xref: /netbsd-src/lib/libc/stdio/vfprintf.c (revision fe3c9ceaf70aa7ba8f3b594263951794d20b57da)
1 /*	$NetBSD: vfprintf.c,v 1.36 2001/04/28 15:41:29 kleink Exp $	*/
2 
3 /*-
4  * Copyright (c) 1990 The Regents of the University of California.
5  * 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. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  */
38 
39 #include <sys/cdefs.h>
40 #if defined(LIBC_SCCS) && !defined(lint)
41 #if 0
42 static char *sccsid = "@(#)vfprintf.c	5.50 (Berkeley) 12/16/92";
43 #else
44 __RCSID("$NetBSD: vfprintf.c,v 1.36 2001/04/28 15:41:29 kleink Exp $");
45 #endif
46 #endif /* LIBC_SCCS and not lint */
47 
48 /*
49  * Actual printf innards.
50  *
51  * This code is large and complicated...
52  */
53 
54 #include "namespace.h"
55 #include <sys/types.h>
56 
57 #include <assert.h>
58 #include <errno.h>
59 #include <stddef.h>
60 #include <stdint.h>
61 #include <stdio.h>
62 #include <stdlib.h>
63 #include <string.h>
64 #include <wchar.h>
65 
66 #if __STDC__
67 #include <stdarg.h>
68 #else
69 #include <varargs.h>
70 #endif
71 
72 #include "local.h"
73 #include "fvwrite.h"
74 #include "extern.h"
75 #include "reentrant.h"
76 
77 static int __sprint __P((FILE *, struct __suio *));
78 static int __sbprintf __P((FILE *, const char *, va_list))
79      __attribute__((__format__(__printf__, 2, 0)));
80 
81 /*
82  * Flush out all the vectors defined by the given uio,
83  * then reset it so that it can be reused.
84  */
85 static int
86 __sprint(fp, uio)
87 	FILE *fp;
88 	struct __suio *uio;
89 {
90 	int err;
91 
92 	_DIAGASSERT(fp != NULL);
93 	_DIAGASSERT(uio != NULL);
94 
95 	if (uio->uio_resid == 0) {
96 		uio->uio_iovcnt = 0;
97 		return (0);
98 	}
99 	err = __sfvwrite(fp, uio);
100 	uio->uio_resid = 0;
101 	uio->uio_iovcnt = 0;
102 	return (err);
103 }
104 
105 /*
106  * Helper function for `fprintf to unbuffered unix file': creates a
107  * temporary buffer.  We only work on write-only files; this avoids
108  * worries about ungetc buffers and so forth.
109  */
110 static int
111 __sbprintf(fp, fmt, ap)
112 	FILE *fp;
113 	const char *fmt;
114 	va_list ap;
115 {
116 	int ret;
117 	FILE fake;
118 	unsigned char buf[BUFSIZ];
119 
120 	_DIAGASSERT(fp != NULL);
121 	_DIAGASSERT(fmt != NULL);
122 
123 	/* copy the important variables */
124 	fake._flags = fp->_flags & ~__SNBF;
125 	fake._file = fp->_file;
126 	fake._cookie = fp->_cookie;
127 	fake._write = fp->_write;
128 
129 	/* set up the buffer */
130 	fake._bf._base = fake._p = buf;
131 	fake._bf._size = fake._w = sizeof(buf);
132 	fake._lbfsize = 0;	/* not actually used, but Just In Case */
133 
134 	/* do the work, then copy any error status */
135 	ret = vfprintf(&fake, fmt, ap);
136 	if (ret >= 0 && fflush(&fake))
137 		ret = -1;
138 	if (fake._flags & __SERR)
139 		fp->_flags |= __SERR;
140 	return (ret);
141 }
142 
143 
144 #ifdef FLOATING_POINT
145 #include <locale.h>
146 #include <math.h>
147 #include "floatio.h"
148 
149 #define	BUF		(MAXEXP+MAXFRACT+1)	/* + decimal point */
150 #define	DEFPREC		6
151 
152 static char *cvt __P((double, int, int, char *, int *, int, int *));
153 static int exponent __P((char *, int, int));
154 
155 #else /* no FLOATING_POINT */
156 
157 #define	BUF		40
158 
159 #endif /* FLOATING_POINT */
160 
161 #ifdef lint
162 static __inline void *__UNCONST __P((const void *));
163 static __inline void *
164 __UNCONST(v)
165 	const void *v;
166 {
167 	/* LINTED */
168 	return (void *) v;
169 }
170 #else
171 #define __UNCONST(v)	(void *)(v)
172 #endif
173 
174 /*
175  * Macros for converting digits to letters and vice versa
176  */
177 #define	to_digit(c)	((c) - '0')
178 #define is_digit(c)	((unsigned)to_digit(c) <= 9)
179 #define	to_char(n)	((char)((n) + '0'))
180 
181 /*
182  * Flags used during conversion.
183  */
184 #define	ALT		0x001		/* alternate form */
185 #define	HEXPREFIX	0x002		/* add 0x or 0X prefix */
186 #define	LADJUST		0x004		/* left adjustment */
187 #define	LONGDBL		0x008		/* long double; unimplemented */
188 #define	LONGINT		0x010		/* long integer */
189 #define	QUADINT		0x020		/* quad integer */
190 #define	SHORTINT	0x040		/* short integer */
191 #define	MAXINT		0x080		/* (unsigned) intmax_t */
192 #define	PTRINT		0x100		/* (unsigned) ptrdiff_t */
193 #define	SIZEINT		0x200		/* (signed) size_t */
194 #define	ZEROPAD		0x400		/* zero (as opposed to blank) pad */
195 #define FPT		0x800		/* Floating point number */
196 int
197 vfprintf(fp, fmt0, ap)
198 	FILE *fp;
199 	const char *fmt0;
200 	_BSD_VA_LIST_ ap;
201 {
202 	const char *fmt;/* format string */
203 	int ch;	/* character from fmt */
204 	int n, m;	/* handy integers (short term usage) */
205 	const char *cp;	/* handy char pointer (short term usage) */
206 	char *bp;	/* handy char pointer (short term usage) */
207 	struct __siov *iovp;/* for PRINT macro */
208 	int flags;	/* flags as above */
209 	int ret;		/* return value accumulator */
210 	int width;		/* width from format (%8d), or 0 */
211 	int prec;		/* precision from format (%.3d), or -1 */
212 	char sign;		/* sign prefix (' ', '+', '-', or \0) */
213 	wchar_t wc;
214 	mbstate_t ps;
215 #ifdef FLOATING_POINT
216 	char *decimal_point = localeconv()->decimal_point;
217 	char softsign;		/* temporary negative sign for floats */
218 	double _double = 0;	/* double precision arguments %[eEfgG] */
219 	int expt;		/* integer value of exponent */
220 	int expsize = 0;	/* character count for expstr */
221 	int ndig;		/* actual number of digits returned by cvt */
222 	char expstr[7];		/* buffer for exponent string */
223 #endif
224 
225 #ifdef __GNUC__			/* gcc has builtin quad type (long long) SOS */
226 #define	quad_t	  long long
227 #define	u_quad_t  unsigned long long
228 #endif
229 
230 #define	INTMAX_T	intmax_t
231 #define	UINTMAX_T	uintmax_t
232 
233 	UINTMAX_T _uintmax;	/* integer arguments %[diouxX] */
234 	enum { OCT, DEC, HEX } base;/* base for [diouxX] conversion */
235 	int dprec;		/* a copy of prec if [diouxX], 0 otherwise */
236 	int realsz;		/* field size expanded by dprec */
237 	int size;		/* size of converted field or string */
238 	char *xdigs = NULL;	/* digits for [xX] conversion */
239 #define NIOV 8
240 	struct __suio uio;	/* output information: summary */
241 	struct __siov iov[NIOV];/* ... and individual io vectors */
242 	char buf[BUF];		/* space for %c, %[diouxX], %[eEfgG] */
243 	char ox[2];		/* space for 0x hex-prefix */
244 
245 	/*
246 	 * Choose PADSIZE to trade efficiency vs. size.  If larger printf
247 	 * fields occur frequently, increase PADSIZE and make the initialisers
248 	 * below longer.
249 	 */
250 #define	PADSIZE	16		/* pad chunk size */
251 	static const char blanks[PADSIZE] =
252 	 {' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' '};
253 	static const char zeroes[PADSIZE] =
254 	 {'0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'};
255 
256 	/*
257 	 * BEWARE, these `goto error' on error, and PAD uses `n'.
258 	 */
259 #define	PRINT(ptr, len) { \
260 	iovp->iov_base = __UNCONST(ptr); \
261 	iovp->iov_len = (len); \
262 	uio.uio_resid += (len); \
263 	iovp++; \
264 	if (++uio.uio_iovcnt >= NIOV) { \
265 		if (__sprint(fp, &uio)) \
266 			goto error; \
267 		iovp = iov; \
268 	} \
269 }
270 #define	PAD(howmany, with) { \
271 	if ((n = (howmany)) > 0) { \
272 		while (n > PADSIZE) { \
273 			PRINT(with, PADSIZE); \
274 			n -= PADSIZE; \
275 		} \
276 		PRINT(with, n); \
277 	} \
278 }
279 #define	FLUSH() { \
280 	if (uio.uio_resid && __sprint(fp, &uio)) \
281 		goto error; \
282 	uio.uio_iovcnt = 0; \
283 	iovp = iov; \
284 }
285 
286 	/*
287 	 * To extend shorts properly, we need both signed and unsigned
288 	 * argument extraction methods.
289 	 */
290 #define	SARG() \
291 	(flags&MAXINT ? va_arg(ap, intmax_t) : \
292 	    flags&PTRINT ? va_arg(ap, ptrdiff_t) : \
293 	    flags&SIZEINT ? va_arg(ap, ssize_t) : /* XXX */ \
294 	    flags&QUADINT ? va_arg(ap, quad_t) : \
295 	    flags&LONGINT ? va_arg(ap, long) : \
296 	    flags&SHORTINT ? (long)(short)va_arg(ap, int) : \
297 	    (long)va_arg(ap, int))
298 #define	UARG() \
299 	(flags&MAXINT ? va_arg(ap, uintmax_t) : \
300 	    flags&PTRINT ? va_arg(ap, uintptr_t) : /* XXX */ \
301 	    flags&SIZEINT ? va_arg(ap, size_t) : \
302 	    flags&QUADINT ? va_arg(ap, u_quad_t) : \
303 	    flags&LONGINT ? va_arg(ap, u_long) : \
304 	    flags&SHORTINT ? (u_long)(u_short)va_arg(ap, int) : \
305 	    (u_long)va_arg(ap, u_int))
306 
307 	_DIAGASSERT(fp != NULL);
308 	_DIAGASSERT(fmt0 != NULL);
309 
310 	FLOCKFILE(fp);
311 
312 	/* sorry, fprintf(read_only_file, "") returns -1, not 0 */
313 	if (cantwrite(fp)) {
314 		errno = EBADF;
315 		FUNLOCKFILE(fp);
316 		return (-1);
317 	}
318 
319 	/* optimise fprintf(stderr) (and other unbuffered Unix files) */
320 	if ((fp->_flags & (__SNBF|__SWR|__SRW)) == (__SNBF|__SWR) &&
321 	    fp->_file >= 0) {
322 		ret = __sbprintf(fp, fmt0, ap);
323 		FUNLOCKFILE(fp);
324 		return (ret);
325 	}
326 
327 	fmt = fmt0;
328 	uio.uio_iov = iovp = iov;
329 	uio.uio_resid = 0;
330 	uio.uio_iovcnt = 0;
331 	ret = 0;
332 
333 	memset(&ps, 0, sizeof(ps));
334 
335 	/*
336 	 * Scan the format for conversions (`%' character).
337 	 */
338 	for (;;) {
339 		cp = fmt;
340 		while ((n = mbrtowc(&wc, fmt, MB_CUR_MAX, &ps)) > 0) {
341 			fmt += n;
342 			if (wc == '%') {
343 				fmt--;
344 				break;
345 			}
346 		}
347 		if ((m = fmt - cp) != 0) {
348 			PRINT(cp, m);
349 			ret += m;
350 		}
351 		if (n <= 0)
352 			goto done;
353 		fmt++;		/* skip over '%' */
354 
355 		flags = 0;
356 		dprec = 0;
357 		width = 0;
358 		prec = -1;
359 		sign = '\0';
360 
361 rflag:		ch = *fmt++;
362 reswitch:	switch (ch) {
363 		case ' ':
364 			/*
365 			 * ``If the space and + flags both appear, the space
366 			 * flag will be ignored.''
367 			 *	-- ANSI X3J11
368 			 */
369 			if (!sign)
370 				sign = ' ';
371 			goto rflag;
372 		case '#':
373 			flags |= ALT;
374 			goto rflag;
375 		case '*':
376 			/*
377 			 * ``A negative field width argument is taken as a
378 			 * - flag followed by a positive field width.''
379 			 *	-- ANSI X3J11
380 			 * They don't exclude field widths read from args.
381 			 */
382 			if ((width = va_arg(ap, int)) >= 0)
383 				goto rflag;
384 			width = -width;
385 			/* FALLTHROUGH */
386 		case '-':
387 			flags |= LADJUST;
388 			goto rflag;
389 		case '+':
390 			sign = '+';
391 			goto rflag;
392 		case '.':
393 			if ((ch = *fmt++) == '*') {
394 				n = va_arg(ap, int);
395 				prec = n < 0 ? -1 : n;
396 				goto rflag;
397 			}
398 			n = 0;
399 			while (is_digit(ch)) {
400 				n = 10 * n + to_digit(ch);
401 				ch = *fmt++;
402 			}
403 			prec = n < 0 ? -1 : n;
404 			goto reswitch;
405 		case '0':
406 			/*
407 			 * ``Note that 0 is taken as a flag, not as the
408 			 * beginning of a field width.''
409 			 *	-- ANSI X3J11
410 			 */
411 			flags |= ZEROPAD;
412 			goto rflag;
413 		case '1': case '2': case '3': case '4':
414 		case '5': case '6': case '7': case '8': case '9':
415 			n = 0;
416 			do {
417 				n = 10 * n + to_digit(ch);
418 				ch = *fmt++;
419 			} while (is_digit(ch));
420 			width = n;
421 			goto reswitch;
422 #ifdef FLOATING_POINT
423 		case 'L':
424 			flags |= LONGDBL;
425 			goto rflag;
426 #endif
427 		case 'h':
428 			flags |= SHORTINT;
429 			goto rflag;
430 		case 'j':
431 			flags |= MAXINT;
432 			goto rflag;
433 		case 'l':
434 			if (*fmt == 'l') {
435 				fmt++;
436 				flags |= QUADINT;
437 			} else {
438 				flags |= LONGINT;
439 			}
440 			goto rflag;
441 		case 'q':
442 			flags |= QUADINT;
443 			goto rflag;
444 		case 't':
445 			flags |= PTRINT;
446 			goto rflag;
447 		case 'z':
448 			flags |= SIZEINT;
449 			goto rflag;
450 		case 'c':
451 			*buf = va_arg(ap, int);
452 			cp = buf;
453 			size = 1;
454 			sign = '\0';
455 			break;
456 		case 'D':
457 			flags |= LONGINT;
458 			/*FALLTHROUGH*/
459 		case 'd':
460 		case 'i':
461 			_uintmax = SARG();
462 			if ((intmax_t)_uintmax < 0) {
463 				_uintmax = -_uintmax;
464 				sign = '-';
465 			}
466 			base = DEC;
467 			goto number;
468 #ifdef FLOATING_POINT
469 		case 'e':
470 		case 'E':
471 		case 'f':
472 		case 'g':
473 		case 'G':
474 			if (prec == -1) {
475 				prec = DEFPREC;
476 			} else if ((ch == 'g' || ch == 'G') && prec == 0) {
477 				prec = 1;
478 			}
479 
480 			if (flags & LONGDBL) {
481 				_double = (double) va_arg(ap, long double);
482 			} else {
483 				_double = va_arg(ap, double);
484 			}
485 
486 			/* do this before tricky precision changes */
487 			if (isinf(_double)) {
488 				if (_double < 0)
489 					sign = '-';
490 				cp = "Inf";
491 				size = 3;
492 				break;
493 			}
494 			if (isnan(_double)) {
495 				cp = "NaN";
496 				size = 3;
497 				break;
498 			}
499 
500 			flags |= FPT;
501 			cp = cvt(_double, prec, flags, &softsign,
502 				&expt, ch, &ndig);
503 			if (ch == 'g' || ch == 'G') {
504 				if (expt <= -4 || expt > prec)
505 					ch = (ch == 'g') ? 'e' : 'E';
506 				else
507 					ch = 'g';
508 			}
509 			if (ch <= 'e') {	/* 'e' or 'E' fmt */
510 				--expt;
511 				expsize = exponent(expstr, expt, ch);
512 				size = expsize + ndig;
513 				if (ndig > 1 || flags & ALT)
514 					++size;
515 			} else if (ch == 'f') {		/* f fmt */
516 				if (expt > 0) {
517 					size = expt;
518 					if (prec || flags & ALT)
519 						size += prec + 1;
520 				} else	/* "0.X" */
521 					size = prec + 2;
522 			} else if (expt >= ndig) {	/* fixed g fmt */
523 				size = expt;
524 				if (flags & ALT)
525 					++size;
526 			} else
527 				size = ndig + (expt > 0 ?
528 					1 : 2 - expt);
529 
530 			if (softsign)
531 				sign = '-';
532 			break;
533 #endif /* FLOATING_POINT */
534 		case 'n':
535 			if (flags & MAXINT)
536 				*va_arg(ap, intmax_t *) = ret;
537 			else if (flags & PTRINT)
538 				*va_arg(ap, ptrdiff_t *) = ret;
539 			else if (flags & SIZEINT)
540 				*va_arg(ap, ssize_t *) = ret;	/* XXX */
541 			else if (flags & QUADINT)
542 				*va_arg(ap, quad_t *) = ret;
543 			else if (flags & LONGINT)
544 				*va_arg(ap, long *) = ret;
545 			else if (flags & SHORTINT)
546 				*va_arg(ap, short *) = ret;
547 			else
548 				*va_arg(ap, int *) = ret;
549 			continue;	/* no output */
550 		case 'O':
551 			flags |= LONGINT;
552 			/*FALLTHROUGH*/
553 		case 'o':
554 			_uintmax = UARG();
555 			base = OCT;
556 			goto nosign;
557 		case 'p':
558 			/*
559 			 * ``The argument shall be a pointer to void.  The
560 			 * value of the pointer is converted to a sequence
561 			 * of printable characters, in an implementation-
562 			 * defined manner.''
563 			 *	-- ANSI X3J11
564 			 */
565 			/* NOSTRICT */
566 			_uintmax = (u_long)va_arg(ap, void *);
567 			base = HEX;
568 			xdigs = "0123456789abcdef";
569 			flags |= HEXPREFIX;
570 			ch = 'x';
571 			goto nosign;
572 		case 's':
573 			if ((cp = va_arg(ap, char *)) == NULL)
574 				cp = "(null)";
575 			if (prec >= 0) {
576 				/*
577 				 * can't use strlen; can only look for the
578 				 * NUL in the first `prec' characters, and
579 				 * strlen() will go further.
580 				 */
581 				char *p = memchr(cp, 0, (size_t)prec);
582 
583 				if (p != NULL) {
584 					size = p - cp;
585 					if (size > prec)
586 						size = prec;
587 				} else
588 					size = prec;
589 			} else
590 				size = strlen(cp);
591 			sign = '\0';
592 			break;
593 		case 'U':
594 			flags |= LONGINT;
595 			/*FALLTHROUGH*/
596 		case 'u':
597 			_uintmax = UARG();
598 			base = DEC;
599 			goto nosign;
600 		case 'X':
601 			xdigs = "0123456789ABCDEF";
602 			goto hex;
603 		case 'x':
604 			xdigs = "0123456789abcdef";
605 hex:			_uintmax = UARG();
606 			base = HEX;
607 			/* leading 0x/X only if non-zero */
608 			if (flags & ALT && _uintmax != 0)
609 				flags |= HEXPREFIX;
610 
611 			/* unsigned conversions */
612 nosign:			sign = '\0';
613 			/*
614 			 * ``... diouXx conversions ... if a precision is
615 			 * specified, the 0 flag will be ignored.''
616 			 *	-- ANSI X3J11
617 			 */
618 number:			if ((dprec = prec) >= 0)
619 				flags &= ~ZEROPAD;
620 
621 			/*
622 			 * ``The result of converting a zero value with an
623 			 * explicit precision of zero is no characters.''
624 			 *	-- ANSI X3J11
625 			 */
626 			bp = buf + BUF;
627 			if (_uintmax != 0 || prec != 0) {
628 				/*
629 				 * Unsigned mod is hard, and unsigned mod
630 				 * by a constant is easier than that by
631 				 * a variable; hence this switch.
632 				 */
633 				switch (base) {
634 				case OCT:
635 					do {
636 						*--bp = to_char(_uintmax & 7);
637 						_uintmax >>= 3;
638 					} while (_uintmax);
639 					/* handle octal leading 0 */
640 					if (flags & ALT && *bp != '0')
641 						*--bp = '0';
642 					break;
643 
644 				case DEC:
645 					/* many numbers are 1 digit */
646 					while (_uintmax >= 10) {
647 						*--bp = to_char(_uintmax % 10);
648 						_uintmax /= 10;
649 					}
650 					*--bp = to_char(_uintmax);
651 					break;
652 
653 				case HEX:
654 					do {
655 						*--bp = xdigs[(size_t)
656 						    (_uintmax & 15)];
657 						_uintmax >>= 4;
658 					} while (_uintmax);
659 					break;
660 
661 				default:
662 					cp = "bug in vfprintf: bad base";
663 					size = strlen(cp);
664 					goto skipsize;
665 				}
666 			}
667 			cp = bp;
668 			size = buf + BUF - bp;
669 		skipsize:
670 			break;
671 		default:	/* "%?" prints ?, unless ? is NUL */
672 			if (ch == '\0')
673 				goto done;
674 			/* pretend it was %c with argument ch */
675 			*buf = ch;
676 			cp = buf;
677 			size = 1;
678 			sign = '\0';
679 			break;
680 		}
681 
682 		/*
683 		 * All reasonable formats wind up here.  At this point, `cp'
684 		 * points to a string which (if not flags&LADJUST) should be
685 		 * padded out to `width' places.  If flags&ZEROPAD, it should
686 		 * first be prefixed by any sign or other prefix; otherwise,
687 		 * it should be blank padded before the prefix is emitted.
688 		 * After any left-hand padding and prefixing, emit zeroes
689 		 * required by a decimal [diouxX] precision, then print the
690 		 * string proper, then emit zeroes required by any leftover
691 		 * floating precision; finally, if LADJUST, pad with blanks.
692 		 *
693 		 * Compute actual size, so we know how much to pad.
694 		 * size excludes decimal prec; realsz includes it.
695 		 */
696 		realsz = dprec > size ? dprec : size;
697 		if (sign)
698 			realsz++;
699 		else if (flags & HEXPREFIX)
700 			realsz+= 2;
701 
702 		/* right-adjusting blank padding */
703 		if ((flags & (LADJUST|ZEROPAD)) == 0)
704 			PAD(width - realsz, blanks);
705 
706 		/* prefix */
707 		if (sign) {
708 			PRINT(&sign, 1);
709 		} else if (flags & HEXPREFIX) {
710 			ox[0] = '0';
711 			ox[1] = ch;
712 			PRINT(ox, 2);
713 		}
714 
715 		/* right-adjusting zero padding */
716 		if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD)
717 			PAD(width - realsz, zeroes);
718 
719 		/* leading zeroes from decimal precision */
720 		PAD(dprec - size, zeroes);
721 
722 		/* the string or number proper */
723 #ifdef FLOATING_POINT
724 		if ((flags & FPT) == 0) {
725 			PRINT(cp, size);
726 		} else {	/* glue together f_p fragments */
727 			if (ch >= 'f') {	/* 'f' or 'g' */
728 				if (_double == 0) {
729 					/* kludge for __dtoa irregularity */
730 					PRINT("0", 1);
731 					if (expt < ndig || (flags & ALT) != 0) {
732 						PRINT(decimal_point, 1);
733 						PAD(ndig - 1, zeroes);
734 					}
735 				} else if (expt <= 0) {
736 					PRINT("0", 1);
737 					PRINT(decimal_point, 1);
738 					PAD(-expt, zeroes);
739 					PRINT(cp, ndig);
740 				} else if (expt >= ndig) {
741 					PRINT(cp, ndig);
742 					PAD(expt - ndig, zeroes);
743 					if (flags & ALT)
744 						PRINT(".", 1);
745 				} else {
746 					PRINT(cp, expt);
747 					cp += expt;
748 					PRINT(".", 1);
749 					PRINT(cp, ndig-expt);
750 				}
751 			} else {	/* 'e' or 'E' */
752 				if (ndig > 1 || flags & ALT) {
753 					ox[0] = *cp++;
754 					ox[1] = '.';
755 					PRINT(ox, 2);
756 					if (_double) {
757 						PRINT(cp, ndig-1);
758 					} else	/* 0.[0..] */
759 						/* __dtoa irregularity */
760 						PAD(ndig - 1, zeroes);
761 				} else	/* XeYYY */
762 					PRINT(cp, 1);
763 				PRINT(expstr, expsize);
764 			}
765 		}
766 #else
767 		PRINT(cp, size);
768 #endif
769 		/* left-adjusting padding (always blank) */
770 		if (flags & LADJUST)
771 			PAD(width - realsz, blanks);
772 
773 		/* finally, adjust ret */
774 		ret += width > realsz ? width : realsz;
775 
776 		FLUSH();	/* copy out the I/O vectors */
777 	}
778 done:
779 	FLUSH();
780 error:
781 	if (__sferror(fp))
782 		ret = -1;
783 	FUNLOCKFILE(fp);
784 	return (ret);
785 }
786 
787 #ifdef FLOATING_POINT
788 
789 static char *
790 cvt(value, ndigits, flags, sign, decpt, ch, length)
791 	double value;
792 	int ndigits, flags, *decpt, ch, *length;
793 	char *sign;
794 {
795 	int mode, dsgn;
796 	char *digits, *bp, *rve;
797 
798 	_DIAGASSERT(decpt != NULL);
799 	_DIAGASSERT(length != NULL);
800 	_DIAGASSERT(sign != NULL);
801 
802 	if (ch == 'f') {
803 		mode = 3;		/* ndigits after the decimal point */
804 	} else {
805 		/* To obtain ndigits after the decimal point for the 'e'
806 		 * and 'E' formats, round to ndigits + 1 significant
807 		 * figures.
808 		 */
809 		if (ch == 'e' || ch == 'E') {
810 			ndigits++;
811 		}
812 		mode = 2;		/* ndigits significant digits */
813 	}
814 
815 	if (value < 0) {
816 		value = -value;
817 		*sign = '-';
818 	} else
819 		*sign = '\000';
820 	digits = __dtoa(value, mode, ndigits, decpt, &dsgn, &rve);
821 	if ((ch != 'g' && ch != 'G') || flags & ALT) {	/* Print trailing zeros */
822 		bp = digits + ndigits;
823 		if (ch == 'f') {
824 			if (*digits == '0' && value)
825 				*decpt = -ndigits + 1;
826 			bp += *decpt;
827 		}
828 		if (value == 0)	/* kludge for __dtoa irregularity */
829 			rve = bp;
830 		while (rve < bp)
831 			*rve++ = '0';
832 	}
833 	*length = rve - digits;
834 	return (digits);
835 }
836 
837 static int
838 exponent(p0, exp, fmtch)
839 	char *p0;
840 	int exp, fmtch;
841 {
842 	char *p, *t;
843 	char expbuf[MAXEXP];
844 
845 	_DIAGASSERT(p0 != NULL);
846 
847 	p = p0;
848 	*p++ = fmtch;
849 	if (exp < 0) {
850 		exp = -exp;
851 		*p++ = '-';
852 	}
853 	else
854 		*p++ = '+';
855 	t = expbuf + MAXEXP;
856 	if (exp > 9) {
857 		do {
858 			*--t = to_char(exp % 10);
859 		} while ((exp /= 10) > 9);
860 		*--t = to_char(exp);
861 		for (; t < expbuf + MAXEXP; *p++ = *t++);
862 	}
863 	else {
864 		*p++ = '0';
865 		*p++ = to_char(exp);
866 	}
867 	return (p - p0);
868 }
869 #endif /* FLOATING_POINT */
870