mongo_support.c

/*
 *  Copyright 2009 10gen, Inc.
 *
 *  Licensed 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.
 */

#include "mongo_support.h"

#ifdef WIN32
#include <memory.h>
#endif

#include "regcomp.h"

static stackette* check_circular_ref(void *ptr, stackette *stack);
static int isUTF8(const char*, int);
static void serialize_regex(buffer*, const char*, REGEXP*, int is_insert);
static void serialize_regex_flags(buffer*, SV*);
static void append_sv (buffer *buf, const char *key, SV *sv, stackette *stack, int is_insert);

int perl_mongo_inc = 0;

// void
// perl_mongo_call_xs (pTHX_ void (*subaddr) (pTHX_ CV *), CV *cv, SV **mark)
// {
//     dSP;
//     PUSHMARK (mark);
//     (*subaddr) (aTHX_ cv);
//     PUTBACK;
// }

SV *
perl_mongo_call_reader (SV *self, const char *reader)
{
    dSP;
    SV *ret;
    I32 count;

    ENTER;
    SAVETMPS;

    PUSHMARK (SP);
    XPUSHs (self);
    PUTBACK;

    count = call_method (reader, G_SCALAR);

    SPAGAIN;

    if (count != 1) {
        croak ("reader didn't return a value");
    }

    ret = POPs;
    SvREFCNT_inc (ret);

    PUTBACK;
    FREETMPS;
    LEAVE;

    return ret;
}


SV *
perl_mongo_call_method (SV *self, const char *method, int num, ...)
{
    dSP;
    SV *ret;
    I32 count;
    va_list args;

    ENTER;
    SAVETMPS;

    PUSHMARK (SP);
    XPUSHs (self);

    va_start( args, num );
 
    for( ; num > 0; num-- ) {
      XPUSHs (va_arg( args, SV* ));
    }
 
    va_end( args );

    PUTBACK;

    count = call_method (method, G_SCALAR);

    SPAGAIN;

    if (count != 1) {
        croak ("method didn't return a value");
    }

    ret = POPs;
    SvREFCNT_inc (ret);

    PUTBACK;
    FREETMPS;
    LEAVE;

    return ret;
}

SV *
perl_mongo_call_function (const char *func, int num, ...)
{
    dSP;
    SV *ret;
    I32 count;
    va_list args;

    ENTER;
    SAVETMPS;

    PUSHMARK (SP);

    va_start( args, num );
 
    for( ; num > 0; num-- ) {
      XPUSHs (va_arg( args, SV* ));
    }
 
    va_end( args );

    PUTBACK;

    count = call_pv (func, G_SCALAR);

    SPAGAIN;

    if (count != 1) {
        croak ("method didn't return a value");
    }

    ret = POPs;
    SvREFCNT_inc (ret);

    PUTBACK;
    FREETMPS;
    LEAVE;

    return ret;
}


void
perl_mongo_attach_ptr_to_instance (SV *self, void *ptr)
{
    sv_magic (SvRV (self), 0, PERL_MAGIC_ext, (const char *)ptr, 0);
}

void *
perl_mongo_get_ptr_from_instance (SV *self)
{
    MAGIC *mg;

    if (!self || !SvOK (self) || !SvROK (self)
     || !(mg = mg_find (SvRV (self), PERL_MAGIC_ext))) {
        croak ("invalid object");
    }

    return mg->mg_ptr;
}

SV *
perl_mongo_construct_instance (const char *klass, ...)
{
    SV *ret;
    va_list ap;
    va_start (ap, klass);
    ret = perl_mongo_construct_instance_va (klass, ap);
    va_end(ap);
    return ret;
}

SV *
perl_mongo_construct_instance_va (const char *klass, va_list ap)
{
    dSP;
    SV *ret;
    I32 count;
    char *init_arg;

    ENTER;
    SAVETMPS;

    PUSHMARK (SP);
    mXPUSHp (klass, strlen (klass));
    while ((init_arg = va_arg (ap, char *))) {
        mXPUSHp (init_arg, strlen (init_arg));
        XPUSHs (va_arg (ap, SV *));
    }
    PUTBACK;

    count = call_method ("new", G_SCALAR);

    SPAGAIN;

    if (count != 1) {
        croak ("constructor didn't return an instance");
    }

    ret = POPs;
    SvREFCNT_inc (ret);

    PUTBACK;
    FREETMPS;
    LEAVE;

    return ret;
}

SV *
perl_mongo_construct_instance_with_magic (const char *klass, void *ptr, ...)
{
    SV *ret;
    va_list ap;

    va_start (ap, ptr);
    ret = perl_mongo_construct_instance_va (klass, ap);
    va_end (ap);

    perl_mongo_attach_ptr_to_instance (ret, ptr);

    return ret;
}

static SV *bson_to_av (buffer *buf);

void perl_mongo_make_oid(char *twelve, char *twenty4) {
  int i;
  char *id_str = twelve;
  char *movable = twenty4;

  for(i=0; i<12; i++) {
    int x = *id_str;
    if (*id_str < 0) {
      x = 256 + *id_str;
    }
    sprintf(movable, "%02x", x);
    movable += 2;
    id_str++;
  }
  twenty4[24] = '\0';
}

static SV *
oid_to_sv (buffer *buf)
{
    HV *stash, *id_hv;
    char oid_s[25];
    perl_mongo_make_oid(buf->pos, oid_s);

    id_hv = newHV();
    hv_store(id_hv, "value", strlen("value"), newSVpvn(oid_s, 24), 0);

    stash = gv_stashpv("AnyMongo::BSON::OID", 0);
    return sv_bless(newRV_noinc((SV *)id_hv), stash);
}

static SV *
elem_to_sv (int type, buffer *buf)
{
  SV *value = 0;
  
  SV *flag = get_sv("AnyMongo::BSON::utf8_flag_on", 0);

  switch(type) {
  case BSON_OID: {
    value = oid_to_sv(buf);
    buf->pos += OID_SIZE;
    break;
  }
  case BSON_DOUBLE: {
    double d = *(double*)buf->pos;
    int64_t i, *i_p;
    i_p = &i;

    memcpy(i_p, &d, DOUBLE_64);
    i = MONGO_64(i);
    memcpy(&d, i_p, DOUBLE_64);
 
    value = newSVnv(d);
    buf->pos += DOUBLE_64;
    break;
  }
  case BSON_SYMBOL:
  case BSON_STRING: {
    int len = MONGO_32(*((int*)buf->pos));
    buf->pos += INT_32;

    // this makes a copy of the buffer
    // len includes \0
    value = newSVpvn(buf->pos, len-1);
    
    if (!flag || !SvIOK(flag) || SvIV(flag) != 0) {
      SvUTF8_on(value);
    }

    buf->pos += len; 
    break;
  }
  case BSON_OBJECT: {
    value = perl_mongo_bson_to_sv(buf);
    break;
  }
  case BSON_ARRAY: {
    value = bson_to_av(buf);
    break;
  }
  case BSON_BINARY: {
    int len = MONGO_32(*(int*)buf->pos);
    char type;

    buf->pos += INT_32;

    // we should do something with type
    type = *buf->pos++;

    if (type == 2) {
      int len2 = MONGO_32(*(int*)buf->pos);
      if (len2 == len - 4) {
        len = len2;
        buf->pos += INT_32;
      }
    }

    value = newSVpvn(buf->pos, len);
    buf->pos += len;

    break;
  }
  case BSON_BOOL: {
    dSP;
    char d = *buf->pos++;
    int count;
    SV *use_bool = get_sv("AnyMongo::BSON::use_boolean", 0);

    if (!use_bool) {
      value = newSViv(d);
      break;
    }

    SAVETMPS;
    
    PUSHMARK(SP);
    PUTBACK;
    if (d) {
        count = call_pv("boolean::true", G_SCALAR);
    }
    else {
        count = call_pv("boolean::false", G_SCALAR);
    }
    SPAGAIN;
    if (count == 1)
        value = newSVsv(POPs);
    
    if (count != 1 || !SvOK(value)) {
        value = newSViv(d);
    }
    
    PUTBACK;
    FREETMPS;
    break;
  }
  case BSON_UNDEF:
  case BSON_NULL: {
    value = newSV(0);
    break;
  }
  case BSON_INT: {
    value = newSViv(MONGO_32(*((int*)buf->pos)));
    buf->pos += INT_32;
    break;
  }
  case BSON_LONG: {
#if defined(USE_64_BIT_INT)
    value = newSViv(MONGO_64(*((int64_t*)buf->pos)));
#else
    value = newSVnv((double)MONGO_64(*((int64_t*)buf->pos)));
#endif
    buf->pos += INT_64;
    break;
  }
  case BSON_DATE: {
    int64_t ms_i = MONGO_64(*(int64_t*)buf->pos);
    SV *datetime, *ms, **heval;
    HV *named_params;
    buf->pos += INT_64;
    ms_i /= 1000;

    datetime = sv_2mortal(newSVpv("DateTime", 0));
    ms = newSViv(ms_i);

    named_params = newHV();
    heval = hv_store(named_params, "epoch", strlen("epoch"), ms, 0);

    value = perl_mongo_call_function("DateTime::from_epoch", 2, datetime, 
                                     sv_2mortal(newRV_inc(sv_2mortal((SV*)named_params))));
    break;
  }
  case BSON_REGEX: {
    SV *pattern, *regex, *regex_ref;
    HV *stash;
    U32 flags = 0;
    REGEXP *re;
#if PERL_REVISION==5 && PERL_VERSION<=8
    PMOP pm;
    STRLEN len;
    char *pat;
#endif

    pattern = sv_2mortal(newSVpv(buf->pos, 0));
    buf->pos += strlen(buf->pos)+1;

    while(*(buf->pos) != 0) {
      switch(*(buf->pos)) {
      case 'l':
        flags |= PMf_LOCALE;
        break;
      case 'm':
        flags |= PMf_MULTILINE;
        break;
      case 'i':
        flags |= PMf_FOLD;
        break;
      case 'x':
        flags |= PMf_EXTENDED;
        break;
      case 's':
        flags |= PMf_SINGLELINE;
        break;
      }
      buf->pos++;
    }
    buf->pos++;

#if PERL_REVISION==5 && PERL_VERSION<=8
    /* 5.8 */
    pm.op_pmdynflags = flags;
    pat = SvPV(pattern, len);
    re = pregcomp(pat, pat + len, &pm);
#else
    /* 5.10 and beyond */
    re = re_compile(pattern, flags);
#endif
     // eo version-dependent code

#if PERL_REVISION==5 && PERL_VERSION>=12
    // they removed magic and made this a normal obj in 5.12
    regex_ref = newRV((SV*)re);
#else
    regex = sv_2mortal(newSVpv("",0));
    regex_ref = newRV((SV*)regex);

    sv_magic(regex, (SV*)re, PERL_MAGIC_qr, 0, 0);
#endif

    stash = gv_stashpv("Regexp", 0);
    sv_bless(regex_ref, stash);

    value = regex_ref;
    break;
  }
  case BSON_CODE:
  case BSON_CODE__D: {
    SV *code, *scope;
    int code_len;

    if (type == BSON_CODE) {
      buf->pos += INT_32;
    }

    code_len = MONGO_32(*(int*)buf->pos);
    buf->pos += INT_32;

    code = sv_2mortal(newSVpvn(buf->pos, code_len-1));
    buf->pos += code_len;

    if (type == BSON_CODE) {
      scope = perl_mongo_bson_to_sv(buf);

      value = perl_mongo_construct_instance("AnyMongo::BSON::Code", "code", code, "scope", scope, NULL);
    }
    else {
      value = perl_mongo_construct_instance("AnyMongo::BSON::Code", "code", code, NULL);
    }

    break;
  }
  case BSON_TIMESTAMP: {
    SV *sec_sv, *inc_sv;
    int sec, inc;
    HV *hv = newHV();

    inc = MONGO_32(*(int*)buf->pos);
    buf->pos += INT_32;
    sec = MONGO_32(*(int*)buf->pos);
    buf->pos += INT_32;

    sec_sv = sv_2mortal(newSViv(sec));
    inc_sv = sv_2mortal(newSViv(inc));

    value = perl_mongo_construct_instance("AnyMongo::BSON::Timestamp", "sec", sec_sv, "inc", inc_sv, NULL);
    break;
  }
  case BSON_MINKEY: {
      // warn("BSON_MINKEY +++");
    HV *stash = gv_stashpv("AnyMongo::BSON::MinKey", GV_ADD);
        // warn("BSON_MINKEY ---");
    value = sv_bless(newRV((SV*)newHV()), stash);
        // warn("BSON_MINKEY ===");
    break;
  }
  case BSON_MAXKEY: {
      // warn("BSON_MAXKEY +++");
    HV *stash = gv_stashpv("AnyMongo::BSON::MaxKey", GV_ADD);
    // warn("BSON_MINKEY ---");
    value = sv_bless(newRV((SV*)newHV()), stash);
    // warn("BSON_MINKEY ===");
    break;
  }
  default: {
    croak("type %d not supported\n", type);
    // give up, it'll be trouble if we keep going
  }
  }
  return value;
}

static SV *
bson_to_av (buffer *buf)
{
    AV *ret = newAV ();

    char type;

    // for size
    buf->pos += INT_32;
  
    while ((type = *buf->pos++) != 0) {
      SV *sv;
    
      // get past field name
      buf->pos += strlen(buf->pos) + 1;

      // get value
      if ((sv = elem_to_sv (type, buf))) {
        av_push (ret, sv);
      }
    }

    return newRV_noinc ((SV *)ret);
}

SV *
perl_mongo_bson_to_sv (buffer *buf)
{
    HV *ret = newHV();

    char type;

    // for size
    buf->pos += INT_32;
  
    // warn("perl_mongo_bson_to_sv before while");
    int i=0;
    while ((type = *buf->pos++) != 0) {
      char *name;
      SV *value;
    
      name = buf->pos;
      // get past field name
      buf->pos += strlen(buf->pos) + 1;
      // warn("elem_to_sv BEGIN %d",i);

      // get value
      value = elem_to_sv(type, buf);
      // warn("elem_to_sv END %d",i++);
      
      if (!hv_store (ret, name, strlen (name), value, 0)) {
        croak ("failed storing value in hash");
      }
    }
    

    return newRV_noinc ((SV *)ret);
}

int perl_mongo_resize_buf(buffer *buf, int size) {
  int total = buf->end - buf->start;
  int used = buf->pos - buf->start;

  total = total < GROW_SLOWLY ? total*2 : total+INITIAL_BUF_SIZE;
  while (total-used < size) {
    total += size;
  }

  Renew(buf->start, total, char);
  buf->pos = buf->start + used;
  buf->end = buf->start + total;
  return total;
}

void perl_mongo_serialize_byte(buffer *buf, char b) {
  if(BUF_REMAINING <= 1) {
    perl_mongo_resize_buf(buf, 1);
  }
  *(buf->pos) = b;
  buf->pos += 1;
}

void perl_mongo_serialize_bytes(buffer *buf, const char *str, int str_len) {
  if(BUF_REMAINING <= str_len) {
    perl_mongo_resize_buf(buf, str_len);
  }
  memcpy(buf->pos, str, str_len);
  buf->pos += str_len;
}

void perl_mongo_serialize_string(buffer *buf, const char *str, int str_len) {
  if(BUF_REMAINING <= str_len+1) {
    perl_mongo_resize_buf(buf, str_len+1);
  }

  memcpy(buf->pos, str, str_len);
  // add \0 at the end of the string
  buf->pos[str_len] = 0;
  buf->pos += str_len + 1;
}

void perl_mongo_serialize_int(buffer *buf, int num) {
  int i = MONGO_32(num);

  if(BUF_REMAINING <= INT_32) {
    perl_mongo_resize_buf(buf, INT_32);
  }

  memcpy(buf->pos, &i, INT_32);
  buf->pos += INT_32;
}

void perl_mongo_serialize_long(buffer *buf, int64_t num) {
  int64_t i = MONGO_64(num);

  if(BUF_REMAINING <= INT_64) {
    perl_mongo_resize_buf(buf, INT_64);
  }

  memcpy(buf->pos, &i, INT_64);
  buf->pos += INT_64;
}

void perl_mongo_serialize_double(buffer *buf, double num) {
  int64_t dest, *dest_p;
  dest_p = &dest;
  memcpy(dest_p, &num, 8);
  dest = MONGO_64(dest);
 
  if(BUF_REMAINING <= DOUBLE_64) {
    perl_mongo_resize_buf(buf, DOUBLE_64);
  }
 
  memcpy(buf->pos, dest_p, DOUBLE_64);
  buf->pos += DOUBLE_64;
}

void perl_mongo_serialize_oid(buffer *buf, char *id) {
  int i;

  if(BUF_REMAINING <= OID_SIZE) {
    perl_mongo_resize_buf(buf, OID_SIZE);
  }

  for(i=0;i<OID_SIZE;i++) {
    char digit1 = id[i*2], digit2 = id[i*2+1];
    digit1 = digit1 >= 'a' && digit1 <= 'f' ? digit1 - 87 : digit1;
    digit1 = digit1 >= 'A' && digit1 <= 'F' ? digit1 - 55 : digit1;
    digit1 = digit1 >= '0' && digit1 <= '9' ? digit1 - 48 : digit1;

    digit2 = digit2 >= 'a' && digit2 <= 'f' ? digit2 - 87 : digit2;
    digit2 = digit2 >= 'A' && digit2 <= 'F' ? digit2 - 55 : digit2;
    digit2 = digit2 >= '0' && digit2 <= '9' ? digit2 - 48 : digit2;

    buf->pos[i] = digit1*16+digit2;
  }
  buf->pos += OID_SIZE;
}

void perl_mongo_serialize_bindata(buffer *buf, SV *sv)
{
  STRLEN len;
  const char *bytes = SvPVbyte (sv, len);

  // length of length+bindata
  perl_mongo_serialize_int(buf, len+4);
  
  // TODO: type
  perl_mongo_serialize_byte(buf, 2);
  
  // length
  perl_mongo_serialize_int(buf, len);
  // bindata
  perl_mongo_serialize_bytes(buf, bytes, len);
}

void perl_mongo_serialize_key(buffer *buf, const char *str, int is_insert) {
  SV *c = get_sv("AnyMongo::BSON::char", 0);

  if(BUF_REMAINING <= strlen(str)+1) {
    perl_mongo_resize_buf(buf, strlen(str)+1);
  }

  if (strlen(str) == 0) {
      croak("empty key name, did you use a $ with double quotes?");
  }

  if (is_insert && strchr(str, '.')) {
      croak("inserts cannot contain the . character");
  }

  if (c && SvPOK(c) && SvPV_nolen(c)[0] == str[0]) {
    *(buf->pos) = '$';
    memcpy(buf->pos+1, str+1, strlen(str)-1);
  }
  else {
    memcpy(buf->pos, str, strlen(str));
  }

  // add \0 at the end of the string
  buf->pos[strlen(str)] = 0;
  buf->pos += strlen(str) + 1;
}


/* the position is not increased, we are just filling
 * in the first 4 bytes with the size.
 */
void perl_mongo_serialize_size(char *start, buffer *buf) {
  int total = buf->pos - start;
  total = MONGO_32(total);

  memcpy(start, &total, INT_32);
}

void perl_mongo_make_id(char *id) {
  //SV *temp;
  char *data = id;

  // the pid is stored in $$
  SV *pid_s = get_sv("$", 0);
  // ...but if it's not, don't crash
  int pid = pid_s ? SvIV(pid_s) : rand();

  int r1 = rand();
  int inc = perl_mongo_inc++;

  unsigned t = (unsigned) time(0);

  char *T = (char*)&t,
    *M = (char*)&r1,
    *P = (char*)&pid,
    *I = (char*)&inc;

#if MONGO_BIG_ENDIAN
  memcpy(data, T, 4);
  memcpy(data+4, M+1, 3);
  memcpy(data+7, P+2, 2);
  memcpy(data+9, I+1, 3);
#else
  data[0] = T[3];
  data[1] = T[2];
  data[2] = T[1];
  data[3] = T[0];

  memcpy(data+4, M, 3);
  memcpy(data+7, P, 2);
  memcpy(data+9, I, 3);
#endif
}


/* add an _id */
static void
perl_mongo_prep(buffer *buf, AV *ids) {
  //  SV *id = perl_mongo_construct_instance ("MongoDB::OID", NULL);
  SV *id;
  HV *id_hv, *stash;
  char id_s[12], oid_s[25];

  stash = gv_stashpv("AnyMongo::BSON::OID", 0);

  perl_mongo_make_id(id_s);
  set_type(buf, BSON_OID);
  perl_mongo_serialize_key(buf, "_id", 0);
  perl_mongo_serialize_bytes(buf, id_s, 12);

  perl_mongo_make_oid(id_s, oid_s);
  id_hv = newHV();
  hv_store(id_hv, "value", strlen("value"), newSVpvn(oid_s, 24), 0);

  id = sv_bless(newRV_noinc((SV *)id_hv), stash);

  av_push(ids, id);
}

/**
 * checks if a ptr has been parsed already and, if not, adds it to the stack. If
 * we do have a circular ref, this function returns 0.
 */
static stackette* check_circular_ref(void *ptr, stackette *stack) {
  stackette *ette, *start = stack;

  while (stack) {
    if (ptr == stack->ptr) {
      return 0;
    }
    stack = stack->prev;
  }

  // push this onto the circular ref stack
  New(0, ette, 1, stackette);
  ette->ptr = ptr;
  // if stack has not been initialized, stack will be 0 so this will work out
  ette->prev = start;

  return ette;
}

static void
hv_to_bson (buffer *buf, SV *sv, AV *ids, stackette *stack, int is_insert)
{
    int start;
    HE *he;
    HV *hv;

    /* keep a record of the starting position
     * as an offset, in case the memory is resized */
    start = buf->pos-buf->start;

    /* skip first 4 bytes to leave room for size */
    buf->pos += INT_32;

    if (!SvROK(sv)) {
        perl_mongo_serialize_null(buf);
        perl_mongo_serialize_size(buf->start+start, buf);
        return;
    }

    hv = (HV*)SvRV(sv);
    if (!(stack = check_circular_ref(hv, stack))) {
        Safefree(buf->start);
        croak("circular ref");
    }

    if (ids) {
        if(hv_exists(hv, "_id", strlen("_id"))) {
            SV **id = hv_fetch(hv, "_id", strlen("_id"), 0);
            append_sv(buf, "_id", *id, stack, is_insert);
            SvREFCNT_inc(*id);
            av_push(ids, *id);
        }
        else {
            perl_mongo_prep(buf, ids);
        }
    }


    (void)hv_iterinit (hv);
    while ((he = hv_iternext (hv))) {
        SV **hval;
        STRLEN len;
        const char *key = HePV (he, len);

        /* if we've already added the oid field, continue */
        if (ids && strcmp(key, "_id") == 0) {
            continue;
        }

        /* 
         * HeVAL doesn't return the correct value for tie(%foo, 'Tie::IxHash')
         * so we're using hv_fetch
         */
        hval = hv_fetch(hv, key, len, 0);
        append_sv (buf, key, *hval, stack, is_insert);
    }

    perl_mongo_serialize_null(buf);
    perl_mongo_serialize_size(buf->start+start, buf);

    // free the hv elem
    Safefree(stack);
}

static void
av_to_bson (buffer *buf, AV *av, stackette *stack, int is_insert)
{
    I32 i;
    int start;

    if (!(stack = check_circular_ref(av, stack))) {
        Safefree(buf->start);
        croak("circular ref");
    }

    start = buf->pos-buf->start;
    buf->pos += INT_32;

    for (i = 0; i <= av_len (av); i++) {
        SV **sv;
        SV *key = newSViv (i);
        if (!(sv = av_fetch (av, i, 0)))
            append_sv (buf, SvPV_nolen(key), newSV(0), stack, is_insert);
        else
            append_sv (buf, SvPV_nolen(key), *sv, stack, is_insert);

        SvREFCNT_dec (key);
    }

    perl_mongo_serialize_null(buf);
    perl_mongo_serialize_size(buf->start+start, buf);

    // free the av elem
    Safefree(stack);
}

static void
ixhash_to_bson(buffer *buf, SV *sv, AV *ids, stackette *stack, int is_insert) {
    int start, i;
    SV **keys_sv, **values_sv;
    AV *array, *keys, *values;
    
    /* skip 4 bytes for size */
    start = buf->pos-buf->start;
    buf->pos += INT_32;
    
    /*
     * a Tie::IxHash is of the form:
     * [ {hash}, [keys], [order], 0 ]
     */
    array = (AV*)SvRV(sv);

    // check if we're in an infinite loop
    if (!(stack = check_circular_ref(array, stack))) {
      Safefree(buf->start);
      croak("circular ref");
    }

    /* keys in order, from position 1 */
    keys_sv = av_fetch(array, 1, 0);
    keys = (AV*)SvRV(*keys_sv);

    /* values in order, from position 2 */
    values_sv = av_fetch(array, 2, 0);
    values = (AV*)SvRV(*values_sv);

    if (ids) {
      /* check if the hash in position 0 contains an _id */
      SV **hash_sv = av_fetch(array, 0, 0);
      if (hv_exists((HV*)SvRV(*hash_sv), "_id", strlen("_id"))) {
        /*
         * if so, the value of the _id key is its index
         * in the values array.
         */
        SV **index = hv_fetch((HV*)SvRV(*hash_sv), "_id", strlen("_id"), 0);
        SV **id = av_fetch(values, SvIV(*index), 0);
        /*
         * add it to the bson and the ids array
         */
        append_sv(buf, "_id", *id, stack, is_insert);
        av_push(ids, *id);
      }
      else {
        perl_mongo_prep(buf, ids);
      }
    }
    
    for (i=0; i<=av_len(keys); i++) {
        SV **k, **v;
        STRLEN len;
        const char *str;

        if (!(k = av_fetch(keys, i, 0)) ||
            !(v = av_fetch(values, i, 0))) {
            croak ("failed to fetch associative array value");
        }

        str = SvPV(*k, len);

        if (isUTF8(str, len)) {
          str = SvPVutf8(*k, len);
        }

        append_sv(buf, str, *v, stack, is_insert);
    }

    perl_mongo_serialize_null(buf);
    perl_mongo_serialize_size(buf->start+start, buf);

    // free the ixhash elem
    Safefree(stack);
}

static int isUTF8(const char *s, int len) {
  int i;

  for (i=0; i<len; i++) {
    if (i+3 < len &&
        (s[i] & 248) == 240 &&
        (s[i+1] & 192) == 128 &&
        (s[i+2] & 192) == 128 &&
        (s[i+3] & 192) == 128) {
      i += 3;
    }
    else if (i+2 < len && 
             (s[i] & 240) == 224 &&
             (s[i+1] & 192) == 128 &&
             (s[i+2] & 192) == 128) {
      i += 2;
    }
    else if (i+1 < len &&
             (s[i] & 224) == 192 &&
             (s[i+1] & 192) == 128) {
      i += 1;
    }
    else if ((s[i] & 128) != 0) {
      return 0;
    }
  }
  return 1;
}


static void
append_sv (buffer *buf, const char *key, SV *sv, stackette *stack, int is_insert)
{
    if (!SvOK(sv)) {
      if (SvGMAGICAL(sv)) {
        mg_get(sv);
      }
      else {
        set_type(buf, BSON_NULL);
        perl_mongo_serialize_key(buf, key, is_insert);
        return;
      }
    }

    if (SvROK (sv)) {
        if (sv_isobject (sv)) {
            /* OIDs */
            if (sv_derived_from (sv, "AnyMongo::BSON::OID")) {
                SV *attr = perl_mongo_call_reader (sv, "value");
                char *str = SvPV_nolen (attr);

                set_type(buf, BSON_OID);
                perl_mongo_serialize_key(buf, key, is_insert);
                perl_mongo_serialize_oid(buf, str);

                SvREFCNT_dec (attr);
            }
            /* 64-bit integers */
            else if (sv_isa(sv, "Math::BigInt")) {
              int64_t big = 0, offset = 1;
              int i = 0, length = 0, sign = 1;
              SV **av_ref, **sign_ref;
              AV *av;
 
              set_type(buf, BSON_LONG);
              perl_mongo_serialize_key(buf, key, is_insert);

              // get sign
              sign_ref = hv_fetch((HV*)SvRV(sv), "sign", strlen("sign"), 0);
              if (!sign_ref) {
                croak( "couldn't get BigInt sign" );
              }
              else if ( SvPOK(*sign_ref) && strcmp(SvPV_nolen( *sign_ref ), "-") == 0 ) {
                sign = -1;
              }

              // get value
              av_ref = hv_fetch((HV*)SvRV(sv), "value", strlen("value"), 0);
              if (!av_ref) {
                croak( "couldn't get BigInt value" );
              }

              av = (AV*)SvRV(*av_ref);

              if ( av_len( av ) > 3 ) {
                croak( "BigInt is too large" );
              }

              for (i = 0; i <= av_len( av ); i++) {
                int j = 0;
                SV **val;
                
                if ( !(val = av_fetch (av, i, 0)) || !(SvPOK(*val) || SvIOK(*val)) ) {
                  sv_dump( sv );
                  croak ("failed to fetch BigInt element");
                }

                if ( SvIOK(*val) ) {
                  int64_t temp = SvIV(*val);

                  while (temp > 0) {
                    temp = temp / 10;
                    length++;
                  }

                  temp = (int64_t)(((int64_t)SvIV(*val)) * (int64_t)offset);
                  big = big + temp;
                }
                else {
                  STRLEN len;
                  char *str = SvPV(*val, len);

                  length += len;
                  big += ((int64_t)atoi(SvPV_nolen(*val))) * offset;
                }

                for (j = 0; j < length; j++) {
                  offset *= 10;
                }
              }

              perl_mongo_serialize_long(buf, big*sign);
            }
	    /* Tie::IxHash */
            else if (sv_isa(sv, "Tie::IxHash")) {
              set_type(buf, BSON_OBJECT);
              perl_mongo_serialize_key(buf, key, is_insert);
              ixhash_to_bson(buf, sv, NO_PREP, stack, is_insert);
            }
	    /* DateTime */
            else if (sv_isa(sv, "DateTime")) {
              SV *sec, *ms;
              set_type(buf, BSON_DATE);
              perl_mongo_serialize_key(buf, key, is_insert);
              sec = perl_mongo_call_reader (sv, "epoch");
              ms = perl_mongo_call_method (sv, "millisecond", 0);

              perl_mongo_serialize_long(buf, (int64_t)SvIV(sec)*1000+SvIV(ms));

              SvREFCNT_dec (sec);
              SvREFCNT_dec (ms);
            }
	    /* boolean */
            else if (sv_isa(sv, "boolean")) {
              set_type(buf, BSON_BOOL);
              perl_mongo_serialize_key(buf, key, is_insert);
              perl_mongo_serialize_byte(buf, SvIV(SvRV(sv)));
            }
            else if (sv_isa(sv, "AnyMongo::BSON::Code") || sv_derived_from(sv,"AnyMongo::BSON::Code")) {
              SV *code, *scope;
              char *code_str;
              STRLEN code_len;
              int start;

              set_type(buf, BSON_CODE);
              perl_mongo_serialize_key(buf, key, is_insert);

              start = buf->pos-buf->start;
              buf->pos += INT_32;

              code = perl_mongo_call_reader (sv, "code");
              code_str = SvPV(code, code_len);
              perl_mongo_serialize_int(buf, code_len+1);
              perl_mongo_serialize_string(buf, code_str, code_len);

              scope = perl_mongo_call_method (sv, "scope", 0);
              hv_to_bson(buf, scope, NO_PREP, EMPTY_STACK, is_insert);

              perl_mongo_serialize_size(buf->start+start, buf);

              SvREFCNT_dec(code);
              SvREFCNT_dec(scope);
            }
            else if (sv_isa(sv, "AnyMongo::BSON::Timestamp") || sv_derived_from(sv,"AnyMongo::BSON::Timestamp")) {
              SV *sec, *inc;
              set_type(buf, BSON_TIMESTAMP);
              perl_mongo_serialize_key(buf, key, is_insert);
              
              inc = perl_mongo_call_reader(sv, "inc");
              perl_mongo_serialize_int(buf, SvIV(inc));
              sec = perl_mongo_call_reader(sv, "sec");
              perl_mongo_serialize_int(buf, SvIV(sec));

              SvREFCNT_dec(sec);
              SvREFCNT_dec(inc);
            }
            else if (sv_isa(sv, "AnyMongo::BSON::MinKey") || sv_isa(sv, "MongoDB::MinKey")) {
              set_type(buf, BSON_MINKEY);
              perl_mongo_serialize_key(buf, key, is_insert);
            }
            else if (sv_isa(sv, "AnyMongo::BSON::MaxKey") || sv_isa(sv, "MongoDB::MaxKey")) {
              set_type(buf, BSON_MAXKEY);
              perl_mongo_serialize_key(buf, key, is_insert);
            }
#if PERL_REVISION==5 && PERL_VERSION>=12
            // Perl 5.12 regexes
            else if (sv_isa(sv, "Regexp")) {
              REGEXP * re = SvRX(sv);
              
              serialize_regex(buf, key, re, is_insert);
              serialize_regex_flags(buf, sv);
            }
#endif
            else if (SvTYPE(SvRV(sv)) == SVt_PVMG) {

              MAGIC *remg;

              /* regular expression */
              if ((remg = mg_find((SV*)SvRV(sv), PERL_MAGIC_qr)) != 0) {
                REGEXP *re = (REGEXP *) remg->mg_obj;

                serialize_regex(buf, key, re, is_insert);
                serialize_regex_flags(buf, sv);                
              }
              else {
		/* binary */
                set_type(buf, BSON_BINARY);
                perl_mongo_serialize_key(buf, key, is_insert);
                perl_mongo_serialize_bindata(buf, SvRV(sv));
              }
            }
        } else {
            switch (SvTYPE (SvRV (sv))) {
                case SVt_PVHV:
                    /* hash */
                    set_type(buf, BSON_OBJECT);
                    perl_mongo_serialize_key(buf, key, is_insert);
                    /* don't add a _id to inner objs */
                    hv_to_bson (buf, sv, NO_PREP, stack, is_insert);
                    break;
                case SVt_PVAV:
                    /* array */
                    set_type(buf, BSON_ARRAY);
                    perl_mongo_serialize_key(buf, key, is_insert);
                    av_to_bson (buf, (AV *)SvRV (sv), stack, is_insert);
                    break;
                case SVt_PV:
                    /* binary */
                    set_type(buf, BSON_BINARY);
                    perl_mongo_serialize_key(buf, key, is_insert);
                    perl_mongo_serialize_bindata(buf, SvRV(sv));
                    break;
                default:
                    sv_dump(SvRV(sv));
                    croak ("type (ref) unhandled");
            }
        }
    } else {
        switch (SvTYPE (sv)) {
	    /* double */
            case SVt_NV: 
            case SVt_PVNV: {
              if (SvNOK(sv)) {
                set_type(buf, BSON_DOUBLE);
                perl_mongo_serialize_key(buf, key, is_insert);
                perl_mongo_serialize_double(buf, (double)SvNV (sv));
                break;
              }
            }
            /* int */
            case SVt_IV:
            case SVt_PVIV: 
            case SVt_PVLV:
            case SVt_PVMG: {
              if (SvIOK(sv)) {
#if defined(USE_64_BIT_INT)
                set_type(buf, BSON_LONG);
                perl_mongo_serialize_key(buf, key, is_insert);
                perl_mongo_serialize_long(buf, (int64_t)SvIV(sv));
#else
                set_type(buf, BSON_INT);
                perl_mongo_serialize_key(buf, key, is_insert);
                perl_mongo_serialize_int(buf, (int)SvIV(sv));
#endif
                break;
              }

            }
	    /* string */
            case SVt_PV:
                if (sv_len (sv) != strlen (SvPV_nolen (sv))) {
                    set_type(buf, BSON_BINARY);
                    perl_mongo_serialize_key(buf, key, is_insert);
                    perl_mongo_serialize_bindata(buf, sv);
                }
                else {
                    STRLEN len;
                    const char *str = SvPV(sv, len);

                    if (!isUTF8(str, len)) {
                      str = SvPVutf8(sv, len);
                    }


                    set_type(buf, BSON_STRING);
                    perl_mongo_serialize_key(buf, key, is_insert);
                    perl_mongo_serialize_int(buf, len+1);
                    perl_mongo_serialize_string(buf, str, len);
                }
                break;
            default:
                sv_dump(sv);
                croak ("type (sv) unhandled");
        }
    }
}

static void serialize_regex(buffer *buf, const char *key, REGEXP *re, int is_insert) {
  set_type(buf, BSON_REGEX);
  perl_mongo_serialize_key(buf, key, is_insert);
  perl_mongo_serialize_string(buf, RX_PRECOMP(re), RX_PRELEN(re));
}

static void serialize_regex_flags(buffer *buf, SV *sv) {
  char flags[] = {0,0,0,0,0,0};
  int i = 0, f = 0;
  STRLEN string_length;
  char *string = SvPV(sv, string_length);
                
  for(i = 2; i < string_length && string[i] != '-'; i++) {
    if (string[i] == 'i' ||
        string[i] == 'm' ||
        string[i] == 'x' ||
        string[i] == 'l' ||
        string[i] == 's' ||
        string[i] == 'u') {
      flags[f++] = string[i];
    }
    else if(string[i] == ':') {
      break;
    }
  }

  perl_mongo_serialize_string(buf, flags, strlen(flags));
}


void
perl_mongo_sv_to_bson (buffer *buf, SV *sv, AV *ids)
{
    if (!SvROK (sv)) {
        croak ("not a reference");
    }

    switch (SvTYPE (SvRV (sv))) {
    case SVt_PVHV:
        hv_to_bson (buf, sv, ids, EMPTY_STACK, ids != 0);
        break;
    case SVt_PVAV: {
        if (sv_isa(sv, "Tie::IxHash")) {
            ixhash_to_bson(buf, sv, ids, EMPTY_STACK, ids != 0);
        }
        else {
            /*
             * this is a special case of array:
             * ("foo" => "bar", "baz" => "bat")
             * which is, as far as i can tell,
             * indistinguishable from a "normal"
             * array.
             */

            I32 i;
            AV *av = (AV *)SvRV (sv);
            int start;
            
            if ((av_len (av) % 2) == 0) {
                croak ("odd number of elements in structure");
            }
            
            start = buf->pos-buf->start;
            buf->pos += INT_32;
            
            /* 
             * the best (and not very good) way i can think of for 
             * checking for ids is to go through the array once
             * looking for them... blah
             */
            if (ids) {
                int has_id = 0;
                for (i = 0; i <= av_len(av); i+= 2) {
                    SV **key = av_fetch(av, i, 0);
                    if (strcmp(SvPV_nolen(*key), "_id") == 0) {
                        SV **val = av_fetch(av, i+1, 0);
                        has_id = 1;
                        append_sv(buf, "_id", *val, EMPTY_STACK, ids != 0);
                        av_push(ids, *val);
                        break;
                    }
                }
                if (!has_id) {
                    perl_mongo_prep(buf, ids);
                }
            }

            for (i = 0; i <= av_len (av); i += 2) {
                SV **key, **val;
                STRLEN len;
                const char *str;

                if ( !((key = av_fetch (av, i, 0)) && (val = av_fetch (av, i + 1, 0))) ) {
                    croak ("failed to fetch array element");
                }

                str = SvPV(*key, len);

                if (!isUTF8(str, len)) {
                    str = SvPVutf8(*key, len);
                }
                append_sv (buf, str, *val, EMPTY_STACK, ids != 0);
            }

            perl_mongo_serialize_null(buf);
            perl_mongo_serialize_size(buf->start+start, buf);
        }
        break;
    }
    default:
        sv_dump(sv);
        croak ("type unhandled");
    }
}