xref: /netbsd-src/lib/libc/stdio/vfprintf.c (revision 481fca6e59249d8ffcf24fef7cfbe7b131bfb080)
1 /*	$NetBSD: vfprintf.c,v 1.33 2000/07/08 14:57:57 sommerfeld 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 1.33 2000/07/08 14:57:57 sommerfeld 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 <stdio.h>
60 #include <stdlib.h>
61 #include <string.h>
62 
63 #if __STDC__
64 #include <stdarg.h>
65 #else
66 #include <varargs.h>
67 #endif
68 
69 #include "local.h"
70 #include "fvwrite.h"
71 #include "extern.h"
72 #include "reentrant.h"
73 
74 static int __sprint __P((FILE *, struct __suio *));
75 static int __sbprintf __P((FILE *, const char *, va_list))
76      __attribute__((__format__(__printf__, 2, 0)));
77 
78 /*
79  * Flush out all the vectors defined by the given uio,
80  * then reset it so that it can be reused.
81  */
82 static int
83 __sprint(fp, uio)
84 	FILE *fp;
85 	struct __suio *uio;
86 {
87 	int err;
88 
89 	_DIAGASSERT(fp != NULL);
90 	_DIAGASSERT(uio != NULL);
91 
92 	if (uio->uio_resid == 0) {
93 		uio->uio_iovcnt = 0;
94 		return (0);
95 	}
96 	err = __sfvwrite(fp, uio);
97 	uio->uio_resid = 0;
98 	uio->uio_iovcnt = 0;
99 	return (err);
100 }
101 
102 /*
103  * Helper function for `fprintf to unbuffered unix file': creates a
104  * temporary buffer.  We only work on write-only files; this avoids
105  * worries about ungetc buffers and so forth.
106  */
107 static int
108 __sbprintf(fp, fmt, ap)
109 	FILE *fp;
110 	const char *fmt;
111 	va_list ap;
112 {
113 	int ret;
114 	FILE fake;
115 	unsigned char buf[BUFSIZ];
116 
117 	_DIAGASSERT(fp != NULL);
118 	_DIAGASSERT(fmt != NULL);
119 
120 	/* copy the important variables */
121 	fake._flags = fp->_flags & ~__SNBF;
122 	fake._file = fp->_file;
123 	fake._cookie = fp->_cookie;
124 	fake._write = fp->_write;
125 
126 	/* set up the buffer */
127 	fake._bf._base = fake._p = buf;
128 	fake._bf._size = fake._w = sizeof(buf);
129 	fake._lbfsize = 0;	/* not actually used, but Just In Case */
130 
131 	/* do the work, then copy any error status */
132 	ret = vfprintf(&fake, fmt, ap);
133 	if (ret >= 0 && fflush(&fake))
134 		ret = -1;
135 	if (fake._flags & __SERR)
136 		fp->_flags |= __SERR;
137 	return (ret);
138 }
139 
140 
141 #ifdef FLOATING_POINT
142 #include <locale.h>
143 #include <math.h>
144 #include "floatio.h"
145 
146 #define	BUF		(MAXEXP+MAXFRACT+1)	/* + decimal point */
147 #define	DEFPREC		6
148 
149 static char *cvt __P((double, int, int, char *, int *, int, int *));
150 static int exponent __P((char *, int, int));
151 
152 #else /* no FLOATING_POINT */
153 
154 #define	BUF		40
155 
156 #endif /* FLOATING_POINT */
157 
158 #ifdef lint
159 static __inline void *__UNCONST __P((const void *));
160 static __inline void *
161 __UNCONST(v)
162 	const void *v;
163 {
164 	/* LINTED */
165 	return (void *) v;
166 }
167 #else
168 #define __UNCONST(v)	(void *)(v)
169 #endif
170 
171 /*
172  * Macros for converting digits to letters and vice versa
173  */
174 #define	to_digit(c)	((c) - '0')
175 #define is_digit(c)	((unsigned)to_digit(c) <= 9)
176 #define	to_char(n)	((char)((n) + '0'))
177 
178 /*
179  * Flags used during conversion.
180  */
181 #define	ALT		0x001		/* alternate form */
182 #define	HEXPREFIX	0x002		/* add 0x or 0X prefix */
183 #define	LADJUST		0x004		/* left adjustment */
184 #define	LONGDBL		0x008		/* long double; unimplemented */
185 #define	LONGINT		0x010		/* long integer */
186 #define	QUADINT		0x020		/* quad integer */
187 #define	SHORTINT	0x040		/* short integer */
188 #define	ZEROPAD		0x080		/* zero (as opposed to blank) pad */
189 #define FPT		0x100		/* Floating point number */
190 int
191 vfprintf(fp, fmt0, ap)
192 	FILE *fp;
193 	const char *fmt0;
194 	_BSD_VA_LIST_ ap;
195 {
196 	const char *fmt;/* format string */
197 	int ch;	/* character from fmt */
198 	int n, m;	/* handy integers (short term usage) */
199 	const char *cp;	/* handy char pointer (short term usage) */
200 	char *bp;	/* handy char pointer (short term usage) */
201 	struct __siov *iovp;/* for PRINT macro */
202 	int flags;	/* flags as above */
203 	int ret;		/* return value accumulator */
204 	int width;		/* width from format (%8d), or 0 */
205 	int prec;		/* precision from format (%.3d), or -1 */
206 	char sign;		/* sign prefix (' ', '+', '-', or \0) */
207 	wchar_t wc;
208 #ifdef FLOATING_POINT
209 	char *decimal_point = localeconv()->decimal_point;
210 	char softsign;		/* temporary negative sign for floats */
211 	double _double = 0;	/* double precision arguments %[eEfgG] */
212 	int expt;		/* integer value of exponent */
213 	int expsize = 0;	/* character count for expstr */
214 	int ndig;		/* actual number of digits returned by cvt */
215 	char expstr[7];		/* buffer for exponent string */
216 #endif
217 
218 #ifdef __GNUC__			/* gcc has builtin quad type (long long) SOS */
219 #define	quad_t	  long long
220 #define	u_quad_t  unsigned long long
221 #endif
222 
223 	u_quad_t _uquad;	/* integer arguments %[diouxX] */
224 	enum { OCT, DEC, HEX } base;/* base for [diouxX] conversion */
225 	int dprec;		/* a copy of prec if [diouxX], 0 otherwise */
226 	int realsz;		/* field size expanded by dprec */
227 	int size;		/* size of converted field or string */
228 	char *xdigs = NULL;	/* digits for [xX] conversion */
229 #define NIOV 8
230 	struct __suio uio;	/* output information: summary */
231 	struct __siov iov[NIOV];/* ... and individual io vectors */
232 	char buf[BUF];		/* space for %c, %[diouxX], %[eEfgG] */
233 	char ox[2];		/* space for 0x hex-prefix */
234 
235 	/*
236 	 * Choose PADSIZE to trade efficiency vs. size.  If larger printf
237 	 * fields occur frequently, increase PADSIZE and make the initialisers
238 	 * below longer.
239 	 */
240 #define	PADSIZE	16		/* pad chunk size */
241 	static const char blanks[PADSIZE] =
242 	 {' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' ',' '};
243 	static const char zeroes[PADSIZE] =
244 	 {'0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0'};
245 
246 	/*
247 	 * BEWARE, these `goto error' on error, and PAD uses `n'.
248 	 */
249 #define	PRINT(ptr, len) { \
250 	iovp->iov_base = __UNCONST(ptr); \
251 	iovp->iov_len = (len); \
252 	uio.uio_resid += (len); \
253 	iovp++; \
254 	if (++uio.uio_iovcnt >= NIOV) { \
255 		if (__sprint(fp, &uio)) \
256 			goto error; \
257 		iovp = iov; \
258 	} \
259 }
260 #define	PAD(howmany, with) { \
261 	if ((n = (howmany)) > 0) { \
262 		while (n > PADSIZE) { \
263 			PRINT(with, PADSIZE); \
264 			n -= PADSIZE; \
265 		} \
266 		PRINT(with, n); \
267 	} \
268 }
269 #define	FLUSH() { \
270 	if (uio.uio_resid && __sprint(fp, &uio)) \
271 		goto error; \
272 	uio.uio_iovcnt = 0; \
273 	iovp = iov; \
274 }
275 
276 	/*
277 	 * To extend shorts properly, we need both signed and unsigned
278 	 * argument extraction methods.
279 	 */
280 #define	SARG() \
281 	(flags&QUADINT ? va_arg(ap, quad_t) : \
282 	    flags&LONGINT ? va_arg(ap, long) : \
283 	    flags&SHORTINT ? (long)(short)va_arg(ap, int) : \
284 	    (long)va_arg(ap, int))
285 #define	UARG() \
286 	(flags&QUADINT ? va_arg(ap, u_quad_t) : \
287 	    flags&LONGINT ? va_arg(ap, u_long) : \
288 	    flags&SHORTINT ? (u_long)(u_short)va_arg(ap, int) : \
289 	    (u_long)va_arg(ap, u_int))
290 
291 	_DIAGASSERT(fp != NULL);
292 	_DIAGASSERT(fmt0 != NULL);
293 
294 	FLOCKFILE(fp);
295 
296 	/* sorry, fprintf(read_only_file, "") returns -1, not 0 */
297 	if (cantwrite(fp)) {
298 		errno = EBADF;
299 		FUNLOCKFILE(fp);
300 		return (-1);
301 	}
302 
303 	/* optimise fprintf(stderr) (and other unbuffered Unix files) */
304 	if ((fp->_flags & (__SNBF|__SWR|__SRW)) == (__SNBF|__SWR) &&
305 	    fp->_file >= 0) {
306 		ret = __sbprintf(fp, fmt0, ap);
307 		FUNLOCKFILE(fp);
308 		return (ret);
309 	}
310 
311 	fmt = fmt0;
312 	uio.uio_iov = iovp = iov;
313 	uio.uio_resid = 0;
314 	uio.uio_iovcnt = 0;
315 	ret = 0;
316 
317 	/*
318 	 * Scan the format for conversions (`%' character).
319 	 */
320 	for (;;) {
321 		cp = fmt;
322 		while ((n = mbtowc(&wc, fmt, MB_CUR_MAX)) > 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 			if ((width = va_arg(ap, int)) >= 0)
365 				goto rflag;
366 			width = -width;
367 			/* FALLTHROUGH */
368 		case '-':
369 			flags |= LADJUST;
370 			goto rflag;
371 		case '+':
372 			sign = '+';
373 			goto rflag;
374 		case '.':
375 			if ((ch = *fmt++) == '*') {
376 				n = va_arg(ap, int);
377 				prec = n < 0 ? -1 : n;
378 				goto rflag;
379 			}
380 			n = 0;
381 			while (is_digit(ch)) {
382 				n = 10 * n + to_digit(ch);
383 				ch = *fmt++;
384 			}
385 			prec = n < 0 ? -1 : n;
386 			goto reswitch;
387 		case '0':
388 			/*
389 			 * ``Note that 0 is taken as a flag, not as the
390 			 * beginning of a field width.''
391 			 *	-- ANSI X3J11
392 			 */
393 			flags |= ZEROPAD;
394 			goto rflag;
395 		case '1': case '2': case '3': case '4':
396 		case '5': case '6': case '7': case '8': case '9':
397 			n = 0;
398 			do {
399 				n = 10 * n + to_digit(ch);
400 				ch = *fmt++;
401 			} while (is_digit(ch));
402 			width = n;
403 			goto reswitch;
404 #ifdef FLOATING_POINT
405 		case 'L':
406 			flags |= LONGDBL;
407 			goto rflag;
408 #endif
409 		case 'h':
410 			flags |= SHORTINT;
411 			goto rflag;
412 		case 'l':
413 			if (*fmt == 'l') {
414 				fmt++;
415 				flags |= QUADINT;
416 			} else {
417 				flags |= LONGINT;
418 			}
419 			goto rflag;
420 		case 'q':
421 			flags |= QUADINT;
422 			goto rflag;
423 		case 'c':
424 			*buf = va_arg(ap, int);
425 			cp = buf;
426 			size = 1;
427 			sign = '\0';
428 			break;
429 		case 'D':
430 			flags |= LONGINT;
431 			/*FALLTHROUGH*/
432 		case 'd':
433 		case 'i':
434 			_uquad = SARG();
435 			if ((quad_t)_uquad < 0) {
436 				_uquad = -_uquad;
437 				sign = '-';
438 			}
439 			base = DEC;
440 			goto number;
441 #ifdef FLOATING_POINT
442 		case 'e':
443 		case 'E':
444 		case 'f':
445 		case 'g':
446 		case 'G':
447 			if (prec == -1) {
448 				prec = DEFPREC;
449 			} else if ((ch == 'g' || ch == 'G') && prec == 0) {
450 				prec = 1;
451 			}
452 
453 			if (flags & LONGDBL) {
454 				_double = (double) va_arg(ap, long double);
455 			} else {
456 				_double = va_arg(ap, double);
457 			}
458 
459 			/* do this before tricky precision changes */
460 			if (isinf(_double)) {
461 				if (_double < 0)
462 					sign = '-';
463 				cp = "Inf";
464 				size = 3;
465 				break;
466 			}
467 			if (isnan(_double)) {
468 				cp = "NaN";
469 				size = 3;
470 				break;
471 			}
472 
473 			flags |= FPT;
474 			cp = cvt(_double, prec, flags, &softsign,
475 				&expt, ch, &ndig);
476 			if (ch == 'g' || ch == 'G') {
477 				if (expt <= -4 || expt > prec)
478 					ch = (ch == 'g') ? 'e' : 'E';
479 				else
480 					ch = 'g';
481 			}
482 			if (ch <= 'e') {	/* 'e' or 'E' fmt */
483 				--expt;
484 				expsize = exponent(expstr, expt, ch);
485 				size = expsize + ndig;
486 				if (ndig > 1 || flags & ALT)
487 					++size;
488 			} else if (ch == 'f') {		/* f fmt */
489 				if (expt > 0) {
490 					size = expt;
491 					if (prec || flags & ALT)
492 						size += prec + 1;
493 				} else	/* "0.X" */
494 					size = prec + 2;
495 			} else if (expt >= ndig) {	/* fixed g fmt */
496 				size = expt;
497 				if (flags & ALT)
498 					++size;
499 			} else
500 				size = ndig + (expt > 0 ?
501 					1 : 2 - expt);
502 
503 			if (softsign)
504 				sign = '-';
505 			break;
506 #endif /* FLOATING_POINT */
507 		case 'n':
508 			if (flags & QUADINT)
509 				*va_arg(ap, quad_t *) = ret;
510 			else if (flags & LONGINT)
511 				*va_arg(ap, long *) = ret;
512 			else if (flags & SHORTINT)
513 				*va_arg(ap, short *) = ret;
514 			else
515 				*va_arg(ap, int *) = ret;
516 			continue;	/* no output */
517 		case 'O':
518 			flags |= LONGINT;
519 			/*FALLTHROUGH*/
520 		case 'o':
521 			_uquad = UARG();
522 			base = OCT;
523 			goto nosign;
524 		case 'p':
525 			/*
526 			 * ``The argument shall be a pointer to void.  The
527 			 * value of the pointer is converted to a sequence
528 			 * of printable characters, in an implementation-
529 			 * defined manner.''
530 			 *	-- ANSI X3J11
531 			 */
532 			/* NOSTRICT */
533 			_uquad = (u_long)va_arg(ap, void *);
534 			base = HEX;
535 			xdigs = "0123456789abcdef";
536 			flags |= HEXPREFIX;
537 			ch = 'x';
538 			goto nosign;
539 		case 's':
540 			if ((cp = va_arg(ap, char *)) == NULL)
541 				cp = "(null)";
542 			if (prec >= 0) {
543 				/*
544 				 * can't use strlen; can only look for the
545 				 * NUL in the first `prec' characters, and
546 				 * strlen() will go further.
547 				 */
548 				char *p = memchr(cp, 0, (size_t)prec);
549 
550 				if (p != NULL) {
551 					size = p - cp;
552 					if (size > prec)
553 						size = prec;
554 				} else
555 					size = prec;
556 			} else
557 				size = strlen(cp);
558 			sign = '\0';
559 			break;
560 		case 'U':
561 			flags |= LONGINT;
562 			/*FALLTHROUGH*/
563 		case 'u':
564 			_uquad = UARG();
565 			base = DEC;
566 			goto nosign;
567 		case 'X':
568 			xdigs = "0123456789ABCDEF";
569 			goto hex;
570 		case 'x':
571 			xdigs = "0123456789abcdef";
572 hex:			_uquad = UARG();
573 			base = HEX;
574 			/* leading 0x/X only if non-zero */
575 			if (flags & ALT && _uquad != 0)
576 				flags |= HEXPREFIX;
577 
578 			/* unsigned conversions */
579 nosign:			sign = '\0';
580 			/*
581 			 * ``... diouXx conversions ... if a precision is
582 			 * specified, the 0 flag will be ignored.''
583 			 *	-- ANSI X3J11
584 			 */
585 number:			if ((dprec = prec) >= 0)
586 				flags &= ~ZEROPAD;
587 
588 			/*
589 			 * ``The result of converting a zero value with an
590 			 * explicit precision of zero is no characters.''
591 			 *	-- ANSI X3J11
592 			 */
593 			bp = buf + BUF;
594 			if (_uquad != 0 || prec != 0) {
595 				/*
596 				 * Unsigned mod is hard, and unsigned mod
597 				 * by a constant is easier than that by
598 				 * a variable; hence this switch.
599 				 */
600 				switch (base) {
601 				case OCT:
602 					do {
603 						*--bp = to_char(_uquad & 7);
604 						_uquad >>= 3;
605 					} while (_uquad);
606 					/* handle octal leading 0 */
607 					if (flags & ALT && *bp != '0')
608 						*--bp = '0';
609 					break;
610 
611 				case DEC:
612 					/* many numbers are 1 digit */
613 					while (_uquad >= 10) {
614 						*--bp = to_char(_uquad % 10);
615 						_uquad /= 10;
616 					}
617 					*--bp = to_char(_uquad);
618 					break;
619 
620 				case HEX:
621 					do {
622 						*--bp = xdigs[(size_t)
623 						    (_uquad & 15)];
624 						_uquad >>= 4;
625 					} while (_uquad);
626 					break;
627 
628 				default:
629 					cp = "bug in vfprintf: bad base";
630 					size = strlen(cp);
631 					goto skipsize;
632 				}
633 			}
634 			cp = bp;
635 			size = buf + BUF - bp;
636 		skipsize:
637 			break;
638 		default:	/* "%?" prints ?, unless ? is NUL */
639 			if (ch == '\0')
640 				goto done;
641 			/* pretend it was %c with argument ch */
642 			*buf = ch;
643 			cp = buf;
644 			size = 1;
645 			sign = '\0';
646 			break;
647 		}
648 
649 		/*
650 		 * All reasonable formats wind up here.  At this point, `cp'
651 		 * points to a string which (if not flags&LADJUST) should be
652 		 * padded out to `width' places.  If flags&ZEROPAD, it should
653 		 * first be prefixed by any sign or other prefix; otherwise,
654 		 * it should be blank padded before the prefix is emitted.
655 		 * After any left-hand padding and prefixing, emit zeroes
656 		 * required by a decimal [diouxX] precision, then print the
657 		 * string proper, then emit zeroes required by any leftover
658 		 * floating precision; finally, if LADJUST, pad with blanks.
659 		 *
660 		 * Compute actual size, so we know how much to pad.
661 		 * size excludes decimal prec; realsz includes it.
662 		 */
663 		realsz = dprec > size ? dprec : size;
664 		if (sign)
665 			realsz++;
666 		else if (flags & HEXPREFIX)
667 			realsz+= 2;
668 
669 		/* right-adjusting blank padding */
670 		if ((flags & (LADJUST|ZEROPAD)) == 0)
671 			PAD(width - realsz, blanks);
672 
673 		/* prefix */
674 		if (sign) {
675 			PRINT(&sign, 1);
676 		} else if (flags & HEXPREFIX) {
677 			ox[0] = '0';
678 			ox[1] = ch;
679 			PRINT(ox, 2);
680 		}
681 
682 		/* right-adjusting zero padding */
683 		if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD)
684 			PAD(width - realsz, zeroes);
685 
686 		/* leading zeroes from decimal precision */
687 		PAD(dprec - size, zeroes);
688 
689 		/* the string or number proper */
690 #ifdef FLOATING_POINT
691 		if ((flags & FPT) == 0) {
692 			PRINT(cp, size);
693 		} else {	/* glue together f_p fragments */
694 			if (ch >= 'f') {	/* 'f' or 'g' */
695 				if (_double == 0) {
696 					/* kludge for __dtoa irregularity */
697 					PRINT("0", 1);
698 					if (expt < ndig || (flags & ALT) != 0) {
699 						PRINT(decimal_point, 1);
700 						PAD(ndig - 1, zeroes);
701 					}
702 				} else if (expt <= 0) {
703 					PRINT("0", 1);
704 					PRINT(decimal_point, 1);
705 					PAD(-expt, zeroes);
706 					PRINT(cp, ndig);
707 				} else if (expt >= ndig) {
708 					PRINT(cp, ndig);
709 					PAD(expt - ndig, zeroes);
710 					if (flags & ALT)
711 						PRINT(".", 1);
712 				} else {
713 					PRINT(cp, expt);
714 					cp += expt;
715 					PRINT(".", 1);
716 					PRINT(cp, ndig-expt);
717 				}
718 			} else {	/* 'e' or 'E' */
719 				if (ndig > 1 || flags & ALT) {
720 					ox[0] = *cp++;
721 					ox[1] = '.';
722 					PRINT(ox, 2);
723 					if (_double) {
724 						PRINT(cp, ndig-1);
725 					} else	/* 0.[0..] */
726 						/* __dtoa irregularity */
727 						PAD(ndig - 1, zeroes);
728 				} else	/* XeYYY */
729 					PRINT(cp, 1);
730 				PRINT(expstr, expsize);
731 			}
732 		}
733 #else
734 		PRINT(cp, size);
735 #endif
736 		/* left-adjusting padding (always blank) */
737 		if (flags & LADJUST)
738 			PAD(width - realsz, blanks);
739 
740 		/* finally, adjust ret */
741 		ret += width > realsz ? width : realsz;
742 
743 		FLUSH();	/* copy out the I/O vectors */
744 	}
745 done:
746 	FLUSH();
747 error:
748 	if (__sferror(fp))
749 		ret = -1;
750 	FUNLOCKFILE(fp);
751 	return (ret);
752 }
753 
754 #ifdef FLOATING_POINT
755 
756 static char *
757 cvt(value, ndigits, flags, sign, decpt, ch, length)
758 	double value;
759 	int ndigits, flags, *decpt, ch, *length;
760 	char *sign;
761 {
762 	int mode, dsgn;
763 	char *digits, *bp, *rve;
764 
765 	_DIAGASSERT(decpt != NULL);
766 	_DIAGASSERT(length != NULL);
767 	_DIAGASSERT(sign != NULL);
768 
769 	if (ch == 'f') {
770 		mode = 3;		/* ndigits after the decimal point */
771 	} else {
772 		/* To obtain ndigits after the decimal point for the 'e'
773 		 * and 'E' formats, round to ndigits + 1 significant
774 		 * figures.
775 		 */
776 		if (ch == 'e' || ch == 'E') {
777 			ndigits++;
778 		}
779 		mode = 2;		/* ndigits significant digits */
780 	}
781 
782 	if (value < 0) {
783 		value = -value;
784 		*sign = '-';
785 	} else
786 		*sign = '\000';
787 	digits = __dtoa(value, mode, ndigits, decpt, &dsgn, &rve);
788 	if ((ch != 'g' && ch != 'G') || flags & ALT) {	/* Print trailing zeros */
789 		bp = digits + ndigits;
790 		if (ch == 'f') {
791 			if (*digits == '0' && value)
792 				*decpt = -ndigits + 1;
793 			bp += *decpt;
794 		}
795 		if (value == 0)	/* kludge for __dtoa irregularity */
796 			rve = bp;
797 		while (rve < bp)
798 			*rve++ = '0';
799 	}
800 	*length = rve - digits;
801 	return (digits);
802 }
803 
804 static int
805 exponent(p0, exp, fmtch)
806 	char *p0;
807 	int exp, fmtch;
808 {
809 	char *p, *t;
810 	char expbuf[MAXEXP];
811 
812 	_DIAGASSERT(p0 != NULL);
813 
814 	p = p0;
815 	*p++ = fmtch;
816 	if (exp < 0) {
817 		exp = -exp;
818 		*p++ = '-';
819 	}
820 	else
821 		*p++ = '+';
822 	t = expbuf + MAXEXP;
823 	if (exp > 9) {
824 		do {
825 			*--t = to_char(exp % 10);
826 		} while ((exp /= 10) > 9);
827 		*--t = to_char(exp);
828 		for (; t < expbuf + MAXEXP; *p++ = *t++);
829 	}
830 	else {
831 		*p++ = '0';
832 		*p++ = to_char(exp);
833 	}
834 	return (p - p0);
835 }
836 #endif /* FLOATING_POINT */
837