!888 Optimize printf performance

Merge pull request !888 from yinchuang/musl_print

musl_src.gni

@@ -2165,6 +2165,7 @@ musl_src_porting_file = [
   "src/ldso/riscv64/dlvsym.s",
   "src/ldso/x86_64/dlvsym.s",
   "src/stdio/__fdopen.c",
+  "src/stdio/vfprintf.c",
   "src/stdio/__stdio_read.c",
   "src/stdio/fread.c",
   "src/internal/stdio_impl.h",

porting/linux/user/src/stdio/vfprintf.c

+#include "stdio_impl.h"
+#include <errno.h>
+#include <ctype.h>
+#include <limits.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <wchar.h>
+#include <inttypes.h>
+#include <math.h>
+#include <float.h>
+
+/* Some useful macros */
+
+#define MAX(a,b) ((a)>(b) ? (a) : (b))
+#define MIN(a,b) ((a)<(b) ? (a) : (b))
+
+/* Convenient bit representation for modifier flags, which all fall
+ * within 31 codepoints of the space character. */
+
+#define ALT_FORM   (1U<<'#'-' ')
+#define ZERO_PAD   (1U<<'0'-' ')
+#define LEFT_ADJ   (1U<<'-'-' ')
+#define PAD_POS    (1U<<' '-' ')
+#define MARK_POS   (1U<<'+'-' ')
+#define GROUPED    (1U<<'\''-' ')
+
+#define FLAGMASK (ALT_FORM|ZERO_PAD|LEFT_ADJ|PAD_POS|MARK_POS|GROUPED)
+
+/* State machine to accept length modifiers + conversion specifiers.
+ * Result is 0 on failure, or an argument type to pop on success. */
+
+enum {
+	BARE, LPRE, LLPRE, HPRE, HHPRE, BIGLPRE,
+	ZTPRE, JPRE,
+	STOP,
+	PTR, INT, UINT, ULLONG,
+	LONG, ULONG,
+	SHORT, USHORT, CHAR, UCHAR,
+	LLONG, SIZET, IMAX, UMAX, PDIFF, UIPTR,
+	DBL, LDBL,
+	NOARG,
+	MAXSTATE
+};
+
+#define S(x) [(x)-'A']
+
+static const unsigned char states[]['z'-'A'+1] = {
+	{ /* 0: bare types */
+		S('d') = INT, S('i') = INT,
+		S('o') = UINT, S('u') = UINT, S('x') = UINT, S('X') = UINT,
+		S('e') = DBL, S('f') = DBL, S('g') = DBL, S('a') = DBL,
+		S('E') = DBL, S('F') = DBL, S('G') = DBL, S('A') = DBL,
+		S('c') = CHAR, S('C') = INT,
+		S('s') = PTR, S('S') = PTR, S('p') = UIPTR, S('n') = PTR,
+		S('m') = NOARG,
+		S('l') = LPRE, S('h') = HPRE, S('L') = BIGLPRE,
+		S('z') = ZTPRE, S('j') = JPRE, S('t') = ZTPRE,
+	}, { /* 1: l-prefixed */
+		S('d') = LONG, S('i') = LONG,
+		S('o') = ULONG, S('u') = ULONG, S('x') = ULONG, S('X') = ULONG,
+		S('e') = DBL, S('f') = DBL, S('g') = DBL, S('a') = DBL,
+		S('E') = DBL, S('F') = DBL, S('G') = DBL, S('A') = DBL,
+		S('c') = INT, S('s') = PTR, S('n') = PTR,
+		S('l') = LLPRE,
+	}, { /* 2: ll-prefixed */
+		S('d') = LLONG, S('i') = LLONG,
+		S('o') = ULLONG, S('u') = ULLONG,
+		S('x') = ULLONG, S('X') = ULLONG,
+		S('n') = PTR,
+	}, { /* 3: h-prefixed */
+		S('d') = SHORT, S('i') = SHORT,
+		S('o') = USHORT, S('u') = USHORT,
+		S('x') = USHORT, S('X') = USHORT,
+		S('n') = PTR,
+		S('h') = HHPRE,
+	}, { /* 4: hh-prefixed */
+		S('d') = CHAR, S('i') = CHAR,
+		S('o') = UCHAR, S('u') = UCHAR,
+		S('x') = UCHAR, S('X') = UCHAR,
+		S('n') = PTR,
+	}, { /* 5: L-prefixed */
+		S('e') = LDBL, S('f') = LDBL, S('g') = LDBL, S('a') = LDBL,
+		S('E') = LDBL, S('F') = LDBL, S('G') = LDBL, S('A') = LDBL,
+		S('n') = PTR,
+	}, { /* 6: z- or t-prefixed (assumed to be same size) */
+		S('d') = PDIFF, S('i') = PDIFF,
+		S('o') = SIZET, S('u') = SIZET,
+		S('x') = SIZET, S('X') = SIZET,
+		S('n') = PTR,
+	}, { /* 7: j-prefixed */
+		S('d') = IMAX, S('i') = IMAX,
+		S('o') = UMAX, S('u') = UMAX,
+		S('x') = UMAX, S('X') = UMAX,
+		S('n') = PTR,
+	}
+};
+
+#define OOB(x) ((unsigned)(x)-'A' > 'z'-'A')
+
+union arg
+{
+	uintmax_t i;
+	long double f;
+	void *p;
+};
+
+static void pop_arg(union arg *arg, int type, va_list *ap)
+{
+	switch (type) {
+	       case PTR:	arg->p = va_arg(*ap, void *);
+	break; case INT:	arg->i = va_arg(*ap, int);
+	break; case UINT:	arg->i = va_arg(*ap, unsigned int);
+	break; case LONG:	arg->i = va_arg(*ap, long);
+	break; case ULONG:	arg->i = va_arg(*ap, unsigned long);
+	break; case ULLONG:	arg->i = va_arg(*ap, unsigned long long);
+	break; case SHORT:	arg->i = (short)va_arg(*ap, int);
+	break; case USHORT:	arg->i = (unsigned short)va_arg(*ap, int);
+	break; case CHAR:	arg->i = (signed char)va_arg(*ap, int);
+	break; case UCHAR:	arg->i = (unsigned char)va_arg(*ap, int);
+	break; case LLONG:	arg->i = va_arg(*ap, long long);
+	break; case SIZET:	arg->i = va_arg(*ap, size_t);
+	break; case IMAX:	arg->i = va_arg(*ap, intmax_t);
+	break; case UMAX:	arg->i = va_arg(*ap, uintmax_t);
+	break; case PDIFF:	arg->i = va_arg(*ap, ptrdiff_t);
+	break; case UIPTR:	arg->i = (uintptr_t)va_arg(*ap, void *);
+	break; case DBL:	arg->f = va_arg(*ap, double);
+	break; case LDBL:	arg->f = va_arg(*ap, long double);
+	}
+}
+
+static void out(FILE *f, const char *s, size_t l)
+{
+	if (!(f->flags & F_ERR)) __fwritex((void *)s, l, f);
+}
+
+static void pad(FILE *f, char c, int w, int l, int fl)
+{
+	char pad[256];
+	if (fl & (LEFT_ADJ | ZERO_PAD) || l >= w) return;
+	l = w - l;
+	memset(pad, c, l>sizeof pad ? sizeof pad : l);
+	for (; l >= sizeof pad; l -= sizeof pad)
+		out(f, pad, sizeof pad);
+	out(f, pad, l);
+}
+
+static const char xdigits[16] = {
+	"0123456789ABCDEF"
+};
+
+static char *fmt_x(uintmax_t x, char *s, int lower)
+{
+	for (; x; x>>=4) *--s = xdigits[(x&15)]|lower;
+	return s;
+}
+
+static char *fmt_o(uintmax_t x, char *s)
+{
+	for (; x; x>>=3) *--s = '0' + (x&7);
+	return s;
+}
+
+static char *fmt_u(uintmax_t x, char *s)
+{
+	unsigned long y;
+	for (   ; x>ULONG_MAX; x/=10) *--s = '0' + x%10;
+	for (y=x;           y; y/=10) *--s = '0' + y%10;
+	return s;
+}
+
+/* Do not override this check. The floating point printing code below
+ * depends on the float.h constants being right. If they are wrong, it
+ * may overflow the stack. */
+#if LDBL_MANT_DIG == 53
+typedef char compiler_defines_long_double_incorrectly[9-(int)sizeof(long double)];
+#endif
+
+static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
+{
+	uint32_t big[(LDBL_MANT_DIG+28)/29 + 1          // mantissa expansion
+		+ (LDBL_MAX_EXP+LDBL_MANT_DIG+28+8)/9]; // exponent expansion
+	uint32_t *a, *d, *r, *z;
+	int e2=0, e, i, j, l;
+	char buf[9+LDBL_MANT_DIG/4], *s;
+	const char *prefix="-0X+0X 0X-0x+0x 0x";
+	int pl;
+	char ebuf0[3*sizeof(int)], *ebuf=&ebuf0[3*sizeof(int)], *estr;
+
+	pl=1;
+	if (signbit(y)) {
+		y=-y;
+	} else if (fl & MARK_POS) {
+		prefix+=3;
+	} else if (fl & PAD_POS) {
+		prefix+=6;
+	} else prefix++, pl=0;
+
+	if (!isfinite(y)) {
+		char *s = (t&32)?"inf":"INF";
+		if (y!=y) s=(t&32)?"nan":"NAN";
+		pad(f, ' ', w, 3+pl, fl&~ZERO_PAD);
+		out(f, prefix, pl);
+		out(f, s, 3);
+		pad(f, ' ', w, 3+pl, fl^LEFT_ADJ);
+		return MAX(w, 3+pl);
+	}
+
+	y = frexpl(y, &e2) * 2;
+	if (y) e2--;
+
+	if ((t|32)=='a') {
+		long double round = 8.0;
+		int re;
+
+		if (t&32) prefix += 9;
+		pl += 2;
+
+		if (p<0 || p>=LDBL_MANT_DIG/4-1) re=0;
+		else re=LDBL_MANT_DIG/4-1-p;
+
+		if (re) {
+			round *= 1<<(LDBL_MANT_DIG%4);
+			while (re--) round*=16;
+			if (*prefix=='-') {
+				y=-y;
+				y-=round;
+				y+=round;
+				y=-y;
+			} else {
+				y+=round;
+				y-=round;
+			}
+		}
+
+		estr=fmt_u(e2<0 ? -e2 : e2, ebuf);
+		if (estr==ebuf) *--estr='0';
+		*--estr = (e2<0 ? '-' : '+');
+		*--estr = t+('p'-'a');
+
+		s=buf;
+		do {
+			int x=y;
+			*s++=xdigits[x]|(t&32);
+			y=16*(y-x);
+			if (s-buf==1 && (y||p>0||(fl&ALT_FORM))) *s++='.';
+		} while (y);
+
+		if (p > INT_MAX-2-(ebuf-estr)-pl)
+			return -1;
+		if (p && s-buf-2 < p)
+			l = (p+2) + (ebuf-estr);
+		else
+			l = (s-buf) + (ebuf-estr);
+
+		pad(f, ' ', w, pl+l, fl);
+		out(f, prefix, pl);
+		pad(f, '0', w, pl+l, fl^ZERO_PAD);
+		out(f, buf, s-buf);
+		pad(f, '0', l-(ebuf-estr)-(s-buf), 0, 0);
+		out(f, estr, ebuf-estr);
+		pad(f, ' ', w, pl+l, fl^LEFT_ADJ);
+		return MAX(w, pl+l);
+	}
+	if (p<0) p=6;
+
+	if (y) y *= 0x1p28, e2-=28;
+
+	if (e2<0) a=r=z=big;
+	else a=r=z=big+sizeof(big)/sizeof(*big) - LDBL_MANT_DIG - 1;
+
+	do {
+		*z = y;
+		y = 1000000000*(y-*z++);
+	} while (y);
+
+	while (e2>0) {
+		uint32_t carry=0;
+		int sh=MIN(29,e2);
+		for (d=z-1; d>=a; d--) {
+			uint64_t x = ((uint64_t)*d<<sh)+carry;
+			*d = x % 1000000000;
+			carry = x / 1000000000;
+		}
+		if (carry) *--a = carry;
+		while (z>a && !z[-1]) z--;
+		e2-=sh;
+	}
+	while (e2<0) {
+		uint32_t carry=0, *b;
+		int sh=MIN(9,-e2), need=1+(p+LDBL_MANT_DIG/3U+8)/9;
+		for (d=a; d<z; d++) {
+			uint32_t rm = *d & (1<<sh)-1;
+			*d = (*d>>sh) + carry;
+			carry = (1000000000>>sh) * rm;
+		}
+		if (!*a) a++;
+		if (carry) *z++ = carry;
+		/* Avoid (slow!) computation past requested precision */
+		b = (t|32)=='f' ? r : a;
+		if (z-b > need) z = b+need;
+		e2+=sh;
+	}
+
+	if (a<z) for (i=10, e=9*(r-a); *a>=i; i*=10, e++);
+	else e=0;
+
+	/* Perform rounding: j is precision after the radix (possibly neg) */
+	j = p - ((t|32)!='f')*e - ((t|32)=='g' && p);
+	if (j < 9*(z-r-1)) {
+		uint32_t x;
+		/* We avoid C's broken division of negative numbers */
+		d = r + 1 + ((j+9*LDBL_MAX_EXP)/9 - LDBL_MAX_EXP);
+		j += 9*LDBL_MAX_EXP;
+		j %= 9;
+		for (i=10, j++; j<9; i*=10, j++);
+		x = *d % i;
+		/* Are there any significant digits past j? */
+		if (x || d+1!=z) {
+			long double round = 2/LDBL_EPSILON;
+			long double small;
+			if ((*d/i & 1) || (i==1000000000 && d>a && (d[-1]&1)))
+				round += 2;
+			if (x<i/2) small=0x0.8p0;
+			else if (x==i/2 && d+1==z) small=0x1.0p0;
+			else small=0x1.8p0;
+			if (pl && *prefix=='-') round*=-1, small*=-1;
+			*d -= x;
+			/* Decide whether to round by probing round+small */
+			if (round+small != round) {
+				*d = *d + i;
+				while (*d > 999999999) {
+					*d--=0;
+					if (d<a) *--a=0;
+					(*d)++;
+				}
+				for (i=10, e=9*(r-a); *a>=i; i*=10, e++);
+			}
+		}
+		if (z>d+1) z=d+1;
+	}
+	for (; z>a && !z[-1]; z--);
+	
+	if ((t|32)=='g') {
+		if (!p) p++;
+		if (p>e && e>=-4) {
+			t--;
+			p-=e+1;
+		} else {
+			t-=2;
+			p--;
+		}
+		if (!(fl&ALT_FORM)) {
+			/* Count trailing zeros in last place */
+			if (z>a && z[-1]) for (i=10, j=0; z[-1]%i==0; i*=10, j++);
+			else j=9;
+			if ((t|32)=='f')
+				p = MIN(p,MAX(0,9*(z-r-1)-j));
+			else
+				p = MIN(p,MAX(0,9*(z-r-1)+e-j));
+		}
+	}
+	if (p > INT_MAX-1-(p || (fl&ALT_FORM)))
+		return -1;
+	l = 1 + p + (p || (fl&ALT_FORM));
+	if ((t|32)=='f') {
+		if (e > INT_MAX-l) return -1;
+		if (e>0) l+=e;
+	} else {
+		estr=fmt_u(e<0 ? -e : e, ebuf);
+		while(ebuf-estr<2) *--estr='0';
+		*--estr = (e<0 ? '-' : '+');
+		*--estr = t;
+		if (ebuf-estr > INT_MAX-l) return -1;
+		l += ebuf-estr;
+	}
+
+	if (l > INT_MAX-pl) return -1;
+	pad(f, ' ', w, pl+l, fl);
+	out(f, prefix, pl);
+	pad(f, '0', w, pl+l, fl^ZERO_PAD);
+
+	if ((t|32)=='f') {
+		if (a>r) a=r;
+		for (d=a; d<=r; d++) {
+			char *s = fmt_u(*d, buf+9);
+			if (d!=a) while (s>buf) *--s='0';
+			else if (s==buf+9) *--s='0';
+			out(f, s, buf+9-s);
+		}
+		if (p || (fl&ALT_FORM)) out(f, ".", 1);
+		for (; d<z && p>0; d++, p-=9) {
+			char *s = fmt_u(*d, buf+9);
+			while (s>buf) *--s='0';
+			out(f, s, MIN(9,p));
+		}
+		pad(f, '0', p+9, 9, 0);
+	} else {
+		if (z<=a) z=a+1;
+		for (d=a; d<z && p>=0; d++) {
+			char *s = fmt_u(*d, buf+9);
+			if (s==buf+9) *--s='0';
+			if (d!=a) while (s>buf) *--s='0';
+			else {
+				out(f, s++, 1);
+				if (p>0||(fl&ALT_FORM)) out(f, ".", 1);
+			}
+			out(f, s, MIN(buf+9-s, p));
+			p -= buf+9-s;
+		}
+		pad(f, '0', p+18, 18, 0);
+		out(f, estr, ebuf-estr);
+	}
+
+	pad(f, ' ', w, pl+l, fl^LEFT_ADJ);
+
+	return MAX(w, pl+l);
+}
+
+static int getint(char **s) {
+	int i;
+	for (i=0; isdigit(**s); (*s)++) {
+		if (i > INT_MAX/10U || **s-'0' > INT_MAX-10*i) i = -1;
+		else i = 10*i + (**s-'0');
+	}
+	return i;
+}
+
+static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg, int *nl_type, char nl_arg_filled)
+{
+	char *a, *z, *s=(char *)fmt;
+	unsigned l10n=0, fl;
+	int w, p, xp;
+	union arg arg;
+	int argpos;
+	unsigned st, ps;
+	int cnt=0, l=0;
+	size_t i;
+	const char *prefix;
+	int t, pl;
+	wchar_t wc[2], *ws;
+	char mb[4];
+
+	for (;;) {
+		/* This error is only specified for snprintf, but since it's
+		 * unspecified for other forms, do the same. Stop immediately
+		 * on overflow; otherwise %n could produce wrong results. */
+		if (l > INT_MAX - cnt) goto overflow;
+
+		/* Update output count, end loop when fmt is exhausted */
+		cnt += l;
+		if (!*s) break;
+
+		/* Handle literal text and %% format specifiers */
+		for (a=s; *s && *s!='%'; s++);
+		for (z=s; s[0]=='%' && s[1]=='%'; z++, s+=2);
+		if (z-a > INT_MAX-cnt) goto overflow;
+		l = z-a;
+		if (f) out(f, a, l);
+		if (l) continue;
+
+		if (isdigit(s[1]) && s[2]=='$') {
+			if (!nl_arg_filled) {
+				if (printf_core(0, fmt, ap, nl_arg, nl_type, 1) < 0) {
+					return -1;
+				}
+			}
+			l10n=1;
+			argpos = s[1]-'0';
+			s+=3;
+		} else {
+			argpos = -1;
+			s++;
+		}
+
+		/* Read modifier flags */
+		for (fl=0; (unsigned)*s-' '<32 && (FLAGMASK&(1U<<*s-' ')); s++)
+			fl |= 1U<<*s-' ';
+
+		/* Read field width */
+		if (*s=='*') {
+			if (isdigit(s[1]) && s[2]=='$') {
+				l10n=1;
+				nl_type[s[1]-'0'] = INT;
+				w = nl_arg[s[1]-'0'].i;
+				s+=3;
+			} else if (!l10n) {
+				w = f ? va_arg(*ap, int) : 0;
+				s++;
+			} else goto inval;
+			if (w<0) fl|=LEFT_ADJ, w=-w;
+		} else if ((w=getint(&s))<0) goto overflow;
+
+		/* Read precision */
+		if (*s=='.' && s[1]=='*') {
+			if (isdigit(s[2]) && s[3]=='$') {
+				nl_type[s[2]-'0'] = INT;
+				p = nl_arg[s[2]-'0'].i;
+				s+=4;
+			} else if (!l10n) {
+				p = f ? va_arg(*ap, int) : 0;
+				s+=2;
+			} else goto inval;
+			xp = (p>=0);
+		} else if (*s=='.') {
+			s++;
+			p = getint(&s);
+			xp = 1;
+		} else {
+			p = -1;
+			xp = 0;
+		}
+
+		/* Format specifier state machine */
+		st=0;
+		do {
+			if (OOB(*s)) goto inval;
+			ps=st;
+			st=states[st]S(*s++);
+		} while (st-1<STOP);
+		if (!st) goto inval;
+
+		/* Check validity of argument type (nl/normal) */
+		if (st==NOARG) {
+			if (argpos>=0) goto inval;
+		} else {
+			if (argpos>=0) nl_type[argpos]=st, arg=nl_arg[argpos];
+			else if (f) pop_arg(&arg, st, ap);
+			else return 0;
+		}
+
+		if (!f) continue;
+
+		char buf[sizeof(uintmax_t)*3+3+LDBL_MANT_DIG/4];
+		z = buf + sizeof(buf);
+		prefix = "-+   0X0x";
+		pl = 0;
+		t = s[-1];
+
+		/* Transform ls,lc -> S,C */
+		if (ps && (t&15)==3) t&=~32;
+
+		/* - and 0 flags are mutually exclusive */
+		if (fl & LEFT_ADJ) fl &= ~ZERO_PAD;
+
+		switch(t) {
+		case 'n':
+			switch(ps) {
+			case BARE: *(int *)arg.p = cnt; break;
+			case LPRE: *(long *)arg.p = cnt; break;
+			case LLPRE: *(long long *)arg.p = cnt; break;
+			case HPRE: *(unsigned short *)arg.p = cnt; break;
+			case HHPRE: *(unsigned char *)arg.p = cnt; break;
+			case ZTPRE: *(size_t *)arg.p = cnt; break;
+			case JPRE: *(uintmax_t *)arg.p = cnt; break;
+			}
+			continue;
+		case 'p':
+			p = MAX(p, 2*sizeof(void*));
+			t = 'x';
+			fl |= ALT_FORM;
+		case 'x': case 'X':
+			a = fmt_x(arg.i, z, t&32);
+			if (arg.i && (fl & ALT_FORM)) prefix+=(t>>4), pl=2;
+			if (0) {
+		case 'o':
+			a = fmt_o(arg.i, z);
+			if ((fl&ALT_FORM) && p<z-a+1) p=z-a+1;
+			} if (0) {
+		case 'd': case 'i':
+			pl=1;
+			if (arg.i>INTMAX_MAX) {
+				arg.i=-arg.i;
+			} else if (fl & MARK_POS) {
+				prefix++;
+			} else if (fl & PAD_POS) {
+				prefix+=2;
+			} else pl=0;
+		case 'u':
+			a = fmt_u(arg.i, z);
+			}
+			if (xp && p<0) goto overflow;
+			if (xp) fl &= ~ZERO_PAD;
+			if (!arg.i && !p) {
+				a=z;
+				break;
+			}
+			p = MAX(p, z-a + !arg.i);
+			break;
+		case 'c':
+			*(a=z-(p=1))=arg.i;
+			fl &= ~ZERO_PAD;
+			break;
+		case 'm':
+			if (1) a = strerror(errno); else
+		case 's':
+			a = arg.p ? arg.p : "(null)";
+			z = a + strnlen(a, p<0 ? INT_MAX : p);
+			if (p<0 && *z) goto overflow;
+			p = z-a;
+			fl &= ~ZERO_PAD;
+			break;
+		case 'C':
+			wc[0] = arg.i;
+			wc[1] = 0;
+			arg.p = wc;
+			p = -1;
+		case 'S':
+			ws = arg.p;
+			for (i=l=0; i<p && *ws && (l=wctomb(mb, *ws++))>=0 && l<=p-i; i+=l);
+			if (l<0) return -1;
+			if (i > INT_MAX) goto overflow;
+			p = i;
+			pad(f, ' ', w, p, fl);
+			ws = arg.p;
+			for (i=0; i<0U+p && *ws && i+(l=wctomb(mb, *ws++))<=p; i+=l)
+				out(f, mb, l);
+			pad(f, ' ', w, p, fl^LEFT_ADJ);
+			l = w>p ? w : p;
+			continue;
+		case 'e': case 'f': case 'g': case 'a':
+		case 'E': case 'F': case 'G': case 'A':
+			if (xp && p<0) goto overflow;
+			l = fmt_fp(f, arg.f, w, p, fl, t);
+			if (l<0) goto overflow;
+			continue;
+		}
+
+		if (p < z-a) p = z-a;
+		if (p > INT_MAX-pl) goto overflow;
+		if (w < pl+p) w = pl+p;
+		if (w > INT_MAX-cnt) goto overflow;
+
+		pad(f, ' ', w, pl+p, fl);
+		out(f, prefix, pl);
+		pad(f, '0', w, pl+p, fl^ZERO_PAD);
+		pad(f, '0', p, z-a, 0);
+		out(f, a, z-a);
+		pad(f, ' ', w, pl+p, fl^LEFT_ADJ);
+
+		l = w;
+	}
+
+	if (f) return cnt;
+	if (!l10n) return 0;
+
+	for (i=1; i<=NL_ARGMAX && nl_type[i]; i++)
+		pop_arg(nl_arg+i, nl_type[i], ap);
+	for (; i<=NL_ARGMAX && !nl_type[i]; i++);
+	if (i<=NL_ARGMAX) goto inval;
+	return 1;
+
+inval:
+	errno = EINVAL;
+	return -1;
+overflow:
+	errno = EOVERFLOW;
+	return -1;
+}
+
+int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap)
+{
+	va_list ap2;
+	int nl_type[NL_ARGMAX+1] = {0};
+	union arg nl_arg[NL_ARGMAX+1];
+	unsigned char internal_buf[80], *saved_buf = 0;
+	int olderr;
+	int ret;
+
+	/* the copy allows passing va_list* even if va_list is an array */
+	va_copy(ap2, ap);
+
+	FLOCK(f);
+	olderr = f->flags & F_ERR;
+	if (f->mode < 1) f->flags &= ~F_ERR;
+	if (!f->buf_size) {
+		saved_buf = f->buf;
+		f->buf = internal_buf;
+		f->buf_size = sizeof internal_buf;
+		f->wpos = f->wbase = f->wend = 0;
+	}
+	if (!f->wend && __towrite(f)) ret = -1;
+	else ret = printf_core(f, fmt, &ap2, nl_arg, nl_type, 0);
+	if (saved_buf) {
+		f->write(f, 0, 0);
+		if (!f->wpos) ret = -1;
+		f->buf = saved_buf;
+		f->buf_size = 0;
+		f->wpos = f->wbase = f->wend = 0;
+	}
+	if (f->flags & F_ERR) ret = -1;
+	f->flags |= olderr;
+	FUNLOCK(f);
+	va_end(ap2);
+	return ret;
+}