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Copy pathduk_api_stack.c
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6862 lines (5707 loc) · 199 KB
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/*
* API calls related to general value stack manipulation: resizing the value
* stack, pushing and popping values, type checking and reading values,
* coercing values, etc.
*
* Also contains internal functions (such as duk_get_tval()), defined
* in duk_api_internal.h, with semantics similar to the public API.
*/
/* XXX: repetition of stack pre-checks -> helper or macro or inline */
/* XXX: shared api error strings, and perhaps even throw code for rare cases? */
#include "duk_internal.h"
/*
* Forward declarations
*/
DUK_LOCAL_DECL duk_idx_t duk__push_c_function_raw(duk_hthread *thr, duk_c_function func, duk_idx_t nargs, duk_uint_t flags, duk_small_uint_t proto_bidx);
/*
* Global state for working around missing variadic macros
*/
#if !defined(DUK_USE_VARIADIC_MACROS)
DUK_EXTERNAL const char *duk_api_global_filename = NULL;
DUK_EXTERNAL duk_int_t duk_api_global_line = 0;
#endif
/*
* Misc helpers
*/
DUK_LOCAL const char * const duk__symbol_type_strings[4] = {
"hidden", "global", "local", "wellknown"
};
#if !defined(DUK_USE_PACKED_TVAL)
DUK_LOCAL const duk_uint_t duk__type_from_tag[] = {
DUK_TYPE_NUMBER,
DUK_TYPE_NUMBER, /* fastint */
DUK_TYPE_UNDEFINED,
DUK_TYPE_NULL,
DUK_TYPE_BOOLEAN,
DUK_TYPE_POINTER,
DUK_TYPE_LIGHTFUNC,
DUK_TYPE_NONE,
DUK_TYPE_STRING,
DUK_TYPE_OBJECT,
DUK_TYPE_BUFFER,
};
DUK_LOCAL const duk_uint_t duk__type_mask_from_tag[] = {
DUK_TYPE_MASK_NUMBER,
DUK_TYPE_MASK_NUMBER, /* fastint */
DUK_TYPE_MASK_UNDEFINED,
DUK_TYPE_MASK_NULL,
DUK_TYPE_MASK_BOOLEAN,
DUK_TYPE_MASK_POINTER,
DUK_TYPE_MASK_LIGHTFUNC,
DUK_TYPE_MASK_NONE,
DUK_TYPE_MASK_STRING,
DUK_TYPE_MASK_OBJECT,
DUK_TYPE_MASK_BUFFER,
};
#endif /* !DUK_USE_PACKED_TVAL */
/* Assert that there's room for one value. */
#define DUK__ASSERT_SPACE() do { \
DUK_ASSERT(!(thr->valstack_top >= thr->valstack_end)); \
} while (0)
/* Check that there's room to push one value. */
#if defined(DUK_USE_VALSTACK_UNSAFE)
/* Faster but value stack overruns are memory unsafe. */
#define DUK__CHECK_SPACE() DUK__ASSERT_SPACE()
#else
#define DUK__CHECK_SPACE() do { \
if (DUK_UNLIKELY(thr->valstack_top >= thr->valstack_end)) { \
DUK_ERROR_RANGE_PUSH_BEYOND(thr); \
} \
} while (0)
#endif
DUK_LOCAL duk_small_uint_t duk__get_symbol_type(duk_hstring *h) {
const duk_uint8_t *data;
duk_size_t len;
DUK_ASSERT(h != NULL);
DUK_ASSERT(DUK_HSTRING_HAS_SYMBOL(h));
DUK_ASSERT(DUK_HSTRING_GET_BYTELEN(h) >= 1); /* always true, symbol prefix */
data = (const duk_uint8_t *) DUK_HSTRING_GET_DATA(h);
len = DUK_HSTRING_GET_BYTELEN(h);
DUK_ASSERT(len >= 1);
/* XXX: differentiate between 0x82 and 0xff (hidden vs. internal?)? */
if (data[0] == 0xffU) {
return DUK_SYMBOL_TYPE_HIDDEN;
} else if (data[0] == 0x82U) {
return DUK_SYMBOL_TYPE_HIDDEN;
} else if (data[0] == 0x80U) {
return DUK_SYMBOL_TYPE_GLOBAL;
} else if (data[len - 1] != 0xffU) {
return DUK_SYMBOL_TYPE_LOCAL;
} else {
return DUK_SYMBOL_TYPE_WELLKNOWN;
}
}
DUK_LOCAL const char *duk__get_symbol_type_string(duk_hstring *h) {
duk_small_uint_t idx;
idx = duk__get_symbol_type(h);
DUK_ASSERT(idx < sizeof(duk__symbol_type_strings));
return duk__symbol_type_strings[idx];
}
DUK_LOCAL_DECL duk_heaphdr *duk__get_tagged_heaphdr_raw(duk_hthread *thr, duk_idx_t idx, duk_uint_t tag);
DUK_LOCAL duk_int_t duk__api_coerce_d2i(duk_hthread *thr, duk_idx_t idx, duk_int_t def_value, duk_bool_t require) {
duk_tval *tv;
duk_small_int_t c;
duk_double_t d;
tv = duk_get_tval_or_unused(thr, idx);
DUK_ASSERT(tv != NULL);
/*
* Special cases like NaN and +/- Infinity are handled explicitly
* because a plain C coercion from double to int handles these cases
* in undesirable ways. For instance, NaN may coerce to INT_MIN
* (not zero), and INT_MAX + 1 may coerce to INT_MIN (not INT_MAX).
*
* This double-to-int coercion differs from ToInteger() because it
* has a finite range (ToInteger() allows e.g. +/- Infinity). It
* also differs from ToInt32() because the INT_MIN/INT_MAX clamping
* depends on the size of the int type on the platform. In particular,
* on platforms with a 64-bit int type, the full range is allowed.
*/
#if defined(DUK_USE_FASTINT)
if (DUK_TVAL_IS_FASTINT(tv)) {
duk_int64_t t = DUK_TVAL_GET_FASTINT(tv);
#if (DUK_INT_MAX <= 0x7fffffffL)
/* Clamping only necessary for 32-bit ints. */
if (t < DUK_INT_MIN) {
t = DUK_INT_MIN;
} else if (t > DUK_INT_MAX) {
t = DUK_INT_MAX;
}
#endif
return (duk_int_t) t;
}
#endif
if (DUK_TVAL_IS_NUMBER(tv)) {
d = DUK_TVAL_GET_NUMBER(tv);
c = (duk_small_int_t) DUK_FPCLASSIFY(d);
if (c == DUK_FP_NAN) {
return 0;
} else if (d < (duk_double_t) DUK_INT_MIN) {
/* covers -Infinity */
return DUK_INT_MIN;
} else if (d > (duk_double_t) DUK_INT_MAX) {
/* covers +Infinity */
return DUK_INT_MAX;
} else {
/* coerce towards zero */
return (duk_int_t) d;
}
}
if (require) {
DUK_ERROR_REQUIRE_TYPE_INDEX(thr, idx, "number", DUK_STR_NOT_NUMBER);
DUK_WO_NORETURN(return 0;);
}
return def_value;
}
DUK_LOCAL duk_uint_t duk__api_coerce_d2ui(duk_hthread *thr, duk_idx_t idx, duk_uint_t def_value, duk_bool_t require) {
duk_tval *tv;
duk_small_int_t c;
duk_double_t d;
/* Same as above but for unsigned int range. */
tv = duk_get_tval_or_unused(thr, idx);
DUK_ASSERT(tv != NULL);
#if defined(DUK_USE_FASTINT)
if (DUK_TVAL_IS_FASTINT(tv)) {
duk_int64_t t = DUK_TVAL_GET_FASTINT(tv);
if (t < 0) {
t = 0;
}
#if (DUK_UINT_MAX <= 0xffffffffUL)
/* Clamping only necessary for 32-bit ints. */
else if (t > DUK_UINT_MAX) {
t = DUK_UINT_MAX;
}
#endif
return (duk_uint_t) t;
}
#endif
if (DUK_TVAL_IS_NUMBER(tv)) {
d = DUK_TVAL_GET_NUMBER(tv);
c = (duk_small_int_t) DUK_FPCLASSIFY(d);
if (c == DUK_FP_NAN) {
return 0;
} else if (d < 0.0) {
/* covers -Infinity */
return (duk_uint_t) 0;
} else if (d > (duk_double_t) DUK_UINT_MAX) {
/* covers +Infinity */
return (duk_uint_t) DUK_UINT_MAX;
} else {
/* coerce towards zero */
return (duk_uint_t) d;
}
}
if (require) {
DUK_ERROR_REQUIRE_TYPE_INDEX(thr, idx, "number", DUK_STR_NOT_NUMBER);
DUK_WO_NORETURN(return 0;);
}
return def_value;
}
/*
* Stack index validation/normalization and getting a stack duk_tval ptr.
*
* These are called by many API entrypoints so the implementations must be
* fast and "inlined".
*
* There's some repetition because of this; keep the functions in sync.
*/
DUK_EXTERNAL duk_idx_t duk_normalize_index(duk_hthread *thr, duk_idx_t idx) {
duk_uidx_t vs_size;
duk_uidx_t uidx;
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(DUK_INVALID_INDEX < 0);
/* Care must be taken to avoid pointer wrapping in the index
* validation. For instance, on a 32-bit platform with 8-byte
* duk_tval the index 0x20000000UL would wrap the memory space
* once.
*/
/* Assume value stack sizes (in elements) fits into duk_idx_t. */
DUK_ASSERT(thr->valstack_top >= thr->valstack_bottom);
vs_size = (duk_uidx_t) (thr->valstack_top - thr->valstack_bottom);
DUK_ASSERT_DISABLE(vs_size >= 0); /* unsigned */
if (idx < 0) {
uidx = vs_size + (duk_uidx_t) idx;
} else {
/* since index non-negative */
DUK_ASSERT(idx != DUK_INVALID_INDEX);
uidx = (duk_uidx_t) idx;
}
/* DUK_INVALID_INDEX won't be accepted as a valid index. */
DUK_ASSERT(vs_size + (duk_uidx_t) DUK_INVALID_INDEX >= vs_size);
if (DUK_LIKELY(uidx < vs_size)) {
return (duk_idx_t) uidx;
}
return DUK_INVALID_INDEX;
}
DUK_EXTERNAL duk_idx_t duk_require_normalize_index(duk_hthread *thr, duk_idx_t idx) {
duk_uidx_t vs_size;
duk_uidx_t uidx;
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(DUK_INVALID_INDEX < 0);
DUK_ASSERT(thr->valstack_top >= thr->valstack_bottom);
vs_size = (duk_uidx_t) (thr->valstack_top - thr->valstack_bottom);
DUK_ASSERT_DISABLE(vs_size >= 0); /* unsigned */
if (idx < 0) {
uidx = vs_size + (duk_uidx_t) idx;
} else {
DUK_ASSERT(idx != DUK_INVALID_INDEX);
uidx = (duk_uidx_t) idx;
}
/* DUK_INVALID_INDEX won't be accepted as a valid index. */
DUK_ASSERT(vs_size + (duk_uidx_t) DUK_INVALID_INDEX >= vs_size);
if (DUK_LIKELY(uidx < vs_size)) {
return (duk_idx_t) uidx;
}
DUK_ERROR_RANGE_INDEX(thr, idx);
DUK_WO_NORETURN(return 0;);
}
DUK_INTERNAL duk_tval *duk_get_tval(duk_hthread *thr, duk_idx_t idx) {
duk_uidx_t vs_size;
duk_uidx_t uidx;
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(DUK_INVALID_INDEX < 0);
DUK_ASSERT(thr->valstack_top >= thr->valstack_bottom);
vs_size = (duk_uidx_t) (thr->valstack_top - thr->valstack_bottom);
DUK_ASSERT_DISABLE(vs_size >= 0); /* unsigned */
if (idx < 0) {
uidx = vs_size + (duk_uidx_t) idx;
} else {
DUK_ASSERT(idx != DUK_INVALID_INDEX);
uidx = (duk_uidx_t) idx;
}
/* DUK_INVALID_INDEX won't be accepted as a valid index. */
DUK_ASSERT(vs_size + (duk_uidx_t) DUK_INVALID_INDEX >= vs_size);
if (DUK_LIKELY(uidx < vs_size)) {
return thr->valstack_bottom + uidx;
}
return NULL;
}
/* Variant of duk_get_tval() which is guaranteed to return a valid duk_tval
* pointer. When duk_get_tval() would return NULL, this variant returns a
* pointer to a duk_tval with tag DUK_TAG_UNUSED. This allows the call site
* to avoid an unnecessary NULL check which sometimes leads to better code.
* The return duk_tval is read only (at least for the UNUSED value).
*/
DUK_LOCAL const duk_tval_unused duk__const_tval_unused = DUK_TVAL_UNUSED_INITIALIZER();
DUK_INTERNAL duk_tval *duk_get_tval_or_unused(duk_hthread *thr, duk_idx_t idx) {
duk_tval *tv;
DUK_ASSERT_API_ENTRY(thr);
tv = duk_get_tval(thr, idx);
if (tv != NULL) {
return tv;
}
return (duk_tval *) DUK_LOSE_CONST(&duk__const_tval_unused);
}
DUK_INTERNAL duk_tval *duk_require_tval(duk_hthread *thr, duk_idx_t idx) {
duk_uidx_t vs_size;
duk_uidx_t uidx;
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(DUK_INVALID_INDEX < 0);
DUK_ASSERT(thr->valstack_top >= thr->valstack_bottom);
vs_size = (duk_uidx_t) (thr->valstack_top - thr->valstack_bottom);
DUK_ASSERT_DISABLE(vs_size >= 0); /* unsigned */
/* Use unsigned arithmetic to optimize comparison. */
if (idx < 0) {
uidx = vs_size + (duk_uidx_t) idx;
} else {
DUK_ASSERT(idx != DUK_INVALID_INDEX);
uidx = (duk_uidx_t) idx;
}
/* DUK_INVALID_INDEX won't be accepted as a valid index. */
DUK_ASSERT(vs_size + (duk_uidx_t) DUK_INVALID_INDEX >= vs_size);
if (DUK_LIKELY(uidx < vs_size)) {
return thr->valstack_bottom + uidx;
}
DUK_ERROR_RANGE_INDEX(thr, idx);
DUK_WO_NORETURN(return NULL;);
}
/* Non-critical. */
DUK_EXTERNAL duk_bool_t duk_is_valid_index(duk_hthread *thr, duk_idx_t idx) {
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(DUK_INVALID_INDEX < 0);
return (duk_normalize_index(thr, idx) >= 0);
}
/* Non-critical. */
DUK_EXTERNAL void duk_require_valid_index(duk_hthread *thr, duk_idx_t idx) {
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(DUK_INVALID_INDEX < 0);
if (DUK_UNLIKELY(duk_normalize_index(thr, idx) < 0)) {
DUK_ERROR_RANGE_INDEX(thr, idx);
DUK_WO_NORETURN(return;);
}
}
/*
* Value stack top handling
*/
DUK_EXTERNAL duk_idx_t duk_get_top(duk_hthread *thr) {
DUK_ASSERT_API_ENTRY(thr);
return (duk_idx_t) (thr->valstack_top - thr->valstack_bottom);
}
/* Internal helper to get current top but to require a minimum top value
* (TypeError if not met).
*/
DUK_INTERNAL duk_idx_t duk_get_top_require_min(duk_hthread *thr, duk_idx_t min_top) {
duk_idx_t ret;
DUK_ASSERT_API_ENTRY(thr);
ret = (duk_idx_t) (thr->valstack_top - thr->valstack_bottom);
if (DUK_UNLIKELY(ret < min_top)) {
DUK_ERROR_TYPE_INVALID_ARGS(thr);
DUK_WO_NORETURN(return 0;);
}
return ret;
}
/* Set stack top within currently allocated range, but don't reallocate.
* This is performance critical especially for call handling, so whenever
* changing, profile and look at generated code.
*/
DUK_EXTERNAL void duk_set_top(duk_hthread *thr, duk_idx_t idx) {
duk_uidx_t vs_size;
duk_uidx_t vs_limit;
duk_uidx_t uidx;
duk_tval *tv;
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(DUK_INVALID_INDEX < 0);
DUK_ASSERT(thr->valstack_top >= thr->valstack_bottom);
DUK_ASSERT(thr->valstack_end >= thr->valstack_bottom);
vs_size = (duk_uidx_t) (thr->valstack_top - thr->valstack_bottom);
vs_limit = (duk_uidx_t) (thr->valstack_end - thr->valstack_bottom);
if (idx < 0) {
/* Negative indices are always within allocated stack but
* must not go below zero index.
*/
uidx = vs_size + (duk_uidx_t) idx;
} else {
/* Positive index can be higher than valstack top but must
* not go above allocated stack (equality is OK).
*/
uidx = (duk_uidx_t) idx;
}
/* DUK_INVALID_INDEX won't be accepted as a valid index. */
DUK_ASSERT(vs_size + (duk_uidx_t) DUK_INVALID_INDEX >= vs_size);
DUK_ASSERT(vs_size + (duk_uidx_t) DUK_INVALID_INDEX >= vs_limit);
#if defined(DUK_USE_VALSTACK_UNSAFE)
DUK_ASSERT(uidx <= vs_limit);
DUK_UNREF(vs_limit);
#else
if (DUK_UNLIKELY(uidx > vs_limit)) {
DUK_ERROR_RANGE_INDEX(thr, idx);
DUK_WO_NORETURN(return;);
}
#endif
DUK_ASSERT(uidx <= vs_limit);
/* Handle change in value stack top. Respect value stack
* initialization policy: 'undefined' above top. Note that
* DECREF may cause a side effect that reallocates valstack,
* so must relookup after DECREF.
*/
if (uidx >= vs_size) {
/* Stack size increases or stays the same. */
#if defined(DUK_USE_ASSERTIONS)
duk_uidx_t count;
count = uidx - vs_size;
while (count != 0) {
count--;
tv = thr->valstack_top + count;
DUK_ASSERT(DUK_TVAL_IS_UNDEFINED(tv));
}
#endif
thr->valstack_top = thr->valstack_bottom + uidx;
} else {
/* Stack size decreases. */
#if defined(DUK_USE_REFERENCE_COUNTING)
duk_uidx_t count;
duk_tval *tv_end;
count = vs_size - uidx;
DUK_ASSERT(count > 0);
tv = thr->valstack_top;
tv_end = tv - count;
DUK_ASSERT(tv > tv_end); /* Because count > 0. */
do {
tv--;
DUK_ASSERT(tv >= thr->valstack_bottom);
DUK_TVAL_SET_UNDEFINED_UPDREF_NORZ(thr, tv);
} while (tv != tv_end);
thr->valstack_top = tv_end;
DUK_REFZERO_CHECK_FAST(thr);
#else /* DUK_USE_REFERENCE_COUNTING */
duk_uidx_t count;
duk_tval *tv_end;
count = vs_size - uidx;
tv = thr->valstack_top;
tv_end = tv - count;
DUK_ASSERT(tv > tv_end);
do {
tv--;
DUK_TVAL_SET_UNDEFINED(tv);
} while (tv != tv_end);
thr->valstack_top = tv_end;
#endif /* DUK_USE_REFERENCE_COUNTING */
}
}
/* Internal variant with a non-negative index and no runtime size checks. */
#if defined(DUK_USE_PREFER_SIZE)
DUK_INTERNAL void duk_set_top_unsafe(duk_hthread *thr, duk_idx_t idx) {
DUK_ASSERT_API_ENTRY(thr);
duk_set_top(thr, idx);
}
#else /* DUK_USE_PREFER_SIZE */
DUK_INTERNAL void duk_set_top_unsafe(duk_hthread *thr, duk_idx_t idx) {
duk_uidx_t uidx;
duk_uidx_t vs_size;
duk_tval *tv;
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(thr->valstack_top >= thr->valstack_bottom);
DUK_ASSERT(thr->valstack_end >= thr->valstack_bottom);
DUK_ASSERT(idx >= 0);
DUK_ASSERT(idx <= (duk_idx_t) (thr->valstack_end - thr->valstack_bottom));
/* XXX: byte arithmetic */
uidx = (duk_uidx_t) idx;
vs_size = (duk_uidx_t) (thr->valstack_top - thr->valstack_bottom);
if (uidx >= vs_size) {
/* Stack size increases or stays the same. */
#if defined(DUK_USE_ASSERTIONS)
duk_uidx_t count;
count = uidx - vs_size;
while (count != 0) {
count--;
tv = thr->valstack_top + count;
DUK_ASSERT(DUK_TVAL_IS_UNDEFINED(tv));
}
#endif
thr->valstack_top = thr->valstack_bottom + uidx;
} else {
/* Stack size decreases. */
#if defined(DUK_USE_REFERENCE_COUNTING)
duk_uidx_t count;
duk_tval *tv_end;
count = vs_size - uidx;
DUK_ASSERT(count > 0);
tv = thr->valstack_top;
tv_end = tv - count;
DUK_ASSERT(tv > tv_end); /* Because count > 0. */
do {
tv--;
DUK_ASSERT(tv >= thr->valstack_bottom);
DUK_TVAL_SET_UNDEFINED_UPDREF_NORZ(thr, tv);
} while (tv != tv_end);
thr->valstack_top = tv_end;
DUK_REFZERO_CHECK_FAST(thr);
#else /* DUK_USE_REFERENCE_COUNTING */
duk_uidx_t count;
duk_tval *tv_end;
count = vs_size - uidx;
tv = thr->valstack_top;
tv_end = tv - count;
DUK_ASSERT(tv > tv_end);
do {
tv--;
DUK_TVAL_SET_UNDEFINED(tv);
} while (tv != tv_end);
thr->valstack_top = tv_end;
#endif /* DUK_USE_REFERENCE_COUNTING */
}
}
#endif /* DUK_USE_PREFER_SIZE */
/* Internal helper: set top to 'top', and set [idx_wipe_start,top[ to
* 'undefined' (doing nothing if idx_wipe_start == top). Indices are
* positive and within value stack reserve. This is used by call handling.
*/
DUK_INTERNAL void duk_set_top_and_wipe(duk_hthread *thr, duk_idx_t top, duk_idx_t idx_wipe_start) {
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(top >= 0);
DUK_ASSERT(idx_wipe_start >= 0);
DUK_ASSERT(idx_wipe_start <= top);
DUK_ASSERT(thr->valstack_bottom + top <= thr->valstack_end);
DUK_ASSERT(thr->valstack_bottom + idx_wipe_start <= thr->valstack_end);
duk_set_top_unsafe(thr, idx_wipe_start);
duk_set_top_unsafe(thr, top);
}
DUK_EXTERNAL duk_idx_t duk_get_top_index(duk_hthread *thr) {
duk_idx_t ret;
DUK_ASSERT_API_ENTRY(thr);
ret = (duk_idx_t) (thr->valstack_top - thr->valstack_bottom) - 1;
if (DUK_UNLIKELY(ret < 0)) {
/* Return invalid index; if caller uses this without checking
* in another API call, the index won't map to a valid stack
* entry.
*/
return DUK_INVALID_INDEX;
}
return ret;
}
/* Internal variant: call assumes there is at least one element on the value
* stack frame; this is only asserted for.
*/
DUK_INTERNAL duk_idx_t duk_get_top_index_unsafe(duk_hthread *thr) {
duk_idx_t ret;
DUK_ASSERT_API_ENTRY(thr);
ret = (duk_idx_t) (thr->valstack_top - thr->valstack_bottom) - 1;
return ret;
}
DUK_EXTERNAL duk_idx_t duk_require_top_index(duk_hthread *thr) {
duk_idx_t ret;
DUK_ASSERT_API_ENTRY(thr);
ret = (duk_idx_t) (thr->valstack_top - thr->valstack_bottom) - 1;
if (DUK_UNLIKELY(ret < 0)) {
DUK_ERROR_RANGE_INDEX(thr, -1);
DUK_WO_NORETURN(return 0;);
}
return ret;
}
/*
* Value stack resizing.
*
* This resizing happens above the current "top": the value stack can be
* grown or shrunk, but the "top" is not affected. The value stack cannot
* be resized to a size below the current reserve.
*
* The low level reallocation primitive must carefully recompute all value
* stack pointers, and must also work if ALL pointers are NULL. The resize
* is quite tricky because the valstack realloc may cause a mark-and-sweep,
* which may run finalizers. Running finalizers may resize the valstack
* recursively (the same value stack we're working on). So, after realloc
* returns, we know that the valstack bottom, top, and reserve should still
* be the same (there should not be live values above the "top"), but its
* underlying size, alloc_end, and base pointer may have changed.
*
* 'new_size' is known to be <= DUK_USE_VALSTACK_LIMIT, which ensures that
* size_t and pointer arithmetic won't wrap in duk__resize_valstack().
*/
/* Low level valstack resize primitive, used for both grow and shrink. All
* adjustments for slack etc have already been done. Doesn't throw but does
* have allocation side effects.
*/
DUK_LOCAL DUK_COLD DUK_NOINLINE duk_bool_t duk__resize_valstack(duk_hthread *thr, duk_size_t new_size) {
duk_tval *pre_valstack;
duk_tval *pre_bottom;
duk_tval *pre_top;
duk_tval *pre_end;
duk_tval *pre_alloc_end;
duk_ptrdiff_t ptr_diff;
duk_tval *new_valstack;
duk_size_t new_alloc_size;
duk_tval *tv_prev_alloc_end;
duk_tval *p;
DUK_ASSERT_HTHREAD_VALID(thr);
DUK_ASSERT(thr->valstack_bottom >= thr->valstack);
DUK_ASSERT(thr->valstack_top >= thr->valstack_bottom);
DUK_ASSERT(thr->valstack_end >= thr->valstack_top);
DUK_ASSERT(thr->valstack_alloc_end >= thr->valstack_end);
DUK_ASSERT((duk_size_t) (thr->valstack_top - thr->valstack) <= new_size); /* can't resize below 'top' */
DUK_ASSERT(new_size <= DUK_USE_VALSTACK_LIMIT); /* valstack limit caller has check, prevents wrapping */
DUK_ASSERT(new_size <= DUK_SIZE_MAX / sizeof(duk_tval)); /* specific assert for wrapping */
/* Pre-realloc pointer copies for asserts and debug logs. */
pre_valstack = thr->valstack;
pre_bottom = thr->valstack_bottom;
pre_top = thr->valstack_top;
pre_end = thr->valstack_end;
pre_alloc_end = thr->valstack_alloc_end;
DUK_UNREF(pre_valstack);
DUK_UNREF(pre_bottom);
DUK_UNREF(pre_top);
DUK_UNREF(pre_end);
DUK_UNREF(pre_alloc_end);
/* If finalizer torture enabled, force base pointer change every time
* when it would be allowed.
*/
#if defined(DUK_USE_FINALIZER_TORTURE)
if (thr->heap->pf_prevent_count == 0) {
duk_hthread_valstack_torture_realloc(thr);
}
#endif
/* Allocate a new valstack using DUK_REALLOC_DIRECT() to deal with
* a side effect changing the base pointer.
*/
new_alloc_size = sizeof(duk_tval) * new_size;
new_valstack = (duk_tval *) DUK_REALLOC_INDIRECT(thr->heap, duk_hthread_get_valstack_ptr, (void *) thr, new_alloc_size);
if (DUK_UNLIKELY(new_valstack == NULL)) {
/* Because new_size != 0, if condition doesn't need to be
* (new_valstack != NULL || new_size == 0).
*/
DUK_ASSERT(new_size != 0);
DUK_D(DUK_DPRINT("failed to resize valstack to %lu entries (%lu bytes)",
(unsigned long) new_size, (unsigned long) new_alloc_size));
return 0;
}
/* Debug log any changes in pointer(s) by side effects. These don't
* necessarily imply any incorrect behavior, but should be rare in
* practice.
*/
#if defined(DUK_USE_DEBUG)
if (thr->valstack != pre_valstack) {
DUK_D(DUK_DPRINT("valstack base pointer changed during valstack resize: %p -> %p",
(void *) pre_valstack, (void *) thr->valstack));
}
if (thr->valstack_bottom != pre_bottom) {
DUK_D(DUK_DPRINT("valstack bottom pointer changed during valstack resize: %p -> %p",
(void *) pre_bottom, (void *) thr->valstack_bottom));
}
if (thr->valstack_top != pre_top) {
DUK_D(DUK_DPRINT("valstack top pointer changed during valstack resize: %p -> %p",
(void *) pre_top, (void *) thr->valstack_top));
}
if (thr->valstack_end != pre_end) {
DUK_D(DUK_DPRINT("valstack end pointer changed during valstack resize: %p -> %p",
(void *) pre_end, (void *) thr->valstack_end));
}
if (thr->valstack_alloc_end != pre_alloc_end) {
DUK_D(DUK_DPRINT("valstack alloc_end pointer changed during valstack resize: %p -> %p",
(void *) pre_alloc_end, (void *) thr->valstack_alloc_end));
}
#endif
/* Assertions: offsets for bottom, top, and end (reserve) must not
* have changed even with side effects because they are always
* restored in unwind. For alloc_end there's no guarantee: it may
* have grown or shrunk (but remain above 'end').
*/
DUK_ASSERT(thr->valstack_bottom - thr->valstack == pre_bottom - pre_valstack);
DUK_ASSERT(thr->valstack_top - thr->valstack == pre_top - pre_valstack);
DUK_ASSERT(thr->valstack_end - thr->valstack == pre_end - pre_valstack);
DUK_ASSERT(thr->valstack_alloc_end >= thr->valstack_end);
/* Write new pointers. Most pointers can be handled as a pointer
* difference.
*/
ptr_diff = (duk_ptrdiff_t) ((duk_uint8_t *) new_valstack - (duk_uint8_t *) thr->valstack);
tv_prev_alloc_end = (duk_tval *) (void *) ((duk_uint8_t *) thr->valstack_alloc_end + ptr_diff);
thr->valstack = new_valstack;
thr->valstack_bottom = (duk_tval *) (void *) ((duk_uint8_t *) thr->valstack_bottom + ptr_diff);
thr->valstack_top = (duk_tval *) (void *) ((duk_uint8_t *) thr->valstack_top + ptr_diff);
thr->valstack_end = (duk_tval *) (void *) ((duk_uint8_t *) thr->valstack_end + ptr_diff);
thr->valstack_alloc_end = (duk_tval *) (void *) ((duk_uint8_t *) new_valstack + new_alloc_size);
/* Assertions: pointer sanity after pointer updates. */
DUK_ASSERT(thr->valstack_bottom >= thr->valstack);
DUK_ASSERT(thr->valstack_top >= thr->valstack_bottom);
DUK_ASSERT(thr->valstack_end >= thr->valstack_top);
DUK_ASSERT(thr->valstack_alloc_end >= thr->valstack_end);
DUK_D(DUK_DPRINT("resized valstack %lu -> %lu elements (%lu -> %lu bytes): "
"base=%p -> %p, bottom=%p -> %p (%ld), top=%p -> %p (%ld), "
"end=%p -> %p (%ld), alloc_end=%p -> %p (%ld);"
" tv_prev_alloc_end=%p (-> %ld inits; <0 means shrink)",
(unsigned long) (pre_alloc_end - pre_valstack),
(unsigned long) new_size,
(unsigned long) ((duk_uint8_t *) pre_alloc_end - (duk_uint8_t *) pre_valstack),
(unsigned long) new_alloc_size,
(void *) pre_valstack, (void *) thr->valstack,
(void *) pre_bottom, (void *) thr->valstack_bottom, (long) (thr->valstack_bottom - thr->valstack),
(void *) pre_top, (void *) thr->valstack_top, (long) (thr->valstack_top - thr->valstack),
(void *) pre_end, (void *) thr->valstack_end, (long) (thr->valstack_end - thr->valstack),
(void *) pre_alloc_end, (void *) thr->valstack_alloc_end, (long) (thr->valstack_alloc_end - thr->valstack),
(void *) tv_prev_alloc_end, (long) (thr->valstack_alloc_end - tv_prev_alloc_end)));
/* If allocation grew, init any new slots to 'undefined'. */
p = tv_prev_alloc_end;
while (p < thr->valstack_alloc_end) {
/* Never executed if new size is smaller. */
DUK_TVAL_SET_UNDEFINED(p);
p++;
}
/* Assert for value stack initialization policy. */
#if defined(DUK_USE_ASSERTIONS)
p = thr->valstack_top;
while (p < thr->valstack_alloc_end) {
DUK_ASSERT(DUK_TVAL_IS_UNDEFINED(p));
p++;
}
#endif
return 1;
}
DUK_LOCAL DUK_COLD DUK_NOINLINE duk_bool_t duk__valstack_grow(duk_hthread *thr, duk_size_t min_bytes, duk_bool_t throw_on_error) {
duk_size_t min_size;
duk_size_t new_size;
DUK_ASSERT(min_bytes / sizeof(duk_tval) * sizeof(duk_tval) == min_bytes);
min_size = min_bytes / sizeof(duk_tval); /* from bytes to slots */
#if defined(DUK_USE_VALSTACK_GROW_SHIFT)
/* New size is minimum size plus a proportional slack, e.g. shift of
* 2 means a 25% slack.
*/
new_size = min_size + (min_size >> DUK_USE_VALSTACK_GROW_SHIFT);
#else
/* New size is tight with no slack. This is sometimes preferred in
* low memory environments.
*/
new_size = min_size;
#endif
if (DUK_UNLIKELY(new_size > DUK_USE_VALSTACK_LIMIT || new_size < min_size /*wrap*/)) {
/* Note: may be triggered even if minimal new_size would not reach the limit,
* plan limit accordingly.
*/
if (throw_on_error) {
DUK_ERROR_RANGE(thr, DUK_STR_VALSTACK_LIMIT);
DUK_WO_NORETURN(return 0;);
}
return 0;
}
if (duk__resize_valstack(thr, new_size) == 0) {
if (throw_on_error) {
DUK_ERROR_ALLOC_FAILED(thr);
DUK_WO_NORETURN(return 0;);
}
return 0;
}
thr->valstack_end = thr->valstack + min_size;
DUK_ASSERT(thr->valstack_alloc_end >= thr->valstack_end);
return 1;
}
/* Hot, inlined value stack grow check. Because value stack almost never
* grows, the actual resize call is in a NOINLINE helper.
*/
DUK_INTERNAL DUK_INLINE void duk_valstack_grow_check_throw(duk_hthread *thr, duk_size_t min_bytes) {
duk_tval *tv;
tv = (duk_tval *) (void *) ((duk_uint8_t *) thr->valstack + min_bytes);
if (DUK_LIKELY(thr->valstack_end >= tv)) {
return;
}
if (DUK_LIKELY(thr->valstack_alloc_end >= tv)) {
/* Values in [valstack_top,valstack_alloc_end[ are initialized
* to 'undefined' so we can just move the end pointer.
*/
thr->valstack_end = tv;
return;
}
(void) duk__valstack_grow(thr, min_bytes, 1 /*throw_on_error*/);
}
/* Hot, inlined value stack grow check which doesn't throw. */
DUK_INTERNAL DUK_INLINE duk_bool_t duk_valstack_grow_check_nothrow(duk_hthread *thr, duk_size_t min_bytes) {
duk_tval *tv;
tv = (duk_tval *) (void *) ((duk_uint8_t *) thr->valstack + min_bytes);
if (DUK_LIKELY(thr->valstack_end >= tv)) {
return 1;
}
if (DUK_LIKELY(thr->valstack_alloc_end >= tv)) {
thr->valstack_end = tv;
return 1;
}
return duk__valstack_grow(thr, min_bytes, 0 /*throw_on_error*/);
}
/* Value stack shrink check, called from mark-and-sweep. */
DUK_INTERNAL void duk_valstack_shrink_check_nothrow(duk_hthread *thr, duk_bool_t snug) {
duk_size_t alloc_bytes;
duk_size_t reserve_bytes;
duk_size_t shrink_bytes;
alloc_bytes = (duk_size_t) ((duk_uint8_t *) thr->valstack_alloc_end - (duk_uint8_t *) thr->valstack);
reserve_bytes = (duk_size_t) ((duk_uint8_t *) thr->valstack_end - (duk_uint8_t *) thr->valstack);
DUK_ASSERT(alloc_bytes >= reserve_bytes);
/* We're free to shrink the value stack allocation down to
* reserve_bytes but not more. If 'snug' (emergency GC)
* shrink whatever we can. Otherwise only shrink if the new
* size would be considerably smaller.
*/
#if defined(DUK_USE_VALSTACK_SHRINK_CHECK_SHIFT)
if (snug) {
shrink_bytes = reserve_bytes;
} else {
duk_size_t proportion, slack;
/* Require that value stack shrinks by at least X% of its
* current size. For example, shift of 2 means at least
* 25%. The proportion is computed as bytes and may not
* be a multiple of sizeof(duk_tval); that's OK here.
*/
proportion = alloc_bytes >> DUK_USE_VALSTACK_SHRINK_CHECK_SHIFT;
if (alloc_bytes - reserve_bytes < proportion) {
/* Too little would be freed, do nothing. */
return;
}
/* Keep a slack after shrinking. The slack is again a
* proportion of the current size (the proportion should
* of course be smaller than the check proportion above).
*/
#if defined(DUK_USE_VALSTACK_SHRINK_SLACK_SHIFT)
DUK_ASSERT(DUK_USE_VALSTACK_SHRINK_SLACK_SHIFT > DUK_USE_VALSTACK_SHRINK_CHECK_SHIFT);
slack = alloc_bytes >> DUK_USE_VALSTACK_SHRINK_SLACK_SHIFT;
#else
slack = 0;
#endif
shrink_bytes = reserve_bytes +
slack / sizeof(duk_tval) * sizeof(duk_tval); /* multiple of duk_tval */
}
#else /* DUK_USE_VALSTACK_SHRINK_CHECK_SHIFT */
/* Always snug, useful in some low memory environments. */
DUK_UNREF(snug);
shrink_bytes = reserve_bytes;
#endif /* DUK_USE_VALSTACK_SHRINK_CHECK_SHIFT */
DUK_D(DUK_DPRINT("valstack shrink check: alloc_bytes=%ld, reserve_bytes=%ld, shrink_bytes=%ld (unvalidated)",
(long) alloc_bytes, (long) reserve_bytes, (long) shrink_bytes));
DUK_ASSERT(shrink_bytes >= reserve_bytes);
if (shrink_bytes >= alloc_bytes) {
/* Skip if shrink target is same as current one (or higher,
* though that shouldn't happen in practice).
*/
return;
}
DUK_ASSERT(shrink_bytes / sizeof(duk_tval) * sizeof(duk_tval) == shrink_bytes);
DUK_D(DUK_DPRINT("valstack shrink check: decided to shrink, snug: %ld", (long) snug));
duk__resize_valstack(thr, shrink_bytes / sizeof(duk_tval));
}
DUK_EXTERNAL duk_bool_t duk_check_stack(duk_hthread *thr, duk_idx_t extra) {
duk_size_t min_new_bytes;
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(thr != NULL);
if (DUK_UNLIKELY(extra < 0 || extra > DUK_USE_VALSTACK_LIMIT)) {
if (extra < 0) {
/* Clamping to zero makes the API more robust to calling code
* calculation errors.
*/
extra = 0;
} else {
/* Cause grow check to fail without wrapping arithmetic. */
extra = DUK_USE_VALSTACK_LIMIT;
}
}
min_new_bytes = (duk_size_t) ((duk_uint8_t *) thr->valstack_top - (duk_uint8_t *) thr->valstack) +
sizeof(duk_tval) * ((duk_size_t) extra + DUK_VALSTACK_INTERNAL_EXTRA);
return duk_valstack_grow_check_nothrow(thr, min_new_bytes);
}
DUK_EXTERNAL void duk_require_stack(duk_hthread *thr, duk_idx_t extra) {
duk_size_t min_new_bytes;
DUK_ASSERT_API_ENTRY(thr);
DUK_ASSERT(thr != NULL);
if (DUK_UNLIKELY(extra < 0 || extra > DUK_USE_VALSTACK_LIMIT)) {