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-rw-r--r--js/xpconnect/src/XPCString.cpp283
1 files changed, 283 insertions, 0 deletions
diff --git a/js/xpconnect/src/XPCString.cpp b/js/xpconnect/src/XPCString.cpp
new file mode 100644
index 0000000000..5d784a02fd
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+++ b/js/xpconnect/src/XPCString.cpp
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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
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * 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
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