1051 		ADDTYPE(T_INT); \
1052 		nextarg = hold; \
1053 		fmt = ++cp; \
1054 	} else { \
1055 		ADDTYPE(T_INT); \
1056 	}
1057 	fmt = (char *)fmt0;
1058 	typetable = stattypetable;
1059 	tablesize = STATIC_ARG_TBL_SIZE;
1060 	tablemax = 0;
1061 	nextarg = 1;
1062 	memset(typetable, T_UNUSED, STATIC_ARG_TBL_SIZE);
1063 	memset(&ps, 0, sizeof(ps));
1064 
1065 	/*
1066 	 * Scan the format for conversions (`%' character).
1067 	 */
1068 	for (;;) {
1069 		cp = fmt;
1070 		while ((n = mbrtowc(&wc, fmt, MB_CUR_MAX, &ps)) > 0) {
1071 			fmt += n;
1072 			if (wc == '%') {
1073 				fmt--;
1074 				break;
1075 			}
1076 		}
1077 		if (n <= 0)
1078 			goto done;
1079 		fmt++;		/* skip over '%' */
1080 
1081 		flags = 0;
1082 
1083 rflag:		ch = *fmt++;
1084 reswitch:	switch (ch) {
1085 		case ' ':
1086 		case '#':
1087 			goto rflag;
1088 		case '*':
1089 			ADDASTER();
1090 			goto rflag;
1091 		case '-':
1092 		case '+':
1093 			goto rflag;
1094 		case '.':
1095 			if ((ch = *fmt++) == '*') {
1096 				ADDASTER();
1097 				goto rflag;
1098 			}
1099 			while (is_digit(ch)) {
1100 				ch = *fmt++;
1101 			}
1102 			goto reswitch;
1103 		case '0':
1104 			goto rflag;
1105 		case '1': case '2': case '3': case '4':
1106 		case '5': case '6': case '7': case '8': case '9':
1107 			n = 0;
1108 			do {
1109 				APPEND_DIGIT(n ,ch);
1110 				ch = *fmt++;
1111 			} while (is_digit(ch));
1112 			if (ch == '$') {
1113 				nextarg = n;
1114 				goto rflag;
1115 			}
1116 			goto reswitch;
1117 #ifdef FLOATING_POINT
1118 		case 'L':
1119 			flags |= LONGDBL;
1120 			goto rflag;
1121 #endif
1122 		case 'h':
1123 			if (*fmt == 'h') {
1124 				fmt++;
1125 				flags |= CHARINT;
1126 			} else {
1127 				flags |= SHORTINT;
1128 			}
1129 			goto rflag;
1130 		case 'l':
1131 			if (*fmt == 'l') {
1132 				fmt++;
1133 				flags |= LLONGINT;
1134 			} else {
1135 				flags |= LONGINT;
1136 			}
1137 			goto rflag;
1138 		case 'q':
1139 			flags |= LLONGINT;
1140 			goto rflag;
1141 		case 't':
1142 			flags |= PTRINT;
1143 			goto rflag;
1144 		case 'z':
1145 			flags |= SIZEINT;
1146 			goto rflag;
1147 		case 'c':
1148 			ADDTYPE(T_INT);
1149 			break;
1150 		case 'D':
1151 			flags |= LONGINT;
1152 			/*FALLTHROUGH*/
1153 		case 'd':
1154 		case 'i':
1155 			ADDSARG();
1156 			break;
1157 #ifdef FLOATING_POINT
1158 		case 'a':
1159 		case 'A':
1160 		case 'e':
1161 		case 'E':
1162 		case 'f':
1163 		case 'F':
1164 		case 'g':
1165 		case 'G':
1166 			if (flags & LONGDBL)
1167 				ADDTYPE(T_LONG_DOUBLE);
1168 			else
1169 				ADDTYPE(T_DOUBLE);
1170 			break;
1171 #endif /* FLOATING_POINT */
1172 		case 'n':
1173 			if (flags & LLONGINT)
1174 				ADDTYPE(TP_LLONG);
1175 			else if (flags & LONGINT)
1176 				ADDTYPE(TP_LONG);
1177 			else if (flags & SHORTINT)
1178 				ADDTYPE(TP_SHORT);
1179 			else if (flags & PTRINT)
1180 				ADDTYPE(TP_PTRINT);
1181 			else if (flags & SIZEINT)
1182 				ADDTYPE(TP_SSIZEINT);
1183 			else if (flags & MAXINT)
1184 				ADDTYPE(TP_MAXINT);
1185 			else
1186 				ADDTYPE(TP_INT);
1187 			continue;	/* no output */
1188 		case 'O':
1189 			flags |= LONGINT;
1190 			/*FALLTHROUGH*/
1191 		case 'o':
1192 			ADDUARG();
1193 			break;
1194 		case 'p':
1195 			ADDTYPE(TP_VOID);
1196 			break;
1197 		case 's':
1198 			ADDTYPE(TP_CHAR);
1199 			break;
1200 		case 'U':
1201 			flags |= LONGINT;
1202 			/*FALLTHROUGH*/
1203 		case 'u':
1204 		case 'X':
1205 		case 'x':
1206 			ADDUARG();
1207 			break;
1208 		default:	/* "%?" prints ?, unless ? is NUL */
1209 			if (ch == '\0')
1210 				goto done;
1211 			break;
1212 		}
1213 	}
1214 done:
1215 	/*
1216 	 * Build the argument table.
1217 	 */
1218 	if (tablemax >= STATIC_ARG_TBL_SIZE) {
1219 		*argtablesiz = sizeof(union arg) * (tablemax + 1);
1220 		*argtable = mmap(NULL, *argtablesiz,
1221 		    PROT_WRITE|PROT_READ, MAP_ANON|MAP_PRIVATE, -1, 0);
1222 		if (*argtable == MAP_FAILED)
1223 			return (-1);
1224 	}
1225 
1226 #if 0
1227 	/* XXX is this required? */
1228 	(*argtable)[0].intarg = 0;
1229 #endif
1230 	for (n = 1; n <= tablemax; n++) {
1231 		switch (typetable[n]) {
1232 		case T_UNUSED:
1233 		case T_CHAR:
1234 		case T_U_CHAR:
1235 		case T_SHORT:
1236 		case T_U_SHORT:
1237 		case T_INT:
1238 			(*argtable)[n].intarg = va_arg(ap, int);
1239 			break;
1240 		case TP_SHORT:
1241 			(*argtable)[n].pshortarg = va_arg(ap, short *);
1242 			break;
1243 		case T_U_INT:
1244 			(*argtable)[n].uintarg = va_arg(ap, unsigned int);
1245 			break;
1246 		case TP_INT:
1247 			(*argtable)[n].pintarg = va_arg(ap, int *);
1248 			break;
1249 		case T_LONG:
1250 			(*argtable)[n].longarg = va_arg(ap, long);
1251 			break;
1252 		case T_U_LONG:
1253 			(*argtable)[n].ulongarg = va_arg(ap, unsigned long);
1254 			break;
1255 		case TP_LONG:
1256 			(*argtable)[n].plongarg = va_arg(ap, long *);
1257 			break;
1258 		case T_LLONG:
1259 			(*argtable)[n].longlongarg = va_arg(ap, long long);
1260 			break;
1261 		case T_U_LLONG:
1262 			(*argtable)[n].ulonglongarg = va_arg(ap, unsigned long long);
1263 			break;
1264 		case TP_LLONG:
1265 			(*argtable)[n].plonglongarg = va_arg(ap, long long *);
1266 			break;
1267 #ifdef FLOATING_POINT
1268 		case T_DOUBLE:
1269 			(*argtable)[n].doublearg = va_arg(ap, double);
1270 			break;
1271 		case T_LONG_DOUBLE:
1272 			(*argtable)[n].longdoublearg = va_arg(ap, long double);
1273 			break;
1274 #endif
1275 		case TP_CHAR:
1276 			(*argtable)[n].pchararg = va_arg(ap, char *);
1277 			break;
1278 		case TP_VOID:
1279 			(*argtable)[n].pvoidarg = va_arg(ap, void *);
1280 			break;
1281 		case T_PTRINT:
1282 			(*argtable)[n].ptrdiffarg = va_arg(ap, ptrdiff_t);
1283 			break;
1284 		case TP_PTRINT:
1285 			(*argtable)[n].pptrdiffarg = va_arg(ap, ptrdiff_t *);
1286 			break;
1287 		case T_SIZEINT:
1288 			(*argtable)[n].sizearg = va_arg(ap, size_t);
1289 			break;
1290 		case T_SSIZEINT:
1291 			(*argtable)[n].ssizearg = va_arg(ap, ssize_t);
1292 			break;
1293 		case TP_SSIZEINT:
1294 			(*argtable)[n].pssizearg = va_arg(ap, ssize_t *);
1295 			break;
1296 		case TP_MAXINT:
1297 			(*argtable)[n].intmaxarg = va_arg(ap, intmax_t);
1298 			break;
1299 		}
1300 	}
1301 	goto finish;
1302 
1303 overflow:
1304 	errno = ENOMEM;
1305 	ret = -1;
1306 
1307 finish:
1308 	if (typetable != NULL && typetable != stattypetable) {
1309 		munmap(typetable, *argtablesiz);
1310 		typetable = NULL;
1311 	}
1312 	return (ret);
1313 }
1314 
1315 /*
1316  * Increase the size of the type table.
1317  */
1318 static int
1319 __grow_type_table(unsigned char **typetable, int *tablesize)
1320 {
1321 	unsigned char *oldtable = *typetable;
1322 	int newsize = *tablesize * 2;
1323 
1324 	if (newsize < getpagesize())
1325 		newsize = getpagesize();
1326 
1327 	if (*tablesize == STATIC_ARG_TBL_SIZE) {
1328 		*typetable = mmap(NULL, newsize, PROT_WRITE|PROT_READ,
1329 		    MAP_ANON|MAP_PRIVATE, -1, 0);
1330 		if (*typetable == MAP_FAILED)
1331 			return (-1);
1332 		bcopy(oldtable, *typetable, *tablesize);
1333 	} else {
1334 		unsigned char *new = mmap(NULL, newsize, PROT_WRITE|PROT_READ,
1335 		    MAP_ANON|MAP_PRIVATE, -1, 0);
1336 		if (new == MAP_FAILED)
1337 			return (-1);
1338 		memmove(new, *typetable, *tablesize);
1339 		munmap(*typetable, *tablesize);
1340 		*typetable = new;
1341 	}
1342 	memset(*typetable + *tablesize, T_UNUSED, (newsize - *tablesize));
1343 
1344 	*tablesize = newsize;
1345 	return (0);
1346 }
1347 
1348 
1349 #ifdef FLOATING_POINT
1350 static int
1351 exponent(char *p0, int exp, int fmtch)
1352 {
1353 	char *p, *t;
1354 	char expbuf[MAXEXPDIG];
1355 
1356 	p = p0;
1357 	*p++ = fmtch;
1358 	if (exp < 0) {
1359 		exp = -exp;
1360 		*p++ = '-';
1361 	} else
1362 		*p++ = '+';
1363 	t = expbuf + MAXEXPDIG;
1364 	if (exp > 9) {
1365 		do {
1366 			*--t = to_char(exp % 10);
1367 		} while ((exp /= 10) > 9);
1368 		*--t = to_char(exp);
1369 		for (; t < expbuf + MAXEXPDIG; *p++ = *t++)
1370 			/* nothing */;
1371 	} else {
1372 		/*
1373 		 * Exponents for decimal floating point conversions
1374 		 * (%[eEgG]) must be at least two characters long,
1375 		 * whereas exponents for hexadecimal conversions can
1376 		 * be only one character long.
1377 		 */
1378 		if (fmtch == 'e' || fmtch == 'E')
1379 			*p++ = '0';
1380 		*p++ = to_char(exp);
1381 	}
1382 	return (p - p0);
1383 }
1384 #endif /* FLOATING_POINT */
1385