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/* -*- 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
/*
* Infrastructure for sharing DOMString data with JSStrings.
*
* Importing an nsAString into JS:
* If possible (GetSharedBufferHandle works) use the external string support in
* JS to create a JSString that points to the readable's buffer. We keep a
* reference to the buffer handle until the JSString is finalized.
*
* Exporting a JSString as an nsAReadable:
* Wrap the JSString with a root-holding XPCJSReadableStringWrapper, which roots
* the string and exposes its buffer via the nsAString interface, as
* well as providing refcounting support.
*/
#include "nscore.h"
#include "nsString.h"
#include "nsStringBuffer.h"
#include "jsapi.h"
#include "xpcpublic.h"
using namespace JS;
const XPCStringConvert::LiteralExternalString
XPCStringConvert::sLiteralExternalString;
const XPCStringConvert::DOMStringExternalString
XPCStringConvert::sDOMStringExternalString;
void XPCStringConvert::LiteralExternalString::finalize(
JS::Latin1Char* aChars) const {
// Nothing to do.
}
void XPCStringConvert::LiteralExternalString::finalize(char16_t* aChars) const {
// Nothing to do.
}
size_t XPCStringConvert::LiteralExternalString::sizeOfBuffer(
const JS::Latin1Char* aChars, mozilla::MallocSizeOf aMallocSizeOf) const {
// This string's buffer is not heap-allocated, so its malloc size is 0.
return 0;
}
size_t XPCStringConvert::LiteralExternalString::sizeOfBuffer(
const char16_t* aChars, mozilla::MallocSizeOf aMallocSizeOf) const {
// This string's buffer is not heap-allocated, so its malloc size is 0.
return 0;
}
void XPCStringConvert::DOMStringExternalString::finalize(
JS::Latin1Char* aChars) const {
nsStringBuffer* buf = nsStringBuffer::FromData(aChars);
buf->Release();
}
void XPCStringConvert::DOMStringExternalString::finalize(
char16_t* aChars) const {
nsStringBuffer* buf = nsStringBuffer::FromData(aChars);
buf->Release();
}
size_t XPCStringConvert::DOMStringExternalString::sizeOfBuffer(
const JS::Latin1Char* aChars, mozilla::MallocSizeOf aMallocSizeOf) const {
// We promised the JS engine we would not GC. Enforce that:
JS::AutoCheckCannotGC autoCannotGC;
const nsStringBuffer* buf =
nsStringBuffer::FromData(const_cast<JS::Latin1Char*>(aChars));
// We want sizeof including this, because the entire string buffer is owned by
// the external string. But only report here if we're unshared; if we're
// shared then we don't know who really owns this data.
return buf->SizeOfIncludingThisIfUnshared(aMallocSizeOf);
}
size_t XPCStringConvert::DOMStringExternalString::sizeOfBuffer(
const char16_t* aChars, mozilla::MallocSizeOf aMallocSizeOf) const {
// We promised the JS engine we would not GC. Enforce that:
JS::AutoCheckCannotGC autoCannotGC;
const nsStringBuffer* buf =
nsStringBuffer::FromData(const_cast<char16_t*>(aChars));
// We want sizeof including this, because the entire string buffer is owned by
// the external string. But only report here if we're unshared; if we're
// shared then we don't know who really owns this data.
return buf->SizeOfIncludingThisIfUnshared(aMallocSizeOf);
}
// convert a readable to a JSString, copying string data
// static
bool XPCStringConvert::ReadableToJSVal(JSContext* cx, const nsAString& readable,
nsStringBuffer** sharedBuffer,
MutableHandleValue vp) {
*sharedBuffer = nullptr;
uint32_t length = readable.Length();
if (readable.IsLiteral()) {
return StringLiteralToJSVal(cx, readable.BeginReading(), length, vp);
}
nsStringBuffer* buf = nsStringBuffer::FromString(readable);
if (buf) {
bool shared;
if (!UCStringBufferToJSVal(cx, buf, length, vp, &shared)) {
return false;
}
if (shared) {
*sharedBuffer = buf;
}
return true;
}
// blech, have to copy.
JSString* str = JS_NewUCStringCopyN(cx, readable.BeginReading(), length);
if (!str) {
return false;
}
vp.setString(str);
return true;
}
bool XPCStringConvert::Latin1ToJSVal(JSContext* cx, const nsACString& latin1,
nsStringBuffer** sharedBuffer,
MutableHandleValue vp) {
*sharedBuffer = nullptr;
uint32_t length = latin1.Length();
if (latin1.IsLiteral()) {
return StringLiteralToJSVal(
cx, reinterpret_cast<const JS::Latin1Char*>(latin1.BeginReading()),
length, vp);
}
nsStringBuffer* buf = nsStringBuffer::FromString(latin1);
if (buf) {
bool shared;
if (!Latin1StringBufferToJSVal(cx, buf, length, vp, &shared)) {
return false;
}
if (shared) {
*sharedBuffer = buf;
}
return true;
}
JSString* str = JS_NewStringCopyN(cx, latin1.BeginReading(), length);
if (!str) {
return false;
}
vp.setString(str);
return true;
}
bool XPCStringConvert::UTF8ToJSVal(JSContext* cx, const nsACString& utf8,
nsStringBuffer** sharedBuffer,
MutableHandleValue vp) {
*sharedBuffer = nullptr;
uint32_t length = utf8.Length();
if (utf8.IsLiteral()) {
return UTF8StringLiteralToJSVal(
cx, JS::UTF8Chars(utf8.BeginReading(), length), vp);
}
nsStringBuffer* buf = nsStringBuffer::FromString(utf8);
if (buf) {
bool shared;
if (!UTF8StringBufferToJSVal(cx, buf, length, vp, &shared)) {
return false;
}
if (shared) {
*sharedBuffer = buf;
}
return true;
}
JSString* str =
JS_NewStringCopyUTF8N(cx, JS::UTF8Chars(utf8.BeginReading(), length));
if (!str) {
return false;
}
vp.setString(str);
return true;
}
namespace xpc {
bool NonVoidStringToJsval(JSContext* cx, nsAString& str,
MutableHandleValue rval) {
nsStringBuffer* sharedBuffer;
if (!XPCStringConvert::ReadableToJSVal(cx, str, &sharedBuffer, rval)) {
return false;
}
if (sharedBuffer) {
// The string was shared but ReadableToJSVal didn't addref it.
// Move the ownership from str to jsstr.
str.ForgetSharedBuffer();
}
return true;
}
bool NonVoidStringToJsval(JSContext* cx, const nsAString& str,
MutableHandleValue rval) {
nsStringBuffer* sharedBuffer;
if (!XPCStringConvert::ReadableToJSVal(cx, str, &sharedBuffer, rval)) {
return false;
}
if (sharedBuffer) {
// The string was shared but ReadableToJSVal didn't addref it.
sharedBuffer->AddRef();
}
return true;
}
bool NonVoidLatin1StringToJsval(JSContext* cx, nsACString& str,
MutableHandleValue rval) {
nsStringBuffer* sharedBuffer;
if (!XPCStringConvert::Latin1ToJSVal(cx, str, &sharedBuffer, rval)) {
return false;
}
if (sharedBuffer) {
// The string was shared but Latin1ToJSVal didn't addref it.
// Move the ownership from str to jsstr.
str.ForgetSharedBuffer();
}
return true;
}
bool NonVoidLatin1StringToJsval(JSContext* cx, const nsACString& str,
MutableHandleValue rval) {
nsStringBuffer* sharedBuffer;
if (!XPCStringConvert::Latin1ToJSVal(cx, str, &sharedBuffer, rval)) {
return false;
}
if (sharedBuffer) {
// The string was shared but Latin1ToJSVal didn't addref it.
sharedBuffer->AddRef();
}
return true;
}
bool NonVoidUTF8StringToJsval(JSContext* cx, nsACString& str,
MutableHandleValue rval) {
nsStringBuffer* sharedBuffer;
if (!XPCStringConvert::UTF8ToJSVal(cx, str, &sharedBuffer, rval)) {
return false;
}
if (sharedBuffer) {
// The string was shared but UTF8ToJSVal didn't addref it.
// Move the ownership from str to jsstr.
str.ForgetSharedBuffer();
}
return true;
}
bool NonVoidUTF8StringToJsval(JSContext* cx, const nsACString& str,
MutableHandleValue rval) {
nsStringBuffer* sharedBuffer;
if (!XPCStringConvert::UTF8ToJSVal(cx, str, &sharedBuffer, rval)) {
return false;
}
if (sharedBuffer) {
// The string was shared but UTF8ToJSVal didn't addref it.
sharedBuffer->AddRef();
}
return true;
}
} // namespace xpc