snprintf.c

/* snprintf - compatibility implementation of snprintf, vsnprintf
 *
 * Copyright (c) 2013, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"

#ifndef HAVE_VSNPRINTF

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include <errno.h>
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#include <limits.h>

/* for test */
/* #define SNPRINTF_TEST 1 */
#ifdef SNPRINTF_TEST
#define snprintf my_snprintf
#define vsnprintf my_vsnprintf
#endif				/* SNPRINTF_TEST */

int snprintf(char *str, size_t size, const char *format, ...);
int vsnprintf(char *str, size_t size, const char *format, va_list arg);

/**
 * Very portable snprintf implementation, limited in functionality,
 * esp. for %[capital] %[nonportable] and so on.  Reduced float functionality,
 * mostly in formatting and range (e+-16), for %f and %g.
 *
 * %s, %d, %u, %i, %x, %c, %n and %% are fully supported.
 *   This includes width, precision, flags 0- +, and *(arg for wid,prec).
 * %f, %g, %m, %p have reduced support, support for wid,prec,flags,*, but
 *   less floating point range, no %e formatting for %g.
 */
int snprintf(char *str, size_t size, const char *format, ...)
{
    int r;
    va_list args;
    va_start(args, format);
    r = vsnprintf(str, size, format, args);
    va_end(args);
    return r;
}

/** add padding to string */
static void print_pad(char **at, size_t * left, int *ret, char p, int num)
{
    while (num--) {
	if (*left > 1) {
	    *(*at)++ = p;
	    (*left)--;
	}
	(*ret)++;
    }
}

/** get negative symbol, 0 if none */
static char get_negsign(int negative, int plus, int space)
{
    if (negative)
	return '-';
    if (plus)
	return '+';
    if (space)
	return ' ';
    return 0;
}

#define PRINT_DEC_BUFSZ 32	/* 20 is enough for 64 bit decimals */
/** print decimal into buffer, returns length */
static int print_dec(char *buf, int max, unsigned int value)
{
    int i = 0;
    if (value == 0) {
	if (max > 0) {
	    buf[0] = '0';
	    i = 1;
	}
    } else
	while (value && i < max) {
	    buf[i++] = '0' + value % 10;
	    value /= 10;
	}
    return i;
}

/** print long decimal into buffer, returns length */
static int print_dec_l(char *buf, int max, unsigned long value)
{
    int i = 0;
    if (value == 0) {
	if (max > 0) {
	    buf[0] = '0';
	    i = 1;
	}
    } else
	while (value && i < max) {
	    buf[i++] = '0' + value % 10;
	    value /= 10;
	}
    return i;
}

/** print long decimal into buffer, returns length */
static int print_dec_ll(char *buf, int max, unsigned long long value)
{
    int i = 0;
    if (value == 0) {
	if (max > 0) {
	    buf[0] = '0';
	    i = 1;
	}
    } else
	while (value && i < max) {
	    buf[i++] = '0' + value % 10;
	    value /= 10;
	}
    return i;
}

/** print hex into buffer, returns length */
static int print_hex(char *buf, int max, unsigned int value)
{
    const char *h = "0123456789abcdef";
    int i = 0;
    if (value == 0) {
	if (max > 0) {
	    buf[0] = '0';
	    i = 1;
	}
    } else
	while (value && i < max) {
	    buf[i++] = h[value & 0x0f];
	    value >>= 4;
	}
    return i;
}

/** print long hex into buffer, returns length */
static int print_hex_l(char *buf, int max, unsigned long value)
{
    const char *h = "0123456789abcdef";
    int i = 0;
    if (value == 0) {
	if (max > 0) {
	    buf[0] = '0';
	    i = 1;
	}
    } else
	while (value && i < max) {
	    buf[i++] = h[value & 0x0f];
	    value >>= 4;
	}
    return i;
}

/** print long long hex into buffer, returns length */
static int print_hex_ll(char *buf, int max, unsigned long long value)
{
    const char *h = "0123456789abcdef";
    int i = 0;
    if (value == 0) {
	if (max > 0) {
	    buf[0] = '0';
	    i = 1;
	}
    } else
	while (value && i < max) {
	    buf[i++] = h[value & 0x0f];
	    value >>= 4;
	}
    return i;
}

/** copy string into result, reversed */
static void
spool_str_rev(char **at, size_t * left, int *ret, const char *buf, int len)
{
    int i = len;
    while (i) {
	if (*left > 1) {
	    *(*at)++ = buf[--i];
	    (*left)--;
	} else
	    --i;
	(*ret)++;
    }
}

/** copy string into result */
static void
spool_str(char **at, size_t * left, int *ret, const char *buf, int len)
{
    int i;
    for (i = 0; i < len; i++) {
	if (*left > 1) {
	    *(*at)++ = buf[i];
	    (*left)--;
	}
	(*ret)++;
    }
}

/** print number formatted */
static void
print_num(char **at, size_t * left, int *ret, int minw, int precision,
	  int prgiven, int zeropad, int minus, int plus, int space,
	  int zero, int negative, char *buf, int len)
{
    int w = len;		/* excludes minus sign */
    char s = get_negsign(negative, plus, space);
    if (minus) {
	/* left adjust the number into the field, space padding */
	/* calc numw = [sign][zeroes][number] */
	int numw = w;
	if (precision == 0 && zero)
	    numw = 0;
	if (numw < precision)
	    numw = precision;
	if (s)
	    numw++;

	/* sign */
	if (s)
	    print_pad(at, left, ret, s, 1);

	/* number */
	if (precision == 0 && zero) {
	    /* "" for the number */
	} else {
	    if (w < precision)
		print_pad(at, left, ret, '0', precision - w);
	    spool_str_rev(at, left, ret, buf, len);
	}
	/* spaces */
	if (numw < minw)
	    print_pad(at, left, ret, ' ', minw - numw);
    } else {
	/* pad on the left of the number */
	/* calculate numw has width of [sign][zeroes][number] */
	int numw = w;
	if (precision == 0 && zero)
	    numw = 0;
	if (numw < precision)
	    numw = precision;
	if (!prgiven && zeropad && numw < minw)
	    numw = minw;
	else if (s)
	    numw++;

	/* pad with spaces */
	if (numw < minw)
	    print_pad(at, left, ret, ' ', minw - numw);
	/* print sign (and one less zeropad if so) */
	if (s) {
	    print_pad(at, left, ret, s, 1);
	    numw--;
	}
	/* pad with zeroes */
	if (w < numw)
	    print_pad(at, left, ret, '0', numw - w);
	if (precision == 0 && zero)
	    return;
	/* print the characters for the value */
	spool_str_rev(at, left, ret, buf, len);
    }
}

/** print %d and %i */
static void
print_num_d(char **at, size_t * left, int *ret, int value,
	    int minw, int precision, int prgiven, int zeropad, int minus,
	    int plus, int space)
{
    char buf[PRINT_DEC_BUFSZ];
    int negative = (value < 0);
    int zero = (value == 0);
    int len = print_dec(buf, (int)sizeof(buf),
			(unsigned int)(negative ? -value : value));
    print_num(at, left, ret, minw, precision, prgiven, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/** print %ld and %li */
static void
print_num_ld(char **at, size_t * left, int *ret, long value,
	     int minw, int precision, int prgiven, int zeropad, int minus,
	     int plus, int space)
{
    char buf[PRINT_DEC_BUFSZ];
    int negative = (value < 0);
    int zero = (value == 0);
    int len = print_dec_l(buf, (int)sizeof(buf),
			  (unsigned long)(negative ? -value : value));
    print_num(at, left, ret, minw, precision, prgiven, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/** print %lld and %lli */
static void
print_num_lld(char **at, size_t * left, int *ret, long long value,
	      int minw, int precision, int prgiven, int zeropad, int minus,
	      int plus, int space)
{
    char buf[PRINT_DEC_BUFSZ];
    int negative = (value < 0);
    int zero = (value == 0);
    int len = print_dec_ll(buf, (int)sizeof(buf),
			   (unsigned long long)(negative ? -value : value));
    print_num(at, left, ret, minw, precision, prgiven, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/** print %u */
static void
print_num_u(char **at, size_t * left, int *ret, unsigned int value,
	    int minw, int precision, int prgiven, int zeropad, int minus,
	    int plus, int space)
{
    char buf[PRINT_DEC_BUFSZ];
    int negative = 0;
    int zero = (value == 0);
    int len = print_dec(buf, (int)sizeof(buf), value);
    print_num(at, left, ret, minw, precision, prgiven, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/** print %lu */
static void
print_num_lu(char **at, size_t * left, int *ret, unsigned long value,
	     int minw, int precision, int prgiven, int zeropad, int minus,
	     int plus, int space)
{
    char buf[PRINT_DEC_BUFSZ];
    int negative = 0;
    int zero = (value == 0);
    int len = print_dec_l(buf, (int)sizeof(buf), value);
    print_num(at, left, ret, minw, precision, prgiven, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/** print %llu */
static void
print_num_llu(char **at, size_t * left, int *ret, unsigned long long value,
	      int minw, int precision, int prgiven, int zeropad, int minus,
	      int plus, int space)
{
    char buf[PRINT_DEC_BUFSZ];
    int negative = 0;
    int zero = (value == 0);
    int len = print_dec_ll(buf, (int)sizeof(buf), value);
    print_num(at, left, ret, minw, precision, prgiven, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/** print %x */
static void
print_num_x(char **at, size_t * left, int *ret, unsigned int value,
	    int minw, int precision, int prgiven, int zeropad, int minus,
	    int plus, int space)
{
    char buf[PRINT_DEC_BUFSZ];
    int negative = 0;
    int zero = (value == 0);
    int len = print_hex(buf, (int)sizeof(buf), value);
    print_num(at, left, ret, minw, precision, prgiven, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/** print %lx */
static void
print_num_lx(char **at, size_t * left, int *ret, unsigned long value,
	     int minw, int precision, int prgiven, int zeropad, int minus,
	     int plus, int space)
{
    char buf[PRINT_DEC_BUFSZ];
    int negative = 0;
    int zero = (value == 0);
    int len = print_hex_l(buf, (int)sizeof(buf), value);
    print_num(at, left, ret, minw, precision, prgiven, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/** print %llx */
static void
print_num_llx(char **at, size_t * left, int *ret, unsigned long long value,
	      int minw, int precision, int prgiven, int zeropad, int minus,
	      int plus, int space)
{
    char buf[PRINT_DEC_BUFSZ];
    int negative = 0;
    int zero = (value == 0);
    int len = print_hex_ll(buf, (int)sizeof(buf), value);
    print_num(at, left, ret, minw, precision, prgiven, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/** print %llp */
static void
print_num_llp(char **at, size_t * left, int *ret, void *value,
	      int minw, int precision, int prgiven, int zeropad, int minus,
	      int plus, int space)
{
    char buf[PRINT_DEC_BUFSZ];
    int negative = 0;
    int zero = (value == 0);
#if defined(SIZE_MAX) && defined(UINT32_MAX) && (UINT32_MAX == SIZE_MAX || INT32_MAX == SIZE_MAX)
    /* avoid warning about upcast on 32bit systems */
    unsigned long long llvalue = (unsigned long)value;
#else
    unsigned long long llvalue = (unsigned long long)value;
#endif
    int len = print_hex_ll(buf, (int)sizeof(buf), llvalue);
    if (zero) {
	buf[0] = ')';
	buf[1] = 'l';
	buf[2] = 'i';
	buf[3] = 'n';
	buf[4] = '(';
	len = 5;
    } else {
	/* put '0x' in front of the (reversed) buffer result */
	if (len < PRINT_DEC_BUFSZ)
	    buf[len++] = 'x';
	if (len < PRINT_DEC_BUFSZ)
	    buf[len++] = '0';
    }
    print_num(at, left, ret, minw, precision, prgiven, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

#define PRINT_FLOAT_BUFSZ 64	/* xx.yy with 20.20 about the max */
/** spool remainder after the decimal point to buffer, in reverse */
static int print_remainder(char *buf, int max, double r, int prec)
{
    unsigned long long cap = 1;
    unsigned long long value;
    int len, i;
    if (prec > 19)
	prec = 19;		/* max we can do */
    if (max < prec)
	return 0;
    for (i = 0; i < prec; i++) {
	cap *= 10;
    }
    r *= (double)cap;
    value = (unsigned long long)r;
    /* see if we need to round up */
    if (((unsigned long long)((r - (double)value) * 10.0)) >= 5) {
	value++;
	/* that might carry to numbers before the comma, if so,
	 * just ignore that rounding. failure because 64bitprintout */
	if (value >= cap)
	    value = cap - 1;
    }
    len = print_dec_ll(buf, max, value);
    while (len < prec) {	/* pad with zeroes, e.g. if 0.0012 */
	buf[len++] = '0';
    }
    if (len < max)
	buf[len++] = '.';
    return len;
}

/** spool floating point to buffer */
static int print_float(char *buf, int max, double value, int prec)
{
    /* as xxx.xxx  if prec==0, no '.', with prec decimals after . */
    /* no conversion for NAN and INF, because we do not want to require
       linking with -lm. */
    /* Thus, the conversions use 64bit integers to convert the numbers,
     * which makes 19 digits before and after the decimal point the max */
    unsigned long long whole = (unsigned long long)value;
    double remain = value - (double)whole;
    int len = 0;
    if (prec != 0)
	len = print_remainder(buf, max, remain, prec);
    len += print_dec_ll(buf + len, max - len, whole);
    return len;
}

/** print %f */
static void
print_num_f(char **at, size_t * left, int *ret, double value,
	    int minw, int precision, int prgiven, int zeropad, int minus,
	    int plus, int space)
{
    char buf[PRINT_FLOAT_BUFSZ];
    int negative = (value < 0);
    int zero = 0;
    int len;
    if (!prgiven)
	precision = 6;
    len = print_float(buf, (int)sizeof(buf), negative ? -value : value,
		      precision);
    print_num(at, left, ret, minw, 1, 0, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/* rudimentary %g support */
static int print_float_g(char *buf, int max, double value, int prec)
{
    unsigned long long whole = (unsigned long long)value;
    double remain = value - (double)whole;
    int before = 0;
    int len = 0;

    /* number of digits before the decimal point */
    while (whole > 0) {
	before++;
	whole /= 10;
    }
    whole = (unsigned long long)value;

    if (prec > before && remain != 0.0) {
	/* see if the last decimals are zero, if so, skip them */
	len = print_remainder(buf, max, remain, prec - before);
	while (len > 0 && buf[0] == '0') {
	    memmove(buf, buf + 1, --len);
	}
    }
    len += print_dec_ll(buf + len, max - len, whole);
    return len;
}

/** print %g */
static void
print_num_g(char **at, size_t * left, int *ret, double value,
	    int minw, int precision, int prgiven, int zeropad, int minus,
	    int plus, int space)
{
    char buf[PRINT_FLOAT_BUFSZ];
    int negative = (value < 0);
    int zero = 0;
    int len;
    if (!prgiven)
	precision = 6;
    if (precision == 0)
	precision = 1;
    len = print_float_g(buf, (int)sizeof(buf), negative ? -value : value,
			precision);
    print_num(at, left, ret, minw, 1, 0, zeropad, minus,
	      plus, space, zero, negative, buf, len);
}

/** strnlen (compat implementation) */
static int my_strnlen(const char *s, int max)
{
    int i;
    for (i = 0; i < max; i++)
	if (s[i] == 0)
	    return i;
    return max;
}

/** print %s */
static void
print_str(char **at, size_t * left, int *ret, char *s,
	  int minw, int precision, int prgiven, int minus)
{
    int w;
    /* with prec: no more than x characters from this string, stop at 0 */
    if (prgiven)
	w = my_strnlen(s, precision);
    else
	w = (int)strlen(s);	/* up to the nul */
    if (w < minw && !minus)
	print_pad(at, left, ret, ' ', minw - w);
    spool_str(at, left, ret, s, w);
    if (w < minw && minus)
	print_pad(at, left, ret, ' ', minw - w);
}

/** print %c */
static void
print_char(char **at, size_t * left, int *ret, int c, int minw, int minus)
{
    if (1 < minw && !minus)
	print_pad(at, left, ret, ' ', minw - 1);
    print_pad(at, left, ret, c, 1);
    if (1 < minw && minus)
	print_pad(at, left, ret, ' ', minw - 1);
}

/** 
 * Print to string.
 * str: string buffer for result. result will be null terminated.
 * size: size of the buffer. null is put inside buffer.
 * format: printf format string.
 * arg: '...' arguments to print.
 * returns number of characters. a null is printed after this.
 * return number of bytes that would have been written
 *	   if the buffer had been large enough.
 * 
 * supported format specifiers:
 * 	%s, %u, %d, %x, %i, %f, %g, %c, %p, %n.
 * 	length: l, ll (for d, u, x).
 * 	precision: 6.6d (for d, u, x)
 * 		%f, %g precisions, 0.3f
 * 		%20s, '.*s'
 * 	and %%.
 */
int vsnprintf(char *str, size_t size, const char *format, va_list arg)
{
    char *at = str;
    size_t left = size;
    int ret = 0;
    const char *fmt = format;
    int conv, minw, precision, prgiven, zeropad, minus, plus, space, length;
    while (*fmt) {
	/* copy string before % */
	while (*fmt && *fmt != '%') {
	    if (left > 1) {
		*at++ = *fmt++;
		left--;
	    } else
		fmt++;
	    ret++;
	}

	/* see if we are at end */
	if (!*fmt)
	    break;

	/* fetch next argument % designation from format string */
	fmt++;			/* skip the '%' */

		/********************************/
	/* get the argument designation */
		/********************************/
	/* we must do this vararg stuff inside this function for
	 * portability.  Hence, get_designation, and print_designation
	 * are not their own functions. */

	/* printout designation:
	 * conversion specifier: x, d, u, s, c, n, m, p
	 * flags: # not supported
	 *        0 zeropad (on the left)
	 *        - left adjust (right by default)
	 *        ' ' printspace for positive number (in - position).
	 *        + alwayssign
	 * fieldwidth: [1-9][0-9]* minimum field width.
	 *      if this is * then type int next argument specifies the minwidth.
	 *      if this is negative, the - flag is set (with positive width).
	 * precision: period[digits]*, %.2x.
	 *      if this is * then type int next argument specifies the precision.
	 *      just '.' or negative value means precision=0.
	 *              this is mindigits to print for d, i, u, x
	 *              this is aftercomma digits for f
	 *              this is max number significant digits for g
	 *              maxnumber characters to be printed for s
	 * length: 0-none (int), 1-l (long), 2-ll (long long)
	 *      notsupported: hh (char), h (short), L (long double), q, j, z, t
	 * Does not support %m$ and *m$ argument designation as array indices.
	 * Does not support %#x
	 *
	 */
	minw = 0;
	precision = 1;
	prgiven = 0;
	zeropad = 0;
	minus = 0;
	plus = 0;
	space = 0;
	length = 0;

	/* get flags in any order */
	for (;;) {
	    if (*fmt == '0')
		zeropad = 1;
	    else if (*fmt == '-')
		minus = 1;
	    else if (*fmt == '+')
		plus = 1;
	    else if (*fmt == ' ')
		space = 1;
	    else
		break;
	    fmt++;
	}

	/* field width */
	if (*fmt == '*') {
	    fmt++;		/* skip char */
	    minw = va_arg(arg, int);
	    if (minw < 0) {
		minus = 1;
		minw = -minw;
	    }
	} else
	    while (*fmt >= '0' && *fmt <= '9') {
		minw = minw * 10 + (*fmt++) - '0';
	    }

	/* precision */
	if (*fmt == '.') {
	    fmt++;		/* skip period */
	    prgiven = 1;
	    precision = 0;
	    if (*fmt == '*') {
		fmt++;		/* skip char */
		precision = va_arg(arg, int);
		if (precision < 0)
		    precision = 0;
	    } else
		while (*fmt >= '0' && *fmt <= '9') {
		    precision = precision * 10 + (*fmt++) - '0';
		}
	}

	/* length */
	if (*fmt == 'l') {
	    fmt++;		/* skip char */
	    length = 1;
	    if (*fmt == 'l') {
		fmt++;		/* skip char */
		length = 2;
	    }
	}

	/* get the conversion */
	if (!*fmt)
	    conv = 0;
	else
	    conv = *fmt++;

		/***********************************/
	/* print that argument designation */
		/***********************************/
	switch (conv) {
	case 'i':
	case 'd':
	    if (length == 0)
		print_num_d(&at, &left, &ret, va_arg(arg, int),
			    minw, precision, prgiven, zeropad, minus, plus,
			    space);
	    else if (length == 1)
		print_num_ld(&at, &left, &ret, va_arg(arg, long),
			     minw, precision, prgiven, zeropad, minus, plus,
			     space);
	    else if (length == 2)
		print_num_lld(&at, &left, &ret,
			      va_arg(arg, long long),
			      minw, precision, prgiven, zeropad, minus, plus,
			      space);
	    break;
	case 'u':
	    if (length == 0)
		print_num_u(&at, &left, &ret,
			    va_arg(arg, unsigned int),
			    minw, precision, prgiven, zeropad, minus, plus,
			    space);
	    else if (length == 1)
		print_num_lu(&at, &left, &ret,
			     va_arg(arg, unsigned long),
			     minw, precision, prgiven, zeropad, minus, plus,
			     space);
	    else if (length == 2)
		print_num_llu(&at, &left, &ret,
			      va_arg(arg, unsigned long long),
			      minw, precision, prgiven, zeropad, minus, plus,
			      space);
	    break;
	case 'x':
	    if (length == 0)
		print_num_x(&at, &left, &ret,
			    va_arg(arg, unsigned int),
			    minw, precision, prgiven, zeropad, minus, plus,
			    space);
	    else if (length == 1)
		print_num_lx(&at, &left, &ret,
			     va_arg(arg, unsigned long),
			     minw, precision, prgiven, zeropad, minus, plus,
			     space);
	    else if (length == 2)
		print_num_llx(&at, &left, &ret,
			      va_arg(arg, unsigned long long),
			      minw, precision, prgiven, zeropad, minus, plus,
			      space);
	    break;
	case 's':
	    print_str(&at, &left, &ret, va_arg(arg, char *),
		      minw, precision, prgiven, minus);
	    break;
	case 'c':
	    print_char(&at, &left, &ret, va_arg(arg, int), minw, minus);
	    break;
	case 'n':
	    *va_arg(arg, int *) = ret;
	    break;
	case 'm':
	    print_str(&at, &left, &ret, strerror(errno),
		      minw, precision, prgiven, minus);
	    break;
	case 'p':
	    print_num_llp(&at, &left, &ret, va_arg(arg, void *),
			  minw, precision, prgiven, zeropad, minus, plus,
			  space);
	    break;
	case '%':
	    print_pad(&at, &left, &ret, '%', 1);
	    break;
	case 'f':
	    print_num_f(&at, &left, &ret, va_arg(arg, double),
			minw, precision, prgiven, zeropad, minus, plus, space);
	    break;
	case 'g':
	    print_num_g(&at, &left, &ret, va_arg(arg, double),
			minw, precision, prgiven, zeropad, minus, plus, space);
	    break;
	    /* unknown */
	default:
	case 0:
	    break;
	}
    }

    /* zero terminate */
    if (left > 0)
	*at = 0;
    return ret;
}

#endif				/* !HAVE_VSNPRINTF */

#ifdef SNPRINTF_TEST

/** do tests */
#undef snprintf
#define DOTEST(bufsz, result, retval, ...) do { \
	char buf[bufsz]; \
	printf("now test %s\n", #__VA_ARGS__); \
	int r=my_snprintf(buf, sizeof(buf), __VA_ARGS__); \
	if(r != retval || strcmp(buf, result) != 0) { \
		printf("error test(%s) was \"%s\":%d\n", \
			""#bufsz", "#result", "#retval", "#__VA_ARGS__, \
			buf, r); \
		exit(1); \
		} \
	r=snprintf(buf, sizeof(buf), __VA_ARGS__); \
	if(r != retval || strcmp(buf, result) != 0) { \
		printf("error test(%s) differs with system, \"%s\":%d\n", \
			""#bufsz", "#result", "#retval", "#__VA_ARGS__, \
			buf, r); \
		exit(1); \
		} \
	printf("test(\"%s\":%d) passed\n", buf, r); \
	} while(0);

/** test program */
int main(void)
{
    int x = 0;

    /* bufsize, expectedstring, expectedretval, snprintf arguments */
    DOTEST(1024, "hello", 5, "hello");
    DOTEST(1024, "h", 1, "h");
    /* warning from gcc for format string, but it does work
     * DOTEST(1024, "", 0, ""); */

    DOTEST(3, "he", 5, "hello");
    DOTEST(1, "", 7, "%d", 7823089);

    /* test positive numbers */
    DOTEST(1024, "0", 1, "%d", 0);
    DOTEST(1024, "1", 1, "%d", 1);
    DOTEST(1024, "9", 1, "%d", 9);
    DOTEST(1024, "15", 2, "%d", 15);
    DOTEST(1024, "ab15cd", 6, "ab%dcd", 15);
    DOTEST(1024, "167", 3, "%d", 167);
    DOTEST(1024, "7823089", 7, "%d", 7823089);
    DOTEST(1024, " 12", 3, "%3d", 12);
    DOTEST(1024, "012", 3, "%.3d", 12);
    DOTEST(1024, "012", 3, "%3.3d", 12);
    DOTEST(1024, "012", 3, "%03d", 12);
    DOTEST(1024, " 012", 4, "%4.3d", 12);
    DOTEST(1024, "", 0, "%.0d", 0);

    /* test negative numbers */
    DOTEST(1024, "-1", 2, "%d", -1);
    DOTEST(1024, "-12", 3, "%3d", -12);
    DOTEST(1024, " -2", 3, "%3d", -2);
    DOTEST(1024, "-012", 4, "%.3d", -12);
    DOTEST(1024, "-012", 4, "%3.3d", -12);
    DOTEST(1024, "-012", 4, "%4.3d", -12);
    DOTEST(1024, " -012", 5, "%5.3d", -12);
    DOTEST(1024, "-12", 3, "%03d", -12);
    DOTEST(1024, "-02", 3, "%03d", -2);
    DOTEST(1024, "-15", 3, "%d", -15);
    DOTEST(1024, "-7307", 5, "%d", -7307);
    DOTEST(1024, "-12  ", 5, "%-5d", -12);
    DOTEST(1024, "-00012", 6, "%-.5d", -12);

    /* test + and space flags */
    DOTEST(1024, "+12", 3, "%+d", 12);
    DOTEST(1024, " 12", 3, "% d", 12);

    /* test %u */
    DOTEST(1024, "12", 2, "%u", 12);
    DOTEST(1024, "0", 1, "%u", 0);
    DOTEST(1024, "4294967295", 10, "%u", 0xffffffff);

    /* test %x */
    DOTEST(1024, "0", 1, "%x", 0);
    DOTEST(1024, "c", 1, "%x", 12);
    DOTEST(1024, "12ab34cd", 8, "%x", 0x12ab34cd);

    /* test %llu, %lld */
    DOTEST(1024, "18446744073709551615", 20, "%llu",
	   (long long)0xffffffffffffffff);
    DOTEST(1024, "-9223372036854775808", 20, "%lld",
	   (long long)0x8000000000000000);
    DOTEST(1024, "9223372036854775808", 19, "%llu",
	   (long long)0x8000000000000000);

    /* test %s */
    DOTEST(1024, "hello", 5, "%s", "hello");
    DOTEST(1024, "     hello", 10, "%10s", "hello");
    DOTEST(1024, "hello     ", 10, "%-10s", "hello");
    DOTEST(1024, "he", 2, "%.2s", "hello");
    DOTEST(1024, "  he", 4, "%4.2s", "hello");
    DOTEST(1024, "   h", 4, "%4.2s", "h");

    /* test %c */
    DOTEST(1024, "a", 1, "%c", 'a');
    /* warning from gcc for format string, but it does work
       DOTEST(1024, "    a", 5, "%5c", 'a');
       DOTEST(1024, "a", 1, "%.0c", 'a'); */

    /* test %n */
    DOTEST(1024, "hello", 5, "hello%n", &x);
    if (x != 5) {
	printf("the %%n failed\n");
	exit(1);
    }

    /* test %m */
    errno = 0;
    DOTEST(1024, "Success", 7, "%m");

    /* test %p */
    DOTEST(1024, "0x10", 4, "%p", (void *)0x10);
    DOTEST(1024, "(nil)", 5, "%p", (void *)0x0);

    /* test %% */
    DOTEST(1024, "%", 1, "%%");

    /* test %f */
    DOTEST(1024, "0.000000", 8, "%f", 0.0);
    DOTEST(1024, "0.00", 4, "%.2f", 0.0);
    /* differs, "-0.00" DOTEST(1024, "0.00", 4, "%.2f", -0.0); */
    DOTEST(1024, "234.00", 6, "%.2f", 234.005);
    DOTEST(1024, "8973497.1246", 12, "%.4f", 8973497.12456);
    DOTEST(1024, "-12.000000", 10, "%f", -12.0);
    DOTEST(1024, "6", 1, "%.0f", 6.0);

    DOTEST(1024, "6", 1, "%g", 6.0);
    DOTEST(1024, "6.1", 3, "%g", 6.1);
    DOTEST(1024, "6.15", 4, "%g", 6.15);

    /* These format strings are from the code of NSD, Unbound, ldns */

    DOTEST(1024, "abcdef", 6, "%s", "abcdef");
    DOTEST(1024, "005", 3, "%03u", 5);
    DOTEST(1024, "12345", 5, "%03u", 12345);
    DOTEST(1024, "5", 1, "%d", 5);
    DOTEST(1024, "(nil)", 5, "%p", NULL);
    DOTEST(1024, "12345", 5, "%ld", (long)12345);
    DOTEST(1024, "12345", 5, "%lu", (long)12345);
    DOTEST(1024, "       12345", 12, "%12u", (unsigned)12345);
    DOTEST(1024, "12345", 5, "%u", (unsigned)12345);
    DOTEST(1024, "12345", 5, "%llu", (unsigned long long)12345);
    DOTEST(1024, "12345", 5, "%x", 0x12345);
    DOTEST(1024, "12345", 5, "%llx", (long long)0x12345);
    DOTEST(1024, "012345", 6, "%6.6d", 12345);
    DOTEST(1024, "012345", 6, "%6.6u", 12345);
    DOTEST(1024, "1234.54", 7, "%g", 1234.54);
    DOTEST(1024, "123456789.54", 12, "%.12g", 123456789.54);
    DOTEST(1024, "3456789123456.54", 16, "%.16g", 3456789123456.54);
    /* %24g does not work with 24 digits, not enough accuracy,
     * the first 16 digits are correct */
    DOTEST(1024, "12345", 5, "%3.3d", 12345);
    DOTEST(1024, "000", 3, "%3.3d", 0);
    DOTEST(1024, "001", 3, "%3.3d", 1);
    DOTEST(1024, "012", 3, "%3.3d", 12);
    DOTEST(1024, "-012", 4, "%3.3d", -12);
    DOTEST(1024, "he", 2, "%.2s", "hello");
    DOTEST(1024, "helloworld", 10, "%s%s", "hello", "world");
    DOTEST(1024, "he", 2, "%.*s", 2, "hello");
    DOTEST(1024, "  hello", 7, "%*s", 7, "hello");
    DOTEST(1024, "hello  ", 7, "%*s", -7, "hello");
    DOTEST(1024, "0", 1, "%c", '0');
    DOTEST(1024, "A", 1, "%c", 'A');
    DOTEST(1024, "", 1, "%c", 0);
    DOTEST(1024, "\010", 1, "%c", 8);
    DOTEST(1024, "%", 1, "%%");
    DOTEST(1024, "0a", 2, "%02x", 0x0a);
    DOTEST(1024, "bd", 2, "%02x", 0xbd);
    DOTEST(1024, "12", 2, "%02ld", (long)12);
    DOTEST(1024, "02", 2, "%02ld", (long)2);
    DOTEST(1024, "02", 2, "%02u", (unsigned)2);
    DOTEST(1024, "765432", 6, "%05u", (unsigned)765432);
    DOTEST(1024, "10.234", 6, "%0.3f", 10.23421);
    DOTEST(1024, "123456.234", 10, "%0.3f", 123456.23421);
    DOTEST(1024, "123456789.234", 13, "%0.3f", 123456789.23421);
    DOTEST(1024, "123456.23", 9, "%.2f", 123456.23421);
    DOTEST(1024, "123456", 6, "%.0f", 123456.23421);
    DOTEST(1024, "0123", 4, "%.4x", 0x0123);
    DOTEST(1024, "00000123", 8, "%.8x", 0x0123);
    DOTEST(1024, "ffeb0cde", 8, "%.8x", 0xffeb0cde);
    DOTEST(1024, " 987654321", 10, "%10lu", (unsigned long)987654321);
    DOTEST(1024, "   987654321", 12, "%12lu", (unsigned long)987654321);
    DOTEST(1024, "987654321", 9, "%i", 987654321);
    DOTEST(1024, "-87654321", 9, "%i", -87654321);
    DOTEST(1024, "hello           ", 16, "%-16s", "hello");
    DOTEST(1024, "                ", 16, "%-16s", "");
    DOTEST(1024, "a               ", 16, "%-16s", "a");
    DOTEST(1024, "foobarfoobar    ", 16, "%-16s", "foobarfoobar");
    DOTEST(1024, "foobarfoobarfoobar", 18, "%-16s", "foobarfoobarfoobar");

    /* combined expressions */
    DOTEST(1024, "foo 1.0 size 512 edns", 21,
	   "foo %s size %d %s%s", "1.0", 512, "", "edns");
    DOTEST(15, "foo 1.0 size 5", 21,
	   "foo %s size %d %s%s", "1.0", 512, "", "edns");
    DOTEST(1024, "packet 1203ceff id", 18,
	   "packet %2.2x%2.2x%2.2x%2.2x id", 0x12, 0x03, 0xce, 0xff);
    DOTEST(1024, "/tmp/testbound_123abcd.tmp", 26, "/tmp/testbound_%u%s%s.tmp",
	   123, "ab", "cd");

    return 0;
}
#endif				/* SNPRINTF_TEST */