Source code
Revision control
Copy as Markdown
Other Tools
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "vm/StringType-inl.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/HashFunctions.h"
#include "mozilla/Latin1.h"
#include "mozilla/MathAlgorithms.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/PodOperations.h"
#include "mozilla/RangedPtr.h"
#include "mozilla/TextUtils.h"
#include "mozilla/Utf8.h"
#include "mozilla/Vector.h"
#include <algorithm> // std::{all_of,copy_n,enable_if,is_const,move}
#include <iterator> // std::size
#include <type_traits> // std::is_same, std::is_unsigned
#include "jsfriendapi.h"
#include "jsnum.h"
#include "builtin/Boolean.h"
#ifdef ENABLE_RECORD_TUPLE
# include "builtin/RecordObject.h"
#endif
#include "gc/AllocKind.h"
#include "gc/MaybeRooted.h"
#include "gc/Nursery.h"
#include "js/CharacterEncoding.h"
#include "js/friend/ErrorMessages.h" // js::GetErrorMessage, JSMSG_*
#include "js/Printer.h" // js::GenericPrinter
#include "js/PropertyAndElement.h" // JS_DefineElement
#include "js/SourceText.h" // JS::SourceText
#include "js/StableStringChars.h"
#include "js/UbiNode.h"
#include "util/Identifier.h" // js::IsIdentifierNameOrPrivateName
#include "util/Unicode.h"
#include "vm/GeckoProfiler.h"
#include "vm/JSONPrinter.h" // js::JSONPrinter
#include "vm/StaticStrings.h"
#include "vm/ToSource.h" // js::ValueToSource
#include "gc/Marking-inl.h"
#include "vm/GeckoProfiler-inl.h"
#ifdef ENABLE_RECORD_TUPLE
# include "vm/RecordType.h"
# include "vm/TupleType.h"
#endif
using namespace js;
using mozilla::AsWritableChars;
using mozilla::ConvertLatin1toUtf16;
using mozilla::IsAsciiDigit;
using mozilla::IsUtf16Latin1;
using mozilla::LossyConvertUtf16toLatin1;
using mozilla::PodCopy;
using mozilla::RangedPtr;
using mozilla::RoundUpPow2;
using mozilla::Span;
using JS::AutoCheckCannotGC;
using JS::AutoStableStringChars;
using UniqueLatin1Chars = UniquePtr<Latin1Char[], JS::FreePolicy>;
size_t JSString::sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) {
// JSRope: do nothing, we'll count all children chars when we hit the leaf
// strings.
if (isRope()) {
return 0;
}
MOZ_ASSERT(isLinear());
// JSDependentString: do nothing, we'll count the chars when we hit the base
// string.
if (isDependent()) {
return 0;
}
// JSExternalString: Ask the embedding to tell us what's going on.
if (isExternal()) {
// Our callback isn't supposed to cause GC.
JS::AutoSuppressGCAnalysis nogc;
JSExternalString& external = asExternal();
if (external.hasLatin1Chars()) {
return asExternal().callbacks()->sizeOfBuffer(external.latin1Chars(),
mallocSizeOf);
} else {
return asExternal().callbacks()->sizeOfBuffer(external.twoByteChars(),
mallocSizeOf);
}
}
// JSExtensibleString: count the full capacity, not just the used space.
if (isExtensible()) {
JSExtensibleString& extensible = asExtensible();
return extensible.hasLatin1Chars()
? mallocSizeOf(extensible.rawLatin1Chars())
: mallocSizeOf(extensible.rawTwoByteChars());
}
// JSInlineString, JSFatInlineString, js::ThinInlineAtom, js::FatInlineAtom:
// the chars are inline.
if (isInline()) {
return 0;
}
// Chars in the nursery are owned by the nursery.
if (!ownsMallocedChars()) {
return 0;
}
// Everything else: measure the space for the chars.
JSLinearString& linear = asLinear();
return linear.hasLatin1Chars() ? mallocSizeOf(linear.rawLatin1Chars())
: mallocSizeOf(linear.rawTwoByteChars());
}
JS::ubi::Node::Size JS::ubi::Concrete<JSString>::size(
mozilla::MallocSizeOf mallocSizeOf) const {
JSString& str = get();
size_t size;
if (str.isAtom()) {
if (str.isInline()) {
size = str.isFatInline() ? sizeof(js::FatInlineAtom)
: sizeof(js::ThinInlineAtom);
} else {
size = sizeof(js::NormalAtom);
}
} else {
size = str.isFatInline() ? sizeof(JSFatInlineString) : sizeof(JSString);
}
if (IsInsideNursery(&str)) {
size += Nursery::nurseryCellHeaderSize();
}
size += str.sizeOfExcludingThis(mallocSizeOf);
return size;
}
const char16_t JS::ubi::Concrete<JSString>::concreteTypeName[] = u"JSString";
mozilla::Maybe<std::tuple<size_t, size_t>> JSString::encodeUTF8Partial(
const JS::AutoRequireNoGC& nogc, mozilla::Span<char> buffer) const {
mozilla::Vector<const JSString*, 16, SystemAllocPolicy> stack;
const JSString* current = this;
char16_t pendingLeadSurrogate = 0; // U+0000 means no pending lead surrogate
size_t totalRead = 0;
size_t totalWritten = 0;
for (;;) {
if (current->isRope()) {
JSRope& rope = current->asRope();
if (!stack.append(rope.rightChild())) {
// OOM
return mozilla::Nothing();
}
current = rope.leftChild();
continue;
}
JSLinearString& linear = current->asLinear();
if (MOZ_LIKELY(linear.hasLatin1Chars())) {
if (MOZ_UNLIKELY(pendingLeadSurrogate)) {
if (buffer.Length() < 3) {
return mozilla::Some(std::make_tuple(totalRead, totalWritten));
}
buffer[0] = '\xEF';
buffer[1] = '\xBF';
buffer[2] = '\xBD';
buffer = buffer.From(3);
totalRead += 1; // pendingLeadSurrogate
totalWritten += 3;
pendingLeadSurrogate = 0;
}
auto src = mozilla::AsChars(
mozilla::Span(linear.latin1Chars(nogc), linear.length()));
size_t read;
size_t written;
std::tie(read, written) =
mozilla::ConvertLatin1toUtf8Partial(src, buffer);
buffer = buffer.From(written);
totalRead += read;
totalWritten += written;
if (read < src.Length()) {
return mozilla::Some(std::make_tuple(totalRead, totalWritten));
}
} else {
auto src = mozilla::Span(linear.twoByteChars(nogc), linear.length());
if (MOZ_UNLIKELY(pendingLeadSurrogate)) {
char16_t first = 0;
if (!src.IsEmpty()) {
first = src[0];
}
if (unicode::IsTrailSurrogate(first)) {
// Got a surrogate pair
if (buffer.Length() < 4) {
return mozilla::Some(std::make_tuple(totalRead, totalWritten));
}
uint32_t astral = unicode::UTF16Decode(pendingLeadSurrogate, first);
buffer[0] = char(0b1111'0000 | (astral >> 18));
buffer[1] = char(0b1000'0000 | ((astral >> 12) & 0b11'1111));
buffer[2] = char(0b1000'0000 | ((astral >> 6) & 0b11'1111));
buffer[3] = char(0b1000'0000 | (astral & 0b11'1111));
src = src.From(1);
buffer = buffer.From(4);
totalRead += 2; // both pendingLeadSurrogate and first!
totalWritten += 4;
} else {
// unpaired surrogate
if (buffer.Length() < 3) {
return mozilla::Some(std::make_tuple(totalRead, totalWritten));
}
buffer[0] = '\xEF';
buffer[1] = '\xBF';
buffer[2] = '\xBD';
buffer = buffer.From(3);
totalRead += 1; // pendingLeadSurrogate
totalWritten += 3;
}
pendingLeadSurrogate = 0;
}
if (!src.IsEmpty()) {
char16_t last = src[src.Length() - 1];
if (unicode::IsLeadSurrogate(last)) {
src = src.To(src.Length() - 1);
pendingLeadSurrogate = last;
} else {
MOZ_ASSERT(!pendingLeadSurrogate);
}
size_t read;
size_t written;
std::tie(read, written) =
mozilla::ConvertUtf16toUtf8Partial(src, buffer);
buffer = buffer.From(written);
totalRead += read;
totalWritten += written;
if (read < src.Length()) {
return mozilla::Some(std::make_tuple(totalRead, totalWritten));
}
}
}
if (stack.empty()) {
break;
}
current = stack.popCopy();
}
if (MOZ_UNLIKELY(pendingLeadSurrogate)) {
if (buffer.Length() < 3) {
return mozilla::Some(std::make_tuple(totalRead, totalWritten));
}
buffer[0] = '\xEF';
buffer[1] = '\xBF';
buffer[2] = '\xBD';
// No need to update buffer and pendingLeadSurrogate anymore
totalRead += 1;
totalWritten += 3;
}
return mozilla::Some(std::make_tuple(totalRead, totalWritten));
}
#if defined(DEBUG) || defined(JS_JITSPEW) || defined(JS_CACHEIR_SPEW)
template <typename CharT>
/*static */
void JSString::dumpCharsNoQuote(const CharT* s, size_t n,
js::GenericPrinter& out) {
for (size_t i = 0; i < n; i++) {
char16_t c = s[i];
if (c == '"') {
out.put("\\\"");
} else if (c == '\'') {
out.put("\\'");
} else if (c == '`') {
out.put("\\`");
} else if (c == '\\') {
out.put("\\\\");
} else if (c == '\r') {
out.put("\\r");
} else if (c == '\n') {
out.put("\\n");
} else if (c == '\t') {
out.put("\\t");
} else if (c >= 32 && c < 127) {
out.putChar((char)s[i]);
} else if (c <= 255) {
out.printf("\\x%02x", unsigned(c));
} else {
out.printf("\\u%04x", unsigned(c));
}
}
}
/* static */
template void JSString::dumpCharsNoQuote(const Latin1Char* s, size_t n,
js::GenericPrinter& out);
/* static */
template void JSString::dumpCharsNoQuote(const char16_t* s, size_t n,
js::GenericPrinter& out);
void JSString::dump() const {
js::Fprinter out(stderr);
dump(out);
}
void JSString::dump(js::GenericPrinter& out) const {
js::JSONPrinter json(out);
dump(json);
out.put("\n");
}
void JSString::dump(js::JSONPrinter& json) const {
json.beginObject();
dumpFields(json);
json.endObject();
}
const char* RepresentationToString(const JSString* s) {
if (s->isAtom()) {
return "JSAtom";
}
if (s->isLinear()) {
if (s->isDependent()) {
return "JSDependentString";
}
if (s->isExternal()) {
return "JSExternalString";
}
if (s->isExtensible()) {
return "JSExtensibleString";
}
if (s->isInline()) {
if (s->isFatInline()) {
return "JSFatInlineString";
}
return "JSThinInlineString";
}
return "JSLinearString";
}
if (s->isRope()) {
return "JSRope";
}
return "JSString";
}
template <typename KnownF, typename UnknownF>
void ForEachStringFlag(const JSString* str, uint32_t flags, KnownF known,
UnknownF unknown) {
for (uint32_t i = js::Bit(3); i < js::Bit(17); i = i << 1) {
if (!(flags & i)) {
continue;
}
switch (i) {
case JSString::ATOM_BIT:
known("ATOM_BIT");
break;
case JSString::LINEAR_BIT:
known("LINEAR_BIT");
break;
case JSString::DEPENDENT_BIT:
known("DEPENDENT_BIT");
break;
case JSString::INLINE_CHARS_BIT:
known("INLINE_BIT");
break;
case JSString::LINEAR_IS_EXTENSIBLE_BIT:
static_assert(JSString::LINEAR_IS_EXTENSIBLE_BIT ==
JSString::INLINE_IS_FAT_BIT);
if (str->isLinear()) {
if (str->isInline()) {
known("FAT");
} else if (!str->isAtom()) {
known("EXTENSIBLE");
} else {
unknown(i);
}
} else {
unknown(i);
}
break;
case JSString::LINEAR_IS_EXTERNAL_BIT:
static_assert(JSString::LINEAR_IS_EXTERNAL_BIT ==
JSString::ATOM_IS_PERMANENT_BIT);
if (str->isAtom()) {
known("PERMANENT");
} else if (str->isLinear()) {
known("EXTERNAL");
} else {
unknown(i);
}
break;
case JSString::LATIN1_CHARS_BIT:
known("LATIN1_CHARS_BIT");
break;
case JSString::ATOM_IS_INDEX_BIT:
if (str->isAtom()) {
known("ATOM_IS_INDEX_BIT");
} else {
known("ATOM_REF_BIT");
}
break;
case JSString::INDEX_VALUE_BIT:
known("INDEX_VALUE_BIT");
break;
case JSString::IN_STRING_TO_ATOM_CACHE:
known("IN_STRING_TO_ATOM_CACHE");
break;
case JSString::FLATTEN_VISIT_RIGHT:
if (str->isRope()) {
known("FLATTEN_VISIT_RIGHT");
} else {
known("DEPENDED_ON_BIT");
}
break;
case JSString::FLATTEN_FINISH_NODE:
static_assert(JSString::FLATTEN_FINISH_NODE ==
JSString::PINNED_ATOM_BIT);
if (str->isRope()) {
known("FLATTEN_FINISH_NODE");
} else if (str->isAtom()) {
known("PINNED_ATOM_BIT");
} else {
known("NON_DEDUP_BIT");
}
break;
default:
unknown(i);
break;
}
}
}
void JSString::dumpFields(js::JSONPrinter& json) const {
dumpCommonFields(json);
dumpCharsFields(json);
}
void JSString::dumpCommonFields(js::JSONPrinter& json) const {
json.formatProperty("address", "(%s*)0x%p", RepresentationToString(this),
this);
json.beginInlineListProperty("flags");
ForEachStringFlag(
this, flags(), [&](const char* name) { json.value("%s", name); },
[&](uint32_t value) { json.value("Unknown(%08x)", value); });
json.endInlineList();
if (hasIndexValue()) {
json.property("indexValue", getIndexValue());
}
json.boolProperty("isTenured", isTenured());
json.property("length", length());
}
void JSString::dumpCharsFields(js::JSONPrinter& json) const {
if (isLinear()) {
const JSLinearString* linear = &asLinear();
AutoCheckCannotGC nogc;
if (hasLatin1Chars()) {
const Latin1Char* chars = linear->latin1Chars(nogc);
json.formatProperty("chars", "(JS::Latin1Char*)0x%p", chars);
js::GenericPrinter& out = json.beginStringProperty("value");
dumpCharsNoQuote(chars, length(), out);
json.endStringProperty();
} else {
const char16_t* chars = linear->twoByteChars(nogc);
json.formatProperty("chars", "(char16_t*)0x%p", chars);
js::GenericPrinter& out = json.beginStringProperty("value");
dumpCharsNoQuote(chars, length(), out);
json.endStringProperty();
}
} else {
js::GenericPrinter& out = json.beginStringProperty("value");
dumpCharsNoQuote(out);
json.endStringProperty();
}
}
void JSString::dumpRepresentation() const {
js::Fprinter out(stderr);
dumpRepresentation(out);
}
void JSString::dumpRepresentation(js::GenericPrinter& out) const {
js::JSONPrinter json(out);
dumpRepresentation(json);
out.put("\n");
}
void JSString::dumpRepresentation(js::JSONPrinter& json) const {
json.beginObject();
dumpRepresentationFields(json);
json.endObject();
}
void JSString::dumpRepresentationFields(js::JSONPrinter& json) const {
dumpCommonFields(json);
if (isAtom()) {
asAtom().dumpOwnRepresentationFields(json);
} else if (isLinear()) {
asLinear().dumpOwnRepresentationFields(json);
if (isDependent()) {
asDependent().dumpOwnRepresentationFields(json);
} else if (isExternal()) {
asExternal().dumpOwnRepresentationFields(json);
} else if (isExtensible()) {
asExtensible().dumpOwnRepresentationFields(json);
} else if (isInline()) {
asInline().dumpOwnRepresentationFields(json);
}
} else if (isRope()) {
asRope().dumpOwnRepresentationFields(json);
// Rope already shows the chars.
return;
}
dumpCharsFields(json);
}
void JSString::dumpStringContent(js::GenericPrinter& out) const {
dumpCharsSingleQuote(out);
out.printf(" @ (%s*)0x%p", RepresentationToString(this), this);
}
void JSString::dumpPropertyName(js::GenericPrinter& out) const {
dumpCharsNoQuote(out);
}
void JSString::dumpChars(js::GenericPrinter& out) const {
out.putChar('"');
dumpCharsNoQuote(out);
out.putChar('"');
}
void JSString::dumpCharsSingleQuote(js::GenericPrinter& out) const {
out.putChar('\'');
dumpCharsNoQuote(out);
out.putChar('\'');
}
void JSString::dumpCharsNoQuote(js::GenericPrinter& out) const {
if (isLinear()) {
const JSLinearString* linear = &asLinear();
AutoCheckCannotGC nogc;
if (hasLatin1Chars()) {
dumpCharsNoQuote(linear->latin1Chars(nogc), length(), out);
} else {
dumpCharsNoQuote(linear->twoByteChars(nogc), length(), out);
}
} else if (isRope()) {
JSRope* rope = &asRope();
rope->leftChild()->dumpCharsNoQuote(out);
rope->rightChild()->dumpCharsNoQuote(out);
}
}
bool JSString::equals(const char* s) {
JSLinearString* linear = ensureLinear(nullptr);
if (!linear) {
// This is DEBUG-only code.
fprintf(stderr, "OOM in JSString::equals!\n");
return false;
}
return StringEqualsAscii(linear, s);
}
#endif /* defined(DEBUG) || defined(JS_JITSPEW) || defined(JS_CACHEIR_SPEW) */
JSExtensibleString& JSLinearString::makeExtensible(size_t capacity) {
MOZ_ASSERT(!isDependent());
MOZ_ASSERT(!isInline());
MOZ_ASSERT(!isAtom());
MOZ_ASSERT(!isExternal());
MOZ_ASSERT(capacity >= length());
js::RemoveCellMemory(this, allocSize(), js::MemoryUse::StringContents);
setLengthAndFlags(length(), flags() | EXTENSIBLE_FLAGS);
d.s.u3.capacity = capacity;
js::AddCellMemory(this, allocSize(), js::MemoryUse::StringContents);
return asExtensible();
}
template <typename CharT>
static MOZ_ALWAYS_INLINE bool AllocCharsForFlatten(JSString* str, size_t length,
CharT** chars,
size_t* capacity) {
/*
* Grow by 12.5% if the buffer is very large. Otherwise, round up to the
* next power of 2. This is similar to what we do with arrays; see
* JSObject::ensureDenseArrayElements.
*/
static const size_t DOUBLING_MAX = 1024 * 1024;
*capacity =
length > DOUBLING_MAX ? length + (length / 8) : RoundUpPow2(length);
static_assert(JSString::MAX_LENGTH * sizeof(CharT) <= UINT32_MAX);
*chars =
str->zone()->pod_arena_malloc<CharT>(js::StringBufferArena, *capacity);
return *chars != nullptr;
}
UniqueLatin1Chars JSRope::copyLatin1Chars(JSContext* maybecx,
arena_id_t destArenaId) const {
return copyCharsInternal<Latin1Char>(maybecx, destArenaId);
}
UniqueTwoByteChars JSRope::copyTwoByteChars(JSContext* maybecx,
arena_id_t destArenaId) const {
return copyCharsInternal<char16_t>(maybecx, destArenaId);
}
// Allocate chars for a string. If parameters and conditions allow, this will
// try to allocate in the nursery, but this may always fall back to a malloc
// allocation. The return value will record where the allocation happened.
template <typename CharT>
static MOZ_ALWAYS_INLINE JSString::OwnedChars<CharT> AllocChars(JSContext* cx,
size_t length,
gc::Heap heap) {
if (heap == gc::Heap::Default && cx->zone()->allocNurseryStrings()) {
MOZ_ASSERT(cx->nursery().isEnabled());
auto [buffer, isMalloced] = cx->nursery().allocateBuffer(
cx->zone(), length * sizeof(CharT), js::StringBufferArena);
if (!buffer) {
ReportOutOfMemory(cx);
return {nullptr, 0, false, false};
}
return {static_cast<CharT*>(buffer), length, isMalloced, isMalloced};
}
auto buffer = cx->make_pod_arena_array<CharT>(js::StringBufferArena, length);
if (!buffer) {
ReportOutOfMemory(cx);
return {nullptr, 0, false, false};
}
return {std::move(buffer), length, true};
}
template <typename CharT>
UniquePtr<CharT[], JS::FreePolicy> JSRope::copyCharsInternal(
JSContext* maybecx, arena_id_t destArenaId) const {
// Left-leaning ropes are far more common than right-leaning ropes, so
// perform a non-destructive traversal of the rope, right node first,
// splatting each node's characters into a contiguous buffer.
size_t n = length();
UniquePtr<CharT[], JS::FreePolicy> out;
if (maybecx) {
out.reset(maybecx->pod_arena_malloc<CharT>(destArenaId, n));
} else {
out.reset(js_pod_arena_malloc<CharT>(destArenaId, n));
}
if (!out) {
return nullptr;
}
Vector<const JSString*, 8, SystemAllocPolicy> nodeStack;
const JSString* str = this;
CharT* end = out.get() + str->length();
while (true) {
if (str->isRope()) {
if (!nodeStack.append(str->asRope().leftChild())) {
if (maybecx) {
ReportOutOfMemory(maybecx);
}
return nullptr;
}
str = str->asRope().rightChild();
} else {
end -= str->length();
CopyChars(end, str->asLinear());
if (nodeStack.empty()) {
break;
}
str = nodeStack.popCopy();
}
}
MOZ_ASSERT(end == out.get());
return out;
}
template <typename CharT>
void AddStringToHash(uint32_t* hash, const CharT* chars, size_t len) {
// It's tempting to use |HashString| instead of this loop, but that's
// slightly different than our existing implementation for non-ropes. We
// want to pretend we have a contiguous set of chars so we need to
// accumulate char by char rather than generate a new hash for substring
// and then accumulate that.
for (size_t i = 0; i < len; i++) {
*hash = mozilla::AddToHash(*hash, chars[i]);
}
}
void AddStringToHash(uint32_t* hash, const JSString* str) {
AutoCheckCannotGC nogc;
const auto& s = str->asLinear();
if (s.hasLatin1Chars()) {
AddStringToHash(hash, s.latin1Chars(nogc), s.length());
} else {
AddStringToHash(hash, s.twoByteChars(nogc), s.length());
}
}
bool JSRope::hash(uint32_t* outHash) const {
Vector<const JSString*, 8, SystemAllocPolicy> nodeStack;
const JSString* str = this;
*outHash = 0;
while (true) {
if (str->isRope()) {
if (!nodeStack.append(str->asRope().rightChild())) {
return false;
}
str = str->asRope().leftChild();
} else {
AddStringToHash(outHash, str);
if (nodeStack.empty()) {
break;
}
str = nodeStack.popCopy();
}
}
return true;
}
#if defined(DEBUG) || defined(JS_JITSPEW) || defined(JS_CACHEIR_SPEW)
void JSRope::dumpOwnRepresentationFields(js::JSONPrinter& json) const {
json.beginObjectProperty("leftChild");
leftChild()->dumpRepresentationFields(json);
json.endObject();
json.beginObjectProperty("rightChild");
rightChild()->dumpRepresentationFields(json);
json.endObject();
}
#endif
namespace js {
template <>
void CopyChars(char16_t* dest, const JSLinearString& str) {
AutoCheckCannotGC nogc;
if (str.hasTwoByteChars()) {
PodCopy(dest, str.twoByteChars(nogc), str.length());
} else {
CopyAndInflateChars(dest, str.latin1Chars(nogc), str.length());
}
}
template <>
void CopyChars(Latin1Char* dest, const JSLinearString& str) {
AutoCheckCannotGC nogc;
if (str.hasLatin1Chars()) {
PodCopy(dest, str.latin1Chars(nogc), str.length());
} else {
/*
* When we flatten a TwoByte rope, we turn child ropes (including Latin1
* ropes) into TwoByte dependent strings. If one of these strings is
* also part of another Latin1 rope tree, we can have a Latin1 rope with
* a TwoByte descendent and we end up here when we flatten it. Although
* the chars are stored as TwoByte, we know they must be in the Latin1
* range, so we can safely deflate here.
*/
size_t len = str.length();
const char16_t* chars = str.twoByteChars(nogc);
auto src = Span(chars, len);
MOZ_ASSERT(IsUtf16Latin1(src));
LossyConvertUtf16toLatin1(src, AsWritableChars(Span(dest, len)));
}
}
} /* namespace js */
template <typename CharT>
static constexpr uint32_t StringFlagsForCharType(uint32_t baseFlags) {
if constexpr (std::is_same_v<CharT, char16_t>) {
return baseFlags;
}
return baseFlags | JSString::LATIN1_CHARS_BIT;
}
static bool UpdateNurseryBuffersOnTransfer(js::Nursery& nursery, JSString* from,
JSString* to, void* buffer,
size_t size) {
// Update the list of buffers associated with nursery cells when |buffer| is
// moved from string |from| to string |to|, depending on whether those strings
// are in the nursery or not.
if (from->isTenured() && !to->isTenured()) {
// Tenured leftmost child is giving its chars buffer to the
// nursery-allocated root node.
if (!nursery.registerMallocedBuffer(buffer, size)) {
return false;
}
} else if (!from->isTenured() && to->isTenured()) {
// Leftmost child is giving its nursery-held chars buffer to a
// tenured string.
nursery.removeMallocedBuffer(buffer, size);
}
return true;
}
static bool CanReuseLeftmostBuffer(JSString* leftmostChild, size_t wholeLength,
bool hasTwoByteChars) {
if (!leftmostChild->isExtensible()) {
return false;
}
JSExtensibleString& str = leftmostChild->asExtensible();
return str.capacity() >= wholeLength &&
str.hasTwoByteChars() == hasTwoByteChars;
}
JSLinearString* JSRope::flatten(JSContext* maybecx) {
mozilla::Maybe<AutoGeckoProfilerEntry> entry;
if (maybecx) {
entry.emplace(maybecx, "JSRope::flatten");
}
JSLinearString* str = flattenInternal();
if (!str && maybecx) {
ReportOutOfMemory(maybecx);
}
return str;
}
JSLinearString* JSRope::flattenInternal() {
if (zone()->needsIncrementalBarrier()) {
return flattenInternal<WithIncrementalBarrier>();
}
return flattenInternal<NoBarrier>();
}
template <JSRope::UsingBarrier usingBarrier>
JSLinearString* JSRope::flattenInternal() {
if (hasTwoByteChars()) {
return flattenInternal<usingBarrier, char16_t>(this);
}
return flattenInternal<usingBarrier, Latin1Char>(this);
}
template <JSRope::UsingBarrier usingBarrier, typename CharT>
/* static */
JSLinearString* JSRope::flattenInternal(JSRope* root) {
/*
* Consider the DAG of JSRopes rooted at |root|, with non-JSRopes as
* its leaves. Mutate the root JSRope into a JSExtensibleString containing
* the full flattened text that the root represents, and mutate all other
* JSRopes in the interior of the DAG into JSDependentStrings that refer to
* this new JSExtensibleString.
*
* If the leftmost leaf of our DAG is a JSExtensibleString, consider
* stealing its buffer for use in our new root, and transforming it into a
* JSDependentString too. Do not mutate any of the other leaves.
*
* Perform a depth-first dag traversal, splatting each node's characters
* into a contiguous buffer. Visit each rope node three times:
* 1. record position in the buffer and recurse into left child;
* 2. recurse into the right child;
* 3. transform the node into a dependent string.
* To avoid maintaining a stack, tree nodes are mutated to indicate how many
* times they have been visited. Since ropes can be dags, a node may be
* encountered multiple times during traversal. However, step 3 above leaves
* a valid dependent string, so everything works out.
*
* While ropes avoid all sorts of quadratic cases with string concatenation,
* they can't help when ropes are immediately flattened. One idiomatic case
* that we'd like to keep linear (and has traditionally been linear in SM
* and other JS engines) is:
*
* while (...) {
* s += ...
* s.flatten
* }
*
* Two behaviors accomplish this:
*
* - When the leftmost non-rope in the DAG we're flattening is a
* JSExtensibleString with sufficient capacity to hold the entire
* flattened string, we just flatten the DAG into its buffer. Then, when
* we transform the root of the DAG from a JSRope into a
* JSExtensibleString, we steal that buffer, and change the victim from a
* JSExtensibleString to a JSDependentString. In this case, the left-hand
* side of the string never needs to be copied.
*
* - Otherwise, we round up the total flattened size and create a fresh
* JSExtensibleString with that much capacity. If this in turn becomes the
* leftmost leaf of a subsequent flatten, we will hopefully be able to
* fill it, as in the case above.
*
* Note that, even though the code for creating JSDependentStrings avoids
* creating dependents of dependents, we can create that situation here: the
* JSExtensibleStrings we transform into JSDependentStrings might have
* JSDependentStrings pointing to them already. Stealing the buffer doesn't
* change its address, only its owning JSExtensibleString, so all chars()
* pointers in the JSDependentStrings are still valid.
*
* This chain of dependent strings could be problematic if the base string
* moves, either because it was initially allocated in the nursery or it
* gets deduplicated, because you might have a dependent ->
* tenured dependent -> nursery base string, and the store buffer would
* only capture the latter edge. Prevent this case from happening by
* marking the root as nondeduplicatable if the extensible string
* optimization applied.
*/
const size_t wholeLength = root->length();
size_t wholeCapacity;
CharT* wholeChars;
bool setRootDependedOn = false;
AutoCheckCannotGC nogc;
Nursery& nursery = root->runtimeFromMainThread()->gc.nursery();
/* Find the left most string, containing the first string. */
JSRope* leftmostRope = root;
while (leftmostRope->leftChild()->isRope()) {
leftmostRope = &leftmostRope->leftChild()->asRope();
}
JSString* leftmostChild = leftmostRope->leftChild();
bool reuseLeftmostBuffer = CanReuseLeftmostBuffer(
leftmostChild, wholeLength, std::is_same_v<CharT, char16_t>);
if (reuseLeftmostBuffer) {
JSExtensibleString& left = leftmostChild->asExtensible();
wholeCapacity = left.capacity();
wholeChars = const_cast<CharT*>(left.nonInlineChars<CharT>(nogc));
// Nursery::registerMallocedBuffer is fallible, so attempt it first before
// doing anything irreversible.
if (!UpdateNurseryBuffersOnTransfer(nursery, &left, root, wholeChars,
wholeCapacity * sizeof(CharT))) {
return nullptr;
}
} else {
// If we can't reuse the leftmost child's buffer, allocate a new one.
if (!AllocCharsForFlatten(root, wholeLength, &wholeChars, &wholeCapacity)) {
return nullptr;
}
if (!root->isTenured()) {
if (!nursery.registerMallocedBuffer(wholeChars,
wholeCapacity * sizeof(CharT))) {
js_free(wholeChars);
return nullptr;
}
}
}
JSRope* str = root;
CharT* pos = wholeChars;
JSRope* parent = nullptr;
uint32_t parentFlag = 0;
first_visit_node: {
MOZ_ASSERT_IF(str != root, parent && parentFlag);
MOZ_ASSERT(!str->asRope().isBeingFlattened());
ropeBarrierDuringFlattening<usingBarrier>(str);
JSString& left = *str->d.s.u2.left;
str->d.s.u2.parent = parent;
str->setFlagBit(parentFlag);
parent = nullptr;
parentFlag = 0;
if (left.isRope()) {
/* Return to this node when 'left' done, then goto visit_right_child. */
parent = str;
parentFlag = FLATTEN_VISIT_RIGHT;
str = &left.asRope();
goto first_visit_node;
}
if (!(reuseLeftmostBuffer && pos == wholeChars)) {
CopyChars(pos, left.asLinear());
}
pos += left.length();
}
visit_right_child: {
JSString& right = *str->d.s.u3.right;
if (right.isRope()) {
/* Return to this node when 'right' done, then goto finish_node. */
parent = str;
parentFlag = FLATTEN_FINISH_NODE;
str = &right.asRope();
goto first_visit_node;
}
CopyChars(pos, right.asLinear());
pos += right.length();
}
finish_node: {
if (str == root) {
goto finish_root;
}
MOZ_ASSERT(pos >= wholeChars);
CharT* chars = pos - str->length();
JSRope* strParent = str->d.s.u2.parent;
str->setNonInlineChars(chars);
MOZ_ASSERT(str->asRope().isBeingFlattened());
mozilla::DebugOnly<bool> visitRight = str->flags() & FLATTEN_VISIT_RIGHT;
bool finishNode = str->flags() & FLATTEN_FINISH_NODE;
MOZ_ASSERT(visitRight != finishNode);
// This also clears the flags related to flattening.
str->setLengthAndFlags(str->length(),
StringFlagsForCharType<CharT>(INIT_DEPENDENT_FLAGS));
str->d.s.u3.base =
reinterpret_cast<JSLinearString*>(root); /* will be true on exit */
setRootDependedOn = true;
// Every interior (rope) node in the rope's tree will be visited during
// the traversal and post-barriered here, so earlier additions of
// dependent.base -> root pointers are handled by this barrier as well.
//
// The only time post-barriers need do anything is when the root is in
// the nursery. Note that the root was a rope but will be an extensible
// string when we return, so it will not point to any strings and need
// not be barriered.
if (str->isTenured() && !root->isTenured()) {
root->storeBuffer()->putWholeCell(str);
}
str = strParent;
if (finishNode) {
goto finish_node;
}
MOZ_ASSERT(visitRight);
goto visit_right_child;
}
finish_root:
// We traversed all the way back up to the root so we're finished.
MOZ_ASSERT(str == root);
MOZ_ASSERT(pos == wholeChars + wholeLength);
root->setLengthAndFlags(wholeLength,
StringFlagsForCharType<CharT>(EXTENSIBLE_FLAGS));
root->setNonInlineChars(wholeChars);
root->d.s.u3.capacity = wholeCapacity;
AddCellMemory(root, root->asLinear().allocSize(), MemoryUse::StringContents);
if (reuseLeftmostBuffer) {
// Remove memory association for left node we're about to make into a
// dependent string.
JSString& left = *leftmostChild;
RemoveCellMemory(&left, left.allocSize(), MemoryUse::StringContents);
uint32_t flags = INIT_DEPENDENT_FLAGS;
if (left.inStringToAtomCache()) {
flags |= IN_STRING_TO_ATOM_CACHE;
}
// If left was depended on, we need to make sure we preserve that. Even
// though the string that depended on left's buffer will now depend on
// root's buffer, if left is the only edge to root, replacing left with an
// atom ref would break that edge and allow root's buffer to be freed.
if (left.isDependedOn()) {
flags |= DEPENDED_ON_BIT;
}
left.setLengthAndFlags(left.length(), StringFlagsForCharType<CharT>(flags));
left.d.s.u3.base = &root->asLinear();
if (left.isTenured() && !root->isTenured()) {
// leftmost child -> root is a tenured -> nursery edge. Put the leftmost
// child in the store buffer and prevent the root's chars from moving or
// being freed (because the leftmost child may have a tenured dependent
// string that cannot be updated.)
root->storeBuffer()->putWholeCell(&left);
root->setNonDeduplicatable();
}
setRootDependedOn = true;
}
if (setRootDependedOn) {
root->setDependedOn();
}
return &root->asLinear();
}
template <JSRope::UsingBarrier usingBarrier>
/* static */
inline void JSRope::ropeBarrierDuringFlattening(JSRope* rope) {
MOZ_ASSERT(!rope->isBeingFlattened());
if constexpr (usingBarrier) {
gc::PreWriteBarrierDuringFlattening(rope->leftChild());
gc::PreWriteBarrierDuringFlattening(rope->rightChild());
}
}
template <AllowGC allowGC>
static JSLinearString* EnsureLinear(
JSContext* cx,
typename MaybeRooted<JSString*, allowGC>::HandleType string) {
JSLinearString* linear = string->ensureLinear(cx);
// Don't report an exception if GC is not allowed, just return nullptr.
if (!linear && !allowGC) {
cx->recoverFromOutOfMemory();
}
return linear;
}
template <AllowGC allowGC>
JSString* js::ConcatStrings(
JSContext* cx, typename MaybeRooted<JSString*, allowGC>::HandleType left,
typename MaybeRooted<JSString*, allowGC>::HandleType right, gc::Heap heap) {
MOZ_ASSERT_IF(!left->isAtom(), cx->isInsideCurrentZone(left));
MOZ_ASSERT_IF(!right->isAtom(), cx->isInsideCurrentZone(right));
size_t leftLen = left->length();
if (leftLen == 0) {
return right;
}
size_t rightLen = right->length();
if (rightLen == 0) {
return left;
}
size_t wholeLength = leftLen + rightLen;
if (MOZ_UNLIKELY(wholeLength > JSString::MAX_LENGTH)) {
// Don't report an exception if GC is not allowed, just return nullptr.
if (allowGC) {
js::ReportOversizedAllocation(cx, JSMSG_ALLOC_OVERFLOW);
}
return nullptr;
}
bool isLatin1 = left->hasLatin1Chars() && right->hasLatin1Chars();
bool canUseInline = isLatin1
? JSInlineString::lengthFits<Latin1Char>(wholeLength)
: JSInlineString::lengthFits<char16_t>(wholeLength);
if (canUseInline) {
Latin1Char* latin1Buf = nullptr; // initialize to silence GCC warning
char16_t* twoByteBuf = nullptr; // initialize to silence GCC warning
JSInlineString* str =
isLatin1
? AllocateInlineString<allowGC>(cx, wholeLength, &latin1Buf, heap)
: AllocateInlineString<allowGC>(cx, wholeLength, &twoByteBuf, heap);
if (!str) {
return nullptr;
}
AutoCheckCannotGC nogc;
JSLinearString* leftLinear = EnsureLinear<allowGC>(cx, left);
if (!leftLinear) {
return nullptr;
}
JSLinearString* rightLinear = EnsureLinear<allowGC>(cx, right);
if (!rightLinear) {
return nullptr;
}
if (isLatin1) {
PodCopy(latin1Buf, leftLinear->latin1Chars(nogc), leftLen);
PodCopy(latin1Buf + leftLen, rightLinear->latin1Chars(nogc), rightLen);
} else {
if (leftLinear->hasTwoByteChars()) {
PodCopy(twoByteBuf, leftLinear->twoByteChars(nogc), leftLen);
} else {
CopyAndInflateChars(twoByteBuf, leftLinear->latin1Chars(nogc), leftLen);
}
if (rightLinear->hasTwoByteChars()) {
PodCopy(twoByteBuf + leftLen, rightLinear->twoByteChars(nogc),
rightLen);
} else {
CopyAndInflateChars(twoByteBuf + leftLen,
rightLinear->latin1Chars(nogc), rightLen);
}
}
return str;
}
return JSRope::new_<allowGC>(cx, left, right, wholeLength, heap);
}
template JSString* js::ConcatStrings<CanGC>(JSContext* cx, HandleString left,
HandleString right, gc::Heap heap);
template JSString* js::ConcatStrings<NoGC>(JSContext* cx, JSString* const& left,
JSString* const& right,
gc::Heap heap);
#if defined(DEBUG) || defined(JS_JITSPEW) || defined(JS_CACHEIR_SPEW)
void JSDependentString::dumpOwnRepresentationFields(
js::JSONPrinter& json) const {
json.property("baseOffset", baseOffset());
json.beginObjectProperty("base");
base()->dumpRepresentationFields(json);
json.endObject();
}
#endif
bool js::EqualChars(const JSLinearString* str1, const JSLinearString* str2) {
// Assert this isn't called for strings the caller should handle with a fast
// path.
MOZ_ASSERT(str1->length() == str2->length());
MOZ_ASSERT(str1 != str2);
MOZ_ASSERT(!str1->isAtom() || !str2->isAtom());
size_t len = str1->length();
AutoCheckCannotGC nogc;
if (str1->hasTwoByteChars()) {
if (str2->hasTwoByteChars()) {
return EqualChars(str1->twoByteChars(nogc), str2->twoByteChars(nogc),
len);
}
return EqualChars(str2->latin1Chars(nogc), str1->twoByteChars(nogc), len);
}
if (str2->hasLatin1Chars()) {
return EqualChars(str1->latin1Chars(nogc), str2->latin1Chars(nogc), len);
}
return EqualChars(str1->latin1Chars(nogc), str2->twoByteChars(nogc), len);
}
bool js::HasSubstringAt(JSLinearString* text, JSLinearString* pat,
size_t start) {
MOZ_ASSERT(start + pat->length() <= text->length());
size_t patLen = pat->length();
AutoCheckCannotGC nogc;
if (text->hasLatin1Chars()) {
const Latin1Char* textChars = text->latin1Chars(nogc) + start;
if (pat->hasLatin1Chars()) {
return EqualChars(textChars, pat->latin1Chars(nogc), patLen);
}
return EqualChars(textChars, pat->twoByteChars(nogc), patLen);
}
const char16_t* textChars = text->twoByteChars(nogc) + start;
if (pat->hasTwoByteChars()) {
return EqualChars(textChars, pat->twoByteChars(nogc), patLen);
}
return EqualChars(pat->latin1Chars(nogc), textChars, patLen);
}
bool js::EqualStrings(JSContext* cx, JSString* str1, JSString* str2,
bool* result) {
if (str1 == str2) {
*result = true;
return true;
}
if (str1->length() != str2->length()) {
*result = false;
return true;
}
if (str1->isAtom() && str2->isAtom()) {
*result = false;
return true;
}
JSLinearString* linear1 = str1->ensureLinear(cx);
if (!linear1) {
return false;
}
JSLinearString* linear2 = str2->ensureLinear(cx);
if (!linear2) {
return false;
}
*result = EqualChars(linear1, linear2);
return true;
}
bool js::EqualStrings(const JSLinearString* str1, const JSLinearString* str2) {
if (str1 == str2) {
return true;
}
if (str1->length() != str2->length()) {
return false;
}
if (str1->isAtom() && str2->isAtom()) {
return false;
}
return EqualChars(str1, str2);
}
int32_t js::CompareChars(const char16_t* s1, size_t len1, JSLinearString* s2) {
AutoCheckCannotGC nogc;
return s2->hasLatin1Chars()
? CompareChars(s1, len1, s2->latin1Chars(nogc), s2->length())
: CompareChars(s1, len1, s2->twoByteChars(nogc), s2->length());
}
static int32_t CompareStringsImpl(const JSLinearString* str1,
const JSLinearString* str2) {
size_t len1 = str1->length();
size_t len2 = str2->length();
AutoCheckCannotGC nogc;
if (str1->hasLatin1Chars()) {
const Latin1Char* chars1 = str1->latin1Chars(nogc);
return str2->hasLatin1Chars()
? CompareChars(chars1, len1, str2->latin1Chars(nogc), len2)
: CompareChars(chars1, len1, str2->twoByteChars(nogc), len2);
}
const char16_t* chars1 = str1->twoByteChars(nogc);
return str2->hasLatin1Chars()
? CompareChars(chars1, len1, str2->latin1Chars(nogc), len2)
: CompareChars(chars1, len1, str2->twoByteChars(nogc), len2);
}
bool js::CompareStrings(JSContext* cx, JSString* str1, JSString* str2,
int32_t* result) {
MOZ_ASSERT(str1);
MOZ_ASSERT(str2);
if (str1 == str2) {
*result = 0;
return true;
}
JSLinearString* linear1 = str1->ensureLinear(cx);
if (!linear1) {
return false;
}
JSLinearString* linear2 = str2->ensureLinear(cx);
if (!linear2) {
return false;
}
*result = CompareStringsImpl(linear1, linear2);
return true;
}
int32_t js::CompareStrings(const JSLinearString* str1,
const JSLinearString* str2) {
MOZ_ASSERT(str1);
MOZ_ASSERT(str2);
if (str1 == str2) {
return 0;
}
return CompareStringsImpl(str1, str2);
}
bool js::StringIsAscii(JSLinearString* str) {
JS::AutoCheckCannotGC nogc;
if (str->hasLatin1Chars()) {
return mozilla::IsAscii(
AsChars(Span(str->latin1Chars(nogc), str->length())));
}
return mozilla::IsAscii(Span(str->twoByteChars(nogc), str->length()));
}
bool js::StringEqualsAscii(JSLinearString* str, const char* asciiBytes) {
return StringEqualsAscii(str, asciiBytes, strlen(asciiBytes));
}
bool js::StringEqualsAscii(JSLinearString* str, const char* asciiBytes,
size_t length) {
MOZ_ASSERT(JS::StringIsASCII(Span(asciiBytes, length)));
if (length != str->length()) {
return false;
}
const Latin1Char* latin1 = reinterpret_cast<const Latin1Char*>(asciiBytes);
AutoCheckCannotGC nogc;
return str->hasLatin1Chars()
? EqualChars(latin1, str->latin1Chars(nogc), length)
: EqualChars(latin1, str->twoByteChars(nogc), length);
}
template <typename CharT>
bool js::CheckStringIsIndex(const CharT* s, size_t length, uint32_t* indexp) {
MOZ_ASSERT(length > 0);
MOZ_ASSERT(length <= UINT32_CHAR_BUFFER_LENGTH);
MOZ_ASSERT(IsAsciiDigit(*s),
"caller's fast path must have checked first char");
RangedPtr<const CharT> cp(s, length);
const RangedPtr<const CharT> end(s + length, s, length);
uint32_t index = AsciiDigitToNumber(*cp++);
uint32_t oldIndex = 0;
uint32_t c = 0;
if (index != 0) {
// Consume remaining characters only if the first character isn't '0'.
while (cp < end && IsAsciiDigit(*cp)) {
oldIndex = index;
c = AsciiDigitToNumber(*cp);
index = 10 * index + c;
cp++;
}
}
// It's not an integer index if there are characters after the number.
if (cp != end) {
return false;
}
// Look out for "4294967295" and larger-number strings that fit in
// UINT32_CHAR_BUFFER_LENGTH: only unsigned 32-bit integers less than or equal
// to MAX_ARRAY_INDEX shall pass.
if (oldIndex < MAX_ARRAY_INDEX / 10 ||
(oldIndex == MAX_ARRAY_INDEX / 10 && c <= (MAX_ARRAY_INDEX % 10))) {
MOZ_ASSERT(index <= MAX_ARRAY_INDEX);
*indexp = index;
return true;
}
return false;
}
template bool js::CheckStringIsIndex(const Latin1Char* s, size_t length,
uint32_t* indexp);
template bool js::CheckStringIsIndex(const char16_t* s, size_t length,
uint32_t* indexp);
template <typename CharT>
static uint32_t AtomCharsToIndex(const CharT* s, size_t length) {
// Chars are known to be a valid index value (as determined by
// CheckStringIsIndex) that didn't fit in the "index value" bits in the
// header.
MOZ_ASSERT(length > 0);
MOZ_ASSERT(length <= UINT32_CHAR_BUFFER_LENGTH);
RangedPtr<const CharT> cp(s, length);
const RangedPtr<const CharT> end(s + length, s, length);
MOZ_ASSERT(IsAsciiDigit(*cp));
uint32_t index = AsciiDigitToNumber(*cp++);
MOZ_ASSERT(index != 0);
while (cp < end) {
MOZ_ASSERT(IsAsciiDigit(*cp));
index = 10 * index + AsciiDigitToNumber(*cp);
cp++;
}
MOZ_ASSERT(index <= MAX_ARRAY_INDEX);
return index;
}
uint32_t JSAtom::getIndexSlow() const {
MOZ_ASSERT(isIndex());
MOZ_ASSERT(!hasIndexValue());
size_t len = length();
AutoCheckCannotGC nogc;
return hasLatin1Chars() ? AtomCharsToIndex(latin1Chars(nogc), len)
: AtomCharsToIndex(twoByteChars(nogc), len);
}
// Prevent the actual owner of the string's characters from being deduplicated
// (and thus freeing its characters, which would invalidate the ASSC's chars
// pointer). Intermediate dependent strings on the chain can be deduplicated,
// since the base will be updated to the root base during tenuring anyway and
// the intermediates won't matter.
void PreventRootBaseDeduplication(JSLinearString* s) {
while (s->hasBase()) {
s = s->base();
}
if (!s->isTenured()) {
s->setNonDeduplicatable();
}
}
bool AutoStableStringChars::init(JSContext* cx, JSString* s) {
Rooted<JSLinearString*> linearString(cx, s->ensureLinear(cx));
if (!linearString) {
return false;
}
MOZ_ASSERT(state_ == Uninitialized);
// Inline and nursery-allocated chars may move during a GC, so copy them
// out into a temporary malloced buffer. Note that we cannot update the
// string itself with a malloced buffer, because there may be dependent
// strings that are using the original chars.
if (linearString->hasMovableChars()) {
return linearString->hasTwoByteChars() ? copyTwoByteChars(cx, linearString)
: copyLatin1Chars(cx, linearString);
}
if (linearString->hasLatin1Chars()) {
state_ = Latin1;
latin1Chars_ = linearString->rawLatin1Chars();
} else {
state_ = TwoByte;
twoByteChars_ = linearString->rawTwoByteChars();
}
PreventRootBaseDeduplication(linearString);
s_ = linearString;
return true;
}
bool AutoStableStringChars::initTwoByte(JSContext* cx, JSString* s) {
Rooted<JSLinearString*> linearString(cx, s->ensureLinear(cx));
if (!linearString) {
return false;
}
MOZ_ASSERT(state_ == Uninitialized);
if (linearString->hasLatin1Chars()) {
return copyAndInflateLatin1Chars(cx, linearString);
}
// Copy movable chars since they may be moved by GC (see above).
if (linearString->hasMovableChars()) {
return copyTwoByteChars(cx, linearString);
}
state_ = TwoByte;
twoByteChars_ = linearString->rawTwoByteChars();
PreventRootBaseDeduplication(linearString);
s_ = linearString;
return true;
}
template <typename T>
T* AutoStableStringChars::allocOwnChars(JSContext* cx, size_t count) {
static_assert(
InlineCapacity >=
sizeof(JS::Latin1Char) * JSFatInlineString::MAX_LENGTH_LATIN1 &&
InlineCapacity >=
sizeof(char16_t) * JSFatInlineString::MAX_LENGTH_TWO_BYTE,
"InlineCapacity too small to hold fat inline strings");
static_assert((JSString::MAX_LENGTH &
mozilla::tl::MulOverflowMask<sizeof(T)>::value) == 0,
"Size calculation can overflow");
MOZ_ASSERT(count <= JSString::MAX_LENGTH);
size_t size = sizeof(T) * count;
ownChars_.emplace(cx);
if (!ownChars_->resize(size)) {
ownChars_.reset();
return nullptr;
}
return reinterpret_cast<T*>(ownChars_->begin());
}
bool AutoStableStringChars::copyAndInflateLatin1Chars(
JSContext* cx, Handle<JSLinearString*> linearString) {
size_t length = linearString->length();
char16_t* chars = allocOwnChars<char16_t>(cx, length);
if (!chars) {
return false;
}
// Copy |src[0..length]| to |dest[0..length]| when copying doesn't narrow and
// therefore can't lose information.
auto src = AsChars(Span(linearString->rawLatin1Chars(), length));
auto dest = Span(chars, length);
ConvertLatin1toUtf16(src, dest);
state_ = TwoByte;
twoByteChars_ = chars;
s_ = linearString;
return true;
}
bool AutoStableStringChars::copyLatin1Chars(
JSContext* cx, Handle<JSLinearString*> linearString) {
size_t length = linearString->length();
JS::Latin1Char* chars = allocOwnChars<JS::Latin1Char>(cx, length);
if (!chars) {
return false;
}
PodCopy(chars, linearString->rawLatin1Chars(), length);
state_ = Latin1;
latin1Chars_ = chars;
s_ = linearString;
return true;
}
bool AutoStableStringChars::copyTwoByteChars(
JSContext* cx, Handle<JSLinearString*> linearString) {
size_t length = linearString->length();
char16_t* chars = allocOwnChars<char16_t>(cx, length);
if (!chars) {
return false;
}
PodCopy(chars, linearString->rawTwoByteChars(), length);
state_ = TwoByte;
twoByteChars_ = chars;
s_ = linearString;
return true;
}
template <>
bool JS::SourceText<char16_t>::initMaybeBorrowed(
JSContext* cx, JS::AutoStableStringChars& linearChars) {
MOZ_ASSERT(linearChars.isTwoByte(),
"AutoStableStringChars must be initialized with char16_t");
const char16_t* chars = linearChars.twoByteChars();
size_t length = linearChars.length();
JS::SourceOwnership ownership = linearChars.maybeGiveOwnershipToCaller()
? JS::SourceOwnership::TakeOwnership
: JS::SourceOwnership::Borrowed;
return initImpl(cx, chars, length, ownership);
}
template <>
bool JS::SourceText<char16_t>::initMaybeBorrowed(
JS::FrontendContext* fc, JS::AutoStableStringChars& linearChars) {
MOZ_ASSERT(linearChars.isTwoByte(),
"AutoStableStringChars must be initialized with char16_t");
const char16_t* chars = linearChars.twoByteChars();
size_t length = linearChars.length();
JS::SourceOwnership ownership = linearChars.maybeGiveOwnershipToCaller()
? JS::SourceOwnership::TakeOwnership
: JS::SourceOwnership::Borrowed;
return initImpl(fc, chars, length, ownership);
}
#if defined(DEBUG) || defined(JS_JITSPEW) || defined(JS_CACHEIR_SPEW)
void JSAtom::dump(js::GenericPrinter& out) {
out.printf("JSAtom* (%p) = ", (void*)this);
this->JSString::dump(out);
}
void JSAtom::dump() {
Fprinter out(stderr);
dump(out);
}
void JSExternalString::dumpOwnRepresentationFields(
js::JSONPrinter& json) const {
json.formatProperty("callbacks", "(JSExternalStringCallbacks*)0x%p",
callbacks());
}
#endif /* defined(DEBUG) || defined(JS_JITSPEW) || defined(JS_CACHEIR_SPEW) */
JSLinearString* js::NewDependentString(JSContext* cx, JSString* baseArg,
size_t start, size_t length,
gc::Heap heap) {
if (length == 0) {
return cx->emptyString();
}
JSLinearString* base = baseArg->ensureLinear(cx);
if (!base) {
return nullptr;
}
if (start == 0 && length == base->length()) {
return base;
}
bool useInline;
if (base->hasTwoByteChars()) {
AutoCheckCannotGC nogc;
const char16_t* chars = base->twoByteChars(nogc) + start;
if (JSLinearString* staticStr = cx->staticStrings().lookup(chars, length)) {
return staticStr;
}
useInline = JSInlineString::lengthFits<char16_t>(length);
} else {
AutoCheckCannotGC nogc;
const Latin1Char* chars = base->latin1Chars(nogc) + start;
if (JSLinearString* staticStr = cx->staticStrings().lookup(chars, length)) {
return staticStr;
}
useInline = JSInlineString::lengthFits<Latin1Char>(length);
}
if (useInline) {
Rooted<JSLinearString*> rootedBase(cx, base);
// Do not create a dependent string that would fit into an inline string.
// First, that could create a string dependent on an inline base string's
// chars, which would be an awkward moving-GC hazard. Second, this makes
// it more likely to have a very short string keep a very long string alive.
if (base->hasTwoByteChars()) {
return NewInlineString<char16_t>(cx, rootedBase, start, length, heap);
}
return NewInlineString<Latin1Char>(cx, rootedBase, start, length, heap);
}
return JSDependentString::new_(cx, base, start, length, heap);
}
static constexpr bool CanStoreCharsAsLatin1(const JS::Latin1Char* s,
size_t length) {
return true;
}
static inline bool CanStoreCharsAsLatin1(const char16_t* s, size_t length) {
return IsUtf16Latin1(Span(s, length));
}
/**
* Copy |src[0..length]| to |dest[0..length]| when copying *does* narrow, but
* the user guarantees every runtime |src[i]| value can be stored without change
* of value in |dest[i]|.
*/
static inline void FillFromCompatible(unsigned char* dest, const char16_t* src,
size_t length) {
LossyConvertUtf16toLatin1(Span(src, length),
AsWritableChars(Span(dest, length)));
}
template <AllowGC allowGC>
static MOZ_ALWAYS_INLINE JSInlineString* NewInlineStringDeflated(
JSContext* cx, const mozilla::Range<const char16_t>& chars,
gc::Heap heap = gc::Heap::Default) {
size_t len = chars.length();
Latin1Char* storage;
JSInlineString* str = AllocateInlineString<allowGC>(cx, len, &storage, heap);
if (!str) {
return nullptr;
}
MOZ_ASSERT(CanStoreCharsAsLatin1(chars.begin().get(), len));
FillFromCompatible(storage, chars.begin().get(), len);
return str;
}
template <AllowGC allowGC>
static JSLinearString* NewStringDeflated(JSContext* cx, const char16_t* s,
size_t n, gc::Heap heap) {
if (JSLinearString* str = TryEmptyOrStaticString(cx, s, n)) {
return str;
}
if (JSInlineString::lengthFits<Latin1Char>(n)) {
return NewInlineStringDeflated<allowGC>(
cx, mozilla::Range<const char16_t>(s, n), heap);
}
JS::Rooted<JSString::OwnedChars<Latin1Char>> news(
cx, AllocChars<Latin1Char>(cx, n, heap));
if (!news) {
if (!allowGC) {
cx->recoverFromOutOfMemory();
}
return nullptr;
}
MOZ_ASSERT(CanStoreCharsAsLatin1(s, n));
FillFromCompatible(news.data(), s, n);
return JSLinearString::new_<allowGC, Latin1Char>(cx, &news, heap);
}
static MOZ_ALWAYS_INLINE JSAtom* NewInlineAtomDeflated(JSContext* cx,
const char16_t* chars,
size_t length,
js::HashNumber hash) {
Latin1Char* storage;
JSAtom* str = AllocateInlineAtom(cx, length, &storage, hash);
if (!str) {
return nullptr;
}
MOZ_ASSERT(CanStoreCharsAsLatin1(chars, length));
FillFromCompatible(storage, chars, length);
return str;
}
static JSAtom* NewAtomDeflatedValidLength(JSContext* cx, const char16_t* s,
size_t n, js::HashNumber hash) {
if (JSAtom::lengthFitsInline<Latin1Char>(n)) {
return NewInlineAtomDeflated(cx, s, n, hash);
}
auto news = cx->make_pod_arena_array<Latin1Char>(js::StringBufferArena, n);
if (!news) {
cx->recoverFromOutOfMemory();
return nullptr;
}
MOZ_ASSERT(CanStoreCharsAsLatin1(s, n));
FillFromCompatible(news.get(), s, n);
return JSAtom::newValidLength(cx, std::move(news), n, hash);
}
template <AllowGC allowGC, typename CharT>
JSLinearString* js::NewStringDontDeflate(
JSContext* cx, UniquePtr<CharT[], JS::FreePolicy> chars, size_t length,
gc::Heap heap) {
if (JSLinearString* str = TryEmptyOrStaticString(cx, chars.get(), length)) {
return str;
}
if (JSInlineString::lengthFits<CharT>(length)) {
// |chars.get()| is safe because 1) |NewInlineString| necessarily *copies*,
// and 2) |chars| frees its contents only when this function returns.
return NewInlineString<allowGC>(
cx, mozilla::Range<const CharT>(chars.get(), length), heap);
}
JS::Rooted<JSString::OwnedChars<CharT>> ownedChars(cx, std::move(chars),
length, true);
return JSLinearString::new_<allowGC, CharT>(cx, &ownedChars, heap);
}
template JSLinearString* js::NewStringDontDeflate<CanGC>(
JSContext* cx, UniqueTwoByteChars chars, size_t length, gc::Heap heap);
template JSLinearString* js::NewStringDontDeflate<NoGC>(
JSContext* cx, UniqueTwoByteChars chars, size_t length, gc::Heap heap);
template JSLinearString* js::NewStringDontDeflate<CanGC>(
JSContext* cx, UniqueLatin1Chars chars, size_t length, gc::Heap heap);
template JSLinearString* js::NewStringDontDeflate<NoGC>(JSContext* cx,
UniqueLatin1Chars chars,
size_t length,
gc::Heap heap);
template <AllowGC allowGC, typename CharT>
JSLinearString* js::NewString(JSContext* cx,
UniquePtr<CharT[], JS::FreePolicy> chars,
size_t length, gc::Heap heap) {
if constexpr (std::is_same_v<CharT, char16_t>) {
if (CanStoreCharsAsLatin1(chars.get(), length)) {
// Deflating copies from |chars.get()| and lets |chars| be freed on
// return.
return NewStringDeflated<allowGC>(cx, chars.get(), length, heap);
}
}
return NewStringDontDeflate<allowGC>(cx, std::move(chars), length, heap);
}
template JSLinearString* js::NewString<CanGC>(JSContext* cx,
UniqueTwoByteChars chars,
size_t length, gc::Heap heap);
template JSLinearString* js::NewString<NoGC>(JSContext* cx,
UniqueTwoByteChars chars,
size_t length, gc::Heap heap);
template JSLinearString* js::NewString<CanGC>(JSContext* cx,
UniqueLatin1Chars chars,
size_t length, gc::Heap heap);
template JSLinearString* js::NewString<NoGC>(JSContext* cx,
UniqueLatin1Chars chars,
size_t length, gc::Heap heap);
namespace js {
template <AllowGC allowGC, typename CharT>
JSLinearString* NewStringCopyNDontDeflateNonStaticValidLength(JSContext* cx,
const CharT* s,
size_t n,
gc::Heap heap) {
if (JSInlineString::lengthFits<CharT>(n)) {
return NewInlineString<allowGC>(cx, mozilla::Range<const CharT>(s, n),
heap);
}
Rooted<JSString::OwnedChars<CharT>> news(cx,
::AllocChars<CharT>(cx, n, heap));
if (!news) {
if (!allowGC) {
cx->recoverFromOutOfMemory();
}
return nullptr;
}
PodCopy(news.data(), s, n);
return JSLinearString::newValidLength<allowGC, CharT>(cx, &news, heap);
}
template JSLinearString* NewStringCopyNDontDeflateNonStaticValidLength<CanGC>(
JSContext* cx, const char16_t* s, size_t n, gc::Heap heap);
template JSLinearString* NewStringCopyNDontDeflateNonStaticValidLength<CanGC>(
JSContext* cx, const Latin1Char* s, size_t n, gc::Heap heap);
template <AllowGC allowGC, typename CharT>
JSLinearString* NewStringCopyNDontDeflate(JSContext* cx, const CharT* s,
size_t n, gc::Heap heap) {
if (JSLinearString* str = TryEmptyOrStaticString(cx, s, n)) {
return str;
}
if (MOZ_UNLIKELY(!JSLinearString::validateLength(cx, n))) {
return nullptr;
}
return NewStringCopyNDontDeflateNonStaticValidLength<allowGC>(cx, s, n, heap);
}
template JSLinearString* NewStringCopyNDontDeflate<CanGC>(JSContext* cx,
const char16_t* s,
size_t n,
gc::Heap heap);
template JSLinearString* NewStringCopyNDontDeflate<NoGC>(JSContext* cx,
const char16_t* s,
size_t n,
gc::Heap heap);
template JSLinearString* NewStringCopyNDontDeflate<CanGC>(JSContext* cx,
const Latin1Char* s,
size_t n,
gc::Heap heap);
template JSLinearString* NewStringCopyNDontDeflate<NoGC>(JSContext* cx,
const Latin1Char* s,
size_t n,
gc::Heap heap);
JSLinearString* NewLatin1StringZ(JSContext* cx, UniqueChars chars,
gc::Heap heap) {
size_t length = strlen(chars.get());
UniqueLatin1Chars latin1(reinterpret_cast<Latin1Char*>(chars.release()));
return NewString<CanGC>(cx, std::move(latin1), length, heap);
}
template <AllowGC allowGC, typename CharT>
JSLinearString* NewStringCopyN(JSContext* cx, const CharT* s, size_t n,
gc::Heap heap) {
if constexpr (std::is_same_v<CharT, char16_t>) {
if (CanStoreCharsAsLatin1(s, n)) {
return NewStringDeflated<allowGC>(cx, s, n, heap);
}
}
return NewStringCopyNDontDeflate<allowGC>(cx, s, n, heap);
}
template JSLinearString* NewStringCopyN<CanGC>(JSContext* cx, const char16_t* s,
size_t n, gc::Heap heap);
template JSLinearString* NewStringCopyN<NoGC>(JSContext* cx, const char16_t* s,
size_t n, gc::Heap heap);
template JSLinearString* NewStringCopyN<CanGC>(JSContext* cx,
const Latin1Char* s, size_t n,
gc::Heap heap);
template JSLinearString* NewStringCopyN<NoGC>(JSContext* cx,
const Latin1Char* s, size_t n,
gc::Heap heap);
template <typename CharT>
JSAtom* NewAtomCopyNDontDeflateValidLength(JSContext* cx, const CharT* s,
size_t n, js::HashNumber hash) {
if constexpr (std::is_same_v<CharT, char16_t>) {
MOZ_ASSERT(!CanStoreCharsAsLatin1(s, n));
}
if (JSAtom::lengthFitsInline<CharT>(n)) {
return NewInlineAtom(cx, s, n, hash);
}
auto news = cx->make_pod_arena_array<CharT>(js::StringBufferArena, n);
if (!news) {
cx->recoverFromOutOfMemory();
return nullptr;
}
PodCopy(news.get(), s, n);
return JSAtom::newValidLength(cx, std::move(news), n, hash);
}
template JSAtom* NewAtomCopyNDontDeflateValidLength(JSContext* cx,
const char16_t* s, size_t n,
js::HashNumber hash);
template JSAtom* NewAtomCopyNDontDeflateValidLength(JSContext* cx,
const Latin1Char* s,
size_t n,
js::HashNumber hash);
template <typename CharT>
JSAtom* NewAtomCopyNMaybeDeflateValidLength(JSContext* cx, const CharT* s,
size_t n, js::HashNumber hash) {
if constexpr (std::is_same_v<CharT, char16_t>) {
if (CanStoreCharsAsLatin1(s, n)) {
return NewAtomDeflatedValidLength(cx, s, n, hash);
}
}
return NewAtomCopyNDontDeflateValidLength(cx, s, n, hash);
}
template JSAtom* NewAtomCopyNMaybeDeflateValidLength(JSContext* cx,
const char16_t* s,
size_t n,
js::HashNumber hash);
template JSAtom* NewAtomCopyNMaybeDeflateValidLength(JSContext* cx,
const Latin1Char* s,
size_t n,
js::HashNumber hash);
JSLinearString* NewStringCopyUTF8N(JSContext* cx, const JS::UTF8Chars& utf8,
JS::SmallestEncoding encoding,
gc::Heap heap) {
if (encoding == JS::SmallestEncoding::ASCII) {
return NewStringCopyN<js::CanGC>(cx, utf8.begin().get(), utf8.length(),
heap);
}
size_t length;
if (encoding == JS::SmallestEncoding::Latin1) {
UniqueLatin1Chars latin1(
UTF8CharsToNewLatin1CharsZ(cx, utf8, &length, js::StringBufferArena)
.get());
if (!latin1) {
return nullptr;
}
return NewString<js::CanGC>(cx, std::move(latin1), length, heap);
}
MOZ_ASSERT(encoding == JS::SmallestEncoding::UTF16);
UniqueTwoByteChars utf16(
UTF8CharsToNewTwoByteCharsZ(cx, utf8, &length, js::StringBufferArena)
.get());
if (!utf16) {
return nullptr;
}
return NewString<js::CanGC>(cx, std::move(utf16), length, heap);
}
JSLinearString* NewStringCopyUTF8N(JSContext* cx, const JS::UTF8Chars& utf8,
gc::Heap heap) {
JS::SmallestEncoding encoding = JS::FindSmallestEncoding(utf8);
return NewStringCopyUTF8N(cx, utf8, encoding, heap);
}
template <typename CharT>
MOZ_ALWAYS_INLINE JSExternalString* ExternalStringCache::lookupExternalImpl(
const CharT* chars, size_t len) const {
AutoCheckCannotGC nogc;
for (size_t i = 0; i < NumEntries; i++) {
JSExternalString* str = externalEntries_[i];
if (!str || str->length() != len) {
continue;
}
if constexpr (std::is_same_v<CharT, JS::Latin1Char>) {
if (!str->hasLatin1Chars()) {
continue;
}
} else {
if (!str->hasTwoByteChars()) {
continue;
}
}
const CharT* strChars = str->nonInlineChars<CharT>(nogc);
if (chars == strChars) {
// Note that we don't need an incremental barrier here or below.
// The cache is purged on GC so any string we get from the cache
// must have been allocated after the GC started.
return str;
}
// Compare the chars. Don't do this for long strings as it will be
// faster to allocate a new external string.
static const size_t MaxLengthForCharComparison = 100;
if (len <= MaxLengthForCharComparison && EqualChars(chars, strChars, len)) {
return str;
}
}
return nullptr;
}
MOZ_ALWAYS_INLINE JSExternalString* ExternalStringCache::lookupExternal(
const JS::Latin1Char* chars, size_t len) const {
return lookupExternalImpl(chars, len);
}
MOZ_ALWAYS_INLINE JSExternalString* ExternalStringCache::lookupExternal(
const char16_t* chars, size_t len) const {
return lookupExternalImpl(chars, len);
}
MOZ_ALWAYS_INLINE void ExternalStringCache::putExternal(JSExternalString* str) {
for (size_t i = NumEntries - 1; i > 0; i--) {
externalEntries_[i] = externalEntries_[i - 1];
}
externalEntries_[0] = str;
}
template <typename CharT>
MOZ_ALWAYS_INLINE JSInlineString* ExternalStringCache::lookupInlineImpl(
const CharT* chars, size_t len) const {
MOZ_ASSERT(CanStoreCharsAsLatin1(chars, len));
MOZ_ASSERT(JSThinInlineString::lengthFits<Latin1Char>(len));
AutoCheckCannotGC nogc;
for (size_t i = 0; i < NumEntries; i++) {
JSInlineString* str = inlineEntries_[i];
if (!str || str->length() != len) {
continue;
}
const JS::Latin1Char* strChars = str->latin1Chars(nogc);
if (EqualChars(chars, strChars, len)) {
return str;
}
}
return nullptr;
}
MOZ_ALWAYS_INLINE JSInlineString* ExternalStringCache::lookupInline(
const JS::Latin1Char* chars, size_t len) const {
return lookupInlineImpl(chars, len);
}
MOZ_ALWAYS_INLINE JSInlineString* ExternalStringCache::lookupInline(
const char16_t* chars, size_t len) const {
return lookupInlineImpl(chars, len);
}
MOZ_ALWAYS_INLINE void ExternalStringCache::putInline(JSInlineString* str) {
MOZ_ASSERT(str->hasLatin1Chars());
for (size_t i = NumEntries - 1; i > 0; i--) {
inlineEntries_[i] = inlineEntries_[i - 1];
}
inlineEntries_[0] = str;
}
} /* namespace js */
template <AllowGC allowGC>
static MOZ_ALWAYS_INLINE JSInlineString* NewInlineStringMaybeDeflated(
JSContext* cx, const mozilla::Range<const JS::Latin1Char>& chars,
gc::Heap heap = gc::Heap::Default) {
return NewInlineString<allowGC>(cx, chars, heap);
}
template <AllowGC allowGC>
static MOZ_ALWAYS_INLINE JSInlineString* NewInlineStringMaybeDeflated(
JSContext* cx, const mozilla::Range<const char16_t>& chars,
gc::Heap heap = gc::Heap::Default) {
return NewInlineStringDeflated<allowGC>(cx, chars, heap);
}
namespace js {
template <typename CharT>
JSString* NewMaybeExternalString(JSContext* cx, const CharT* s, size_t n,
const JSExternalStringCallbacks* callbacks,
bool* allocatedExternal, gc::Heap heap) {
if (JSString* str = TryEmptyOrStaticString(cx, s, n)) {
*allocatedExternal = false;
return str;
}
ExternalStringCache& cache = cx->zone()->externalStringCache();
if (JSThinInlineString::lengthFits<Latin1Char>(n) &&
CanStoreCharsAsLatin1(s, n)) {
*allocatedExternal = false;
if (JSInlineString* str = cache.lookupInline(s, n)) {
return str;
}
JSInlineString* str = NewInlineStringMaybeDeflated<AllowGC::CanGC>(
cx, mozilla::Range<const CharT>(s, n), heap);
if (!str) {
return nullptr;
}
cache.putInline(str);
return str;
}
if (JSExternalString* str = cache.lookupExternal(s, n)) {
*allocatedExternal = false;
return str;
}
JSExternalString* str = JSExternalString::new_(cx, s, n, callbacks);
if (!str) {
return nullptr;
}
*allocatedExternal = true;
cache.putExternal(str);
return str;
}
template JSString* NewMaybeExternalString(
JSContext* cx, const JS::Latin1Char* s, size_t n,
const JSExternalStringCallbacks* callbacks, bool* allocatedExternal,
gc::Heap heap);
template JSString* NewMaybeExternalString(
JSContext* cx, const char16_t* s, size_t n,
const JSExternalStringCallbacks* callbacks, bool* allocatedExternal,
gc::Heap heap);
} /* namespace js */
#if defined(DEBUG) || defined(JS_JITSPEW) || defined(JS_CACHEIR_SPEW)
void JSExtensibleString::dumpOwnRepresentationFields(
js::JSONPrinter& json) const {
json.property("capacity", capacity());
}
void JSInlineString::dumpOwnRepresentationFields(js::JSONPrinter& json) const {}
void JSLinearString::dumpOwnRepresentationFields(js::JSONPrinter& json) const {
if (!isInline()) {
// Include whether the chars are in the nursery even for tenured
// strings, which should always be false. For investigating bugs, it's
// better to not assume that.
js::Nursery& nursery = runtimeFromMainThread()->gc.nursery();
bool inNursery = nursery.isInside(nonInlineCharsRaw());
json.boolProperty("charsInNursery", inNursery);
}
}
#endif
struct RepresentativeExternalString : public JSExternalStringCallbacks {
void finalize(JS::Latin1Char* chars) const override {
// Constant chars, nothing to do.
}
void finalize(char16_t* chars) const override {
// Constant chars, nothing to do.
}
size_t sizeOfBuffer(const JS::Latin1Char* chars,
mozilla::MallocSizeOf mallocSizeOf) const override {
// This string's buffer is not heap-allocated, so its malloc size is 0.
return 0;
}
size_t sizeOfBuffer(const char16_t* chars,
mozilla::MallocSizeOf mallocSizeOf) const override {
// This string's buffer is not heap-allocated, so its malloc size is 0.
return 0;
}
};
static const RepresentativeExternalString RepresentativeExternalStringCallbacks;
template <typename CheckString, typename CharT>
static bool FillWithRepresentatives(JSContext* cx, Handle<ArrayObject*> array,
uint32_t* index, const CharT* chars,
size_t len, size_t inlineStringMaxLength,
size_t inlineAtomMaxLength,
const CheckString& check, gc::Heap heap) {
auto AppendString = [&check](JSContext* cx, Handle<ArrayObject*> array,
uint32_t* index, HandleString s) {
MOZ_ASSERT(check(s));
(void)check; // silence clang -Wunused-lambda-capture in opt builds
RootedValue val(cx, StringValue(s));
return JS_DefineElement(cx, array, (*index)++, val, 0);
};
MOZ_ASSERT(len > inlineStringMaxLength);
MOZ_ASSERT(len > inlineAtomMaxLength);
// Normal atom.
RootedString atom1(cx, AtomizeChars(cx, chars, len));
if (!atom1 || !AppendString(cx, array, index, atom1)) {
return false;
}
MOZ_ASSERT(atom1->isAtom());
// Thin inline atom.
RootedString atom2(cx, AtomizeChars(cx, chars, 2));
if (!atom2 || !AppendString(cx, array, index, atom2)) {
return false;
}
MOZ_ASSERT(atom2->isAtom());
MOZ_ASSERT(atom2->isInline());
// Fat inline atom.
RootedString atom3(cx, AtomizeChars(cx, chars, inlineAtomMaxLength));
if (!atom3 || !AppendString(cx, array, index, atom3)) {
return false;
}
MOZ_ASSERT(atom3->isAtom());
MOZ_ASSERT_IF(inlineStringMaxLength < inlineAtomMaxLength,
atom3->isFatInline());
// Normal linear string; maybe nursery.
RootedString linear1(cx, NewStringCopyN<CanGC>(cx, chars, len, heap));
if (!linear1 || !AppendString(cx, array, index, linear1)) {
return false;
}
MOZ_ASSERT(linear1->isLinear());
// Inline string; maybe nursery.
RootedString linear2(cx, NewStringCopyN<CanGC>(cx, chars, 3, heap));
if (!linear2 || !AppendString(cx, array, index, linear2)) {
return false;
}
MOZ_ASSERT(linear2->isLinear());
MOZ_ASSERT(linear2->isInline());
// Fat inline string; maybe nursery.
RootedString linear3(
cx, NewStringCopyN<CanGC>(cx, chars, inlineStringMaxLength, heap));
if (!linear3 || !AppendString(cx, array, index, linear3)) {
return false;
}
MOZ_ASSERT(linear3->isLinear());
MOZ_ASSERT(linear3->isFatInline());
// Rope; maybe nursery.
RootedString rope(cx, ConcatStrings<CanGC>(cx, atom1, atom3, heap));
if (!rope || !AppendString(cx, array, index, rope)) {
return false;
}
MOZ_ASSERT(rope->isRope());
// Dependent; maybe nursery.
RootedString dep(cx, NewDependentString(cx, atom1, 0, len - 2, heap));
if (!dep || !AppendString(cx, array, index, dep)) {
return false;
}
MOZ_ASSERT(dep->isDependent());
// Extensible; maybe nursery.
RootedString temp1(cx, NewStringCopyN<CanGC>(cx, chars, len, heap));
if (!temp1) {
return false;
}
RootedString extensible(cx, ConcatStrings<CanGC>(cx, temp1, atom3, heap));
if (!extensible || !extensible->ensureLinear(cx)) {
return false;
}
if (!AppendString(cx, array, index, extensible)) {
return false;
}
MOZ_ASSERT(extensible->isExtensible());
RootedString external1(cx), external2(cx);
if constexpr (std::is_same_v<CharT, char16_t>) {
external1 = JS_NewExternalUCString(cx, (const char16_t*)chars, len,
&RepresentativeExternalStringCallbacks);
if (!external1 || !AppendString(cx, array, index, external1)) {
return false;
}
MOZ_ASSERT(external1->isExternal());
external2 = JS_NewExternalUCString(cx, (const char16_t*)chars, 2,
&RepresentativeExternalStringCallbacks);
if (!external2 || !AppendString(cx, array, index, external2)) {
return false;
}
MOZ_ASSERT(external2->isExternal());
} else {
external1 =
JS_NewExternalStringLatin1(cx, (const Latin1Char*)chars, len,
&RepresentativeExternalStringCallbacks);
if (!external1 || !AppendString(cx, array, index, external1)) {
return false;
}
MOZ_ASSERT(external1->isExternal());
external2 =
JS_NewExternalStringLatin1(cx, (const Latin1Char*)chars, 2,
&RepresentativeExternalStringCallbacks);
if (!external2 || !AppendString(cx, array, index, external2)) {
return false;
}
MOZ_ASSERT(external2->isExternal());
}
// Assert the strings still have the types we expect after creating the
// other strings.
MOZ_ASSERT(atom1->isAtom());
MOZ_ASSERT(atom2->isAtom());
MOZ_ASSERT(atom3->isAtom());
MOZ_ASSERT(atom2->isInline());
MOZ_ASSERT_IF(inlineStringMaxLength < inlineAtomMaxLength,
atom3->isFatInline());
MOZ_ASSERT(linear1->isLinear());
MOZ_ASSERT(linear2->isLinear());
MOZ_ASSERT(linear3->isLinear());
MOZ_ASSERT(linear2->isInline());
MOZ_ASSERT(linear3->isFatInline());
MOZ_ASSERT(rope->isRope());
MOZ_ASSERT(dep->isDependent());
MOZ_ASSERT(extensible->isExtensible());
MOZ_ASSERT(external1->isExternal());
MOZ_ASSERT(external2->isExternal());
return true;
}
/* static */
bool JSString::fillWithRepresentatives(JSContext* cx,
Handle<ArrayObject*> array) {
uint32_t index = 0;
auto CheckTwoByte = [](JSString* str) { return str->hasTwoByteChars(); };
auto CheckLatin1 = [](JSString* str) { return str->hasLatin1Chars(); };
static const char16_t twoByteChars[] =
u"\u1234abc\0def\u5678ghijklmasdfa\0xyz0123456789";
static const Latin1Char latin1Chars[] = "abc\0defghijklmasdfa\0xyz0123456789";
// Create strings using both the default heap and forcing the tenured heap. If
// nursery strings are available, this is a best effort at creating them in
// the default heap case. Since nursery strings may be disabled or a GC may
// occur during this process, there may be duplicate representatives in the
// final list.
if (!FillWithRepresentatives(cx, array, &index, twoByteChars,
std::size(twoByteChars) - 1,
JSFatInlineString::MAX_LENGTH_TWO_BYTE,
js::FatInlineAtom::MAX_LENGTH_TWO_BYTE,
CheckTwoByte, gc::Heap::Tenured)) {
return false;
}
if (!FillWithRepresentatives(cx, array, &index, latin1Chars,
std::size(latin1Chars) - 1,
JSFatInlineString::MAX_LENGTH_LATIN1,
js::FatInlineAtom::MAX_LENGTH_LATIN1,
CheckLatin1, gc::Heap::Tenured)) {
return false;
}
if (!FillWithRepresentatives(cx, array, &index, twoByteChars,
std::size(twoByteChars) - 1,
JSFatInlineString::MAX_LENGTH_TWO_BYTE,
js::FatInlineAtom::MAX_LENGTH_TWO_BYTE,
CheckTwoByte, gc::Heap::Default)) {
return false;
}
if (!FillWithRepresentatives(cx, array, &index, latin1Chars,
std::size(latin1Chars) - 1,
JSFatInlineString::MAX_LENGTH_LATIN1,
js::FatInlineAtom::MAX_LENGTH_LATIN1,
CheckLatin1, gc::Heap::Default)) {
return false;
}
#ifdef DEBUG
// * Normal atom
// * Inline atom.
// * Fat inline atom.
// * Normal linear string
// * Inline string
// * Fat inline string
// * Rope; maybe nursery.
// * Dependent
// * Extensible
// * External with original len
// * External with len==2
static constexpr uint32_t StringTypes = 11;
// * Latin1
// * TwoByte
static constexpr uint32_t CharTypes = 2;
// * Tenured
// * Default
static constexpr uint32_t HeapType = 2;
MOZ_ASSERT(index == StringTypes * CharTypes * HeapType);
#endif
return true;
}
bool JSString::tryReplaceWithAtomRef(JSAtom* atom) {
MOZ_ASSERT(!isAtomRef());
if (isDependedOn() || isInline() || isExternal()) {
return false;
}
AutoCheckCannotGC nogc;
if (hasOutOfLineChars()) {
void* buffer = asLinear().nonInlineCharsRaw();
// This is a little cheeky and so deserves a comment. If the string is
// not tenured, then either its buffer lives purely in the nursery, in
// which case it will just be forgotten and blown away in the next
// minor GC, or it is tracked in the nursery's mallocedBuffers hashtable,
// in which case it will be freed for us in the next minor GC. We opt
// to let the GC take care of it since there's a chance it will run
// during idle time.
if (isTenured()) {
RemoveCellMemory(this, allocSize(), MemoryUse::StringContents);
js_free(buffer);
}
}
uint32_t flags = INIT_ATOM_REF_FLAGS;
d.s.u3.atom = atom;
if (atom->hasLatin1Chars()) {
flags |= LATIN1_CHARS_BIT;
setLengthAndFlags(length(), flags);
setNonInlineChars(atom->chars<Latin1Char>(nogc));
} else {
setLengthAndFlags(length(), flags);
setNonInlineChars(atom->chars<char16_t>(nogc));
}
// Redundant, but just a reminder that this needs to be true or else we need
// to check and conditionally put ourselves in the store buffer
MOZ_ASSERT(atom->isTenured());
return true;
}
/*** Conversions ************************************************************/
UniqueChars js::EncodeLatin1(JSContext* cx, JSString* str) {
JSLinearString* linear = str->ensureLinear(cx);
if (!linear) {
return nullptr;
}
JS::AutoCheckCannotGC nogc;
if (linear->hasTwoByteChars()) {
JS::Latin1CharsZ chars =
JS::LossyTwoByteCharsToNewLatin1CharsZ(cx, linear->twoByteRange(nogc));
return UniqueChars(chars.c_str());
}
size_t len = str->length();
Latin1Char* buf = cx->pod_malloc<Latin1Char>(len + 1);
if (!buf) {
return nullptr;
}
PodCopy(buf, linear->latin1Chars(nogc), len);
buf[len] = '\0';
return UniqueChars(reinterpret_cast<char*>(buf));
}
UniqueChars js::EncodeAscii(JSContext* cx, JSString* str) {
JSLinearString* linear = str->ensureLinear(cx);
if (!linear) {
return nullptr;
}
MOZ_ASSERT(StringIsAscii(linear));
return EncodeLatin1(cx, linear);
}
UniqueChars js::IdToPrintableUTF8(JSContext* cx, HandleId id,
IdToPrintableBehavior behavior) {
// ToString(<symbol>) throws a TypeError, therefore require that callers
// request source representation when |id| is a property key.
MOZ_ASSERT_IF(behavior == IdToPrintableBehavior::IdIsIdentifier,
id.isAtom() && IsIdentifierNameOrPrivateName(id.toAtom()));
RootedValue v(cx, IdToValue(id));
JSString* str;
if (behavior == IdToPrintableBehavior::IdIsPropertyKey) {
str = ValueToSource(cx, v);
} else {
str = ToString<CanGC>(cx, v);
}
if (!str) {
return nullptr;
}
return StringToNewUTF8CharsZ(cx, *str);
}
template <AllowGC allowGC>
JSString* js::ToStringSlow(
JSContext* cx, typename MaybeRooted<Value, allowGC>::HandleType arg) {
/* As with ToObjectSlow, callers must verify that |arg| isn't a string. */
MOZ_ASSERT(!arg.isString());
Value v = arg;
if (!v.isPrimitive()) {
if (!allowGC) {
return nullptr;
}
RootedValue v2(cx, v);
if (!ToPrimitive(cx, JSTYPE_STRING, &v2)) {
return nullptr;
}
v = v2;
}
JSString* str;
if (v.isString()) {
str = v.toString();
} else if (v.isInt32()) {
str = Int32ToString<allowGC>(cx, v.toInt32());
} else if (v.isDouble()) {
str = NumberToString<allowGC>(cx, v.toDouble());
} else if (v.isBoolean()) {
str = BooleanToString(cx, v.toBoolean());
} else if (v.isNull()) {
str = cx->names().null;
} else if (v.isSymbol()) {
if (allowGC) {
JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
JSMSG_SYMBOL_TO_STRING);
}
return nullptr;
} else if (v.isBigInt()) {
if (!allowGC) {
return nullptr;
}
RootedBigInt i(cx, v.toBigInt());
str = BigInt::toString<CanGC>(cx, i, 10);
}
#ifdef ENABLE_RECORD_TUPLE
else if (v.isExtendedPrimitive()) {
if (!allowGC) {
return nullptr;
}
if (IsTuple(v)) {
Rooted<TupleType*> tup(cx, &TupleType::thisTupleValue(v));
return TupleToSource(cx, tup);
}
Rooted<RecordType*> rec(cx);
MOZ_ALWAYS_TRUE(RecordObject::maybeUnbox(&v.getObjectPayload(), &rec));
return RecordToSource(cx, rec);
}
#endif
else {
MOZ_ASSERT(v.isUndefined());
str = cx->names().undefined;
}
return str;
}
template JSString* js::ToStringSlow<CanGC>(JSContext* cx, HandleValue arg);
template JSString* js::ToStringSlow<NoGC>(JSContext* cx, const Value& arg);
JS_PUBLIC_API JSString* js::ToStringSlow(JSContext* cx, HandleValue v) {
return ToStringSlow<CanGC>(cx, v);
}