apr_snprintf.c

Apache 2.0.63 is the current stable version of the 2.0 series, and is recommended over any previous

                    else
                        i_num = (wide_int) va_arg(ap, int);
                    s = conv_10(i_num, 0, &is_negative,
                            &num_buf[NUM_BUF_SIZE], &s_len);
                }
                FIX_PRECISION(adjust_precision, precision, s, s_len);

                if (is_negative)
                    prefix_char = '-';
                else if (print_sign)
                    prefix_char = '+';
                else if (print_blank)
                    prefix_char = ' ';
                break;


            case 'o':
                if (var_type == IS_QUAD) {
                    ui_quad = va_arg(ap, u_widest_int);
                    s = conv_p2_quad(ui_quad, 3, *fmt,
                            &num_buf[NUM_BUF_SIZE], &s_len);
                }
                else {
                    if (var_type == IS_LONG)
                        ui_num = (u_wide_int) va_arg(ap, u_wide_int);
                    else if (var_type == IS_SHORT)
                        ui_num = (u_wide_int) (unsigned short) va_arg(ap, unsigned int);
                    else
                        ui_num = (u_wide_int) va_arg(ap, unsigned int);
                    s = conv_p2(ui_num, 3, *fmt,
                            &num_buf[NUM_BUF_SIZE], &s_len);
                }
                FIX_PRECISION(adjust_precision, precision, s, s_len);
                if (alternate_form && *s != '0') {
                    *--s = '0';
                    s_len++;
                }
                break;


            case 'x':
            case 'X':
                if (var_type == IS_QUAD) {
                    ui_quad = va_arg(ap, u_widest_int);
                    s = conv_p2_quad(ui_quad, 4, *fmt,
                            &num_buf[NUM_BUF_SIZE], &s_len);
                }
                else {
                    if (var_type == IS_LONG)
                        ui_num = (u_wide_int) va_arg(ap, u_wide_int);
                    else if (var_type == IS_SHORT)
                        ui_num = (u_wide_int) (unsigned short) va_arg(ap, unsigned int);
                    else
                        ui_num = (u_wide_int) va_arg(ap, unsigned int);
                    s = conv_p2(ui_num, 4, *fmt,
                            &num_buf[NUM_BUF_SIZE], &s_len);
                }
                FIX_PRECISION(adjust_precision, precision, s, s_len);
                if (alternate_form && i_num != 0) {
                    *--s = *fmt;        /* 'x' or 'X' */
                    *--s = '0';
                    s_len += 2;
                }
                break;


            case 's':
                s = va_arg(ap, char *);
                if (s != NULL) {
                    if (!adjust_precision) {
                        s_len = strlen(s);
                    }
                    else {
                        /* From the C library standard in section 7.9.6.1:
                         * ...if the precision is specified, no more then
                         * that many characters are written.  If the
                         * precision is not specified or is greater
                         * than the size of the array, the array shall
                         * contain a null character.
                         *
                         * My reading is is precision is specified and
                         * is less then or equal to the size of the
                         * array, no null character is required.  So
                         * we can't do a strlen.
                         *
                         * This figures out the length of the string
                         * up to the precision.  Once it's long enough
                         * for the specified precision, we don't care
                         * anymore.
                         *
                         * NOTE: you must do the length comparison
                         * before the check for the null character.
                         * Otherwise, you'll check one beyond the
                         * last valid character.
                         */
                        const char *walk;

                        for (walk = s, s_len = 0;
                             (s_len < precision) && (*walk != '\0');
                             ++walk, ++s_len);
                    }
                }
                else {
                    s = S_NULL;
                    s_len = S_NULL_LEN;
                }
                pad_char = ' ';
                break;


            case 'f':
            case 'e':
            case 'E':
                fp_num = va_arg(ap, double);
                /*
                 * We use &num_buf[ 1 ], so that we have room for the sign
                 */
                s = NULL;
#ifdef HAVE_ISNAN
                if (isnan(fp_num)) {
                    s = "nan";
                    s_len = 3;
                }
#endif
#ifdef HAVE_ISINF
                if (!s && isinf(fp_num)) {
                    s = "inf";
                    s_len = 3;
                }
#endif
                if (!s) {
                    s = conv_fp(*fmt, fp_num, alternate_form,
                            (adjust_precision == NO) ? FLOAT_DIGITS : precision,
                                &is_negative, &num_buf[1], &s_len);
                    if (is_negative)
                        prefix_char = '-';
                    else if (print_sign)
                        prefix_char = '+';
                    else if (print_blank)
                        prefix_char = ' ';
                }
                break;


            case 'g':
            case 'G':
                if (adjust_precision == NO)
                    precision = FLOAT_DIGITS;
                else if (precision == 0)
                    precision = 1;
                /*
                 * * We use &num_buf[ 1 ], so that we have room for the sign
                 */
                s = apr_gcvt(va_arg(ap, double), precision, &num_buf[1],
                            alternate_form);
                if (*s == '-')
                    prefix_char = *s++;
                else if (print_sign)
                    prefix_char = '+';
                else if (print_blank)
                    prefix_char = ' ';

                s_len = strlen(s);

                if (alternate_form && (q = strchr(s, '.')) == NULL) {
                    s[s_len++] = '.';
                    s[s_len] = '\0'; /* delimit for following strchr() */
                }
                if (*fmt == 'G' && (q = strchr(s, 'e')) != NULL)
                    *q = 'E';
                break;


            case 'c':
                char_buf[0] = (char) (va_arg(ap, int));
                s = &char_buf[0];
                s_len = 1;
                pad_char = ' ';
                break;


            case '%':
                char_buf[0] = '%';
                s = &char_buf[0];
                s_len = 1;
                pad_char = ' ';
                break;


            case 'n':
                if (var_type == IS_QUAD)
                    *(va_arg(ap, widest_int *)) = cc;
                else if (var_type == IS_LONG)
                    *(va_arg(ap, long *)) = cc;
                else if (var_type == IS_SHORT)
                    *(va_arg(ap, short *)) = cc;
                else
                    *(va_arg(ap, int *)) = cc;
                print_something = NO;
                break;

                /*
                 * This is where we extend the printf format, with a second
                 * type specifier
                 */
            case 'p':
                switch(*++fmt) {
                /*
                 * If the pointer size is equal to or smaller than the size
                 * of the largest unsigned int, we convert the pointer to a
                 * hex number, otherwise we print "%p" to indicate that we
                 * don't handle "%p".
                 */
                case 'p':
#if APR_SIZEOF_VOIDP == 8
                    if (sizeof(void *) <= sizeof(u_widest_int)) {
                        ui_quad = (u_widest_int) va_arg(ap, void *);
                        s = conv_p2_quad(ui_quad, 4, 'x',
                                &num_buf[NUM_BUF_SIZE], &s_len);
                    }
#else
                    if (sizeof(void *) <= sizeof(u_wide_int)) {
                        ui_num = (u_wide_int) va_arg(ap, void *);
                        s = conv_p2(ui_num, 4, 'x',
                                &num_buf[NUM_BUF_SIZE], &s_len);
                    }
#endif
                    else {
                        s = "%p";
                        s_len = 2;
                        prefix_char = NUL;
                    }
                    pad_char = ' ';
                    break;

                /* print an apr_sockaddr_t as a.b.c.d:port */
                case 'I':
                {
                    apr_sockaddr_t *sa;

                    sa = va_arg(ap, apr_sockaddr_t *);
                    if (sa != NULL) {
                        s = conv_apr_sockaddr(sa, &num_buf[NUM_BUF_SIZE], &s_len);
                        if (adjust_precision && precision < s_len)
                            s_len = precision;
                    }
                    else {
                        s = S_NULL;
                        s_len = S_NULL_LEN;
                    }
                    pad_char = ' ';
                }
                break;

                /* print a struct in_addr as a.b.c.d */
                case 'A':
                {
                    struct in_addr *ia;

                    ia = va_arg(ap, struct in_addr *);
                    if (ia != NULL) {
                        s = conv_in_addr(ia, &num_buf[NUM_BUF_SIZE], &s_len);
                        if (adjust_precision && precision < s_len)
                            s_len = precision;
                    }
                    else {
                        s = S_NULL;
                        s_len = S_NULL_LEN;
                    }
                    pad_char = ' ';
                }
                break;

                case 'T':
#if APR_HAS_THREADS
                {
                    apr_os_thread_t *tid;

                    tid = va_arg(ap, apr_os_thread_t *);
                    if (tid != NULL) {
                        s = conv_os_thread_t(tid, &num_buf[NUM_BUF_SIZE], &s_len);
                        if (adjust_precision && precision < s_len)
                            s_len = precision;
                    }
                    else {
                        s = S_NULL;
                        s_len = S_NULL_LEN;
                    }
                    pad_char = ' ';
                }
#else
                    char_buf[0] = '0';
                    s = &char_buf[0];
                    s_len = 1;
                    pad_char = ' ';
#endif
                    break;

                case NUL:
                    /* if %p ends the string, oh well ignore it */
                    continue;

                default:
                    s = "bogus %p";
                    s_len = 8;
                    prefix_char = NUL;
                    (void)va_arg(ap, void *); /* skip the bogus argument on the stack */
                    break;
                }
                break;

            case NUL:
                /*
                 * The last character of the format string was %.
                 * We ignore it.
                 */
                continue;


                /*
                 * The default case is for unrecognized %'s.
                 * We print %<char> to help the user identify what
                 * option is not understood.
                 * This is also useful in case the user wants to pass
                 * the output of format_converter to another function
                 * that understands some other %<char> (like syslog).
                 * Note that we can't point s inside fmt because the
                 * unknown <char> could be preceded by width etc.
                 */
            default:
                char_buf[0] = '%';
                char_buf[1] = *fmt;
                s = char_buf;
                s_len = 2;
                pad_char = ' ';
                break;
            }

            if (prefix_char != NUL && s != S_NULL && s != char_buf) {
                *--s = prefix_char;
                s_len++;
            }

            if (adjust_width && adjust == RIGHT && min_width > s_len) {
                if (pad_char == '0' && prefix_char != NUL) {
                    INS_CHAR(*s, sp, bep, cc);
                    s++;
                    s_len--;
                    min_width--;
                }
                PAD(min_width, s_len, pad_char);
            }

            /*
             * Print the string s. 
             */
            if (print_something == YES) {
                for (i = s_len; i != 0; i--) {
                      INS_CHAR(*s, sp, bep, cc);
                    s++;
                }
            }

            if (adjust_width && adjust == LEFT && min_width > s_len)
                PAD(min_width, s_len, pad_char);
        }
        fmt++;
    }
    vbuff->curpos = sp;

    return cc;
}


static int snprintf_flush(apr_vformatter_buff_t *vbuff)
{
    /* if the buffer fills we have to abort immediately, there is no way
     * to "flush" an apr_snprintf... there's nowhere to flush it to.
     */
    return -1;
}


APR_DECLARE_NONSTD(int) apr_snprintf(char *buf, apr_size_t len, 
                                     const char *format, ...)
{
    int cc;
    va_list ap;
    apr_vformatter_buff_t vbuff;

    if (len == 0) {
        /* NOTE: This is a special case; we just want to return the number
         * of chars that would be written (minus \0) if the buffer
         * size was infinite. We leverage the fact that INS_CHAR
         * just does actual inserts iff the buffer pointer is non-NULL.
         * In this case, we don't care what buf is; it can be NULL, since
         * we don't touch it at all.
         */
        vbuff.curpos = NULL;
        vbuff.endpos = NULL;
    } else {
        /* save one byte for nul terminator */
        vbuff.curpos = buf;
        vbuff.endpos = buf + len - 1;
    }
    va_start(ap, format);
    cc = apr_vformatter(snprintf_flush, &vbuff, format, ap);
    va_end(ap);
    if (len != 0) {
        *vbuff.curpos = '\0';
    }
    return (cc == -1) ? (int)len : cc;
}


APR_DECLARE(int) apr_vsnprintf(char *buf, apr_size_t len, const char *format,
                               va_list ap)
{
    int cc;
    apr_vformatter_buff_t vbuff;

    if (len == 0) {
        /* See above note */
        vbuff.curpos = NULL;
        vbuff.endpos = NULL;
    } else {
        /* save one byte for nul terminator */
        vbuff.curpos = buf;
        vbuff.endpos = buf + len - 1;
    }
    cc = apr_vformatter(snprintf_flush, &vbuff, format, ap);
    if (len != 0) {
        *vbuff.curpos = '\0';
    }
    return (cc == -1) ? (int)len : cc;
}