ap_snprintf.c

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/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * This code is based on, and used with the permission of, the
 * SIO stdio-replacement strx_* functions by Panos Tsirigotis
 * <[e-mail]> for xinetd.
 */
#define BUILD_STANDALONE

#ifndef BUILD_STANDALONE
#include "httpd.h"
#else
#include "ap_snprintf.h"
#endif

#include <stdio.h>
#include <ctype.h>
#ifndef NETWARE
#include <sys/types.h>
#endif
#include <stdarg.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#ifdef WIN32
#include <float.h>
#endif

typedef enum {
    NO = 0, YES = 1
} boolean_e;

#ifndef FALSE
#define FALSE                   0
#endif
#ifndef TRUE
#define TRUE                    1
#endif
#ifndef AP_LONGEST_LONG
#define AP_LONGEST_LONG         long
#endif
#define NUL                     '\0'
#define WIDE_INT                long
#define WIDEST_INT              AP_LONGEST_LONG

typedef WIDE_INT wide_int;
typedef unsigned WIDE_INT u_wide_int;
typedef WIDEST_INT widest_int;
#ifdef __TANDEM
/* Although Tandem supports "long long" there is no unsigned variant. */
typedef unsigned long       u_widest_int;
#else
typedef unsigned WIDEST_INT u_widest_int;
#endif
typedef int bool_int;

#define S_NULL                  "(null)"
#define S_NULL_LEN              6

#define FLOAT_DIGITS            6
#define EXPONENT_LENGTH         10

/*
 * NUM_BUF_SIZE is the size of the buffer used for arithmetic conversions
 *
 * XXX: this is a magic number; do not decrease it
 */
#define NUM_BUF_SIZE            512

/*
 * cvt.c - IEEE floating point formatting routines for FreeBSD
 * from GNU libc-4.6.27.  Modified to be thread safe.
 */

/*
 *    ap_ecvt converts to decimal
 *      the number of digits is specified by ndigit
 *      decpt is set to the position of the decimal point
 *      sign is set to 0 for positive, 1 for negative
 */

#define NDIG    80

/* buf must have at least NDIG bytes */
static char *ap_cvt(double arg, int ndigits, int *decpt, int *sign, int eflag, char *buf)
{
    register int r2;
    double fi, fj;
    register char *p, *p1;
    
    if (ndigits >= NDIG - 1)
        ndigits = NDIG - 2;
    r2 = 0;
    *sign = 0;
    p = &buf[0];
    if (arg < 0) {
        *sign = 1;
        arg = -arg;
    }
    arg = modf(arg, &fi);
    p1 = &buf[NDIG];
    /*
     * Do integer part
     */
    if (fi != 0) {
        p1 = &buf[NDIG];
        while (p1 > &buf[0] && fi != 0) {
            fj = modf(fi / 10, &fi);
            *--p1 = (int) ((fj + .03) * 10) + '0';
            r2++;
        }
        while (p1 < &buf[NDIG])
            *p++ = *p1++;
    }
    else if (arg > 0) {
        while ((fj = arg * 10) < 1) {
            arg = fj;
            r2--;
        }
    }
    p1 = &buf[ndigits];
    if (eflag == 0)
        p1 += r2;
    *decpt = r2;
    if (p1 < &buf[0]) {
        buf[0] = '\0';
        return (buf);
    }
    while (p <= p1 && p < &buf[NDIG]) {
        arg *= 10;
        arg = modf(arg, &fj);
        *p++ = (int) fj + '0';
    }
    if (p1 >= &buf[NDIG]) {
        buf[NDIG - 1] = '\0';
        return (buf);
    }
    p = p1;
    *p1 += 5;
    while (*p1 > '9') {
        *p1 = '0';
        if (p1 > buf)
            ++ * --p1;
        else {
            *p1 = '1';
            (*decpt)++;
            if (eflag == 0) {
                if (p > buf)
                    *p = '0';
                p++;
            }
        }
    }
    *p = '\0';
    return (buf);
}

static char *ap_ecvt(double arg, int ndigits, int *decpt, int *sign, char *buf)
{
    return (ap_cvt(arg, ndigits, decpt, sign, 1, buf));
}

static char *ap_fcvt(double arg, int ndigits, int *decpt, int *sign, char *buf)
{
    return (ap_cvt(arg, ndigits, decpt, sign, 0, buf));
}

/*
 * ap_gcvt  - Floating output conversion to
 * minimal length string
 */

static char *ap_gcvt(double number, int ndigit, char *buf, boolean_e altform)
{
    int sign, decpt;
    register char *p1, *p2;
    register int i;
    char buf1[NDIG];

    p1 = ap_ecvt(number, ndigit, &decpt, &sign, buf1);
    p2 = buf;
    if (sign)
        *p2++ = '-';
    for (i = ndigit - 1; i > 0 && p1[i] == '0'; i--)
        ndigit--;
    if ((decpt >= 0 && decpt - ndigit > 4)
        || (decpt < 0 && decpt < -3)) {         /* use E-style */
        decpt--;
        *p2++ = *p1++;
        *p2++ = '.';
        for (i = 1; i < ndigit; i++)
            *p2++ = *p1++;
        *p2++ = 'e';
        if (decpt < 0) {
            decpt = -decpt;
            *p2++ = '-';
        }
        else
            *p2++ = '+';
        if (decpt / 100 > 0)
            *p2++ = decpt / 100 + '0';
        if (decpt / 10 > 0)
            *p2++ = (decpt % 100) / 10 + '0';
        *p2++ = decpt % 10 + '0';
    }
    else {
        if (decpt <= 0) {
            if (*p1 != '0')
                *p2++ = '.';
            while (decpt < 0) {
                decpt++;
                *p2++ = '0';
            }
        }
        for (i = 1; i <= ndigit; i++) {
            *p2++ = *p1++;
            if (i == decpt)
                *p2++ = '.';
        }
        if (ndigit < decpt) {
            while (ndigit++ < decpt)
                *p2++ = '0';
            *p2++ = '.';
        }
    }
    if (p2[-1] == '.' && !altform)
        p2--;
    *p2 = '\0';
    return (buf);
}

/*
 * The INS_CHAR macro inserts a character in the buffer and writes
 * the buffer back to disk if necessary
 * It uses the char pointers sp and bep:
 *      sp points to the next available character in the buffer
 *      bep points to the end-of-buffer+1
 * While using this macro, note that the nextb pointer is NOT updated.
 *
 * NOTE: Evaluation of the c argument should not have any side-effects
 */
#define INS_CHAR(c, sp, bep, cc)                                \
            {                                                   \
                if (sp >= bep) {                                \
                    vbuff->curpos = sp;                         \
                    if (flush_func(vbuff))                      \
                        return -1;                              \
                    sp = vbuff->curpos;                         \
                    bep = vbuff->endpos;                        \
                }                                               \
                *sp++ = (c);                                    \
                cc++;                                           \
            }

#define NUM( c )                        ( c - '0' )

#define STR_TO_DEC( str, num )          \
    num = NUM( *str++ ) ;               \
    while ( ap_isdigit( *str ) )                \
    {                                   \
        num *= 10 ;                     \
        num += NUM( *str++ ) ;          \
    }

/*
 * This macro does zero padding so that the precision
 * requirement is satisfied. The padding is done by
 * adding '0's to the left of the string that is going
 * to be printed. We don't allow precision to be large
 * enough that we continue past the start of s.
 *
 * NOTE: this makes use of the magic info that s is
 * always based on num_buf with a size of NUM_BUF_SIZE.
 */
#define FIX_PRECISION( adjust, precision, s, s_len )    \
    if ( adjust ) {                                     \
        int p = precision < NUM_BUF_SIZE - 1 ? precision : NUM_BUF_SIZE - 1; \
        while ( s_len < p )                             \
        {                                               \
            *--s = '0' ;                                \
            s_len++ ;                                   \
        }                                               \
    }

/*
 * Macro that does padding. The padding is done by printing
 * the character ch.
 */
#define PAD( width, len, ch )   do              \
        {                                       \
            INS_CHAR( ch, sp, bep, cc ) ;       \
            width-- ;                           \
        }                                       \
        while ( width > len )

/*
 * Prefix the character ch to the string str
 * Increase length
 * Set the has_prefix flag
 */
#define PREFIX( str, length, ch )        *--str = ch ; length++ ; has_prefix = YES


/*
 * Convert num to its decimal format.
 * Return value:
 *   - a pointer to a string containing the number (no sign)
 *   - len contains the length of the string
 *   - is_negative is set to TRUE or FALSE depending on the sign
 *     of the number (always set to FALSE if is_unsigned is TRUE)
 *
 * The caller provides a buffer for the string: that is the buf_end argument
 * which is a pointer to the END of the buffer + 1 (i.e. if the buffer
 * is declared as buf[ 100 ], buf_end should be &buf[ 100 ])
 *
 * Note: we have 2 versions. One is used when we need to use quads
 * (conv_10_quad), the other when we don't (conv_10). We're assuming the
 * latter is faster.
 */
static char *conv_10(register wide_int num, register bool_int is_unsigned,
                     register bool_int *is_negative, char *buf_end,
                     register int *len)
{
    register char *p = buf_end;
    register u_wide_int magnitude;

    if (is_unsigned) {
        magnitude = (u_wide_int) num;
        *is_negative = FALSE;
    }
    else {
        *is_negative = (num < 0);

        /*
         * On a 2's complement machine, negating the most negative integer 
         * results in a number that cannot be represented as a signed integer.
         * Here is what we do to obtain the number's magnitude:
         *      a. add 1 to the number
         *      b. negate it (becomes positive)
         *      c. convert it to unsigned
         *      d. add 1
         */
        if (*is_negative) {
            wide_int t = num + 1;

            magnitude = ((u_wide_int) -t) + 1;
        }
        else
            magnitude = (u_wide_int) num;
    }

    /*
     * We use a do-while loop so that we write at least 1 digit 
     */
    do {
        register u_wide_int new_magnitude = magnitude / 10;

        *--p = (char) (magnitude - new_magnitude * 10 + '0');
        magnitude = new_magnitude;
    }
    while (magnitude);

    *len = buf_end - p;
    return (p);
}

static char *conv_10_quad(widest_int num, register bool_int is_unsigned,
                     register bool_int *is_negative, char *buf_end,
                     register int *len)
{
    register char *p = buf_end;
    u_widest_int magnitude;

    /*
     * We see if we can use the faster non-quad version by checking the
     * number against the largest long value it can be. If <=, we
     * punt to the quicker version.
     */
    if ((num <= ULONG_MAX && is_unsigned) || (num <= LONG_MAX && !is_unsigned))