ber_len.c

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/* This file is part of the YAZ toolkit.
 * Copyright (C) Index Data
 * See the file LICENSE for details.
 */

 
#if HAVE_CONFIG_H
#include <config.h>
#endif
 
#include <stdio.h>
#include <limits.h>
#include "odr-priv.h"

int ber_enclen(ODR o, int len, int lenlen, int exact)
{
    unsigned char octs[sizeof(int)];
    int n = 0;
    int lenpos, end;
 
    if (len < 0)      /* Indefinite */
    {
        if (odr_putc(o, 0x80) < 0)
            return 0;
        return 0;
    }
    if (len <= 127 && (lenlen == 1 || !exact)) /* definite short form */
    {
        if (odr_putc(o, (unsigned char) len) < 0)
            return 0;
        return 1;
    }
    if (lenlen == 1)
    {
        if (odr_putc(o, 0x80) < 0)
            return 0;
        return 0;
    }
    /* definite long form */
    do
    {
        octs[n++] = len;
        len >>= 8;
    }
    while (len);
    if (n >= lenlen)
        return -1;
    lenpos = odr_tell(o); /* remember length-of-length position */
    if (odr_putc(o, 0) < 0)  /* dummy */
        return 0;
    if (exact)
        while (n < --lenlen)        /* pad length octets */
            if (odr_putc(o, 0) < 0)
                return 0;
    while (n--)
        if (odr_putc(o, octs[n]) < 0)
            return 0;
    /* set length of length */
    end = odr_tell(o);
    odr_seek(o, ODR_S_SET, lenpos);
    if (odr_putc(o, (end - lenpos - 1) | 0X80) < 0)
        return 0;
    odr_seek(o, ODR_S_END, 0);
    return odr_tell(o) - lenpos;
}

int ber_declen(const char *buf, int *len, int max)
{
    const unsigned char *b = (const unsigned char *) buf;
    int n;
 
    if (max < 1)
        return -1;
    if (*b == 0X80)     /* Indefinite */
    {
        *len = -1;
        return 1;
    }
    if (!(*b & 0X80))   /* Definite short form */
    {
        *len = (int) *b;
        return 1;
    }
    if (*b == 0XFF)     /* reserved value */
        return -2;
    /* definite long form */
    n = *b & 0X7F;
    if (n >= max)
        return -1;
    *len = 0;
    b++;
    while (--n >= 0)
    {
        if (*len > (INT_MAX - *b) / 256)
            return -2;  /* length too large to represent */
        *len = *len * 256 + *b++;
    }
    return ((const char *) b - buf);
}
/*
 * Local variables:
 * c-basic-offset: 4
 * c-file-style: "Stroustrup"
 * indent-tabs-mode: nil
 * End:
 * vim: shiftwidth=4 tabstop=8 expandtab
 */