/*

 * Copyright (c) 2003-2019 Lev Walkin <vlm@lionet.info>.

 * All rights reserved.

 * Redistribution and modifications are permitted subject to BSD license.

 */

#include <asn_internal.h>

#include <INTEGER.h>

#include <errno.h>

#include <inttypes.h>

/*

 * INTEGER basic type description.

 */

static const ber_tlv_tag_t asn_DEF_INTEGER_tags[] = {

    (ASN_TAG_CLASS_UNIVERSAL | (2 << 2))

};

asn_TYPE_operation_t asn_OP_INTEGER = {

    .kind = ASN_KIND_PRIMITIVE,

    INTEGER_free,

#if !defined(ASN_DISABLE_PRINT_SUPPORT)

    INTEGER_print,

#else

    0,

#endif  /* !defined(ASN_DISABLE_PRINT_SUPPORT) */

    INTEGER_compare,

    INTEGER_copy,

#if !defined(ASN_DISABLE_BER_SUPPORT)

    ber_decode_primitive,

    INTEGER_encode_der,

#else

    0,

    0,

#endif  /* !defined(ASN_DISABLE_BER_SUPPORT) */

#if !defined(ASN_DISABLE_XER_SUPPORT)

    INTEGER_decode_xer,

    INTEGER_encode_xer,

#else

    0,

    0,

#endif  /* !defined(ASN_DISABLE_XER_SUPPORT) */

#if !defined(ASN_DISABLE_JER_SUPPORT)

    INTEGER_decode_jer,

    INTEGER_encode_jer,

#else

    0,

    0,

#endif  /* !defined(ASN_DISABLE_JER_SUPPORT) */

#if !defined(ASN_DISABLE_OER_SUPPORT)

    INTEGER_decode_oer,  /* OER decoder */

    INTEGER_encode_oer,  /* Canonical OER encoder */

#else

    0,

    0,

#endif  /* !defined(ASN_DISABLE_OER_SUPPORT) */

#if !defined(ASN_DISABLE_UPER_SUPPORT)

    INTEGER_decode_uper,  /* Unaligned PER decoder */

    INTEGER_encode_uper,  /* Unaligned PER encoder */

#else

    0,

    0,

#endif  /* !defined(ASN_DISABLE_UPER_SUPPORT) */

#if !defined(ASN_DISABLE_APER_SUPPORT)

    INTEGER_decode_aper,  /* Aligned PER decoder */

    INTEGER_encode_aper,  /* Aligned PER encoder */

#else

    0,

    0,

#endif  /* !defined(ASN_DISABLE_APER_SUPPORT) */

#if !defined(ASN_DISABLE_RFILL_SUPPORT)

    INTEGER_random_fill,

#else

    0,

#endif  /* !defined(ASN_DISABLE_RFILL_SUPPORT) */

0,  /* Use generic outmost tag fetcher */

#if !defined(ASN_DISABLE_CBOR_SUPPORT)

    INTEGER_decode_cbor,

    INTEGER_encode_cbor,

#else

    0,

    0,

#endif  /* !defined(ASN_DISABLE_CBOR_SUPPORT) */

};

asn_TYPE_descriptor_t asn_DEF_INTEGER = {

    "INTEGER",

    "INTEGER",

    &asn_OP_INTEGER,

    asn_DEF_INTEGER_tags,

    sizeof(asn_DEF_INTEGER_tags) / sizeof(asn_DEF_INTEGER_tags[0]),

    asn_DEF_INTEGER_tags, /* Same as above */

    sizeof(asn_DEF_INTEGER_tags) / sizeof(asn_DEF_INTEGER_tags[0]),

    {

#if !defined(ASN_DISABLE_OER_SUPPORT)

        0,

#endif  /* !defined(ASN_DISABLE_OER_SUPPORT) */

#if !defined(ASN_DISABLE_UPER_SUPPORT) || !defined(ASN_DISABLE_APER_SUPPORT)

        0,

#endif  /* !defined(ASN_DISABLE_UPER_SUPPORT) || !defined(ASN_DISABLE_APER_SUPPORT) */

#if !defined(ASN_DISABLE_JER_SUPPORT)

        0,

#endif  /* !defined(ASN_DISABLE_JER_SUPPORT) */

        asn_generic_no_constraint

    },

    0, 0,  /* No members */

    0  /* No specifics */

};

/*

 * INTEGER specific human-readable output.

 */

ssize_t

INTEGER__dump(const asn_TYPE_descriptor_t *td, const INTEGER_t *st, asn_app_consume_bytes_f *cb, void *app_key, int plainOrXEROrJER) {

    const asn_INTEGER_specifics_t *specs =

        (const asn_INTEGER_specifics_t *)td->specifics;

  char scratch[32];

  uint8_t *buf = st->buf;

  uint8_t *buf_end = st->buf + st->size;

  intmax_t value = 0;

  ssize_t wrote = 0;

  char *p = NULL;

  int ret = -1;

  if(specs && specs->field_unsigned)

    ret = asn_INTEGER2umax(st, (uintmax_t *)&value);

  else

    ret = asn_INTEGER2imax(st, &value);

  /* Simple case: the integer size is small */

  if(ret == 0) {

    const asn_INTEGER_enum_map_t *el;

    el = (value >= 0 || !specs || !specs->field_unsigned)

      ? INTEGER_map_value2enum(specs, value) : 0;

    if(el) {

      if(plainOrXEROrJER == 0)

        return asn__format_to_callback(cb, app_key,

          "%" ASN_PRIdMAX " (%s)", value, el->enum_name);

      else if (plainOrXEROrJER == 1)

        return asn__format_to_callback(cb, app_key,

          "<%s/>", el->enum_name);

      else if (plainOrXEROrJER == 2)

        return asn__format_to_callback(cb, app_key,

          "\"%s\"", el->enum_name);

    } else if(plainOrXEROrJER && specs && specs->strict_enumeration) {

      ASN_DEBUG("ASN.1 forbids dealing with "

        "unknown value of ENUMERATED type");

      errno = EPERM;

      return -1;

    } else {

            return asn__format_to_callback(cb, app_key,

                                           (specs && specs->field_unsigned)

                                               ? "%" ASN_PRIuMAX

                                               : "%" ASN_PRIdMAX,

                                           value);

        }

  } else if(plainOrXEROrJER && specs && specs->strict_enumeration) {

    /*

     * Here and earlier, we cannot encode the ENUMERATED values

     * if there is no corresponding identifier.

     */

    ASN_DEBUG("ASN.1 forbids dealing with "

      "unknown value of ENUMERATED type");

    errno = EPERM;

    return -1;

  }

  /* Output in the long xx:yy:zz... format */

  /* TODO: replace with generic algorithm (Knuth TAOCP Vol 2, 4.3.1) */

  /* For JER (JSON), large integers should be quoted as strings */

  if(plainOrXEROrJER == 2) {

    if(cb("\"", 1, app_key) < 0) return -1;

    wrote += 1;

  }

  for(p = scratch; buf < buf_end; buf++) {

    const char * const h2c = "0123456789ABCDEF";

    if((p - scratch) >= (ssize_t)(sizeof(scratch) - 4)) {

      /* Flush buffer */

      if(cb(scratch, p - scratch, app_key) < 0)

        return -1;

      wrote += p - scratch;

      p = scratch;

    }

    *p++ = h2c[*buf >> 4];

    *p++ = h2c[*buf & 0x0F];

    *p++ = 0x3a;  /* ":" */

  }

  if(p != scratch)

    p--; /* Remove the last ":" */

  wrote += p - scratch;

  if((cb(scratch, p - scratch, app_key) < 0)) return -1;

  /* Close quote for JER (JSON) */

  if(plainOrXEROrJER == 2) {

    if(cb("\"", 1, app_key) < 0) return -1;

    wrote += 1;

  }

  return wrote;

}

static int

INTEGER__compar_value2enum(const void *kp, const void *am) {

  long a = *(const long *)kp;

  const asn_INTEGER_enum_map_t *el = (const asn_INTEGER_enum_map_t *)am;

  long b = el->nat_value;

  if(a < b) return -1;

  else if(a == b) return 0;

  else return 1;

}

const asn_INTEGER_enum_map_t *

INTEGER_map_value2enum(const asn_INTEGER_specifics_t *specs, long value) {

  int count = specs ? specs->map_count : 0;

  if(!count) return 0;

  return (asn_INTEGER_enum_map_t *)bsearch(&value, specs->value2enum,

    count, sizeof(specs->value2enum[0]),

    INTEGER__compar_value2enum);

}

static intmax_t

asn__integer_convert(const uint8_t *b, const uint8_t *end) {

    uintmax_t value;

    /* Perform the sign initialization */

    /* Actually value = -(*b >> 7); gains nothing, yet unreadable! */

    if((*b >> 7)) {

        value = (uintmax_t)(-1);

    } else {

        value = 0;

    }

    /* Conversion engine */

    for(; b < end; b++) {

        value = (value << 8) | *b;

    }

    return value;

}

int

asn_INTEGER2imax(const INTEGER_t *iptr, intmax_t *lptr) {

  uint8_t *b, *end;

  size_t size = 0;

  /* Sanity checking */

  if(!iptr || !iptr->buf || !lptr) {

    errno = EINVAL;

    return -1;

  }

  /* Cache the begin/end of the buffer */

  b = iptr->buf;  /* Start of the INTEGER buffer */

  size = iptr->size;

  end = b + size; /* Where to stop */

  if(size > sizeof(intmax_t)) {

    uint8_t *end1 = end - 1;

    /*

     * Slightly more advanced processing,

     * able to process INTEGERs with >sizeof(intmax_t) bytes

     * when the actual value is small, e.g. for intmax_t == int32_t

     * (0x0000000000abcdef INTEGER would yield a fine 0x00abcdef int32_t)

     */

    /* Skip out the insignificant leading bytes */

    for(; b < end1; b++) {

      switch(*b) {

        case 0x00: if((b[1] & 0x80) == 0) continue; break;

        case 0xff: if((b[1] & 0x80) != 0) continue; break;

      }

      break;

    }

    size = end - b;

    if(size > sizeof(intmax_t)) {

      /* Still cannot fit the sizeof(intmax_t) */

      errno = ERANGE;

      return -1;

    }

  }

  /* Shortcut processing of a corner case */

  if(end == b) {

    *lptr = 0;

    return 0;

  }

  *lptr = asn__integer_convert(b, end);

  return 0;

}

/* FIXME: negative INTEGER values are silently interpreted as large unsigned ones. */

int

asn_INTEGER2umax(const INTEGER_t *iptr, uintmax_t *lptr) {

  uint8_t *b, *end;

  uintmax_t value;

  size_t size;

  if(!iptr || !iptr->buf || !lptr) {

    errno = EINVAL;

    return -1;

  }

  b = iptr->buf;

  size = iptr->size;

  end = b + size;

  /* If all extra leading bytes are zeroes, ignore them */

  for(; size > sizeof(value); b++, size--) {

    if(*b) {

      /* Value won't fit into uintmax_t */

      errno = ERANGE;

      return -1;

    }

  }

  /* Conversion engine */

  for(value = 0; b < end; b++)

    value = (value << 8) | *b;

  *lptr = value;

  return 0;

}

int

asn_umax2INTEGER(INTEGER_t *st, uintmax_t value) {

    uint8_t *buf;

    uint8_t *end;

    uint8_t *b;

    int shr;

    if(value <= ((~(uintmax_t)0) >> 1)) {

        return asn_imax2INTEGER(st, value);

    }

    buf = (uint8_t *)MALLOC(1 + sizeof(value));

    if(!buf) return -1;

    end = buf + (sizeof(value) + 1);

    buf[0] = 0; /* INTEGERs are signed. 0-byte indicates positive. */

    for(b = buf + 1, shr = (sizeof(value) - 1) * 8; b < end; shr -= 8, b++)

        *b = (uint8_t)(value >> shr);

    if(st->buf) FREEMEM(st->buf);

    st->buf = buf;

    st->size = 1 + sizeof(value);

  return 0;

}

int

asn_imax2INTEGER(INTEGER_t *st, intmax_t value) {

  uint8_t *buf, *bp;

  volatile uint8_t *p;

  volatile uint8_t *pstart;

  volatile uint8_t *pend1;

  int littleEndian = 1; /* Run-time detection */

  volatile int add;

  if(!st) {

    errno = EINVAL;

    return -1;

  }

  buf = (uint8_t *)(long *)MALLOC(sizeof(value));

  if(!buf) return -1;

  if(*(char *)&littleEndian) {

    pstart = (uint8_t *)&value + sizeof(value) - 1;

    pend1 = (uint8_t *)&value;

    add = -1;

  } else {

    pstart = (uint8_t *)&value;

    pend1 = pstart + sizeof(value) - 1;

    add = 1;

  }

  /*

   * If the contents octet consists of more than one octet,

   * then bits of the first octet and bit 8 of the second octet:

   * a) shall not all be ones; and

   * b) shall not all be zero.

   */

  for(p = pstart; p != pend1; p += add) {

    switch(*p) {

    case 0x00: if((*(p+add) & 0x80) == 0)

        continue;

      break;

    case 0xff: if((*(p+add) & 0x80))

        continue;

      break;

    }

    break;

  }

  /* Copy the integer body */

  for(bp = buf, pend1 += add; p != pend1; p += add)

    *bp++ = *p;

  if(st->buf) FREEMEM(st->buf);

  st->buf = buf;

  st->size = bp - buf;

  return 0;

}

int

asn_INTEGER2long(const INTEGER_t *iptr, long *l) {

    intmax_t v;

    if(asn_INTEGER2imax(iptr, &v) == 0) {

        if(v < LONG_MIN || v > LONG_MAX) {

            errno = ERANGE;

            return -1;

        }

        *l = v;

        return 0;

    } else {

        return -1;

    }

}

int

asn_INTEGER2ulong(const INTEGER_t *iptr, unsigned long *l) {

    uintmax_t v;

    if(asn_INTEGER2umax(iptr, &v) == 0) {

        if(v > ULONG_MAX) {

            errno = ERANGE;

            return -1;

        }

        *l = v;

        return 0;

    } else {

        return -1;

    }

}

int

asn_long2INTEGER(INTEGER_t *st, long value) {

    return asn_imax2INTEGER(st, value);

}

int

asn_ulong2INTEGER(INTEGER_t *st, unsigned long value) {

    return asn_imax2INTEGER(st, value);

}

int asn_INTEGER2int64(const INTEGER_t *st, int64_t *value) {

    intmax_t v;

    if(asn_INTEGER2imax(st, &v) == 0) {

        if(v < INT64_MIN || v > INT64_MAX) {

            errno = ERANGE;

            return -1;

        }

        *value = v;

        return 0;

    } else {

        return -1;

    }

}

int asn_INTEGER2uint64(const INTEGER_t *st, uint64_t *value) {

    uintmax_t v;

    if(asn_INTEGER2umax(st, &v) == 0) {

        if(v > UINT64_MAX) {

            errno = ERANGE;

            return -1;

        }

        *value = v;

        return 0;

    } else {

        return -1;

    }

}

int

asn_uint642INTEGER(INTEGER_t *st, uint64_t value) {

  uint8_t *buf;

  uint8_t *end;

  uint8_t *b;

  int shr;

  if(value <= INT64_MAX)

    return asn_int642INTEGER(st, value);

  buf = (uint8_t *)MALLOC(1 + sizeof(value));

  if(!buf) return -1;

  end = buf + (sizeof(value) + 1);

  buf[0] = 0;

  for(b = buf + 1, shr = (sizeof(value)-1)*8; b < end; shr -= 8, b++)

    *b = (uint8_t)(value >> shr);

  if(st->buf) FREEMEM(st->buf);

  st->buf = buf;

  st->size = 1 + sizeof(value);

  return 0;

}

int

asn_int642INTEGER(INTEGER_t *st, int64_t value) {

  uint8_t *buf, *bp;

  volatile uint8_t *p;

  volatile uint8_t *pstart;

  volatile uint8_t *pend1;

  int littleEndian = 1; /* Run-time detection */

  volatile int add;

  if(!st) {

    errno = EINVAL;

    return -1;

  }

  buf = (uint8_t *)MALLOC(sizeof(value));

  if(!buf) return -1;

  if(*(char *)&littleEndian) {

    pstart = (uint8_t *)&value + sizeof(value) - 1;

    pend1 = (uint8_t *)&value;

    add = -1;

  } else {

    pstart = (uint8_t *)&value;

    pend1 = pstart + sizeof(value) - 1;

    add = 1;

  }

  /*

   * If the contents octet consists of more than one octet,

   * then bits of the first octet and bit 8 of the second octet:

   * a) shall not all be ones; and

   * b) shall not all be zero.

   */

  for(p = pstart; p != pend1; p += add) {

    switch(*p) {

    case 0x00: if((*(p+add) & 0x80) == 0)

        continue;

      break;

    case 0xff: if((*(p+add) & 0x80))

        continue;

      break;

    }

    break;

  }

  /* Copy the integer body */

  for(pstart = p, bp = buf, pend1 += add; p != pend1; p += add)

    *bp++ = *p;

  if(st->buf) FREEMEM(st->buf);

  st->buf = buf;

  st->size = bp - buf;

  return 0;

}

/*

 * Parse the number in the given string until the given *end position,

 * returning the position after the last parsed character back using the

 * same (*end) pointer.

 * WARNING: This behavior is different from the standard strtol/strtoimax(3).

 */

enum asn_strtox_result_e

asn_strtoimax_lim(const char *str, const char **end, intmax_t *intp) {

    int sign = 1;

    intmax_t value;

    const intmax_t asn1_intmax_max = ((~(uintmax_t)0) >> 1);

    const intmax_t upper_boundary = asn1_intmax_max / 10;

    intmax_t last_digit_max = asn1_intmax_max % 10;

    if(str >= *end) return ASN_STRTOX_ERROR_INVAL;

    switch(*str) {

    case '-':

        last_digit_max++;

        sign = -1;

        /* FALL THROUGH */

    case '+':

        str++;

        if(str >= *end) {

            *end = str;

            return ASN_STRTOX_EXPECT_MORE;

        }

    }

    for(value = 0; str < (*end); str++) {

        if(*str >= 0x30 && *str <= 0x39) {

            int d = *str - '0';

            if(value < upper_boundary) {

                value = value * 10 + d;

            } else if(value == upper_boundary) {

                if(d <= last_digit_max) {

                    if(sign > 0) {

                        value = value * 10 + d;

                    } else {

                        sign = 1;

                        value = -value * 10 - d;

                    }

                    str += 1;

                    if(str < *end) {

                        // If digits continue, we're guaranteed out of range.

                        *end = str;

                        if(*str >= 0x30 && *str <= 0x39) {

                            return ASN_STRTOX_ERROR_RANGE;

                        } else {

                            *intp = sign * value;

                            return ASN_STRTOX_EXTRA_DATA;

                        }

                    }

                    break;

                } else {

                    *end = str;

                    return ASN_STRTOX_ERROR_RANGE;

                }

            } else {

                *end = str;

                return ASN_STRTOX_ERROR_RANGE;

            }

        } else {

            *end = str;

            *intp = sign * value;

            return ASN_STRTOX_EXTRA_DATA;

        }

    }

    *end = str;

    *intp = sign * value;

    return ASN_STRTOX_OK;

}

/*

 * Parse the number in the given string until the given *end position,

 * returning the position after the last parsed character back using the

 * same (*end) pointer.

 * WARNING: This behavior is different from the standard strtoul/strtoumax(3).

 */

enum asn_strtox_result_e

asn_strtoumax_lim(const char *str, const char **end, uintmax_t *uintp) {

    uintmax_t value;

    const uintmax_t asn1_uintmax_max = ((~(uintmax_t)0));

    const uintmax_t upper_boundary = asn1_uintmax_max / 10;

    uintmax_t last_digit_max = asn1_uintmax_max % 10;

    if(str >= *end) return ASN_STRTOX_ERROR_INVAL;

    switch(*str) {

    case '-':

        return ASN_STRTOX_ERROR_INVAL;

    case '+':

        str++;

        if(str >= *end) {

            *end = str;

            return ASN_STRTOX_EXPECT_MORE;

        }

    }

    for(value = 0; str < (*end); str++) {

        if(*str >= 0x30 && *str <= 0x39) {

            unsigned int d = *str - '0';

            if(value < upper_boundary) {

                value = value * 10 + d;

            } else if(value == upper_boundary) {

                if(d <= last_digit_max) {

                    value = value * 10 + d;

                    str += 1;

                    if(str < *end) {

                        // If digits continue, we're guaranteed out of range.

                        *end = str;

                        if(*str >= 0x30 && *str <= 0x39) {

                            return ASN_STRTOX_ERROR_RANGE;

                        } else {

                            *uintp = value;

                            return ASN_STRTOX_EXTRA_DATA;

                        }

                    }

                    break;

                } else {

                    *end = str;

                    return ASN_STRTOX_ERROR_RANGE;

                }

            } else {

                *end = str;

                return ASN_STRTOX_ERROR_RANGE;

            }

        } else {

            *end = str;

            *uintp = value;

            return ASN_STRTOX_EXTRA_DATA;

        }

    }

    *end = str;

    *uintp = value;

    return ASN_STRTOX_OK;

}

enum asn_strtox_result_e

asn_strtol_lim(const char *str, const char **end, long *lp) {

    intmax_t value;

    switch(asn_strtoimax_lim(str, end, &value)) {

    case ASN_STRTOX_ERROR_RANGE:

        return ASN_STRTOX_ERROR_RANGE;

    case ASN_STRTOX_ERROR_INVAL:

        return ASN_STRTOX_ERROR_INVAL;

    case ASN_STRTOX_EXPECT_MORE:

        return ASN_STRTOX_EXPECT_MORE;

    case ASN_STRTOX_OK:

        if(value >= LONG_MIN && value <= LONG_MAX) {

            *lp = value;

            return ASN_STRTOX_OK;

        } else {

            return ASN_STRTOX_ERROR_RANGE;

        }

    case ASN_STRTOX_EXTRA_DATA:

        if(value >= LONG_MIN && value <= LONG_MAX) {

            *lp = value;

            return ASN_STRTOX_EXTRA_DATA;

        } else {

            return ASN_STRTOX_ERROR_RANGE;

        }

    }

    assert(!"Unreachable");

    return ASN_STRTOX_ERROR_INVAL;

}

enum asn_strtox_result_e

asn_strtoul_lim(const char *str, const char **end, unsigned long *ulp) {

    uintmax_t value;

    switch(asn_strtoumax_lim(str, end, &value)) {

    case ASN_STRTOX_ERROR_RANGE:

        return ASN_STRTOX_ERROR_RANGE;

    case ASN_STRTOX_ERROR_INVAL:

        return ASN_STRTOX_ERROR_INVAL;

    case ASN_STRTOX_EXPECT_MORE:

        return ASN_STRTOX_EXPECT_MORE;

    case ASN_STRTOX_OK:

        if(value <= ULONG_MAX) {

            *ulp = value;

            return ASN_STRTOX_OK;

        } else {

            return ASN_STRTOX_ERROR_RANGE;

        }

    case ASN_STRTOX_EXTRA_DATA:

        if(value <= ULONG_MAX) {

            *ulp = value;

            return ASN_STRTOX_EXTRA_DATA;

        } else {

            return ASN_STRTOX_ERROR_RANGE;

        }

    }

    assert(!"Unreachable");

    return ASN_STRTOX_ERROR_INVAL;

}

int

INTEGER_compare(const asn_TYPE_descriptor_t *td, const void *aptr,

                     const void *bptr) {

    const INTEGER_t *a = aptr;

    const INTEGER_t *b = bptr;

    (void)td;

    if(a && b) {

        if(a->size && b->size) {

            int sign_a = (a->buf[0] & 0x80) ? -1 : 1;

            int sign_b = (b->buf[0] & 0x80) ? -1 : 1;

            if(sign_a < sign_b) return -1;

            if(sign_a > sign_b) return 1;

            /* The shortest integer wins, unless comparing negatives */

            if(a->size < b->size) {

                return -1 * sign_a;

            } else if(a->size > b->size) {

                return 1 * sign_b;

            }

            return sign_a * memcmp(a->buf, b->buf, a->size);

        } else if(a->size) {

            int sign = (a->buf[0] & 0x80) ? -1 : 1;

            return (1) * sign;

        } else if(b->size) {

            int sign = (a->buf[0] & 0x80) ? -1 : 1;

            return (-1) * sign;

        } else {

            return 0;

        }

    } else if(!a && !b) {

        return 0;

    } else if(!a) {

        return -1;

    } else {

        return 1;

    }

}

int

INTEGER_copy(const asn_TYPE_descriptor_t *td, void **aptr,

                     const void *bptr) {

    (void)td;

    INTEGER_t *a = *aptr;

    const INTEGER_t *b = bptr;

    if(!b) {

        if(a) {

            FREEMEM(a->buf);

            FREEMEM(a);

            *aptr = 0;

        }

        return 0;

    }

    if(!a) {

        a = *aptr = CALLOC(1, sizeof(*a));

        if(!a) return -1;

    }

    if(b->size) {

        uint8_t* buf = MALLOC(b->size);

        if(!buf) return -1;

        memcpy(buf, b->buf, b->size);

        FREEMEM(a->buf);

        a->buf = buf;

        a->size = b->size;

    } else {

        FREEMEM(a->buf);

        a->buf = 0;

        a->size = 0;

    }

    return 0;

}