marshal.c

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/**********************************************************************

  marshal.c -

  $Author: nagachika $
  created at: Thu Apr 27 16:30:01 JST 1995

  Copyright (C) 1993-2007 Yukihiro Matsumoto

**********************************************************************/

#include "ruby/ruby.h"
#include "ruby/io.h"
#include "ruby/st.h"
#include "ruby/util.h"
#include "ruby/encoding.h"
#include "internal.h"

#include <math.h>
#ifdef HAVE_FLOAT_H
#include <float.h>
#endif
#ifdef HAVE_IEEEFP_H
#include <ieeefp.h>
#endif

#define BITSPERSHORT (2*CHAR_BIT)
#define SHORTMASK ((1<<BITSPERSHORT)-1)
#define SHORTDN(x) RSHIFT((x),BITSPERSHORT)

#if SIZEOF_SHORT == SIZEOF_BDIGITS
#define SHORTLEN(x) (x)
#else
static long
shortlen(long len, BDIGIT *ds)
{
    BDIGIT num;
    int offset = 0;

    num = ds[len-1];
    while (num) {
        num = SHORTDN(num);
        offset++;
    }
    return (len - 1)*sizeof(BDIGIT)/2 + offset;
}
#define SHORTLEN(x) shortlen((x),d)
#endif

#define MARSHAL_MAJOR   4
#define MARSHAL_MINOR   8

#define TYPE_NIL        '0'
#define TYPE_TRUE       'T'
#define TYPE_FALSE      'F'
#define TYPE_FIXNUM     'i'

#define TYPE_EXTENDED   'e'
#define TYPE_UCLASS     'C'
#define TYPE_OBJECT     'o'
#define TYPE_DATA       'd'
#define TYPE_USERDEF    'u'
#define TYPE_USRMARSHAL 'U'
#define TYPE_FLOAT      'f'
#define TYPE_BIGNUM     'l'
#define TYPE_STRING     '"'
#define TYPE_REGEXP     '/'
#define TYPE_ARRAY      '['
#define TYPE_HASH       '{'
#define TYPE_HASH_DEF   '}'
#define TYPE_STRUCT     'S'
#define TYPE_MODULE_OLD 'M'
#define TYPE_CLASS      'c'
#define TYPE_MODULE     'm'

#define TYPE_SYMBOL     ':'
#define TYPE_SYMLINK    ';'

#define TYPE_IVAR       'I'
#define TYPE_LINK       '@'

static ID s_dump, s_load, s_mdump, s_mload;
static ID s_dump_data, s_load_data, s_alloc, s_call;
static ID s_getbyte, s_read, s_write, s_binmode;

typedef struct {
    VALUE newclass;
    VALUE oldclass;
    VALUE (*dumper)(VALUE);
    VALUE (*loader)(VALUE, VALUE);
} marshal_compat_t;

static st_table *compat_allocator_tbl;
static VALUE compat_allocator_tbl_wrapper;

static int
mark_marshal_compat_i(st_data_t key, st_data_t value)
{
    marshal_compat_t *p = (marshal_compat_t *)value;
    rb_gc_mark(p->newclass);
    rb_gc_mark(p->oldclass);
    return ST_CONTINUE;
}

static void
mark_marshal_compat_t(void *tbl)
{
    if (!tbl) return;
    st_foreach(tbl, mark_marshal_compat_i, 0);
}

void
rb_marshal_define_compat(VALUE newclass, VALUE oldclass, VALUE (*dumper)(VALUE), VALUE (*loader)(VALUE, VALUE))
{
    marshal_compat_t *compat;
    rb_alloc_func_t allocator = rb_get_alloc_func(newclass);

    if (!allocator) {
        rb_raise(rb_eTypeError, "no allocator");
    }

    compat = ALLOC(marshal_compat_t);
    compat->newclass = Qnil;
    compat->oldclass = Qnil;
    compat->newclass = newclass;
    compat->oldclass = oldclass;
    compat->dumper = dumper;
    compat->loader = loader;

    st_insert(compat_allocator_tbl, (st_data_t)allocator, (st_data_t)compat);
}

#define MARSHAL_INFECTION (FL_TAINT|FL_UNTRUSTED)
typedef char ruby_check_marshal_viral_flags[MARSHAL_INFECTION == (int)MARSHAL_INFECTION ? 1 : -1];

struct dump_arg {
    VALUE str, dest;
    st_table *symbols;
    st_table *data;
    st_table *compat_tbl;
    st_table *encodings;
    int infection;
};

struct dump_call_arg {
    VALUE obj;
    struct dump_arg *arg;
    int limit;
};

static void
check_dump_arg(struct dump_arg *arg, ID sym)
{
    if (!arg->symbols) {
        rb_raise(rb_eRuntimeError, "Marshal.dump reentered at %s",
                 rb_id2name(sym));
    }
}

static void clear_dump_arg(struct dump_arg *arg);

static void
mark_dump_arg(void *ptr)
{
    struct dump_arg *p = ptr;
    if (!p->symbols)
        return;
    rb_mark_set(p->data);
    rb_mark_hash(p->compat_tbl);
    rb_gc_mark(p->str);
}

static void
free_dump_arg(void *ptr)
{
    clear_dump_arg(ptr);
    xfree(ptr);
}

static size_t
memsize_dump_arg(const void *ptr)
{
    return ptr ? sizeof(struct dump_arg) : 0;
}

static const rb_data_type_t dump_arg_data = {
    "dump_arg",
    {mark_dump_arg, free_dump_arg, memsize_dump_arg,},
};

static const char *
must_not_be_anonymous(const char *type, VALUE path)
{
    char *n = RSTRING_PTR(path);

    if (!rb_enc_asciicompat(rb_enc_get(path))) {
        /* cannot occur? */
        rb_raise(rb_eTypeError, "can't dump non-ascii %s name", type);
    }
    if (n[0] == '#') {
        rb_raise(rb_eTypeError, "can't dump anonymous %s %.*s", type,
                 (int)RSTRING_LEN(path), n);
    }
    return n;
}

static VALUE
class2path(VALUE klass)
{
    VALUE path = rb_class_path(klass);
    const char *n;

    n = must_not_be_anonymous((RB_TYPE_P(klass, T_CLASS) ? "class" : "module"), path);
    if (rb_path_to_class(path) != rb_class_real(klass)) {
        rb_raise(rb_eTypeError, "%s can't be referred to", n);
    }
    return path;
}

static void w_long(long, struct dump_arg*);
static void w_encoding(VALUE obj, long num, struct dump_call_arg *arg);

static void
w_nbyte(const char *s, long n, struct dump_arg *arg)
{
    VALUE buf = arg->str;
    rb_str_buf_cat(buf, s, n);
    RBASIC(buf)->flags |= arg->infection;
    if (arg->dest && RSTRING_LEN(buf) >= BUFSIZ) {
        rb_io_write(arg->dest, buf);
        rb_str_resize(buf, 0);
    }
}

static void
w_byte(char c, struct dump_arg *arg)
{
    w_nbyte(&c, 1, arg);
}

static void
w_bytes(const char *s, long n, struct dump_arg *arg)
{
    w_long(n, arg);
    w_nbyte(s, n, arg);
}

#define w_cstr(s, arg) w_bytes((s), strlen(s), (arg))

static void
w_short(int x, struct dump_arg *arg)
{
    w_byte((char)((x >> 0) & 0xff), arg);
    w_byte((char)((x >> 8) & 0xff), arg);
}

static void
w_long(long x, struct dump_arg *arg)
{
    char buf[sizeof(long)+1];
    int i, len = 0;

#if SIZEOF_LONG > 4
    if (!(RSHIFT(x, 31) == 0 || RSHIFT(x, 31) == -1)) {
        /* big long does not fit in 4 bytes */
        rb_raise(rb_eTypeError, "long too big to dump");
    }
#endif

    if (x == 0) {
        w_byte(0, arg);
        return;
    }
    if (0 < x && x < 123) {
        w_byte((char)(x + 5), arg);
        return;
    }
    if (-124 < x && x < 0) {
        w_byte((char)((x - 5)&0xff), arg);
        return;
    }
    for (i=1;i<(int)sizeof(long)+1;i++) {
        buf[i] = (char)(x & 0xff);
        x = RSHIFT(x,8);
        if (x == 0) {
            buf[0] = i;
            break;
        }
        if (x == -1) {
            buf[0] = -i;
            break;
        }
    }
    len = i;
    for (i=0;i<=len;i++) {
        w_byte(buf[i], arg);
    }
}

#ifdef DBL_MANT_DIG
#define DECIMAL_MANT (53-16)    /* from IEEE754 double precision */

#if DBL_MANT_DIG > 32
#define MANT_BITS 32
#elif DBL_MANT_DIG > 24
#define MANT_BITS 24
#elif DBL_MANT_DIG > 16
#define MANT_BITS 16
#else
#define MANT_BITS 8
#endif

static double
load_mantissa(double d, const char *buf, long len)
{
    if (!len) return d;
    if (--len > 0 && !*buf++) { /* binary mantissa mark */
        int e, s = d < 0, dig = 0;
        unsigned long m;

        modf(ldexp(frexp(fabs(d), &e), DECIMAL_MANT), &d);
        do {
            m = 0;
            switch (len) {
              default: m = *buf++ & 0xff;
#if MANT_BITS > 24
              case 3: m = (m << 8) | (*buf++ & 0xff);
#endif
#if MANT_BITS > 16
              case 2: m = (m << 8) | (*buf++ & 0xff);
#endif
#if MANT_BITS > 8
              case 1: m = (m << 8) | (*buf++ & 0xff);
#endif
            }
            dig -= len < MANT_BITS / 8 ? 8 * (unsigned)len : MANT_BITS;
            d += ldexp((double)m, dig);
        } while ((len -= MANT_BITS / 8) > 0);
        d = ldexp(d, e - DECIMAL_MANT);
        if (s) d = -d;
    }
    return d;
}
#else
#define load_mantissa(d, buf, len) (d)
#endif

#ifdef DBL_DIG
#define FLOAT_DIG (DBL_DIG+2)
#else
#define FLOAT_DIG 17
#endif

static void
w_float(double d, struct dump_arg *arg)
{
    char *ruby_dtoa(double d_, int mode, int ndigits, int *decpt, int *sign, char **rve);
    char buf[FLOAT_DIG + (DECIMAL_MANT + 7) / 8 + 10];

    if (isinf(d)) {
        if (d < 0) w_cstr("-inf", arg);
        else       w_cstr("inf", arg);
    }
    else if (isnan(d)) {
        w_cstr("nan", arg);
    }
    else if (d == 0.0) {
        if (1.0/d < 0) w_cstr("-0", arg);
        else           w_cstr("0", arg);
    }
    else {
        int decpt, sign, digs, len = 0;
        char *e, *p = ruby_dtoa(d, 0, 0, &decpt, &sign, &e);
        if (sign) buf[len++] = '-';
        digs = (int)(e - p);
        if (decpt < -3 || decpt > digs) {
            buf[len++] = p[0];
            if (--digs > 0) buf[len++] = '.';
            memcpy(buf + len, p + 1, digs);
            len += digs;
            len += snprintf(buf + len, sizeof(buf) - len, "e%d", decpt - 1);
        }
        else if (decpt > 0) {
            memcpy(buf + len, p, decpt);
            len += decpt;
            if ((digs -= decpt) > 0) {
                buf[len++] = '.';
                memcpy(buf + len, p + decpt, digs);
                len += digs;
            }
        }
        else {
            buf[len++] = '0';
            buf[len++] = '.';
            if (decpt) {
                memset(buf + len, '0', -decpt);
                len -= decpt;
            }
            memcpy(buf + len, p, digs);
            len += digs;
        }
        xfree(p);
        w_bytes(buf, len, arg);
    }
}

static void
w_symbol(ID id, struct dump_arg *arg)
{
    VALUE sym;
    st_data_t num;
    int encidx = -1;

    if (st_lookup(arg->symbols, id, &num)) {
        w_byte(TYPE_SYMLINK, arg);
        w_long((long)num, arg);
    }
    else {
        sym = rb_id2str(id);
        if (!sym) {
            rb_raise(rb_eTypeError, "can't dump anonymous ID %"PRIdVALUE, id);
        }
        encidx = rb_enc_get_index(sym);
        if (encidx == rb_usascii_encindex() ||
            rb_enc_str_coderange(sym) == ENC_CODERANGE_7BIT) {
            encidx = -1;
        }
        else {
            w_byte(TYPE_IVAR, arg);
        }
        w_byte(TYPE_SYMBOL, arg);
        w_bytes(RSTRING_PTR(sym), RSTRING_LEN(sym), arg);
        st_add_direct(arg->symbols, id, arg->symbols->num_entries);
        if (encidx != -1) {
            struct dump_call_arg c_arg;
            c_arg.limit = 1;
            c_arg.arg = arg;
            w_encoding(sym, 0, &c_arg);
        }
    }
}

static void
w_unique(VALUE s, struct dump_arg *arg)
{
    must_not_be_anonymous("class", s);
    w_symbol(rb_intern_str(s), arg);
}

static void w_object(VALUE,struct dump_arg*,int);

static int
hash_each(VALUE key, VALUE value, struct dump_call_arg *arg)
{
    w_object(key, arg->arg, arg->limit);
    w_object(value, arg->arg, arg->limit);
    return ST_CONTINUE;
}

#define SINGLETON_DUMP_UNABLE_P(klass) \
    (RCLASS_M_TBL(klass)->num_entries || \
     (RCLASS_IV_TBL(klass) && RCLASS_IV_TBL(klass)->num_entries > 1))

static void
w_extended(VALUE klass, struct dump_arg *arg, int check)
{
    if (check && FL_TEST(klass, FL_SINGLETON)) {
        VALUE origin = RCLASS_ORIGIN(klass);
        if (SINGLETON_DUMP_UNABLE_P(klass) ||
            (origin != klass && SINGLETON_DUMP_UNABLE_P(origin))) {
            rb_raise(rb_eTypeError, "singleton can't be dumped");
        }
        klass = RCLASS_SUPER(klass);
    }
    while (BUILTIN_TYPE(klass) == T_ICLASS) {
        VALUE path = rb_class_name(RBASIC(klass)->klass);
        w_byte(TYPE_EXTENDED, arg);
        w_unique(path, arg);
        klass = RCLASS_SUPER(klass);
    }
}

static void
w_class(char type, VALUE obj, struct dump_arg *arg, int check)
{
    VALUE path;
    st_data_t real_obj;
    VALUE klass;

    if (st_lookup(arg->compat_tbl, (st_data_t)obj, &real_obj)) {
        obj = (VALUE)real_obj;
    }
    klass = CLASS_OF(obj);
    w_extended(klass, arg, check);
    w_byte(type, arg);
    path = class2path(rb_class_real(klass));
    w_unique(path, arg);
}

static void
w_uclass(VALUE obj, VALUE super, struct dump_arg *arg)
{
    VALUE klass = CLASS_OF(obj);

    w_extended(klass, arg, TRUE);
    klass = rb_class_real(klass);
    if (klass != super) {
        w_byte(TYPE_UCLASS, arg);
        w_unique(class2path(klass), arg);
    }
}

static int
w_obj_each(st_data_t key, st_data_t val, st_data_t a)
{
    ID id = (ID)key;
    VALUE value = (VALUE)val;
    struct dump_call_arg *arg = (struct dump_call_arg *)a;

    if (id == rb_id_encoding()) return ST_CONTINUE;
    if (id == rb_intern("E")) return ST_CONTINUE;
    w_symbol(id, arg->arg);
    w_object(value, arg->arg, arg->limit);
    return ST_CONTINUE;
}

static void
w_encoding(VALUE obj, long num, struct dump_call_arg *arg)
{
    int encidx = rb_enc_get_index(obj);
    rb_encoding *enc = 0;
    st_data_t name;

    if (encidx <= 0 || !(enc = rb_enc_from_index(encidx))) {
        w_long(num, arg->arg);
        return;
    }
    w_long(num + 1, arg->arg);

    /* special treatment for US-ASCII and UTF-8 */
    if (encidx == rb_usascii_encindex()) {
        w_symbol(rb_intern("E"), arg->arg);
        w_object(Qfalse, arg->arg, arg->limit + 1);
        return;
    }
    else if (encidx == rb_utf8_encindex()) {
        w_symbol(rb_intern("E"), arg->arg);
        w_object(Qtrue, arg->arg, arg->limit + 1);
        return;
    }

    w_symbol(rb_id_encoding(), arg->arg);
    do {
        if (!arg->arg->encodings)
            arg->arg->encodings = st_init_strcasetable();
        else if (st_lookup(arg->arg->encodings, (st_data_t)rb_enc_name(enc), &name))
            break;
        name = (st_data_t)rb_str_new2(rb_enc_name(enc));
        st_insert(arg->arg->encodings, (st_data_t)rb_enc_name(enc), name);
    } while (0);
    w_object(name, arg->arg, arg->limit + 1);
}

static void
w_ivar(VALUE obj, st_table *tbl, struct dump_call_arg *arg)
{
    long num = tbl ? tbl->num_entries : 0;

    w_encoding(obj, num, arg);
    if (tbl) {
        st_foreach_safe(tbl, w_obj_each, (st_data_t)arg);
    }
}

static void
w_objivar(VALUE obj, struct dump_call_arg *arg)
{
    VALUE *ptr;
    long i, len, num;

    len = ROBJECT_NUMIV(obj);
    ptr = ROBJECT_IVPTR(obj);
    num = 0;
    for (i = 0; i < len; i++)
        if (ptr[i] != Qundef)
            num += 1;

    w_encoding(obj, num, arg);
    if (num != 0) {
        rb_ivar_foreach(obj, w_obj_each, (st_data_t)arg);
    }
}

static void
w_object(VALUE obj, struct dump_arg *arg, int limit)
{
    struct dump_call_arg c_arg;
    st_table *ivtbl = 0;
    st_data_t num;
    int hasiv = 0;
#define has_ivars(obj, ivtbl) (((ivtbl) = rb_generic_ivar_table(obj)) != 0 || \
                               (!SPECIAL_CONST_P(obj) && !ENCODING_IS_ASCII8BIT(obj)))

    if (limit == 0) {
        rb_raise(rb_eArgError, "exceed depth limit");
    }

    limit--;
    c_arg.limit = limit;
    c_arg.arg = arg;

    if (st_lookup(arg->data, obj, &num)) {
        w_byte(TYPE_LINK, arg);
        w_long((long)num, arg);
        return;
    }

    if (obj == Qnil) {
        w_byte(TYPE_NIL, arg);
    }
    else if (obj == Qtrue) {
        w_byte(TYPE_TRUE, arg);
    }
    else if (obj == Qfalse) {
        w_byte(TYPE_FALSE, arg);
    }
    else if (FIXNUM_P(obj)) {
#if SIZEOF_LONG <= 4
        w_byte(TYPE_FIXNUM, arg);
        w_long(FIX2INT(obj), arg);
#else
        if (RSHIFT((long)obj, 31) == 0 || RSHIFT((long)obj, 31) == -1) {
            w_byte(TYPE_FIXNUM, arg);
            w_long(FIX2LONG(obj), arg);
        }
        else {
            w_object(rb_int2big(FIX2LONG(obj)), arg, limit);
        }
#endif
    }
    else if (SYMBOL_P(obj)) {
        w_symbol(SYM2ID(obj), arg);
    }
    else if (FLONUM_P(obj)) {
        st_add_direct(arg->data, obj, arg->data->num_entries);
        w_byte(TYPE_FLOAT, arg);
        w_float(RFLOAT_VALUE(obj), arg);
    }
    else {
        VALUE v;

        arg->infection |= (int)FL_TEST(obj, MARSHAL_INFECTION);

        if (rb_obj_respond_to(obj, s_mdump, TRUE)) {
            st_add_direct(arg->data, obj, arg->data->num_entries);

            v = rb_funcall2(obj, s_mdump, 0, 0);
            check_dump_arg(arg, s_mdump);
            hasiv = has_ivars(v, ivtbl);
            if (hasiv) w_byte(TYPE_IVAR, arg);
            w_class(TYPE_USRMARSHAL, obj, arg, FALSE);
            w_object(v, arg, limit);
            if (hasiv) w_ivar(v, ivtbl, &c_arg);
            return;
        }
        if (rb_obj_respond_to(obj, s_dump, TRUE)) {
            st_table *ivtbl2 = 0;
            int hasiv2;

            v = INT2NUM(limit);
            v = rb_funcall2(obj, s_dump, 1, &v);
            check_dump_arg(arg, s_dump);
            if (!RB_TYPE_P(v, T_STRING)) {
                rb_raise(rb_eTypeError, "_dump() must return string");
            }
            hasiv = has_ivars(obj, ivtbl);
            if (hasiv) w_byte(TYPE_IVAR, arg);
            if ((hasiv2 = has_ivars(v, ivtbl2)) != 0 && !hasiv) {
                w_byte(TYPE_IVAR, arg);
            }
            w_class(TYPE_USERDEF, obj, arg, FALSE);
            w_bytes(RSTRING_PTR(v), RSTRING_LEN(v), arg);
            if (hasiv2) {
                w_ivar(v, ivtbl2, &c_arg);
            }
            else if (hasiv) {
                w_ivar(obj, ivtbl, &c_arg);
            }
            st_add_direct(arg->data, obj, arg->data->num_entries);
            return;
        }

        st_add_direct(arg->data, obj, arg->data->num_entries);

        hasiv = has_ivars(obj, ivtbl);
        {
            st_data_t compat_data;
            rb_alloc_func_t allocator = rb_get_alloc_func(RBASIC(obj)->klass);
            if (st_lookup(compat_allocator_tbl,
                          (st_data_t)allocator,
                          &compat_data)) {
                marshal_compat_t *compat = (marshal_compat_t*)compat_data;
                VALUE real_obj = obj;
                obj = compat->dumper(real_obj);
                st_insert(arg->compat_tbl, (st_data_t)obj, (st_data_t)real_obj);
                if (obj != real_obj && !ivtbl) hasiv = 0;
            }
        }
        if (hasiv) w_byte(TYPE_IVAR, arg);

        switch (BUILTIN_TYPE(obj)) {
          case T_CLASS:
            if (FL_TEST(obj, FL_SINGLETON)) {
                rb_raise(rb_eTypeError, "singleton class can't be dumped");
            }
            w_byte(TYPE_CLASS, arg);
            {
                VALUE path = class2path(obj);
                w_bytes(RSTRING_PTR(path), RSTRING_LEN(path), arg);
                RB_GC_GUARD(path);
            }
            break;

          case T_MODULE:
            w_byte(TYPE_MODULE, arg);
            {
                VALUE path = class2path(obj);
                w_bytes(RSTRING_PTR(path), RSTRING_LEN(path), arg);
                RB_GC_GUARD(path);
            }
            break;

          case T_FLOAT:
            w_byte(TYPE_FLOAT, arg);
            w_float(RFLOAT_VALUE(obj), arg);
            break;

          case T_BIGNUM:
            w_byte(TYPE_BIGNUM, arg);
            {
                char sign = RBIGNUM_SIGN(obj) ? '+' : '-';
                long len = RBIGNUM_LEN(obj);
                BDIGIT *d = RBIGNUM_DIGITS(obj);

                w_byte(sign, arg);
                w_long(SHORTLEN(len), arg); /* w_short? */
                while (len--) {
#if SIZEOF_BDIGITS > SIZEOF_SHORT
                    BDIGIT num = *d;
                    int i;

                    for (i=0; i<SIZEOF_BDIGITS; i+=SIZEOF_SHORT) {
                        w_short(num & SHORTMASK, arg);
                        num = SHORTDN(num);
                        if (len == 0 && num == 0) break;
                    }
#else
                    w_short(*d, arg);
#endif
                    d++;
                }
            }
            break;

          case T_STRING:
            w_uclass(obj, rb_cString, arg);
            w_byte(TYPE_STRING, arg);
            w_bytes(RSTRING_PTR(obj), RSTRING_LEN(obj), arg);
            break;

          case T_REGEXP:
            w_uclass(obj, rb_cRegexp, arg);
            w_byte(TYPE_REGEXP, arg);
            {
                int opts = rb_reg_options(obj);
                w_bytes(RREGEXP_SRC_PTR(obj), RREGEXP_SRC_LEN(obj), arg);
                w_byte((char)opts, arg);
            }
            break;

          case T_ARRAY:
            w_uclass(obj, rb_cArray, arg);
            w_byte(TYPE_ARRAY, arg);
            {
                long i, len = RARRAY_LEN(obj);

                w_long(len, arg);
                for (i=0; i<RARRAY_LEN(obj); i++) {
                    w_object(RARRAY_PTR(obj)[i], arg, limit);
                    if (len != RARRAY_LEN(obj)) {
                        rb_raise(rb_eRuntimeError, "array modified during dump");
                    }
                }
            }
            break;

          case T_HASH:
            w_uclass(obj, rb_cHash, arg);
            if (NIL_P(RHASH_IFNONE(obj))) {
                w_byte(TYPE_HASH, arg);
            }
            else if (FL_TEST(obj, FL_USER2)) {
                /* FL_USER2 means HASH_PROC_DEFAULT (see hash.c) */
                rb_raise(rb_eTypeError, "can't dump hash with default proc");
            }
            else {
                w_byte(TYPE_HASH_DEF, arg);
            }
            w_long(RHASH_SIZE(obj), arg);
            rb_hash_foreach(obj, hash_each, (st_data_t)&c_arg);
            if (!NIL_P(RHASH_IFNONE(obj))) {
                w_object(RHASH_IFNONE(obj), arg, limit);
            }
            break;

          case T_STRUCT:
            w_class(TYPE_STRUCT, obj, arg, TRUE);
            {
                long len = RSTRUCT_LEN(obj);
                VALUE mem;
                long i;

                w_long(len, arg);
                mem = rb_struct_members(obj);
                for (i=0; i<len; i++) {
                    w_symbol(SYM2ID(RARRAY_PTR(mem)[i]), arg);
                    w_object(RSTRUCT_PTR(obj)[i], arg, limit);
                }
            }
            break;

          case T_OBJECT:
            w_class(TYPE_OBJECT, obj, arg, TRUE);
            w_objivar(obj, &c_arg);
            break;

          case T_DATA:
            {
                VALUE v;

                if (!rb_obj_respond_to(obj, s_dump_data, TRUE)) {
                    rb_raise(rb_eTypeError,
                             "no _dump_data is defined for class %s",
                             rb_obj_classname(obj));
                }
                v = rb_funcall2(obj, s_dump_data, 0, 0);
                check_dump_arg(arg, s_dump_data);
                w_class(TYPE_DATA, obj, arg, TRUE);
                w_object(v, arg, limit);
            }
            break;

          default:
            rb_raise(rb_eTypeError, "can't dump %s",
                     rb_obj_classname(obj));
            break;
        }
        RB_GC_GUARD(obj);
    }
    if (hasiv) {
        w_ivar(obj, ivtbl, &c_arg);
    }
}

static void
clear_dump_arg(struct dump_arg *arg)
{
    if (!arg->symbols) return;
    st_free_table(arg->symbols);
    arg->symbols = 0;
    st_free_table(arg->data);
    arg->data = 0;
    st_free_table(arg->compat_tbl);
    arg->compat_tbl = 0;
    if (arg->encodings) {
        st_free_table(arg->encodings);
        arg->encodings = 0;
    }
}

NORETURN(static inline void io_needed(void));
static inline void
io_needed(void)
{
    rb_raise(rb_eTypeError, "instance of IO needed");
}

/*
 * call-seq:
 *      dump( obj [, anIO] , limit=-1 ) -> anIO
 *
 * Serializes obj and all descendant objects. If anIO is
 * specified, the serialized data will be written to it, otherwise the
 * data will be returned as a String. If limit is specified, the
 * traversal of subobjects will be limited to that depth. If limit is
 * negative, no checking of depth will be performed.
 *
 *     class Klass
 *       def initialize(str)
 *         @str = str
 *       end
 *       def say_hello
 *         @str
 *       end
 *     end
 *
 * (produces no output)
 *
 *     o = Klass.new("hello\n")
 *     data = Marshal.dump(o)
 *     obj = Marshal.load(data)
 *     obj.say_hello  #=> "hello\n"
 *
 * Marshal can't dump following objects:
 * * anonymous Class/Module.
 * * objects which related to its system (ex: Dir, File::Stat, IO, File, Socket
 *   and so on)
 * * an instance of MatchData, Data, Method, UnboundMethod, Proc, Thread,
 *   ThreadGroup, Continuation
 * * objects which defines singleton methods
 */
static VALUE
marshal_dump(int argc, VALUE *argv)
{
    VALUE obj, port, a1, a2;
    int limit = -1;
    struct dump_arg *arg;
    volatile VALUE wrapper;

    port = Qnil;
    rb_scan_args(argc, argv, "12", &obj, &a1, &a2);
    if (argc == 3) {
        if (!NIL_P(a2)) limit = NUM2INT(a2);
        if (NIL_P(a1)) io_needed();
        port = a1;
    }
    else if (argc == 2) {
        if (FIXNUM_P(a1)) limit = FIX2INT(a1);
        else if (NIL_P(a1)) io_needed();
        else port = a1;
    }
    RB_GC_GUARD(wrapper) = TypedData_Make_Struct(rb_cData, struct dump_arg, &dump_arg_data, arg);
    arg->dest = 0;
    arg->symbols = st_init_numtable();
    arg->data    = st_init_numtable();
    arg->infection = 0;
    arg->compat_tbl = st_init_numtable();
    arg->encodings = 0;
    arg->str = rb_str_buf_new(0);
    if (!NIL_P(port)) {
        if (!rb_respond_to(port, s_write)) {
            io_needed();
        }
        arg->dest = port;
        if (rb_check_funcall(port, s_binmode, 0, 0) != Qundef) {
            check_dump_arg(arg, s_binmode);
        }
    }
    else {
        port = arg->str;
    }

    w_byte(MARSHAL_MAJOR, arg);
    w_byte(MARSHAL_MINOR, arg);

    w_object(obj, arg, limit);
    if (arg->dest) {
        rb_io_write(arg->dest, arg->str);
        rb_str_resize(arg->str, 0);
    }
    clear_dump_arg(arg);
    RB_GC_GUARD(wrapper);

    return port;
}

struct load_arg {
    VALUE src;
    char *buf;
    long buflen;
    long readable;
    long offset;
    st_table *symbols;
    st_table *data;
    VALUE proc;
    st_table *compat_tbl;
    int infection;
};

static void
check_load_arg(struct load_arg *arg, ID sym)
{
    if (!arg->symbols) {
        rb_raise(rb_eRuntimeError, "Marshal.load reentered at %s",
                 rb_id2name(sym));
    }
}

static void clear_load_arg(struct load_arg *arg);

static void
mark_load_arg(void *ptr)
{
    struct load_arg *p = ptr;
    if (!p->symbols)
        return;
    rb_mark_tbl(p->data);
    rb_mark_hash(p->compat_tbl);
}

static void
free_load_arg(void *ptr)
{
    clear_load_arg(ptr);
    xfree(ptr);
}

static size_t
memsize_load_arg(const void *ptr)
{
    return ptr ? sizeof(struct load_arg) : 0;
}

static const rb_data_type_t load_arg_data = {
    "load_arg",
    {mark_load_arg, free_load_arg, memsize_load_arg,},
};

#define r_entry(v, arg) r_entry0((v), (arg)->data->num_entries, (arg))
static VALUE r_entry0(VALUE v, st_index_t num, struct load_arg *arg);
static VALUE r_object(struct load_arg *arg);
static ID r_symbol(struct load_arg *arg);
static VALUE path2class(VALUE path);

NORETURN(static void too_short(void));
static void
too_short(void)
{
    rb_raise(rb_eArgError, "marshal data too short");
}

static st_index_t
r_prepare(struct load_arg *arg)
{
    st_index_t idx = arg->data->num_entries;

    st_insert(arg->data, (st_data_t)idx, (st_data_t)Qundef);
    return idx;
}

static unsigned char
r_byte1_buffered(struct load_arg *arg)
{
    if (arg->buflen == 0) {
        long readable = arg->readable < BUFSIZ ? arg->readable : BUFSIZ;
        VALUE str, n = LONG2NUM(readable);

        str = rb_funcall2(arg->src, s_read, 1, &n);

        check_load_arg(arg, s_read);
        if (NIL_P(str)) too_short();
        StringValue(str);
        arg->infection |= (int)FL_TEST(str, MARSHAL_INFECTION);
        memcpy(arg->buf, RSTRING_PTR(str), RSTRING_LEN(str));
        arg->offset = 0;
        arg->buflen = RSTRING_LEN(str);
    }
    arg->buflen--;
    return arg->buf[arg->offset++];
}

static int
r_byte(struct load_arg *arg)
{
    int c;

    if (RB_TYPE_P(arg->src, T_STRING)) {
        if (RSTRING_LEN(arg->src) > arg->offset) {
            c = (unsigned char)RSTRING_PTR(arg->src)[arg->offset++];
        }
        else {
            too_short();
        }
    }
    else {
        if (arg->readable >0 || arg->buflen > 0) {
            c = r_byte1_buffered(arg);
        }
        else {
            VALUE v = rb_funcall2(arg->src, s_getbyte, 0, 0);
            check_load_arg(arg, s_getbyte);
            if (NIL_P(v)) rb_eof_error();
            c = (unsigned char)NUM2CHR(v);
        }
    }
    return c;
}

static void
long_toobig(int size)
{
    rb_raise(rb_eTypeError, "long too big for this architecture (size "
             STRINGIZE(SIZEOF_LONG)", given %d)", size);
}

#undef SIGN_EXTEND_CHAR
#if __STDC__
# define SIGN_EXTEND_CHAR(c) ((signed char)(c))
#else  /* not __STDC__ */
/* As in Harbison and Steele.  */
# define SIGN_EXTEND_CHAR(c) ((((unsigned char)(c)) ^ 128) - 128)
#endif

static long
r_long(struct load_arg *arg)
{
    register long x;
    int c = SIGN_EXTEND_CHAR(r_byte(arg));
    long i;

    if (c == 0) return 0;
    if (c > 0) {
        if (4 < c && c < 128) {
            return c - 5;
        }
        if (c > (int)sizeof(long)) long_toobig(c);
        x = 0;
        for (i=0;i<c;i++) {
            x |= (long)r_byte(arg) << (8*i);
        }
    }
    else {
        if (-129 < c && c < -4) {
            return c + 5;
        }
        c = -c;
        if (c > (int)sizeof(long)) long_toobig(c);
        x = -1;
        for (i=0;i<c;i++) {
            x &= ~((long)0xff << (8*i));
            x |= (long)r_byte(arg) << (8*i);
        }
    }
    return x;
}

static VALUE
r_bytes1(long len, struct load_arg *arg)
{
    VALUE str, n = LONG2NUM(len);

    str = rb_funcall2(arg->src, s_read, 1, &n);
    check_load_arg(arg, s_read);
    if (NIL_P(str)) too_short();
    StringValue(str);
    if (RSTRING_LEN(str) != len) too_short();
    arg->infection |= (int)FL_TEST(str, MARSHAL_INFECTION);

    return str;
}

static VALUE
r_bytes1_buffered(long len, struct load_arg *arg)
{
    VALUE str;

    if (len <= arg->buflen) {
        str = rb_str_new(arg->buf+arg->offset, len);
        arg->offset += len;
        arg->buflen -= len;
    }
    else {
        long buflen = arg->buflen;
        long readable = arg->readable + 1;
        long tmp_len, read_len, need_len = len - buflen;
        VALUE tmp, n;

        readable = readable < BUFSIZ ? readable : BUFSIZ;
        read_len = need_len > readable ? need_len : readable;
        n = LONG2NUM(read_len);
        tmp = rb_funcall2(arg->src, s_read, 1, &n);

        check_load_arg(arg, s_read);
        if (NIL_P(tmp)) too_short();
        StringValue(tmp);

        tmp_len = RSTRING_LEN(tmp);

        if (tmp_len < need_len) too_short();
        arg->infection |= (int)FL_TEST(tmp, MARSHAL_INFECTION);

        str = rb_str_new(arg->buf+arg->offset, buflen);
        rb_str_cat(str, RSTRING_PTR(tmp), need_len);

        if (tmp_len > need_len) {
            buflen = tmp_len - need_len;
            memcpy(arg->buf, RSTRING_PTR(tmp)+need_len, buflen);
            arg->buflen = buflen;
        }
        else {
            arg->buflen = 0;
        }
        arg->offset = 0;
    }

    return str;
}

#define r_bytes(arg) r_bytes0(r_long(arg), (arg))

static VALUE
r_bytes0(long len, struct load_arg *arg)
{
    VALUE str;

    if (len == 0) return rb_str_new(0, 0);
    if (RB_TYPE_P(arg->src, T_STRING)) {
        if (RSTRING_LEN(arg->src) - arg->offset >= len) {
            str = rb_str_new(RSTRING_PTR(arg->src)+arg->offset, len);
            arg->offset += len;
        }
        else {
            too_short();
        }
    }
    else {
        if (arg->readable > 0 || arg->buflen > 0) {
            str = r_bytes1_buffered(len, arg);
        }
        else {
            str = r_bytes1(len, arg);
        }
    }
    return str;
}

static int
id2encidx(ID id, VALUE val)
{
    if (id == rb_id_encoding()) {
        int idx = rb_enc_find_index(StringValueCStr(val));
        return idx;
    }
    else if (id == rb_intern("E")) {
        if (val == Qfalse) return rb_usascii_encindex();
        else if (val == Qtrue) return rb_utf8_encindex();
        /* bogus ignore */
    }
    return -1;
}

static ID
r_symlink(struct load_arg *arg)
{
    st_data_t id;
    long num = r_long(arg);

    if (!st_lookup(arg->symbols, num, &id)) {
        rb_raise(rb_eArgError, "bad symbol");
    }
    return (ID)id;
}

static ID
r_symreal(struct load_arg *arg, int ivar)
{
    VALUE s = r_bytes(arg);
    ID id;
    int idx = -1;
    st_index_t n = arg->symbols->num_entries;

    st_insert(arg->symbols, (st_data_t)n, (st_data_t)0);
    if (ivar) {
        long num = r_long(arg);
        while (num-- > 0) {
            id = r_symbol(arg);
            idx = id2encidx(id, r_object(arg));
        }
    }
    if (idx > 0) rb_enc_associate_index(s, idx);
    id = rb_intern_str(s);
    st_insert(arg->symbols, (st_data_t)n, (st_data_t)id);

    return id;
}

static ID
r_symbol(struct load_arg *arg)
{
    int type, ivar = 0;

  again:
    switch ((type = r_byte(arg))) {
      default:
        rb_raise(rb_eArgError, "dump format error for symbol(0x%x)", type);
      case TYPE_IVAR:
        ivar = 1;
        goto again;
      case TYPE_SYMBOL:
        return r_symreal(arg, ivar);
      case TYPE_SYMLINK:
        if (ivar) {
            rb_raise(rb_eArgError, "dump format error (symlink with encoding)");
        }
        return r_symlink(arg);
    }
}

static VALUE
r_unique(struct load_arg *arg)
{
    return rb_id2str(r_symbol(arg));
}

static VALUE
r_string(struct load_arg *arg)
{
    return r_bytes(arg);
}

static VALUE
r_entry0(VALUE v, st_index_t num, struct load_arg *arg)
{
    st_data_t real_obj = (VALUE)Qundef;
    if (st_lookup(arg->compat_tbl, v, &real_obj)) {
        st_insert(arg->data, num, (st_data_t)real_obj);
    }
    else {
        st_insert(arg->data, num, (st_data_t)v);
    }
    if (arg->infection &&
        !RB_TYPE_P(v, T_CLASS) && !RB_TYPE_P(v, T_MODULE)) {
        FL_SET(v, arg->infection);
        if ((VALUE)real_obj != Qundef)
            FL_SET((VALUE)real_obj, arg->infection);
    }
    return v;
}

static VALUE
r_leave(VALUE v, struct load_arg *arg)
{
    st_data_t data;
    if (st_lookup(arg->compat_tbl, v, &data)) {
        VALUE real_obj = (VALUE)data;
        rb_alloc_func_t allocator = rb_get_alloc_func(CLASS_OF(real_obj));
        st_data_t key = v;
        if (st_lookup(compat_allocator_tbl, (st_data_t)allocator, &data)) {
            marshal_compat_t *compat = (marshal_compat_t*)data;
            compat->loader(real_obj, v);
        }
        st_delete(arg->compat_tbl, &key, 0);
        v = real_obj;
    }
    if (arg->proc) {
        v = rb_funcall(arg->proc, s_call, 1, v);
        check_load_arg(arg, s_call);
    }
    return v;
}

static void
r_ivar(VALUE obj, int *has_encoding, struct load_arg *arg)
{
    long len;

    len = r_long(arg);
    if (len > 0) {
        do {
            ID id = r_symbol(arg);
            VALUE val = r_object(arg);
            int idx = id2encidx(id, val);
            if (idx >= 0) {
                rb_enc_associate_index(obj, idx);
                if (has_encoding) *has_encoding = TRUE;
            }
            else {
                rb_ivar_set(obj, id, val);
            }
        } while (--len > 0);
    }
}

static VALUE
path2class(VALUE path)
{
    VALUE v = rb_path_to_class(path);

    if (!RB_TYPE_P(v, T_CLASS)) {
        rb_raise(rb_eArgError, "%"PRIsVALUE" does not refer to class", path);
    }
    return v;
}

static VALUE
path2module(VALUE path)
{
    VALUE v = rb_path_to_class(path);

    if (!RB_TYPE_P(v, T_MODULE)) {
        rb_raise(rb_eArgError, "%"PRIsVALUE" does not refer to module", path);
    }
    return v;
}

static VALUE
obj_alloc_by_klass(VALUE klass, struct load_arg *arg, VALUE *oldclass)
{
    st_data_t data;
    rb_alloc_func_t allocator;

    allocator = rb_get_alloc_func(klass);
    if (st_lookup(compat_allocator_tbl, (st_data_t)allocator, &data)) {
        marshal_compat_t *compat = (marshal_compat_t*)data;
        VALUE real_obj = rb_obj_alloc(klass);
        VALUE obj = rb_obj_alloc(compat->oldclass);
        if (oldclass) *oldclass = compat->oldclass;
        st_insert(arg->compat_tbl, (st_data_t)obj, (st_data_t)real_obj);
        return obj;
    }

    return rb_obj_alloc(klass);
}

static VALUE
obj_alloc_by_path(VALUE path, struct load_arg *arg)
{
    return obj_alloc_by_klass(path2class(path), arg, 0);
}

static VALUE
append_extmod(VALUE obj, VALUE extmod)
{
    long i = RARRAY_LEN(extmod);
    while (i > 0) {
        VALUE m = RARRAY_PTR(extmod)[--i];
        rb_extend_object(obj, m);
    }
    return obj;
}

#define prohibit_ivar(type, str) do { \
        if (!ivp || !*ivp) break; \
        rb_raise(rb_eTypeError, \
                 "can't override instance variable of "type" `%"PRIsVALUE"'", \
                 (str)); \
    } while (0)

static VALUE
r_object0(struct load_arg *arg, int *ivp, VALUE extmod)
{
    VALUE v = Qnil;
    int type = r_byte(arg);
    long id;
    st_data_t link;

    switch (type) {
      case TYPE_LINK:
        id = r_long(arg);
        if (!st_lookup(arg->data, (st_data_t)id, &link)) {
            rb_raise(rb_eArgError, "dump format error (unlinked)");
        }
        v = (VALUE)link;
        if (arg->proc) {
            v = rb_funcall(arg->proc, s_call, 1, v);
            check_load_arg(arg, s_call);
        }
        break;

      case TYPE_IVAR:
        {
            int ivar = TRUE;

            v = r_object0(arg, &ivar, extmod);
            if (ivar) r_ivar(v, NULL, arg);
        }
        break;

      case TYPE_EXTENDED:
        {
            VALUE m = path2module(r_unique(arg));

            if (NIL_P(extmod)) extmod = rb_ary_tmp_new(0);
            rb_ary_push(extmod, m);

            v = r_object0(arg, 0, extmod);
            while (RARRAY_LEN(extmod) > 0) {
                m = rb_ary_pop(extmod);
                rb_extend_object(v, m);
            }
        }
        break;

      case TYPE_UCLASS:
        {
            VALUE c = path2class(r_unique(arg));

            if (FL_TEST(c, FL_SINGLETON)) {
                rb_raise(rb_eTypeError, "singleton can't be loaded");
            }
            v = r_object0(arg, 0, extmod);
            if (rb_special_const_p(v) || RB_TYPE_P(v, T_OBJECT) || RB_TYPE_P(v, T_CLASS)) {
              format_error:
                rb_raise(rb_eArgError, "dump format error (user class)");
            }
            if (RB_TYPE_P(v, T_MODULE) || !RTEST(rb_class_inherited_p(c, RBASIC(v)->klass))) {
                VALUE tmp = rb_obj_alloc(c);

                if (TYPE(v) != TYPE(tmp)) goto format_error;
            }
            RBASIC(v)->klass = c;
        }
        break;

      case TYPE_NIL:
        v = Qnil;
        v = r_leave(v, arg);
        break;

      case TYPE_TRUE:
        v = Qtrue;
        v = r_leave(v, arg);
        break;

      case TYPE_FALSE:
        v = Qfalse;
        v = r_leave(v, arg);
        break;

      case TYPE_FIXNUM:
        {
            long i = r_long(arg);
            v = LONG2FIX(i);
        }
        v = r_leave(v, arg);
        break;

      case TYPE_FLOAT:
        {
            double d;
            VALUE str = r_bytes(arg);
            const char *ptr = RSTRING_PTR(str);

            if (strcmp(ptr, "nan") == 0) {
                d = NAN;
            }
            else if (strcmp(ptr, "inf") == 0) {
                d = INFINITY;
            }
            else if (strcmp(ptr, "-inf") == 0) {
                d = -INFINITY;
            }
            else {
                char *e;
                d = strtod(ptr, &e);
                d = load_mantissa(d, e, RSTRING_LEN(str) - (e - ptr));
            }
            v = DBL2NUM(d);
            v = r_entry(v, arg);
            v = r_leave(v, arg);
        }
        break;

      case TYPE_BIGNUM:
        {
            long len;
            BDIGIT *digits;
            VALUE data;

            NEWOBJ_OF(big, struct RBignum, rb_cBignum, T_BIGNUM);
            RBIGNUM_SET_SIGN(big, (r_byte(arg) == '+'));
            len = r_long(arg);
            data = r_bytes0(len * 2, arg);
#if SIZEOF_BDIGITS == SIZEOF_SHORT
            rb_big_resize((VALUE)big, len);
#else
            rb_big_resize((VALUE)big, (len + 1) * 2 / sizeof(BDIGIT));
#endif
            digits = RBIGNUM_DIGITS(big);
            MEMCPY(digits, RSTRING_PTR(data), char, len * 2);
            rb_str_resize(data, 0L);
#if SIZEOF_BDIGITS > SIZEOF_SHORT
            MEMZERO((char *)digits + len * 2, char,
                    RBIGNUM_LEN(big) * sizeof(BDIGIT) - len * 2);
#endif
            len = RBIGNUM_LEN(big);
            while (len > 0) {
                unsigned char *p = (unsigned char *)digits;
                BDIGIT num = 0;
#if SIZEOF_BDIGITS > SIZEOF_SHORT
                int shift = 0;
                int i;

                for (i=0; i<SIZEOF_BDIGITS; i++) {
                    num |= (int)p[i] << shift;
                    shift += 8;
                }
#else
                num = p[0] | (p[1] << 8);
#endif
                *digits++ = num;
                len--;
            }
            v = rb_big_norm((VALUE)big);
            v = r_entry(v, arg);
            v = r_leave(v, arg);
        }
        break;

      case TYPE_STRING:
        v = r_entry(r_string(arg), arg);
        v = r_leave(v, arg);
        break;

      case TYPE_REGEXP:
        {
            VALUE str = r_bytes(arg);
            int options = r_byte(arg);
            int has_encoding = FALSE;
            st_index_t idx = r_prepare(arg);

            if (ivp) {
                r_ivar(str, &has_encoding, arg);
                *ivp = FALSE;
            }
            if (!has_encoding) {
                /* 1.8 compatibility; remove escapes undefined in 1.8 */
                char *ptr = RSTRING_PTR(str), *dst = ptr, *src = ptr;
                long len = RSTRING_LEN(str);
                long bs = 0;
                for (; len-- > 0; *dst++ = *src++) {
                    switch (*src) {
                      case '\\': bs++; break;
                      case 'g': case 'h': case 'i': case 'j': case 'k': case 'l':
                      case 'm': case 'o': case 'p': case 'q': case 'u': case 'y':
                      case 'E': case 'F': case 'H': case 'I': case 'J': case 'K':
                      case 'L': case 'N': case 'O': case 'P': case 'Q': case 'R':
                      case 'S': case 'T': case 'U': case 'V': case 'X': case 'Y':
                        if (bs & 1) --dst;
                      default: bs = 0; break;
                    }
                }
                rb_str_set_len(str, dst - ptr);
            }
            v = r_entry0(rb_reg_new_str(str, options), idx, arg);
            v = r_leave(v, arg);
        }
        break;

      case TYPE_ARRAY:
        {
            volatile long len = r_long(arg); /* gcc 2.7.2.3 -O2 bug?? */

            v = rb_ary_new2(len);
            v = r_entry(v, arg);
            arg->readable += len - 1;
            while (len--) {
                rb_ary_push(v, r_object(arg));
                arg->readable--;
            }
            v = r_leave(v, arg);
            arg->readable++;
        }
        break;

      case TYPE_HASH:
      case TYPE_HASH_DEF:
        {
            long len = r_long(arg);

            v = rb_hash_new();
            v = r_entry(v, arg);
            arg->readable += (len - 1) * 2;
            while (len--) {
                VALUE key = r_object(arg);
                VALUE value = r_object(arg);
                rb_hash_aset(v, key, value);
                arg->readable -= 2;
            }
            arg->readable += 2;
            if (type == TYPE_HASH_DEF) {
                RHASH_IFNONE(v) = r_object(arg);
            }
            v = r_leave(v, arg);
        }
        break;

      case TYPE_STRUCT:
        {
            VALUE mem, values;
            volatile long i;    /* gcc 2.7.2.3 -O2 bug?? */
            ID slot;
            st_index_t idx = r_prepare(arg);
            VALUE klass = path2class(r_unique(arg));
            long len = r_long(arg);

            v = rb_obj_alloc(klass);
            if (!RB_TYPE_P(v, T_STRUCT)) {
                rb_raise(rb_eTypeError, "class %s not a struct", rb_class2name(klass));
            }
            mem = rb_struct_s_members(klass);
            if (RARRAY_LEN(mem) != len) {
                rb_raise(rb_eTypeError, "struct %s not compatible (struct size differs)",
                         rb_class2name(klass));
            }

            arg->readable += (len - 1) * 2;
            v = r_entry0(v, idx, arg);
            values = rb_ary_new2(len);
            for (i=0; i<len; i++) {
                slot = r_symbol(arg);

                if (RARRAY_PTR(mem)[i] != ID2SYM(slot)) {
                    rb_raise(rb_eTypeError, "struct %s not compatible (:%s for :%s)",
                             rb_class2name(klass),
                             rb_id2name(slot),
                             rb_id2name(SYM2ID(RARRAY_PTR(mem)[i])));
                }
                rb_ary_push(values, r_object(arg));
                arg->readable -= 2;
            }
            rb_struct_initialize(v, values);
            v = r_leave(v, arg);
            arg->readable += 2;
        }
        break;

      case TYPE_USERDEF:
        {
            VALUE klass = path2class(r_unique(arg));
            VALUE data;

            if (!rb_obj_respond_to(klass, s_load, TRUE)) {
                rb_raise(rb_eTypeError, "class %s needs to have method `_load'",
                         rb_class2name(klass));
            }
            data = r_string(arg);
            if (ivp) {
                r_ivar(data, NULL, arg);
                *ivp = FALSE;
            }
            v = rb_funcall2(klass, s_load, 1, &data);
            check_load_arg(arg, s_load);
            v = r_entry(v, arg);
            v = r_leave(v, arg);
        }
        break;

      case TYPE_USRMARSHAL:
        {
            VALUE klass = path2class(r_unique(arg));
            VALUE oldclass = 0;
            VALUE data;

            v = obj_alloc_by_klass(klass, arg, &oldclass);
            if (!NIL_P(extmod)) {
                /* for the case marshal_load is overridden */
                append_extmod(v, extmod);
            }
            if (!rb_obj_respond_to(v, s_mload, TRUE)) {
                rb_raise(rb_eTypeError, "instance of %s needs to have method `marshal_load'",
                         rb_class2name(klass));
            }
            v = r_entry(v, arg);
            data = r_object(arg);
            rb_funcall2(v, s_mload, 1, &data);
            check_load_arg(arg, s_mload);
            v = r_leave(v, arg);
            if (!NIL_P(extmod)) {
                if (oldclass) append_extmod(v, extmod);
                rb_ary_clear(extmod);
            }
        }
        break;

      case TYPE_OBJECT:
        {
            st_index_t idx = r_prepare(arg);
            v = obj_alloc_by_path(r_unique(arg), arg);
            if (!RB_TYPE_P(v, T_OBJECT)) {
                rb_raise(rb_eArgError, "dump format error");
            }
            v = r_entry0(v, idx, arg);
            r_ivar(v, NULL, arg);
            v = r_leave(v, arg);
        }
        break;

      case TYPE_DATA:
        {
            VALUE klass = path2class(r_unique(arg));
            VALUE oldclass = 0;
            VALUE r;

            v = obj_alloc_by_klass(klass, arg, &oldclass);
            if (!RB_TYPE_P(v, T_DATA)) {
                rb_raise(rb_eArgError, "dump format error");
            }
            v = r_entry(v, arg);
            if (!rb_obj_respond_to(v, s_load_data, TRUE)) {
                rb_raise(rb_eTypeError,
                         "class %s needs to have instance method `_load_data'",
                         rb_class2name(klass));
            }
            r = r_object0(arg, 0, extmod);
            rb_funcall2(v, s_load_data, 1, &r);
            check_load_arg(arg, s_load_data);
            v = r_leave(v, arg);
        }
        break;

      case TYPE_MODULE_OLD:
        {
            VALUE str = r_bytes(arg);

            v = rb_path_to_class(str);
            prohibit_ivar("class/module", str);
            v = r_entry(v, arg);
            v = r_leave(v, arg);
        }
        break;

      case TYPE_CLASS:
        {
            VALUE str = r_bytes(arg);

            v = path2class(str);
            prohibit_ivar("class", str);
            v = r_entry(v, arg);
            v = r_leave(v, arg);
        }
        break;

      case TYPE_MODULE:
        {
            VALUE str = r_bytes(arg);

            v = path2module(str);
            prohibit_ivar("module", str);
            v = r_entry(v, arg);
            v = r_leave(v, arg);
        }
        break;

      case TYPE_SYMBOL:
        if (ivp) {
            v = ID2SYM(r_symreal(arg, *ivp));
            *ivp = FALSE;
        }
        else {
            v = ID2SYM(r_symreal(arg, 0));
        }
        v = r_leave(v, arg);
        break;

      case TYPE_SYMLINK:
        v = ID2SYM(r_symlink(arg));
        break;

      default:
        rb_raise(rb_eArgError, "dump format error(0x%x)", type);
        break;
    }
    return v;
}

static VALUE
r_object(struct load_arg *arg)
{
    return r_object0(arg, 0, Qnil);
}

static void
clear_load_arg(struct load_arg *arg)
{
    if (arg->buf) {
        xfree(arg->buf);
        arg->buf = 0;
    }
    arg->buflen = 0;
    arg->offset = 0;
    arg->readable = 0;
    if (!arg->symbols) return;
    st_free_table(arg->symbols);
    arg->symbols = 0;
    st_free_table(arg->data);
    arg->data = 0;
    st_free_table(arg->compat_tbl);
    arg->compat_tbl = 0;
}

/*
 * call-seq:
 *     load( source [, proc] ) -> obj
 *     restore( source [, proc] ) -> obj
 *
 * Returns the result of converting the serialized data in source into a
 * Ruby object (possibly with associated subordinate objects). source
 * may be either an instance of IO or an object that responds to
 * to_str. If proc is specified, it will be passed each object as it
 * is deserialized.
 *
 * Never pass untrusted data (including user supplied input) to this method.
 * Please see the overview for further details.
 */
static VALUE
marshal_load(int argc, VALUE *argv)
{
    VALUE port, proc;
    int major, minor, infection = 0;
    VALUE v;
    volatile VALUE wrapper;
    struct load_arg *arg;

    rb_scan_args(argc, argv, "11", &port, &proc);
    v = rb_check_string_type(port);
    if (!NIL_P(v)) {
        infection = (int)FL_TEST(port, MARSHAL_INFECTION); /* original taintedness */
        port = v;
    }
    else if (rb_respond_to(port, s_getbyte) && rb_respond_to(port, s_read)) {
        rb_check_funcall(port, s_binmode, 0, 0);
        infection = (int)(FL_TAINT | FL_TEST(port, FL_UNTRUSTED));
    }
    else {
        io_needed();
    }
    RB_GC_GUARD(wrapper) = TypedData_Make_Struct(rb_cData, struct load_arg, &load_arg_data, arg);
    arg->infection = infection;
    arg->src = port;
    arg->offset = 0;
    arg->symbols = st_init_numtable();
    arg->data    = st_init_numtable();
    arg->compat_tbl = st_init_numtable();
    arg->proc = 0;
    arg->readable = 0;

    if (NIL_P(v))
        arg->buf = xmalloc(BUFSIZ);
    else
        arg->buf = 0;

    major = r_byte(arg);
    minor = r_byte(arg);
    if (major != MARSHAL_MAJOR || minor > MARSHAL_MINOR) {
        clear_load_arg(arg);
        rb_raise(rb_eTypeError, "incompatible marshal file format (can't be read)\n\
\tformat version %d.%d required; %d.%d given",
                 MARSHAL_MAJOR, MARSHAL_MINOR, major, minor);
    }
    if (RTEST(ruby_verbose) && minor != MARSHAL_MINOR) {
        rb_warn("incompatible marshal file format (can be read)\n\
\tformat version %d.%d required; %d.%d given",
                MARSHAL_MAJOR, MARSHAL_MINOR, major, minor);
    }

    if (!NIL_P(proc)) arg->proc = proc;
    v = r_object(arg);
    clear_load_arg(arg);
    RB_GC_GUARD(wrapper);

    return v;
}

/*
 * The marshaling library converts collections of Ruby objects into a
 * byte stream, allowing them to be stored outside the currently
 * active script. This data may subsequently be read and the original
 * objects reconstituted.
 *
 * Marshaled data has major and minor version numbers stored along
 * with the object information. In normal use, marshaling can only
 * load data written with the same major version number and an equal
 * or lower minor version number. If Ruby's ``verbose'' flag is set
 * (normally using -d, -v, -w, or --verbose) the major and minor
 * numbers must match exactly. Marshal versioning is independent of
 * Ruby's version numbers. You can extract the version by reading the
 * first two bytes of marshaled data.
 *
 *     str = Marshal.dump("thing")
 *     RUBY_VERSION   #=> "1.9.0"
 *     str[0].ord     #=> 4
 *     str[1].ord     #=> 8
 *
 * Some objects cannot be dumped: if the objects to be dumped include
 * bindings, procedure or method objects, instances of class IO, or
 * singleton objects, a TypeError will be raised.
 *
 * If your class has special serialization needs (for example, if you
 * want to serialize in some specific format), or if it contains
 * objects that would otherwise not be serializable, you can implement
 * your own serialization strategy.
 *
 * There are two methods of doing this, your object can define either
 * marshal_dump and marshal_load or _dump and _load.  marshal_dump will take
 * precedence over _dump if both are defined.  marshal_dump may result in
 * smaller Marshal strings.
 *
 * == Security considerations
 *
 * By design, Marshal.load can deserialize almost any class loaded into the
 * Ruby process. In many cases this can lead to remote code execution if the
 * Marshal data is loaded from an untrusted source.
 *
 * As a result, Marshal.load is not suitable as a general purpose serialization
 * format and you should never unmarshal user supplied input or other untrusted
 * data.
 *
 * If you need to deserialize untrusted data, use JSON or another serialization
 * format that is only able to load simple, 'primitive' types such as String,
 * Array, Hash, etc. Never allow user input to specify arbitrary types to
 * deserialize into.
 *
 * == marshal_dump and marshal_load
 *
 * When dumping an object the method marshal_dump will be called.
 * marshal_dump must return a result containing the information necessary for
 * marshal_load to reconstitute the object.  The result can be any object.
 *
 * When loading an object dumped using marshal_dump the object is first
 * allocated then marshal_load is called with the result from marshal_dump.
 * marshal_load must recreate the object from the information in the result.
 *
 * Example:
 *
 *   class MyObj
 *     def initialize name, version, data
 *       @name    = name
 *       @version = version
 *       @data    = data
 *     end
 *
 *     def marshal_dump
 *       [@name, @version]
 *     end
 *
 *     def marshal_load array
 *       @name, @version = array
 *     end
 *   end
 *
 * == _dump and _load
 *
 * Use _dump and _load when you need to allocate the object you're restoring
 * yourself.
 *
 * When dumping an object the instance method _dump is called with an Integer
 * which indicates the maximum depth of objects to dump (a value of -1 implies
 * that you should disable depth checking).  _dump must return a String
 * containing the information necessary to reconstitute the object.
 *
 * The class method _load should take a String and use it to return an object
 * of the same class.
 *
 * Example:
 *
 *   class MyObj
 *     def initialize name, version, data
 *       @name    = name
 *       @version = version
 *       @data    = data
 *     end
 *
 *     def _dump level
 *       [@name, @version].join ':'
 *     end
 *
 *     def self._load args
 *       new(*args.split(':'))
 *     end
 *   end
 *
 * Since Marhsal.dump outputs a string you can have _dump return a Marshal
 * string which is Marshal.loaded in _load for complex objects.
 */
void
Init_marshal(void)
{
#undef rb_intern
#define rb_intern(str) rb_intern_const(str)

    VALUE rb_mMarshal = rb_define_module("Marshal");

    s_dump = rb_intern("_dump");
    s_load = rb_intern("_load");
    s_mdump = rb_intern("marshal_dump");
    s_mload = rb_intern("marshal_load");
    s_dump_data = rb_intern("_dump_data");
    s_load_data = rb_intern("_load_data");
    s_alloc = rb_intern("_alloc");
    s_call = rb_intern("call");
    s_getbyte = rb_intern("getbyte");
    s_read = rb_intern("read");
    s_write = rb_intern("write");
    s_binmode = rb_intern("binmode");

    rb_define_module_function(rb_mMarshal, "dump", marshal_dump, -1);
    rb_define_module_function(rb_mMarshal, "load", marshal_load, -1);
    rb_define_module_function(rb_mMarshal, "restore", marshal_load, -1);

    rb_define_const(rb_mMarshal, "MAJOR_VERSION", INT2FIX(MARSHAL_MAJOR));
    rb_define_const(rb_mMarshal, "MINOR_VERSION", INT2FIX(MARSHAL_MINOR));

    compat_allocator_tbl = st_init_numtable();
    compat_allocator_tbl_wrapper =
        Data_Wrap_Struct(rb_cData, mark_marshal_compat_t, 0, compat_allocator_tbl);
    rb_gc_register_mark_object(compat_allocator_tbl_wrapper);
}

VALUE
rb_marshal_dump(VALUE obj, VALUE port)
{
    int argc = 1;
    VALUE argv[2];

    argv[0] = obj;
    argv[1] = port;
    if (!NIL_P(port)) argc = 2;
    return marshal_dump(argc, argv);
}

VALUE
rb_marshal_load(VALUE port)
{
    return marshal_load(1, &port);
}

---