xref: /openbsd-src/lib/libc/stdio/vfprintf.c (revision 298116df5b000b61a69743d21c92035418df8900)
1 /*-
2  * Copyright (c) 1990 The Regents of the University of California.
3  * All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Chris Torek.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #if defined(LIBC_SCCS) && !defined(lint)
34 static char *rcsid = "$OpenBSD: vfprintf.c,v 1.31 2005/06/17 20:40:32 espie Exp $";
35 #endif /* LIBC_SCCS and not lint */
36 
37 /*
38  * Actual printf innards.
39  *
40  * This code is large and complicated...
41  */
42 
43 #include <sys/types.h>
44 #include <sys/mman.h>
45 
46 #include <stddef.h>
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <string.h>
50 #include <errno.h>
51 #include <stdarg.h>
52 
53 #include "local.h"
54 #include "fvwrite.h"
55 
56 static void __find_arguments(const char *fmt0, va_list ap, va_list **argtable,
57     size_t *argtablesiz);
58 static int __grow_type_table(unsigned char **typetable, int *tablesize);
59 
60 /*
61  * Flush out all the vectors defined by the given uio,
62  * then reset it so that it can be reused.
63  */
64 static int
65 __sprint(FILE *fp, struct __suio *uio)
66 {
67 	int err;
68 
69 	if (uio->uio_resid == 0) {
70 		uio->uio_iovcnt = 0;
71 		return (0);
72 	}
73 	err = __sfvwrite(fp, uio);
74 	uio->uio_resid = 0;
75 	uio->uio_iovcnt = 0;
76 	return (err);
77 }
78 
79 /*
80  * Helper function for `fprintf to unbuffered unix file': creates a
81  * temporary buffer.  We only work on write-only files; this avoids
82  * worries about ungetc buffers and so forth.
83  */
84 static int
85 __sbprintf(FILE *fp, const char *fmt, va_list ap)
86 {
87 	int ret;
88 	FILE fake;
89 	struct __sfileext fakeext;
90 	unsigned char buf[BUFSIZ];
91 
92 	_FILEEXT_SETUP(&fake, &fakeext);
93 	/* copy the important variables */
94 	fake._flags = fp->_flags & ~__SNBF;
95 	fake._file = fp->_file;
96 	fake._cookie = fp->_cookie;
97 	fake._write = fp->_write;
98 
99 	/* set up the buffer */
100 	fake._bf._base = fake._p = buf;
101 	fake._bf._size = fake._w = sizeof(buf);
102 	fake._lbfsize = 0;	/* not actually used, but Just In Case */
103 
104 	/* do the work, then copy any error status */
105 	ret = vfprintf(&fake, fmt, ap);
106 	if (ret >= 0 && fflush(&fake))
107 		ret = EOF;
108 	if (fake._flags & __SERR)
109 		fp->_flags |= __SERR;
110 	return (ret);
111 }
112 
113 
114 #ifdef FLOATING_POINT
115 #include <locale.h>
116 #include <math.h>
117 #include "floatio.h"
118 
119 #define	BUF		(MAXEXP+MAXFRACT+1)	/* + decimal point */
120 #define	DEFPREC		6
121 
122 static char *cvt(double, int, int, char *, int *, int, int *);
123 static int exponent(char *, int, int);
124 
125 #else /* no FLOATING_POINT */
126 #define	BUF		40
127 #endif /* FLOATING_POINT */
128 
129 #define STATIC_ARG_TBL_SIZE 8	/* Size of static argument table. */
130 
131 
132 /*
133  * Macros for converting digits to letters and vice versa
134  */
135 #define	to_digit(c)	((c) - '0')
136 #define is_digit(c)	((unsigned)to_digit(c) <= 9)
137 #define	to_char(n)	((n) + '0')
138 
139 /*
140  * Flags used during conversion.
141  */
142 #define	ALT		0x001		/* alternate form */
143 #define	HEXPREFIX	0x002		/* add 0x or 0X prefix */
144 #define	LADJUST		0x004		/* left adjustment */
145 #define	LONGDBL		0x008		/* long double; unimplemented */
146 #define	LONGINT		0x010		/* long integer */
147 #define	QUADINT		0x020		/* quad integer */
148 #define	SHORTINT	0x040		/* short integer */
149 #define	ZEROPAD		0x080		/* zero (as opposed to blank) pad */
150 #define FPT		0x100		/* Floating point number */
151 #define PTRINT		0x200		/* (unsigned) ptrdiff_t */
152 #define SIZEINT		0x400		/* (signed) size_t */
153 
154 int
155 vfprintf(FILE *fp, const char *fmt0, _BSD_VA_LIST_ ap)
156 {
157 	char *fmt;	/* format string */
158 	int ch;	/* character from fmt */
159 	int n, m, n2;	/* handy integers (short term usage) */
160 	char *cp;	/* handy char pointer (short term usage) */
161 	struct __siov *iovp;/* for PRINT macro */
162 	int flags;	/* flags as above */
163 	int ret;		/* return value accumulator */
164 	int width;		/* width from format (%8d), or 0 */
165 	int prec;		/* precision from format (%.3d), or -1 */
166 	char sign;		/* sign prefix (' ', '+', '-', or \0) */
167 	wchar_t wc;
168 	mbstate_t ps;
169 #ifdef FLOATING_POINT
170 	char *decimal_point = localeconv()->decimal_point;
171 	char softsign;		/* temporary negative sign for floats */
172 	double _double;		/* double precision arguments %[eEfgG] */
173 	int expt;		/* integer value of exponent */
174 	int expsize;		/* character count for expstr */
175 	int ndig;		/* actual number of digits returned by cvt */
176 	char expstr[7];		/* buffer for exponent string */
177 #endif
178 
179 #ifdef __GNUC__			/* gcc has builtin quad type (long long) SOS */
180 #define	quad_t	  long long
181 #define	u_quad_t  unsigned long long
182 #endif
183 
184 	u_quad_t _uquad;	/* integer arguments %[diouxX] */
185 	enum { OCT, DEC, HEX } base;/* base for [diouxX] conversion */
186 	int dprec;		/* a copy of prec if [diouxX], 0 otherwise */
187 	int realsz;		/* field size expanded by dprec */
188 	int size;		/* size of converted field or string */
189 	char *xdigs;		/* digits for [xX] conversion */
190 #define NIOV 8
191 	struct __suio uio;	/* output information: summary */
192 	struct __siov iov[NIOV];/* ... and individual io vectors */
193 	char buf[BUF];		/* space for %c, %[diouxX], %[eEfgG] */
194 	char ox[2];		/* space for 0x hex-prefix */
195 	va_list *argtable;	/* args, built due to positional arg */
196 	va_list statargtable[STATIC_ARG_TBL_SIZE];
197 	size_t argtablesiz;
198 	int nextarg;		/* 1-based argument index */
199 	va_list orgap;		/* original argument pointer */
200 
201 	/*
202 	 * Choose PADSIZE to trade efficiency vs. size.  If larger printf
203 	 * fields occur frequently, increase PADSIZE and make the initialisers
204 	 * below longer.
205 	 */
206 #define	PADSIZE	16		/* pad chunk size */
207 	static char blanks[PADSIZE] =
208 	 {' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' '};
209 	static char zeroes[PADSIZE] =
210 	 {'0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'};
211 
212 	/*
213 	 * BEWARE, these `goto error' on error, and PAD uses `n'.
214 	 */
215 #define	PRINT(ptr, len) do { \
216 	iovp->iov_base = (ptr); \
217 	iovp->iov_len = (len); \
218 	uio.uio_resid += (len); \
219 	iovp++; \
220 	if (++uio.uio_iovcnt >= NIOV) { \
221 		if (__sprint(fp, &uio)) \
222 			goto error; \
223 		iovp = iov; \
224 	} \
225 } while (0)
226 #define	PAD(howmany, with) do { \
227 	if ((n = (howmany)) > 0) { \
228 		while (n > PADSIZE) { \
229 			PRINT(with, PADSIZE); \
230 			n -= PADSIZE; \
231 		} \
232 		PRINT(with, n); \
233 	} \
234 } while (0)
235 #define	FLUSH() do { \
236 	if (uio.uio_resid && __sprint(fp, &uio)) \
237 		goto error; \
238 	uio.uio_iovcnt = 0; \
239 	iovp = iov; \
240 } while (0)
241 
242 	/*
243 	 * To extend shorts properly, we need both signed and unsigned
244 	 * argument extraction methods.
245 	 */
246 #define	SARG() \
247 	(flags&QUADINT ? GETARG(quad_t) : \
248 	    flags&LONGINT ? GETARG(long) : \
249 	    flags&PTRINT ? GETARG(ptrdiff_t) : \
250 	    flags&SIZEINT ? GETARG(ssize_t) : \
251 	    flags&SHORTINT ? (long)(short)GETARG(int) : \
252 	    (long)GETARG(int))
253 #define	UARG() \
254 	(flags&QUADINT ? GETARG(u_quad_t) : \
255 	    flags&LONGINT ? GETARG(u_long) : \
256 	    flags&PTRINT ? GETARG(ptrdiff_t) : /* XXX */ \
257 	    flags&SIZEINT ? GETARG(size_t) : \
258 	    flags&SHORTINT ? (u_long)(u_short)GETARG(int) : \
259 	    (u_long)GETARG(u_int))
260 
261 	 /*
262 	  * Get * arguments, including the form *nn$.  Preserve the nextarg
263 	  * that the argument can be gotten once the type is determined.
264 	  */
265 #define GETASTER(val) \
266 	n2 = 0; \
267 	cp = fmt; \
268 	while (is_digit(*cp)) { \
269 		n2 = 10 * n2 + to_digit(*cp); \
270 		cp++; \
271 	} \
272 	if (*cp == '$') { \
273 		int hold = nextarg; \
274 		if (argtable == NULL) { \
275 			argtable = statargtable; \
276 			__find_arguments(fmt0, orgap, &argtable, &argtablesiz); \
277 		} \
278 		nextarg = n2; \
279 		val = GETARG(int); \
280 		nextarg = hold; \
281 		fmt = ++cp; \
282 	} else { \
283 		val = GETARG(int); \
284 	}
285 
286 /*
287 * Get the argument indexed by nextarg.   If the argument table is
288 * built, use it to get the argument.  If its not, get the next
289 * argument (and arguments must be gotten sequentially).
290 */
291 #define GETARG(type) \
292 	(((argtable != NULL) ? (void)(ap = argtable[nextarg]) : (void)0), \
293 	 nextarg++, va_arg(ap, type))
294 
295 	_SET_ORIENTATION(fp, -1);
296 	/* sorry, fprintf(read_only_file, "") returns EOF, not 0 */
297 	if (cantwrite(fp)) {
298 		errno = EBADF;
299 		return (EOF);
300 	}
301 
302 	/* optimise fprintf(stderr) (and other unbuffered Unix files) */
303 	if ((fp->_flags & (__SNBF|__SWR|__SRW)) == (__SNBF|__SWR) &&
304 	    fp->_file >= 0)
305 		return (__sbprintf(fp, fmt0, ap));
306 
307 	fmt = (char *)fmt0;
308 	argtable = NULL;
309 	nextarg = 1;
310 	va_copy(orgap, ap);
311 	uio.uio_iov = iovp = iov;
312 	uio.uio_resid = 0;
313 	uio.uio_iovcnt = 0;
314 	ret = 0;
315 
316 	memset(&ps, 0, sizeof(ps));
317 	/*
318 	 * Scan the format for conversions (`%' character).
319 	 */
320 	for (;;) {
321 		cp = fmt;
322 		while ((n = mbrtowc(&wc, fmt, MB_CUR_MAX, &ps)) > 0) {
323 			fmt += n;
324 			if (wc == '%') {
325 				fmt--;
326 				break;
327 			}
328 		}
329 		if ((m = fmt - cp) != 0) {
330 			PRINT(cp, m);
331 			ret += m;
332 		}
333 		if (n <= 0)
334 			goto done;
335 		fmt++;		/* skip over '%' */
336 
337 		flags = 0;
338 		dprec = 0;
339 		width = 0;
340 		prec = -1;
341 		sign = '\0';
342 
343 rflag:		ch = *fmt++;
344 reswitch:	switch (ch) {
345 		case ' ':
346 			/*
347 			 * ``If the space and + flags both appear, the space
348 			 * flag will be ignored.''
349 			 *	-- ANSI X3J11
350 			 */
351 			if (!sign)
352 				sign = ' ';
353 			goto rflag;
354 		case '#':
355 			flags |= ALT;
356 			goto rflag;
357 		case '*':
358 			/*
359 			 * ``A negative field width argument is taken as a
360 			 * - flag followed by a positive field width.''
361 			 *	-- ANSI X3J11
362 			 * They don't exclude field widths read from args.
363 			 */
364 			GETASTER(width);
365 			if (width >= 0)
366 				goto rflag;
367 			width = -width;
368 			/* FALLTHROUGH */
369 		case '-':
370 			flags |= LADJUST;
371 			goto rflag;
372 		case '+':
373 			sign = '+';
374 			goto rflag;
375 		case '.':
376 			if ((ch = *fmt++) == '*') {
377 				GETASTER(n);
378 				prec = n < 0 ? -1 : n;
379 				goto rflag;
380 			}
381 			n = 0;
382 			while (is_digit(ch)) {
383 				n = 10 * n + to_digit(ch);
384 				ch = *fmt++;
385 			}
386 			if (ch == '$') {
387 				nextarg = n;
388 				if (argtable == NULL) {
389 					argtable = statargtable;
390 					__find_arguments(fmt0, orgap,
391 					    &argtable, &argtablesiz);
392 				}
393 				goto rflag;
394 			}
395 			prec = n < 0 ? -1 : n;
396 			goto reswitch;
397 		case '0':
398 			/*
399 			 * ``Note that 0 is taken as a flag, not as the
400 			 * beginning of a field width.''
401 			 *	-- ANSI X3J11
402 			 */
403 			flags |= ZEROPAD;
404 			goto rflag;
405 		case '1': case '2': case '3': case '4':
406 		case '5': case '6': case '7': case '8': case '9':
407 			n = 0;
408 			do {
409 				n = 10 * n + to_digit(ch);
410 				ch = *fmt++;
411 			} while (is_digit(ch));
412 			if (ch == '$') {
413 				nextarg = n;
414 				if (argtable == NULL) {
415 					argtable = statargtable;
416 					__find_arguments(fmt0, orgap,
417 					    &argtable, &argtablesiz);
418 				}
419 				goto rflag;
420 			}
421 			width = n;
422 			goto reswitch;
423 #ifdef FLOATING_POINT
424 		case 'L':
425 			flags |= LONGDBL;
426 			goto rflag;
427 #endif
428 		case 'h':
429 			flags |= SHORTINT;
430 			goto rflag;
431 		case 'l':
432 			if (*fmt == 'l') {
433 				fmt++;
434 				flags |= QUADINT;
435 			} else {
436 				flags |= LONGINT;
437 			}
438 			goto rflag;
439 		case 'q':
440 			flags |= QUADINT;
441 			goto rflag;
442 		case 't':
443 			flags |= PTRINT;
444 			goto rflag;
445 		case 'z':
446 			flags |= SIZEINT;
447 			goto rflag;
448 		case 'c':
449 			*(cp = buf) = GETARG(int);
450 			size = 1;
451 			sign = '\0';
452 			break;
453 		case 'D':
454 			flags |= LONGINT;
455 			/*FALLTHROUGH*/
456 		case 'd':
457 		case 'i':
458 			_uquad = SARG();
459 			if ((quad_t)_uquad < 0) {
460 				_uquad = -_uquad;
461 				sign = '-';
462 			}
463 			base = DEC;
464 			goto number;
465 #ifdef FLOATING_POINT
466 		case 'e':
467 		case 'E':
468 		case 'f':
469 		case 'g':
470 		case 'G':
471 			if (prec == -1) {
472 				prec = DEFPREC;
473 			} else if ((ch == 'g' || ch == 'G') && prec == 0) {
474 				prec = 1;
475 			}
476 
477 			if (flags & LONGDBL) {
478 				_double = (double) GETARG(long double);
479 			} else {
480 				_double = GETARG(double);
481 			}
482 
483 			/* do this before tricky precision changes */
484 			if (isinf(_double)) {
485 				if (_double < 0)
486 					sign = '-';
487 				cp = "Inf";
488 				size = 3;
489 				break;
490 			}
491 			if (isnan(_double)) {
492 				cp = "NaN";
493 				size = 3;
494 				break;
495 			}
496 
497 			flags |= FPT;
498 			cp = cvt(_double, prec, flags, &softsign,
499 				&expt, ch, &ndig);
500 			if (ch == 'g' || ch == 'G') {
501 				if (expt <= -4 || expt > prec)
502 					ch = (ch == 'g') ? 'e' : 'E';
503 				else
504 					ch = 'g';
505 			}
506 			if (ch <= 'e') {	/* 'e' or 'E' fmt */
507 				--expt;
508 				expsize = exponent(expstr, expt, ch);
509 				size = expsize + ndig;
510 				if (ndig > 1 || flags & ALT)
511 					++size;
512 			} else if (ch == 'f') {		/* f fmt */
513 				if (expt > 0) {
514 					size = expt;
515 					if (prec || flags & ALT)
516 						size += prec + 1;
517 				} else	/* "0.X" */
518 					size = prec + 2;
519 			} else if (expt >= ndig) {	/* fixed g fmt */
520 				size = expt;
521 				if (flags & ALT)
522 					++size;
523 			} else
524 				size = ndig + (expt > 0 ?
525 					1 : 2 - expt);
526 
527 			if (softsign)
528 				sign = '-';
529 			break;
530 #endif /* FLOATING_POINT */
531 		case 'n':
532 			if (flags & QUADINT)
533 				*GETARG(quad_t *) = ret;
534 			else if (flags & LONGINT)
535 				*GETARG(long *) = ret;
536 			else if (flags & SHORTINT)
537 				*GETARG(short *) = ret;
538 			else if (flags & PTRINT)
539 				*GETARG(ptrdiff_t *) = ret;
540 			else if (flags & SIZEINT)
541 				*GETARG(ssize_t *) = ret;
542 			else
543 				*GETARG(int *) = ret;
544 			continue;	/* no output */
545 		case 'O':
546 			flags |= LONGINT;
547 			/*FALLTHROUGH*/
548 		case 'o':
549 			_uquad = UARG();
550 			base = OCT;
551 			goto nosign;
552 		case 'p':
553 			/*
554 			 * ``The argument shall be a pointer to void.  The
555 			 * value of the pointer is converted to a sequence
556 			 * of printable characters, in an implementation-
557 			 * defined manner.''
558 			 *	-- ANSI X3J11
559 			 */
560 			/* NOSTRICT */
561 			_uquad = (u_long)GETARG(void *);
562 			base = HEX;
563 			xdigs = "0123456789abcdef";
564 			flags |= HEXPREFIX;
565 			ch = 'x';
566 			goto nosign;
567 		case 's':
568 			if ((cp = GETARG(char *)) == NULL)
569 				cp = "(null)";
570 			if (prec >= 0) {
571 				/*
572 				 * can't use strlen; can only look for the
573 				 * NUL in the first `prec' characters, and
574 				 * strlen() will go further.
575 				 */
576 				char *p = memchr(cp, 0, prec);
577 
578 				if (p != NULL) {
579 					size = p - cp;
580 					if (size > prec)
581 						size = prec;
582 				} else
583 					size = prec;
584 			} else
585 				size = strlen(cp);
586 			sign = '\0';
587 			break;
588 		case 'U':
589 			flags |= LONGINT;
590 			/*FALLTHROUGH*/
591 		case 'u':
592 			_uquad = UARG();
593 			base = DEC;
594 			goto nosign;
595 		case 'X':
596 			xdigs = "0123456789ABCDEF";
597 			goto hex;
598 		case 'x':
599 			xdigs = "0123456789abcdef";
600 hex:			_uquad = UARG();
601 			base = HEX;
602 			/* leading 0x/X only if non-zero */
603 			if (flags & ALT && _uquad != 0)
604 				flags |= HEXPREFIX;
605 
606 			/* unsigned conversions */
607 nosign:			sign = '\0';
608 			/*
609 			 * ``... diouXx conversions ... if a precision is
610 			 * specified, the 0 flag will be ignored.''
611 			 *	-- ANSI X3J11
612 			 */
613 number:			if ((dprec = prec) >= 0)
614 				flags &= ~ZEROPAD;
615 
616 			/*
617 			 * ``The result of converting a zero value with an
618 			 * explicit precision of zero is no characters.''
619 			 *	-- ANSI X3J11
620 			 */
621 			cp = buf + BUF;
622 			if (_uquad != 0 || prec != 0) {
623 				/*
624 				 * Unsigned mod is hard, and unsigned mod
625 				 * by a constant is easier than that by
626 				 * a variable; hence this switch.
627 				 */
628 				switch (base) {
629 				case OCT:
630 					do {
631 						*--cp = to_char(_uquad & 7);
632 						_uquad >>= 3;
633 					} while (_uquad);
634 					/* handle octal leading 0 */
635 					if (flags & ALT && *cp != '0')
636 						*--cp = '0';
637 					break;
638 
639 				case DEC:
640 					/* many numbers are 1 digit */
641 					while (_uquad >= 10) {
642 						*--cp = to_char(_uquad % 10);
643 						_uquad /= 10;
644 					}
645 					*--cp = to_char(_uquad);
646 					break;
647 
648 				case HEX:
649 					do {
650 						*--cp = xdigs[_uquad & 15];
651 						_uquad >>= 4;
652 					} while (_uquad);
653 					break;
654 
655 				default:
656 					cp = "bug in vfprintf: bad base";
657 					size = strlen(cp);
658 					goto skipsize;
659 				}
660 			}
661 			size = buf + BUF - cp;
662 		skipsize:
663 			break;
664 		default:	/* "%?" prints ?, unless ? is NUL */
665 			if (ch == '\0')
666 				goto done;
667 			/* pretend it was %c with argument ch */
668 			cp = buf;
669 			*cp = ch;
670 			size = 1;
671 			sign = '\0';
672 			break;
673 		}
674 
675 		/*
676 		 * All reasonable formats wind up here.  At this point, `cp'
677 		 * points to a string which (if not flags&LADJUST) should be
678 		 * padded out to `width' places.  If flags&ZEROPAD, it should
679 		 * first be prefixed by any sign or other prefix; otherwise,
680 		 * it should be blank padded before the prefix is emitted.
681 		 * After any left-hand padding and prefixing, emit zeroes
682 		 * required by a decimal [diouxX] precision, then print the
683 		 * string proper, then emit zeroes required by any leftover
684 		 * floating precision; finally, if LADJUST, pad with blanks.
685 		 *
686 		 * Compute actual size, so we know how much to pad.
687 		 * size excludes decimal prec; realsz includes it.
688 		 */
689 		realsz = dprec > size ? dprec : size;
690 		if (sign)
691 			realsz++;
692 		else if (flags & HEXPREFIX)
693 			realsz+= 2;
694 
695 		/* right-adjusting blank padding */
696 		if ((flags & (LADJUST|ZEROPAD)) == 0)
697 			PAD(width - realsz, blanks);
698 
699 		/* prefix */
700 		if (sign) {
701 			PRINT(&sign, 1);
702 		} else if (flags & HEXPREFIX) {
703 			ox[0] = '0';
704 			ox[1] = ch;
705 			PRINT(ox, 2);
706 		}
707 
708 		/* right-adjusting zero padding */
709 		if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD)
710 			PAD(width - realsz, zeroes);
711 
712 		/* leading zeroes from decimal precision */
713 		PAD(dprec - size, zeroes);
714 
715 		/* the string or number proper */
716 #ifdef FLOATING_POINT
717 		if ((flags & FPT) == 0) {
718 			PRINT(cp, size);
719 		} else {	/* glue together f_p fragments */
720 			if (ch >= 'f') {	/* 'f' or 'g' */
721 				if (_double == 0) {
722 					/* kludge for __dtoa irregularity */
723 					PRINT("0", 1);
724 					if (expt < ndig || (flags & ALT) != 0) {
725 						PRINT(decimal_point, 1);
726 						PAD(ndig - 1, zeroes);
727 					}
728 				} else if (expt <= 0) {
729 					PRINT("0", 1);
730 					PRINT(decimal_point, 1);
731 					PAD(-expt, zeroes);
732 					PRINT(cp, ndig);
733 				} else if (expt >= ndig) {
734 					PRINT(cp, ndig);
735 					PAD(expt - ndig, zeroes);
736 					if (flags & ALT)
737 						PRINT(".", 1);
738 				} else {
739 					PRINT(cp, expt);
740 					cp += expt;
741 					PRINT(".", 1);
742 					PRINT(cp, ndig-expt);
743 				}
744 			} else {	/* 'e' or 'E' */
745 				if (ndig > 1 || flags & ALT) {
746 					ox[0] = *cp++;
747 					ox[1] = '.';
748 					PRINT(ox, 2);
749 					if (_double) {
750 						PRINT(cp, ndig-1);
751 					} else	/* 0.[0..] */
752 						/* __dtoa irregularity */
753 						PAD(ndig - 1, zeroes);
754 				} else	/* XeYYY */
755 					PRINT(cp, 1);
756 				PRINT(expstr, expsize);
757 			}
758 		}
759 #else
760 		PRINT(cp, size);
761 #endif
762 		/* left-adjusting padding (always blank) */
763 		if (flags & LADJUST)
764 			PAD(width - realsz, blanks);
765 
766 		/* finally, adjust ret */
767 		ret += width > realsz ? width : realsz;
768 
769 		FLUSH();	/* copy out the I/O vectors */
770 	}
771 done:
772 	FLUSH();
773 error:
774 	if (argtable != NULL && argtable != statargtable) {
775 		munmap(argtable, argtablesiz);
776 		argtable = NULL;
777 	}
778 	return (__sferror(fp) ? EOF : ret);
779 	/* NOTREACHED */
780 }
781 
782 /*
783  * Type ids for argument type table.
784  */
785 #define T_UNUSED	0
786 #define T_SHORT		1
787 #define T_U_SHORT	2
788 #define TP_SHORT	3
789 #define T_INT		4
790 #define T_U_INT		5
791 #define TP_INT		6
792 #define T_LONG		7
793 #define T_U_LONG	8
794 #define TP_LONG		9
795 #define T_QUAD		10
796 #define T_U_QUAD	11
797 #define TP_QUAD		12
798 #define T_DOUBLE	13
799 #define T_LONG_DOUBLE	14
800 #define TP_CHAR		15
801 #define TP_VOID		16
802 #define T_PTRINT	17
803 #define TP_PTRINT	18
804 #define T_SIZEINT	19
805 #define T_SSIZEINT	20
806 #define TP_SSIZEINT	21
807 
808 /*
809  * Find all arguments when a positional parameter is encountered.  Returns a
810  * table, indexed by argument number, of pointers to each arguments.  The
811  * initial argument table should be an array of STATIC_ARG_TBL_SIZE entries.
812  * It will be replaced with a mmap-ed one if it overflows (malloc cannot be
813  * used since we are attempting to make snprintf thread safe, and alloca is
814  * problematic since we have nested functions..)
815  */
816 static void
817 __find_arguments(const char *fmt0, va_list ap, va_list **argtable,
818     size_t *argtablesiz)
819 {
820 	char *fmt;	/* format string */
821 	int ch;	/* character from fmt */
822 	int n, n2;	/* handy integer (short term usage) */
823 	char *cp;	/* handy char pointer (short term usage) */
824 	int flags;	/* flags as above */
825 	unsigned char *typetable; /* table of types */
826 	unsigned char stattypetable[STATIC_ARG_TBL_SIZE];
827 	int tablesize;		/* current size of type table */
828 	int tablemax;		/* largest used index in table */
829 	int nextarg;		/* 1-based argument index */
830 	wchar_t wc;
831 	mbstate_t ps;
832 
833 	/*
834 	 * Add an argument type to the table, expanding if necessary.
835 	 */
836 #define ADDTYPE(type) \
837 	((nextarg >= tablesize) ? \
838 		__grow_type_table(&typetable, &tablesize) : 0, \
839 	(nextarg > tablemax) ? tablemax = nextarg : 0, \
840 	typetable[nextarg++] = type)
841 
842 #define	ADDSARG() \
843 	((flags&QUADINT) ? ADDTYPE(T_QUAD) : \
844 	    ((flags&LONGINT) ? ADDTYPE(T_LONG) : \
845 		((flags&SHORTINT) ? ADDTYPE(T_SHORT) : ADDTYPE(T_INT))))
846 
847 #define	ADDUARG() \
848 	((flags&QUADINT) ? ADDTYPE(T_U_QUAD) : \
849 	    ((flags&LONGINT) ? ADDTYPE(T_U_LONG) : \
850 		((flags&SHORTINT) ? ADDTYPE(T_U_SHORT) : ADDTYPE(T_U_INT))))
851 
852 	/*
853 	 * Add * arguments to the type array.
854 	 */
855 #define ADDASTER() \
856 	n2 = 0; \
857 	cp = fmt; \
858 	while (is_digit(*cp)) { \
859 		n2 = 10 * n2 + to_digit(*cp); \
860 		cp++; \
861 	} \
862 	if (*cp == '$') { \
863 		int hold = nextarg; \
864 		nextarg = n2; \
865 		ADDTYPE(T_INT); \
866 		nextarg = hold; \
867 		fmt = ++cp; \
868 	} else { \
869 		ADDTYPE(T_INT); \
870 	}
871 	fmt = (char *)fmt0;
872 	typetable = stattypetable;
873 	tablesize = STATIC_ARG_TBL_SIZE;
874 	tablemax = 0;
875 	nextarg = 1;
876 	memset(typetable, T_UNUSED, STATIC_ARG_TBL_SIZE);
877 	memset(&ps, 0, sizeof(ps));
878 
879 	/*
880 	 * Scan the format for conversions (`%' character).
881 	 */
882 	for (;;) {
883 		cp = fmt;
884 		while ((n = mbrtowc(&wc, fmt, MB_CUR_MAX, &ps)) > 0) {
885 			fmt += n;
886 			if (wc == '%') {
887 				fmt--;
888 				break;
889 			}
890 		}
891 		if (n <= 0)
892 			goto done;
893 		fmt++;		/* skip over '%' */
894 
895 		flags = 0;
896 
897 rflag:		ch = *fmt++;
898 reswitch:	switch (ch) {
899 		case ' ':
900 		case '#':
901 			goto rflag;
902 		case '*':
903 			ADDASTER();
904 			goto rflag;
905 		case '-':
906 		case '+':
907 			goto rflag;
908 		case '.':
909 			if ((ch = *fmt++) == '*') {
910 				ADDASTER();
911 				goto rflag;
912 			}
913 			while (is_digit(ch)) {
914 				ch = *fmt++;
915 			}
916 			goto reswitch;
917 		case '0':
918 			goto rflag;
919 		case '1': case '2': case '3': case '4':
920 		case '5': case '6': case '7': case '8': case '9':
921 			n = 0;
922 			do {
923 				n = 10 * n + to_digit(ch);
924 				ch = *fmt++;
925 			} while (is_digit(ch));
926 			if (ch == '$') {
927 				nextarg = n;
928 				goto rflag;
929 			}
930 			goto reswitch;
931 #ifdef FLOATING_POINT
932 		case 'L':
933 			flags |= LONGDBL;
934 			goto rflag;
935 #endif
936 		case 'h':
937 			flags |= SHORTINT;
938 			goto rflag;
939 		case 'l':
940 			if (*fmt == 'l') {
941 				fmt++;
942 				flags |= QUADINT;
943 			} else {
944 				flags |= LONGINT;
945 			}
946 			goto rflag;
947 		case 'q':
948 			flags |= QUADINT;
949 			goto rflag;
950 		case 't':
951 			flags |= PTRINT;
952 			goto rflag;
953 		case 'z':
954 			flags |= SIZEINT;
955 			goto rflag;
956 		case 'c':
957 			ADDTYPE(T_INT);
958 			break;
959 		case 'D':
960 			flags |= LONGINT;
961 			/*FALLTHROUGH*/
962 		case 'd':
963 		case 'i':
964 			if (flags & QUADINT)
965 				ADDTYPE(T_QUAD);
966 			else if (flags & PTRINT)
967 				ADDTYPE(T_PTRINT);
968 			else if (flags & SIZEINT)
969 				ADDTYPE(T_SSIZEINT);
970 			else
971 				ADDSARG();
972 			break;
973 #ifdef FLOATING_POINT
974 		case 'e':
975 		case 'E':
976 		case 'f':
977 		case 'g':
978 		case 'G':
979 			if (flags & LONGDBL)
980 				ADDTYPE(T_LONG_DOUBLE);
981 			else
982 				ADDTYPE(T_DOUBLE);
983 			break;
984 #endif /* FLOATING_POINT */
985 		case 'n':
986 			if (flags & QUADINT)
987 				ADDTYPE(TP_QUAD);
988 			else if (flags & LONGINT)
989 				ADDTYPE(TP_LONG);
990 			else if (flags & SHORTINT)
991 				ADDTYPE(TP_SHORT);
992 			else if (flags & PTRINT)
993 				ADDTYPE(TP_PTRINT);
994 			else if (flags & SIZEINT)
995 				ADDTYPE(TP_SSIZEINT);
996 			else
997 				ADDTYPE(TP_INT);
998 			continue;	/* no output */
999 		case 'O':
1000 			flags |= LONGINT;
1001 			/*FALLTHROUGH*/
1002 		case 'o':
1003 			if (flags & QUADINT)
1004 				ADDTYPE(T_U_QUAD);
1005 			else
1006 				ADDUARG();
1007 			break;
1008 		case 'p':
1009 			ADDTYPE(TP_VOID);
1010 			break;
1011 		case 's':
1012 			ADDTYPE(TP_CHAR);
1013 			break;
1014 		case 'U':
1015 			flags |= LONGINT;
1016 			/*FALLTHROUGH*/
1017 		case 'u':
1018 			if (flags & QUADINT)
1019 				ADDTYPE(T_U_QUAD);
1020 			else
1021 				ADDUARG();
1022 			break;
1023 		case 'X':
1024 		case 'x':
1025 			if (flags & QUADINT)
1026 				ADDTYPE(T_U_QUAD);
1027 			else if (flags & PTRINT)
1028 				ADDTYPE(T_PTRINT);
1029 			else if (flags & SIZEINT)
1030 				ADDTYPE(T_SIZEINT);
1031 			else
1032 				ADDUARG();
1033 			break;
1034 		default:	/* "%?" prints ?, unless ? is NUL */
1035 			if (ch == '\0')
1036 				goto done;
1037 			break;
1038 		}
1039 	}
1040 done:
1041 	/*
1042 	 * Build the argument table.
1043 	 */
1044 	if (tablemax >= STATIC_ARG_TBL_SIZE) {
1045 		*argtablesiz = sizeof (va_list) * (tablemax + 1);
1046 		*argtable = (va_list *)mmap(NULL, *argtablesiz,
1047 		    PROT_WRITE|PROT_READ, MAP_ANON|MAP_PRIVATE, -1, 0);
1048 	}
1049 
1050 #if 0
1051 	/* XXX is this required? */
1052 	(*argtable) [0] = NULL;
1053 #endif
1054 	for (n = 1; n <= tablemax; n++) {
1055 		va_copy((*argtable)[n], ap);
1056 		switch (typetable[n]) {
1057 		case T_UNUSED:
1058 			(void) va_arg(ap, int);
1059 			break;
1060 		case T_SHORT:
1061 			(void) va_arg(ap, int);
1062 			break;
1063 		case T_U_SHORT:
1064 			(void) va_arg(ap, int);
1065 			break;
1066 		case TP_SHORT:
1067 			(void) va_arg(ap, short *);
1068 			break;
1069 		case T_INT:
1070 			(void) va_arg(ap, int);
1071 			break;
1072 		case T_U_INT:
1073 			(void) va_arg(ap, unsigned int);
1074 			break;
1075 		case TP_INT:
1076 			(void) va_arg(ap, int *);
1077 			break;
1078 		case T_LONG:
1079 			(void) va_arg(ap, long);
1080 			break;
1081 		case T_U_LONG:
1082 			(void) va_arg(ap, unsigned long);
1083 			break;
1084 		case TP_LONG:
1085 			(void) va_arg(ap, long *);
1086 			break;
1087 		case T_QUAD:
1088 			(void) va_arg(ap, quad_t);
1089 			break;
1090 		case T_U_QUAD:
1091 			(void) va_arg(ap, u_quad_t);
1092 			break;
1093 		case TP_QUAD:
1094 			(void) va_arg(ap, quad_t *);
1095 			break;
1096 		case T_DOUBLE:
1097 			(void) va_arg(ap, double);
1098 			break;
1099 		case T_LONG_DOUBLE:
1100 			(void) va_arg(ap, long double);
1101 			break;
1102 		case TP_CHAR:
1103 			(void) va_arg(ap, char *);
1104 			break;
1105 		case TP_VOID:
1106 			(void) va_arg(ap, void *);
1107 			break;
1108 		case T_PTRINT:
1109 			(void) va_arg(ap, ptrdiff_t);
1110 			break;
1111 		case TP_PTRINT:
1112 			(void) va_arg(ap, ptrdiff_t *);
1113 			break;
1114 		case T_SIZEINT:
1115 			(void) va_arg(ap, size_t);
1116 			break;
1117 		case T_SSIZEINT:
1118 			(void) va_arg(ap, ssize_t);
1119 			break;
1120 		case TP_SSIZEINT:
1121 			(void) va_arg(ap, ssize_t *);
1122 			break;
1123 		}
1124 	}
1125 
1126 	if (typetable != NULL && typetable != stattypetable) {
1127 		munmap(typetable, *argtablesiz);
1128 		typetable = NULL;
1129 	}
1130 }
1131 
1132 /*
1133  * Increase the size of the type table.
1134  */
1135 static int
1136 __grow_type_table(unsigned char **typetable, int *tablesize)
1137 {
1138 	unsigned char *oldtable = *typetable;
1139 	int newsize = *tablesize * 2;
1140 
1141 	if (*tablesize == STATIC_ARG_TBL_SIZE) {
1142 		*typetable = (unsigned char *)mmap(NULL,
1143 		    sizeof (unsigned char) * newsize, PROT_WRITE|PROT_READ,
1144 		    MAP_ANON|MAP_PRIVATE, -1, 0);
1145 		/* XXX unchecked */
1146 		bcopy(oldtable, *typetable, *tablesize);
1147 	} else {
1148 		unsigned char *new = (unsigned char *)mmap(NULL,
1149 		    sizeof (unsigned char) * newsize, PROT_WRITE|PROT_READ,
1150 		    MAP_ANON|MAP_PRIVATE, -1, 0);
1151 		memmove(new, *typetable, *tablesize);
1152 		munmap(*typetable, *tablesize);
1153 		*typetable = new;
1154 		/* XXX unchecked */
1155 	}
1156 	memset(*typetable + *tablesize, T_UNUSED, (newsize - *tablesize));
1157 
1158 	*tablesize = newsize;
1159 	return(0);
1160 }
1161 
1162 
1163 #ifdef FLOATING_POINT
1164 
1165 extern char *__dtoa(double, int, int, int *, int *, char **);
1166 
1167 static char *
1168 cvt(double value, int ndigits, int flags, char *sign, int *decpt, int ch,
1169     int *length)
1170 {
1171 	int mode, dsgn;
1172 	char *digits, *bp, *rve;
1173 
1174 	if (ch == 'f') {
1175 		mode = 3;		/* ndigits after the decimal point */
1176 	} else {
1177 		/* To obtain ndigits after the decimal point for the 'e'
1178 		 * and 'E' formats, round to ndigits + 1 significant
1179 		 * figures.
1180 		 */
1181 		if (ch == 'e' || ch == 'E') {
1182 			ndigits++;
1183 		}
1184 		mode = 2;		/* ndigits significant digits */
1185 	}
1186 
1187 	if (value < 0) {
1188 		value = -value;
1189 		*sign = '-';
1190 	} else
1191 		*sign = '\000';
1192 	digits = __dtoa(value, mode, ndigits, decpt, &dsgn, &rve);
1193 	if ((ch != 'g' && ch != 'G') || flags & ALT) {	/* Print trailing zeros */
1194 		bp = digits + ndigits;
1195 		if (ch == 'f') {
1196 			if (*digits == '0' && value)
1197 				*decpt = -ndigits + 1;
1198 			bp += *decpt;
1199 		}
1200 		if (value == 0)	/* kludge for __dtoa irregularity */
1201 			rve = bp;
1202 		while (rve < bp)
1203 			*rve++ = '0';
1204 	}
1205 	*length = rve - digits;
1206 	return (digits);
1207 }
1208 
1209 static int
1210 exponent(char *p0, int exp, int fmtch)
1211 {
1212 	char *p, *t;
1213 	char expbuf[MAXEXP];
1214 
1215 	p = p0;
1216 	*p++ = fmtch;
1217 	if (exp < 0) {
1218 		exp = -exp;
1219 		*p++ = '-';
1220 	}
1221 	else
1222 		*p++ = '+';
1223 	t = expbuf + MAXEXP;
1224 	if (exp > 9) {
1225 		do {
1226 			*--t = to_char(exp % 10);
1227 		} while ((exp /= 10) > 9);
1228 		*--t = to_char(exp);
1229 		for (; t < expbuf + MAXEXP; *p++ = *t++);
1230 	}
1231 	else {
1232 		*p++ = '0';
1233 		*p++ = to_char(exp);
1234 	}
1235 	return (p - p0);
1236 }
1237 #endif /* FLOATING_POINT */
1238