duktape-1.8.0/src-separate/duk_api_bytecode.c

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/*
 *  Bytecode dump/load
 *
 *  The bytecode load primitive is more important performance-wise than the
 *  dump primitive.
 *
 *  Unlike most Duktape API calls, bytecode dump/load is not guaranteed to be
 *  memory safe for invalid arguments - caller beware!  There's little point
 *  in trying to achieve memory safety unless bytecode instructions are also
 *  validated which is not easy to do with indirect register references etc.
 */
 
#include "duk_internal.h"
 
#if defined(DUK_USE_BYTECODE_DUMP_SUPPORT)
 
#define DUK__SER_MARKER  0xff
#define DUK__SER_VERSION 0x00
#define DUK__SER_STRING  0x00
#define DUK__SER_NUMBER  0x01
#define DUK__BYTECODE_INITIAL_ALLOC 256
 
/*
 *  Dump/load helpers, xxx_raw() helpers do no buffer checks
 */
 
DUK_LOCAL duk_uint8_t *duk__load_string_raw(duk_context *ctx, duk_uint8_t *p) {
    duk_uint32_t len;
 
    len = DUK_RAW_READ_U32_BE(p);
    duk_push_lstring(ctx, (const char *) p, len);
    p += len;
    return p;
}
 
DUK_LOCAL duk_uint8_t *duk__load_buffer_raw(duk_context *ctx, duk_uint8_t *p) {
    duk_uint32_t len;
    duk_uint8_t *buf;
 
    len = DUK_RAW_READ_U32_BE(p);
    buf = (duk_uint8_t *) duk_push_fixed_buffer(ctx, (duk_size_t) len);
    DUK_ASSERT(buf != NULL);
    DUK_MEMCPY((void *) buf, (const void *) p, (size_t) len);
    p += len;
    return p;
}
 
DUK_LOCAL duk_uint8_t *duk__dump_hstring_raw(duk_uint8_t *p, duk_hstring *h) {
    duk_size_t len;
    duk_uint32_t tmp32;
 
    DUK_ASSERT(h != NULL);
 
    len = DUK_HSTRING_GET_BYTELEN(h);
    DUK_ASSERT(len <= 0xffffffffUL);  /* string limits */
    tmp32 = (duk_uint32_t) len;
    DUK_RAW_WRITE_U32_BE(p, tmp32);
    DUK_MEMCPY((void *) p,
               (const void *) DUK_HSTRING_GET_DATA(h),
               len);
    p += len;
    return p;
}
 
DUK_LOCAL duk_uint8_t *duk__dump_hbuffer_raw(duk_hthread *thr, duk_uint8_t *p, duk_hbuffer *h) {
    duk_size_t len;
    duk_uint32_t tmp32;
 
    DUK_ASSERT(thr != NULL);
    DUK_ASSERT(h != NULL);
    DUK_UNREF(thr);
 
    len = DUK_HBUFFER_GET_SIZE(h);
    DUK_ASSERT(len <= 0xffffffffUL);  /* buffer limits */
    tmp32 = (duk_uint32_t) len;
    DUK_RAW_WRITE_U32_BE(p, tmp32);
    DUK_MEMCPY((void *) p,
               (const void *) DUK_HBUFFER_GET_DATA_PTR(thr->heap, h),
               len);
    p += len;
    return p;
}
 
DUK_LOCAL duk_uint8_t *duk__dump_string_prop(duk_hthread *thr, duk_uint8_t *p, duk_bufwriter_ctx *bw_ctx, duk_hobject *func, duk_small_uint_t stridx) {
    duk_hstring *h_str;
    duk_tval *tv;
 
    tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, (duk_hobject *) func, DUK_HTHREAD_GET_STRING(thr, stridx));
    if (tv != NULL && DUK_TVAL_IS_STRING(tv)) {
        h_str = DUK_TVAL_GET_STRING(tv);
        DUK_ASSERT(h_str != NULL);
    } else {
        h_str = DUK_HTHREAD_STRING_EMPTY_STRING(thr);
        DUK_ASSERT(h_str != NULL);
    }
    DUK_ASSERT(DUK_HSTRING_MAX_BYTELEN <= 0x7fffffffUL);  /* ensures no overflow */
    p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 4 + DUK_HSTRING_GET_BYTELEN(h_str), p);
    p = duk__dump_hstring_raw(p, h_str);
    return p;
}
 
DUK_LOCAL duk_uint8_t *duk__dump_buffer_prop(duk_hthread *thr, duk_uint8_t *p, duk_bufwriter_ctx *bw_ctx, duk_hobject *func, duk_small_uint_t stridx) {
    duk_tval *tv;
 
    tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, (duk_hobject *) func, DUK_HTHREAD_GET_STRING(thr, stridx));
    if (tv != NULL && DUK_TVAL_IS_BUFFER(tv)) {
        duk_hbuffer *h_buf;
        h_buf = DUK_TVAL_GET_BUFFER(tv);
        DUK_ASSERT(h_buf != NULL);
        DUK_ASSERT(DUK_HBUFFER_MAX_BYTELEN <= 0x7fffffffUL);  /* ensures no overflow */
        p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 4 + DUK_HBUFFER_GET_SIZE(h_buf), p);
        p = duk__dump_hbuffer_raw(thr, p, h_buf);
    } else {
        p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 4, p);
        DUK_RAW_WRITE_U32_BE(p, 0);
    }
    return p;
}
 
DUK_LOCAL duk_uint8_t *duk__dump_uint32_prop(duk_hthread *thr, duk_uint8_t *p, duk_bufwriter_ctx *bw_ctx, duk_hobject *func, duk_small_uint_t stridx, duk_uint32_t def_value) {
    duk_tval *tv;
    duk_uint32_t val;
 
    tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, (duk_hobject *) func, DUK_HTHREAD_GET_STRING(thr, stridx));
    if (tv != NULL && DUK_TVAL_IS_NUMBER(tv)) {
        val = (duk_uint32_t) DUK_TVAL_GET_NUMBER(tv);
    } else {
        val = def_value;
    }
    p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 4, p);
    DUK_RAW_WRITE_U32_BE(p, val);
    return p;
}
 
DUK_LOCAL duk_uint8_t *duk__dump_varmap(duk_hthread *thr, duk_uint8_t *p, duk_bufwriter_ctx *bw_ctx, duk_hobject *func) {
    duk_tval *tv;
 
    tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, (duk_hobject *) func, DUK_HTHREAD_STRING_INT_VARMAP(thr));
    if (tv != NULL && DUK_TVAL_IS_OBJECT(tv)) {
        duk_hobject *h;
        duk_uint_fast32_t i;
 
        h = DUK_TVAL_GET_OBJECT(tv);
        DUK_ASSERT(h != NULL);
 
        /* We know _Varmap only has own properties so walk property
         * table directly.  We also know _Varmap is dense and all
         * values are numbers; assert for these.  GC and finalizers
         * shouldn't affect _Varmap so side effects should be fine.
         */
        for (i = 0; i < (duk_uint_fast32_t) DUK_HOBJECT_GET_ENEXT(h); i++) {
            duk_hstring *key;
            duk_tval *tv_val;
            duk_uint32_t val;
 
            key = DUK_HOBJECT_E_GET_KEY(thr->heap, h, i);
            DUK_ASSERT(key != NULL);  /* _Varmap is dense */
            DUK_ASSERT(!DUK_HOBJECT_E_SLOT_IS_ACCESSOR(thr->heap, h, i));
            tv_val = DUK_HOBJECT_E_GET_VALUE_TVAL_PTR(thr->heap, h, i);
            DUK_ASSERT(tv_val != NULL);
            DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv_val));  /* known to be number; in fact an integer */
#if defined(DUK_USE_FASTINT)
            DUK_ASSERT(DUK_TVAL_IS_FASTINT(tv_val));
            DUK_ASSERT(DUK_TVAL_GET_FASTINT(tv_val) == (duk_int64_t) DUK_TVAL_GET_FASTINT_U32(tv_val));  /* known to be 32-bit */
            val = DUK_TVAL_GET_FASTINT_U32(tv_val);
#else
            val = (duk_uint32_t) DUK_TVAL_GET_NUMBER(tv_val);
#endif
 
            DUK_ASSERT(DUK_HSTRING_MAX_BYTELEN <= 0x7fffffffUL);  /* ensures no overflow */
            p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 4 + DUK_HSTRING_GET_BYTELEN(key) + 4, p);
            p = duk__dump_hstring_raw(p, key);
            DUK_RAW_WRITE_U32_BE(p, val);
        }
    }
    p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 4, p);
    DUK_RAW_WRITE_U32_BE(p, 0);  /* end of _Varmap */
    return p;
}
 
DUK_LOCAL duk_uint8_t *duk__dump_formals(duk_hthread *thr, duk_uint8_t *p, duk_bufwriter_ctx *bw_ctx, duk_hobject *func) {
    duk_tval *tv;
 
    tv = duk_hobject_find_existing_entry_tval_ptr(thr->heap, (duk_hobject *) func, DUK_HTHREAD_STRING_INT_FORMALS(thr));
    if (tv != NULL && DUK_TVAL_IS_OBJECT(tv)) {
        duk_hobject *h;
        duk_uint_fast32_t i;
 
        h = DUK_TVAL_GET_OBJECT(tv);
        DUK_ASSERT(h != NULL);
 
        /* We know _Formals is dense and all entries will be in the
         * array part.  GC and finalizers shouldn't affect _Formals
         * so side effects should be fine.
         */
        for (i = 0; i < (duk_uint_fast32_t) DUK_HOBJECT_GET_ASIZE(h); i++) {
            duk_tval *tv_val;
            duk_hstring *varname;
 
            tv_val = DUK_HOBJECT_A_GET_VALUE_PTR(thr->heap, h, i);
            DUK_ASSERT(tv_val != NULL);
            if (DUK_TVAL_IS_STRING(tv_val)) {
                /* Array is dense and contains only strings, but ASIZE may
                 * be larger than used part and there are UNUSED entries.
                 */
                varname = DUK_TVAL_GET_STRING(tv_val);
                DUK_ASSERT(varname != NULL);
 
                DUK_ASSERT(DUK_HSTRING_MAX_BYTELEN <= 0x7fffffffUL);  /* ensures no overflow */
                p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 4 + DUK_HSTRING_GET_BYTELEN(varname), p);
                p = duk__dump_hstring_raw(p, varname);
            }
        }
    }
    p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 4, p);
    DUK_RAW_WRITE_U32_BE(p, 0);  /* end of _Formals */
    return p;
}
 
static duk_uint8_t *duk__dump_func(duk_context *ctx, duk_hcompiledfunction *func, duk_bufwriter_ctx *bw_ctx, duk_uint8_t *p) {
    duk_hthread *thr;
    duk_tval *tv, *tv_end;
    duk_instr_t *ins, *ins_end;
    duk_hobject **fn, **fn_end;
    duk_hstring *h_str;
    duk_uint32_t count_instr;
    duk_uint32_t tmp32;
    duk_uint16_t tmp16;
    duk_double_t d;
 
    thr = (duk_hthread *) ctx;
    DUK_UNREF(ctx);
    DUK_UNREF(thr);
 
    DUK_DD(DUK_DDPRINT("dumping function %p to %p: "
                       "consts=[%p,%p[ (%ld bytes, %ld items), "
                       "funcs=[%p,%p[ (%ld bytes, %ld items), "
                       "code=[%p,%p[ (%ld bytes, %ld items)",
                       (void *) func,
                       (void *) p,
                       (void *) DUK_HCOMPILEDFUNCTION_GET_CONSTS_BASE(thr->heap, func),
                       (void *) DUK_HCOMPILEDFUNCTION_GET_CONSTS_END(thr->heap, func),
                       (long) DUK_HCOMPILEDFUNCTION_GET_CONSTS_SIZE(thr->heap, func),
                       (long) DUK_HCOMPILEDFUNCTION_GET_CONSTS_COUNT(thr->heap, func),
                       (void *) DUK_HCOMPILEDFUNCTION_GET_FUNCS_BASE(thr->heap, func),
                       (void *) DUK_HCOMPILEDFUNCTION_GET_FUNCS_END(thr->heap, func),
                       (long) DUK_HCOMPILEDFUNCTION_GET_FUNCS_SIZE(thr->heap, func),
                       (long) DUK_HCOMPILEDFUNCTION_GET_FUNCS_COUNT(thr->heap, func),
                       (void *) DUK_HCOMPILEDFUNCTION_GET_CODE_BASE(thr->heap, func),
                       (void *) DUK_HCOMPILEDFUNCTION_GET_CODE_END(thr->heap, func),
                       (long) DUK_HCOMPILEDFUNCTION_GET_CODE_SIZE(thr->heap, func),
                       (long) DUK_HCOMPILEDFUNCTION_GET_CODE_COUNT(thr->heap, func)));
 
    DUK_ASSERT(DUK_USE_ESBC_MAX_BYTES <= 0x7fffffffUL);  /* ensures no overflow */
    count_instr = (duk_uint32_t) DUK_HCOMPILEDFUNCTION_GET_CODE_COUNT(thr->heap, func);
    p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 3 * 4 + 2 * 2 + 3 * 4 + count_instr * 4, p);
 
    /* Fixed header info. */
    tmp32 = count_instr;
    DUK_RAW_WRITE_U32_BE(p, tmp32);
    tmp32 = (duk_uint32_t) DUK_HCOMPILEDFUNCTION_GET_CONSTS_COUNT(thr->heap, func);
    DUK_RAW_WRITE_U32_BE(p, tmp32);
    tmp32 = (duk_uint32_t) DUK_HCOMPILEDFUNCTION_GET_FUNCS_COUNT(thr->heap, func);
    DUK_RAW_WRITE_U32_BE(p, tmp32);
    tmp16 = func->nregs;
    DUK_RAW_WRITE_U16_BE(p, tmp16);
    tmp16 = func->nargs;
    DUK_RAW_WRITE_U16_BE(p, tmp16);
#if defined(DUK_USE_DEBUGGER_SUPPORT)
    tmp32 = func->start_line;
    DUK_RAW_WRITE_U32_BE(p, tmp32);
    tmp32 = func->end_line;
    DUK_RAW_WRITE_U32_BE(p, tmp32);
#else
    DUK_RAW_WRITE_U32_BE(p, 0);
    DUK_RAW_WRITE_U32_BE(p, 0);
#endif
    tmp32 = ((duk_heaphdr *) func)->h_flags & DUK_HEAPHDR_FLAGS_FLAG_MASK;
    DUK_RAW_WRITE_U32_BE(p, tmp32);
 
    /* Bytecode instructions: endian conversion needed unless
     * platform is big endian.
     */
    ins = DUK_HCOMPILEDFUNCTION_GET_CODE_BASE(thr->heap, func);
    ins_end = DUK_HCOMPILEDFUNCTION_GET_CODE_END(thr->heap, func);
    DUK_ASSERT((duk_size_t) (ins_end - ins) == (duk_size_t) count_instr);
#if defined(DUK_USE_INTEGER_BE)
    DUK_MEMCPY((void *) p, (const void *) ins, (size_t) (ins_end - ins));
    p += (size_t) (ins_end - ins);
#else
    while (ins != ins_end) {
        tmp32 = (duk_uint32_t) (*ins);
        DUK_RAW_WRITE_U32_BE(p, tmp32);
        ins++;
    }
#endif
 
    /* Constants: variable size encoding. */
    tv = DUK_HCOMPILEDFUNCTION_GET_CONSTS_BASE(thr->heap, func);
    tv_end = DUK_HCOMPILEDFUNCTION_GET_CONSTS_END(thr->heap, func);
    while (tv != tv_end) {
        /* constants are strings or numbers now */
        DUK_ASSERT(DUK_TVAL_IS_STRING(tv) ||
                   DUK_TVAL_IS_NUMBER(tv));
 
        if (DUK_TVAL_IS_STRING(tv)) {
            h_str = DUK_TVAL_GET_STRING(tv);
            DUK_ASSERT(h_str != NULL);
            DUK_ASSERT(DUK_HSTRING_MAX_BYTELEN <= 0x7fffffffUL);  /* ensures no overflow */
            p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 1 + 4 + DUK_HSTRING_GET_BYTELEN(h_str), p),
            *p++ = DUK__SER_STRING;
            p = duk__dump_hstring_raw(p, h_str);
        } else {
            DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv));
            p = DUK_BW_ENSURE_RAW(thr, bw_ctx, 1 + 8, p);
            *p++ = DUK__SER_NUMBER;
            d = DUK_TVAL_GET_NUMBER(tv);
            DUK_RAW_WRITE_DOUBLE_BE(p, d);
        }
        tv++;
    }
 
    /* Inner functions recursively. */
    fn = (duk_hobject **) DUK_HCOMPILEDFUNCTION_GET_FUNCS_BASE(thr->heap, func);
    fn_end = (duk_hobject **) DUK_HCOMPILEDFUNCTION_GET_FUNCS_END(thr->heap, func);
    while (fn != fn_end) {
        /* XXX: This causes recursion up to inner function depth
         * which is normally not an issue, e.g. mark-and-sweep uses
         * a recursion limiter to avoid C stack issues.  Avoiding
         * this would mean some sort of a work list or just refusing
         * to serialize deep functions.
         */
        DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(*fn));
        p = duk__dump_func(ctx, (duk_hcompiledfunction *) *fn, bw_ctx, p);
        fn++;
    }
 
    /* Object extra properties.
     *
     * There are some difference between function templates and functions.
     * For example, function templates don't have .length and nargs is
     * normally used to instantiate the functions.
     */
 
    p = duk__dump_uint32_prop(thr, p, bw_ctx, (duk_hobject *) func, DUK_STRIDX_LENGTH, (duk_uint32_t) func->nargs);
    p = duk__dump_string_prop(thr, p, bw_ctx, (duk_hobject *) func, DUK_STRIDX_NAME);
    p = duk__dump_string_prop(thr, p, bw_ctx, (duk_hobject *) func, DUK_STRIDX_FILE_NAME);
    p = duk__dump_buffer_prop(thr, p, bw_ctx, (duk_hobject *) func, DUK_STRIDX_INT_PC2LINE);
    p = duk__dump_varmap(thr, p, bw_ctx, (duk_hobject *) func);
    p = duk__dump_formals(thr, p, bw_ctx, (duk_hobject *) func);
 
    DUK_DD(DUK_DDPRINT("serialized function %p -> final pointer %p", (void *) func, (void *) p));
 
    return p;
}
 
/* Load a function from bytecode.  The function object returned here must
 * match what is created by duk_js_push_closure() with respect to its flags,
 * properties, etc.
 *
 * NOTE: there are intentionally no input buffer length / bound checks.
 * Adding them would be easy but wouldn't ensure memory safety as untrusted
 * or broken bytecode is unsafe during execution unless the opcodes themselves
 * are validated (which is quite complex, especially for indirect opcodes).
 */
 
#define DUK__ASSERT_LEFT(n) do { \
        DUK_ASSERT((duk_size_t) (p_end - p) >= (duk_size_t) (n)); \
    } while (0)
 
static duk_uint8_t *duk__load_func(duk_context *ctx, duk_uint8_t *p, duk_uint8_t *p_end) {
    duk_hthread *thr;
    duk_hcompiledfunction *h_fun;
    duk_hbuffer *h_data;
    duk_size_t data_size;
    duk_uint32_t count_instr, count_const, count_funcs;
    duk_uint32_t n;
    duk_uint32_t tmp32;
    duk_small_uint_t const_type;
    duk_uint8_t *fun_data;
    duk_uint8_t *q;
    duk_idx_t idx_base;
    duk_tval *tv1;
    duk_uarridx_t arr_idx;
 
    /* XXX: There's some overlap with duk_js_closure() here, but
     * seems difficult to share code.  Ensure that the final function
     * looks the same as created by duk_js_closure().
     */
 
    DUK_ASSERT(ctx != NULL);
    thr = (duk_hthread *) ctx;
 
    DUK_DD(DUK_DDPRINT("loading function, p=%p, p_end=%p", (void *) p, (void *) p_end));
 
    DUK__ASSERT_LEFT(3 * 4);
    count_instr = DUK_RAW_READ_U32_BE(p);
    count_const = DUK_RAW_READ_U32_BE(p);
    count_funcs = DUK_RAW_READ_U32_BE(p);
 
    data_size = sizeof(duk_tval) * count_const +
                sizeof(duk_hobject *) * count_funcs +
                sizeof(duk_instr_t) * count_instr;
 
    DUK_DD(DUK_DDPRINT("instr=%ld, const=%ld, funcs=%ld, data_size=%ld",
                       (long) count_instr, (long) count_const,
                       (long) count_const, (long) data_size));
 
    /* Value stack is used to ensure reachability of constants and
     * inner functions being loaded.  Require enough space to handle
     * large functions correctly.
     */
    duk_require_stack(ctx, 2 + count_const + count_funcs);
    idx_base = duk_get_top(ctx);
 
    /* Push function object, init flags etc.  This must match
     * duk_js_push_closure() quite carefully.
     */
    duk_push_compiledfunction(ctx);
    h_fun = duk_get_hcompiledfunction(ctx, -1);
    DUK_ASSERT(h_fun != NULL);
    DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION((duk_hobject *) h_fun));
    DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_DATA(thr->heap, h_fun) == NULL);
    DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_FUNCS(thr->heap, h_fun) == NULL);
    DUK_ASSERT(DUK_HCOMPILEDFUNCTION_GET_BYTECODE(thr->heap, h_fun) == NULL);
 
    h_fun->nregs = DUK_RAW_READ_U16_BE(p);
    h_fun->nargs = DUK_RAW_READ_U16_BE(p);
#if defined(DUK_USE_DEBUGGER_SUPPORT)
    h_fun->start_line = DUK_RAW_READ_U32_BE(p);
    h_fun->end_line = DUK_RAW_READ_U32_BE(p);
#else
    p += 8;  /* skip line info */
#endif
 
    /* duk_hcompiledfunction flags; quite version specific */
    tmp32 = DUK_RAW_READ_U32_BE(p);
    DUK_HEAPHDR_SET_FLAGS((duk_heaphdr *) h_fun, tmp32);
 
    /* standard prototype */
    DUK_HOBJECT_SET_PROTOTYPE_UPDREF(thr, &h_fun->obj, thr->builtins[DUK_BIDX_FUNCTION_PROTOTYPE]);
 
    /* assert just a few critical flags */
    DUK_ASSERT(DUK_HEAPHDR_GET_TYPE((duk_heaphdr *) h_fun) == DUK_HTYPE_OBJECT);
    DUK_ASSERT(!DUK_HOBJECT_HAS_BOUND(&h_fun->obj));
    DUK_ASSERT(DUK_HOBJECT_HAS_COMPILEDFUNCTION(&h_fun->obj));
    DUK_ASSERT(!DUK_HOBJECT_HAS_NATIVEFUNCTION(&h_fun->obj));
    DUK_ASSERT(!DUK_HOBJECT_HAS_THREAD(&h_fun->obj));
    DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_ARRAY(&h_fun->obj));
    DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_STRINGOBJ(&h_fun->obj));
    DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_ARGUMENTS(&h_fun->obj));
 
    /* Create function 'data' buffer but don't attach it yet. */
    fun_data = (duk_uint8_t *) duk_push_fixed_buffer(ctx, data_size);
    DUK_ASSERT(fun_data != NULL);
 
    /* Load bytecode instructions. */
    DUK_ASSERT(sizeof(duk_instr_t) == 4);
    DUK__ASSERT_LEFT(count_instr * sizeof(duk_instr_t));
#if defined(DUK_USE_INTEGER_BE)
    q = fun_data + sizeof(duk_tval) * count_const + sizeof(duk_hobject *) * count_funcs;
    DUK_MEMCPY((void *) q,
               (const void *) p,
               sizeof(duk_instr_t) * count_instr);
    p += sizeof(duk_instr_t) * count_instr;
#else
    q = fun_data + sizeof(duk_tval) * count_const + sizeof(duk_hobject *) * count_funcs;
    for (n = count_instr; n > 0; n--) {
        *((duk_instr_t *) (void *) q) = DUK_RAW_READ_U32_BE(p);
        q += sizeof(duk_instr_t);
    }
#endif
 
    /* Load constants onto value stack but don't yet copy to buffer. */
    for (n = count_const; n > 0; n--) {
        DUK__ASSERT_LEFT(1);
        const_type = DUK_RAW_READ_U8(p);
        switch (const_type) {
        case DUK__SER_STRING: {
            p = duk__load_string_raw(ctx, p);
            break;
        }
        case DUK__SER_NUMBER: {
            /* Important to do a fastint check so that constants are
             * properly read back as fastints.
             */
            duk_tval tv_tmp;
            duk_double_t val;
            DUK__ASSERT_LEFT(8);
            val = DUK_RAW_READ_DOUBLE_BE(p);
            DUK_TVAL_SET_NUMBER_CHKFAST(&tv_tmp, val);
            duk_push_tval(ctx, &tv_tmp);
            break;
        }
        default: {
            goto format_error;
        }
        }
    }
 
    /* Load inner functions to value stack, but don't yet copy to buffer. */
    for (n = count_funcs; n > 0; n--) {
        p = duk__load_func(ctx, p, p_end);
        if (p == NULL) {
            goto format_error;
        }
    }
 
    /* With constants and inner functions on value stack, we can now
     * atomically finish the function 'data' buffer, bump refcounts,
     * etc.
     *
     * Here we take advantage of the value stack being just a duk_tval
     * array: we can just memcpy() the constants as long as we incref
     * them afterwards.
     */
 
    h_data = (duk_hbuffer *) duk_get_hbuffer(ctx, idx_base + 1);
    DUK_ASSERT(h_data != NULL);
    DUK_ASSERT(!DUK_HBUFFER_HAS_DYNAMIC(h_data));
    DUK_HCOMPILEDFUNCTION_SET_DATA(thr->heap, h_fun, h_data);
    DUK_HBUFFER_INCREF(thr, h_data);
 
    tv1 = duk_get_tval(ctx, idx_base + 2);  /* may be NULL if no constants or inner funcs */
    DUK_ASSERT((count_const == 0 && count_funcs == 0) || tv1 != NULL);
 
    q = fun_data;
    if (count_const > 0) {
        /* Explicit zero size check to avoid NULL 'tv1'. */
        DUK_MEMCPY((void *) q, (const void *) tv1, sizeof(duk_tval) * count_const);
        for (n = count_const; n > 0; n--) {
            DUK_TVAL_INCREF_FAST(thr, (duk_tval *) (void *) q);  /* no side effects */
            q += sizeof(duk_tval);
        }
        tv1 += count_const;
    }
 
    DUK_HCOMPILEDFUNCTION_SET_FUNCS(thr->heap, h_fun, (duk_hobject **) (void *) q);
    for (n = count_funcs; n > 0; n--) {
        duk_hobject *h_obj;
 
        DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv1));
        h_obj = DUK_TVAL_GET_OBJECT(tv1);
        DUK_ASSERT(h_obj != NULL);
        tv1++;
        DUK_HOBJECT_INCREF(thr, h_obj);
 
        *((duk_hobject **) (void *) q) = h_obj;
        q += sizeof(duk_hobject *);
    }
 
    DUK_HCOMPILEDFUNCTION_SET_BYTECODE(thr->heap, h_fun, (duk_instr_t *) (void *) q);
 
    /* The function object is now reachable and refcounts are fine,
     * so we can pop off all the temporaries.
     */
    DUK_DDD(DUK_DDDPRINT("function is reachable, reset top; func: %!iT", duk_get_tval(ctx, idx_base)));
    duk_set_top(ctx, idx_base + 1);
 
    /* Setup function properties. */
    tmp32 = DUK_RAW_READ_U32_BE(p);
    duk_push_u32(ctx, tmp32);
    duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_LENGTH, DUK_PROPDESC_FLAGS_NONE);
 
    p = duk__load_string_raw(ctx, p);
    if (DUK_HOBJECT_HAS_NAMEBINDING((duk_hobject *) h_fun)) {
        /* Original function instance/template had NAMEBINDING.
         * Must create a lexical environment on loading to allow
         * recursive functions like 'function foo() { foo(); }'.
         */
        duk_hobject *proto;
 
        proto = thr->builtins[DUK_BIDX_GLOBAL_ENV];
        (void) duk_push_object_helper_proto(ctx,
                                            DUK_HOBJECT_FLAG_EXTENSIBLE |
                                            DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_DECENV),
                                            proto);
        duk_dup(ctx, -2);                                 /* -> [ func funcname env funcname ] */
        duk_dup(ctx, idx_base);                           /* -> [ func funcname env funcname func ] */
        duk_xdef_prop(ctx, -3, DUK_PROPDESC_FLAGS_NONE);  /* -> [ func funcname env ] */
        duk_xdef_prop_stridx(ctx, idx_base, DUK_STRIDX_INT_LEXENV, DUK_PROPDESC_FLAGS_WC);
        /* since closure has NEWENV, never define DUK_STRIDX_INT_VARENV, as it
         * will be ignored anyway
         */
    }
    duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_NAME, DUK_PROPDESC_FLAGS_NONE);
 
    p = duk__load_string_raw(ctx, p);
    duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_FILE_NAME, DUK_PROPDESC_FLAGS_WC);
 
    duk_push_object(ctx);
    duk_dup(ctx, -2);
    duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_CONSTRUCTOR, DUK_PROPDESC_FLAGS_WC);  /* func.prototype.constructor = func */
    duk_compact(ctx, -1);
    duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_PROTOTYPE, DUK_PROPDESC_FLAGS_W);
 
    p = duk__load_buffer_raw(ctx, p);
    duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_INT_PC2LINE, DUK_PROPDESC_FLAGS_WC);
 
    duk_push_object(ctx);  /* _Varmap */
    for (;;) {
        /* XXX: awkward */
        p = duk__load_string_raw(ctx, p);
        if (duk_get_length(ctx, -1) == 0) {
            duk_pop(ctx);
            break;
        }
        tmp32 = DUK_RAW_READ_U32_BE(p);
        duk_push_u32(ctx, tmp32);
        duk_put_prop(ctx, -3);
    }
    duk_compact(ctx, -1);
    duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_INT_VARMAP, DUK_PROPDESC_FLAGS_NONE);
 
    duk_push_array(ctx);  /* _Formals */
    for (arr_idx = 0; ; arr_idx++) {
        /* XXX: awkward */
        p = duk__load_string_raw(ctx, p);
        if (duk_get_length(ctx, -1) == 0) {
            duk_pop(ctx);
            break;
        }
        duk_put_prop_index(ctx, -2, arr_idx);
    }
    duk_compact(ctx, -1);
    duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_INT_FORMALS, DUK_PROPDESC_FLAGS_NONE);
 
    /* Return with final function pushed on stack top. */
    DUK_DD(DUK_DDPRINT("final loaded function: %!iT", duk_get_tval(ctx, -1)));
    DUK_ASSERT_TOP(ctx, idx_base + 1);
    return p;
 
 format_error:
    return NULL;
}
 
DUK_EXTERNAL void duk_dump_function(duk_context *ctx) {
    duk_hthread *thr;
    duk_hcompiledfunction *func;
    duk_bufwriter_ctx bw_ctx_alloc;
    duk_bufwriter_ctx *bw_ctx = &bw_ctx_alloc;
    duk_uint8_t *p;
 
    DUK_ASSERT(ctx != NULL);
    thr = (duk_hthread *) ctx;
 
    /* Bound functions don't have all properties so we'd either need to
     * lookup the non-bound target function or reject bound functions.
     * For now, bound functions are rejected.
     */
    func = duk_require_hcompiledfunction(ctx, -1);
    DUK_ASSERT(func != NULL);
    DUK_ASSERT(!DUK_HOBJECT_HAS_BOUND(&func->obj));
 
    /* Estimating the result size beforehand would be costly, so
     * start with a reasonable size and extend as needed.
     */
    DUK_BW_INIT_PUSHBUF(thr, bw_ctx, DUK__BYTECODE_INITIAL_ALLOC);
    p = DUK_BW_GET_PTR(thr, bw_ctx);
    *p++ = DUK__SER_MARKER;
    *p++ = DUK__SER_VERSION;
    p = duk__dump_func(ctx, func, bw_ctx, p);
    DUK_BW_SET_PTR(thr, bw_ctx, p);
    DUK_BW_COMPACT(thr, bw_ctx);
 
    DUK_DD(DUK_DDPRINT("serialized result: %!T", duk_get_tval(ctx, -1)));
 
    duk_remove(ctx, -2);  /* [ ... func buf ] -> [ ... buf ] */
}
 
DUK_EXTERNAL void duk_load_function(duk_context *ctx) {
    duk_hthread *thr;
    duk_uint8_t *p_buf, *p, *p_end;
    duk_size_t sz;
 
    DUK_ASSERT(ctx != NULL);
    thr = (duk_hthread *) ctx;
    DUK_UNREF(ctx);
 
    p_buf = (duk_uint8_t *) duk_require_buffer(ctx, -1, &sz);
    DUK_ASSERT(p_buf != NULL);
 
    /* The caller is responsible for being sure that bytecode being loaded
     * is valid and trusted.  Invalid bytecode can cause memory unsafe
     * behavior directly during loading or later during bytecode execution
     * (instruction validation would be quite complex to implement).
     *
     * This signature check is the only sanity check for detecting
     * accidental invalid inputs.  The initial 0xFF byte ensures no
     * ordinary string will be accepted by accident.
     */
    p = p_buf;
    p_end = p_buf + sz;
    if (sz < 2 || p[0] != DUK__SER_MARKER || p[1] != DUK__SER_VERSION) {
        goto format_error;
    }
    p += 2;
 
    p = duk__load_func(ctx, p, p_end);
    if (p == NULL) {
        goto format_error;
    }
 
    duk_remove(ctx, -2);  /* [ ... buf func ] -> [ ... func ] */
    return;
 
 format_error:
    DUK_ERROR_TYPE(thr, DUK_STR_DECODE_FAILED);
}
 
#undef DUK__SER_MARKER
#undef DUK__SER_VERSION
#undef DUK__SER_STRING
#undef DUK__SER_NUMBER
#undef DUK__BYTECODE_INITIAL_ALLOC
 
#else  /* DUK_USE_BYTECODE_DUMP_SUPPORT */
 
DUK_EXTERNAL void duk_dump_function(duk_context *ctx) {
    DUK_ERROR_UNSUPPORTED_DEFMSG((duk_hthread *) ctx);
}
 
DUK_EXTERNAL void duk_load_function(duk_context *ctx) {
    DUK_ERROR_UNSUPPORTED_DEFMSG((duk_hthread *) ctx);
}
 
#endif  /* DUK_USE_BYTECODE_DUMP_SUPPORT */