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// Copyright 2010 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// LiveEdit feature implementation. The script should be executed after
// debug-debugger.js.
// A LiveEdit namespace is declared inside a single function constructor.
Debug.LiveEdit = new function() {
// Changes script text and recompiles all relevant functions if possible.
// The change is always a substring (change_pos, change_pos + change_len)
// being replaced with a completely different string new_str.
//
// Only one function will have its Code changed in result of this function.
// All nested functions (should they have any instances at the moment) are
// left unchanged and re-linked to a newly created script instance
// representing old version of the source. (Generally speaking,
// during the change all nested functions are erased and completely different
// set of nested functions are introduced.) All other functions just have
// their positions updated.
//
// @param {Script} script that is being changed
// @param {Array} change_log a list that collects engineer-readable
// description of what happened.
function ApplyPatch(script, change_pos, change_len, new_str,
change_log) {
// Fully compiles source string as a script. Returns Array of
// FunctionCompileInfo -- a descriptions of all functions of the script.
// Elements of array are ordered by start positions of functions (from top
// to bottom) in the source. Fields outer_index and next_sibling_index help
// to navigate the nesting structure of functions.
//
// The script is used for compilation, because it produces code that
// needs to be linked with some particular script (for nested functions).
function DebugGatherCompileInfo(source) {
// Get function info, elements are partially sorted (it is a tree of
// nested functions serialized as parent followed by serialized children.
var raw_compile_info = %LiveEditGatherCompileInfo(script, source);
// Sort function infos by start position field.
var compile_info = new Array();
var old_index_map = new Array();
for (var i = 0; i < raw_compile_info.length; i++) {
compile_info.push(new FunctionCompileInfo(raw_compile_info[i]));
old_index_map.push(i);
}
for (var i = 0; i < compile_info.length; i++) {
var k = i;
for (var j = i + 1; j < compile_info.length; j++) {
if (compile_info[k].start_position > compile_info[j].start_position) {
k = j;
}
}
if (k != i) {
var temp_info = compile_info[k];
var temp_index = old_index_map[k];
compile_info[k] = compile_info[i];
old_index_map[k] = old_index_map[i];
compile_info[i] = temp_info;
old_index_map[i] = temp_index;
}
}
// After sorting update outer_inder field using old_index_map. Also
// set next_sibling_index field.
var current_index = 0;
// The recursive function, that goes over all children of a particular
// node (i.e. function info).
function ResetIndexes(new_parent_index, old_parent_index) {
var previous_sibling = -1;
while (current_index < compile_info.length &&
compile_info[current_index].outer_index == old_parent_index) {
var saved_index = current_index;
compile_info[saved_index].outer_index = new_parent_index;
if (previous_sibling != -1) {
compile_info[previous_sibling].next_sibling_index = saved_index;
}
previous_sibling = saved_index;
current_index++;
ResetIndexes(saved_index, old_index_map[saved_index]);
}
if (previous_sibling != -1) {
compile_info[previous_sibling].next_sibling_index = -1;
}
}
ResetIndexes(-1, -1);
Assert(current_index == compile_info.length);
return compile_info;
}
// Given a positions, finds a function that fully includes the entire
// change.
function FindChangedFunction(compile_info, offset, len) {
// First condition: function should start before the change region.
// Function #0 (whole-script function) always does, but we want
// one, that is later in this list.
var index = 0;
while (index + 1 < compile_info.length &&
compile_info[index + 1].start_position <= offset) {
index++;
}
// Now we are at the last function that begins before the change
// region. The function that covers entire change region is either
// this function or the enclosing one.
for (; compile_info[index].end_position < offset + len;
index = compile_info[index].outer_index) {
Assert(index != -1);
}
return index;
}
// Variable forward declarations. Preprocessor "Minifier" needs them.
var old_compile_info;
var shared_infos;
// Finds SharedFunctionInfo that corresponds compile info with index
// in old version of the script.
function FindFunctionInfo(index) {
var old_info = old_compile_info[index];
for (var i = 0; i < shared_infos.length; i++) {
var info = shared_infos[i];
if (info.start_position == old_info.start_position &&
info.end_position == old_info.end_position) {
return info;
}
}
}
// Replaces function's Code.
function PatchCode(new_info, shared_info) {
%LiveEditReplaceFunctionCode(new_info.raw_array, shared_info.raw_array);
change_log.push( {function_patched: new_info.function_name} );
}
var change_len_old;
var change_len_new;
// Translate position in old version of script into position in new
// version of script.
function PosTranslator(old_pos) {
if (old_pos <= change_pos) {
return old_pos;
}
if (old_pos >= change_pos + change_len_old) {
return old_pos + change_len_new - change_len_old;
}
return -1;
}
var position_change_array;
var position_patch_report;
function PatchPositions(new_info, shared_info) {
if (!shared_info) {
// TODO(LiveEdit): explain what is happening.
return;
}
var breakpoint_position_update = %LiveEditPatchFunctionPositions(
shared_info.raw_array, position_change_array);
for (var i = 0; i < breakpoint_position_update.length; i += 2) {
var new_pos = breakpoint_position_update[i];
var break_point_object = breakpoint_position_update[i + 1];
change_log.push( { breakpoint_position_update:
{ from: break_point_object.source_position(), to: new_pos } } );
break_point_object.updateSourcePosition(new_pos, script);
}
position_patch_report.push( { name: new_info.function_name } );
}
var link_to_old_script_report;
var old_script;
// Makes a function associated with another instance of a script (the
// one representing its old version). This way the function still
// may access its own text.
function LinkToOldScript(shared_info) {
%LiveEditRelinkFunctionToScript(shared_info.raw_array, old_script);
link_to_old_script_report.push( { name: shared_info.function_name } );
}
var old_source = script.source;
var change_len_old = change_len;
var change_len_new = new_str.length;
// Prepare new source string.
var new_source = old_source.substring(0, change_pos) +
new_str + old_source.substring(change_pos + change_len);
// Find all SharedFunctionInfo's that are compiled from this script.
var shared_raw_list = %LiveEditFindSharedFunctionInfosForScript(script);
var shared_infos = new Array();
for (var i = 0; i < shared_raw_list.length; i++) {
shared_infos.push(new SharedInfoWrapper(shared_raw_list[i]));
}
// Gather compile information about old version of script.
var old_compile_info = DebugGatherCompileInfo(old_source);
// Gather compile information about new version of script.
var new_compile_info;
try {
new_compile_info = DebugGatherCompileInfo(new_source);
} catch (e) {
throw new Failure("Failed to compile new version of script: " + e);
}
// An index of a single function, that is going to have its code replaced.
var function_being_patched =
FindChangedFunction(old_compile_info, change_pos, change_len_old);
// In old and new script versions function with a change should have the
// same indexes.
var function_being_patched2 =
FindChangedFunction(new_compile_info, change_pos, change_len_new);
Assert(function_being_patched == function_being_patched2,
"inconsistent old/new compile info");
// Check that function being patched has the same expectations in a new
// version. Otherwise we cannot safely patch its behavior and should
// choose the outer function instead.
while (!CompareFunctionExpectations(
old_compile_info[function_being_patched],
new_compile_info[function_being_patched])) {
Assert(old_compile_info[function_being_patched].outer_index ==
new_compile_info[function_being_patched].outer_index);
function_being_patched =
old_compile_info[function_being_patched].outer_index;
Assert(function_being_patched != -1);
}
// Check that function being patched is not currently on stack.
CheckStackActivations(
[ FindFunctionInfo(function_being_patched) ], change_log );
// Committing all changes.
var old_script_name = CreateNameForOldScript(script);
// Update the script text and create a new script representing an old
// version of the script.
var old_script = %LiveEditReplaceScript(script, new_source,
old_script_name);
PatchCode(new_compile_info[function_being_patched],
FindFunctionInfo(function_being_patched));
var position_patch_report = new Array();
change_log.push( {position_patched: position_patch_report} );
var position_change_array = [ change_pos,
change_pos + change_len_old,
change_pos + change_len_new ];
// Update positions of all outer functions (i.e. all functions, that
// are partially below the function being patched).
for (var i = new_compile_info[function_being_patched].outer_index;
i != -1;
i = new_compile_info[i].outer_index) {
PatchPositions(new_compile_info[i], FindFunctionInfo(i));
}
// Update positions of all functions that are fully below the function
// being patched.
var old_next_sibling =
old_compile_info[function_being_patched].next_sibling_index;
var new_next_sibling =
new_compile_info[function_being_patched].next_sibling_index;
// We simply go over the tail of both old and new lists. Their tails should
// have an identical structure.
if (old_next_sibling == -1) {
Assert(new_next_sibling == -1);
} else {
Assert(old_compile_info.length - old_next_sibling ==
new_compile_info.length - new_next_sibling);
for (var i = old_next_sibling, j = new_next_sibling;
i < old_compile_info.length; i++, j++) {
PatchPositions(new_compile_info[j], FindFunctionInfo(i));
}
}
var link_to_old_script_report = new Array();
change_log.push( { linked_to_old_script: link_to_old_script_report } );
// We need to link to old script all former nested functions.
for (var i = function_being_patched + 1; i < old_next_sibling; i++) {
LinkToOldScript(FindFunctionInfo(i), old_script);
}
}
// Function is public.
this.ApplyPatch = ApplyPatch;
function Assert(condition, message) {
if (!condition) {
if (message) {
throw "Assert " + message;
} else {
throw "Assert";
}
}
}
// An object describing function compilation details. Its index fields
// apply to indexes inside array that stores these objects.
function FunctionCompileInfo(raw_array) {
this.function_name = raw_array[0];
this.start_position = raw_array[1];
this.end_position = raw_array[2];
this.param_num = raw_array[3];
this.code = raw_array[4];
this.scope_info = raw_array[5];
this.outer_index = raw_array[6];
this.next_sibling_index = null;
this.raw_array = raw_array;
}
function SharedInfoWrapper(raw_array) {
this.function_name = raw_array[0];
this.start_position = raw_array[1];
this.end_position = raw_array[2];
this.info = raw_array[3];
this.raw_array = raw_array;
}
// Adds a suffix to script name to mark that it is old version.
function CreateNameForOldScript(script) {
// TODO(635): try better than this; support several changes.
return script.name + " (old)";
}
// Compares a function interface old and new version, whether it
// changed or not.
function CompareFunctionExpectations(function_info1, function_info2) {
// Check that function has the same number of parameters (there may exist
// an adapter, that won't survive function parameter number change).
if (function_info1.param_num != function_info2.param_num) {
return false;
}
var scope_info1 = function_info1.scope_info;
var scope_info2 = function_info2.scope_info;
if (!scope_info1) {
return !scope_info2;
}
if (scope_info1.length != scope_info2.length) {
return false;
}
// Check that outer scope structure is not changed. Otherwise the function
// will not properly work with existing scopes.
return scope_info1.toString() == scope_info2.toString();
}
// Minifier forward declaration.
var FunctionPatchabilityStatus;
// For array of wrapped shared function infos checks that none of them
// have activations on stack (of any thread). Throws a Failure exception
// if this proves to be false.
function CheckStackActivations(shared_wrapper_list, change_log) {
var shared_list = new Array();
for (var i = 0; i < shared_wrapper_list.length; i++) {
shared_list[i] = shared_wrapper_list[i].info;
}
var result = %LiveEditCheckAndDropActivations(shared_list, true);
if (result[shared_list.length]) {
// Extra array element may contain error message.
throw new Failure(result[shared_list.length]);
}
var problems = new Array();
var dropped = new Array();
for (var i = 0; i < shared_list.length; i++) {
var shared = shared_wrapper_list[i];
if (result[i] == FunctionPatchabilityStatus.REPLACED_ON_ACTIVE_STACK) {
dropped.push({ name: shared.function_name } );
} else if (result[i] != FunctionPatchabilityStatus.AVAILABLE_FOR_PATCH) {
var description = {
name: shared.function_name,
start_pos: shared.start_position,
end_pos: shared.end_position,
replace_problem:
FunctionPatchabilityStatus.SymbolName(result[i])
};
problems.push(description);
}
}
if (dropped.length > 0) {
change_log.push({ dropped_from_stack: dropped });
}
if (problems.length > 0) {
change_log.push( { functions_on_stack: problems } );
throw new Failure("Blocked by functions on stack");
}
}
// A copy of the FunctionPatchabilityStatus enum from liveedit.h
var FunctionPatchabilityStatus = {
AVAILABLE_FOR_PATCH: 1,
BLOCKED_ON_ACTIVE_STACK: 2,
BLOCKED_ON_OTHER_STACK: 3,
BLOCKED_UNDER_NATIVE_CODE: 4,
REPLACED_ON_ACTIVE_STACK: 5
}
FunctionPatchabilityStatus.SymbolName = function(code) {
var enum = FunctionPatchabilityStatus;
for (name in enum) {
if (enum[name] == code) {
return name;
}
}
}
// A logical failure in liveedit process. This means that change_log
// is valid and consistent description of what happened.
function Failure(message) {
this.message = message;
}
// Function (constructor) is public.
this.Failure = Failure;
Failure.prototype.toString = function() {
return "LiveEdit Failure: " + this.message;
}
// A testing entry.
function GetPcFromSourcePos(func, source_pos) {
return %GetFunctionCodePositionFromSource(func, source_pos);
}
// Function is public.
this.GetPcFromSourcePos = GetPcFromSourcePos;
// LiveEdit main entry point: changes a script text to a new string.
function SetScriptSource(script, new_source, change_log) {
var old_source = script.source;
var diff = FindSimpleDiff(old_source, new_source);
if (!diff) {
return;
}
ApplyPatch(script, diff.change_pos, diff.old_len,
new_source.substring(diff.change_pos, diff.change_pos + diff.new_len),
change_log);
}
// Function is public.
this.SetScriptSource = SetScriptSource;
function CompareStringsLinewise(s1, s2) {
return %LiveEditCompareStringsLinewise(s1, s2);
}
// Function is public (for tests).
this.CompareStringsLinewise = CompareStringsLinewise;
// Finds a difference between 2 strings in form of a single chunk.
// This is a temporary solution. We should calculate a read diff instead.
function FindSimpleDiff(old_source, new_source) {
var change_pos;
var old_len;
var new_len;
// A find range block. Whenever control leaves it, it should set 3 local
// variables declared above.
find_range:
{
// First look from the beginning of strings.
var pos1;
{
var next_pos;
for (pos1 = 0; true; pos1 = next_pos) {
if (pos1 >= old_source.length) {
change_pos = pos1;
old_len = 0;
new_len = new_source.length - pos1;
break find_range;
}
if (pos1 >= new_source.length) {
change_pos = pos1;
old_len = old_source.length - pos1;
new_len = 0;
break find_range;
}
if (old_source[pos1] != new_source[pos1]) {
break;
}
next_pos = pos1 + 1;
}
}
// Now compare strings from the ends.
change_pos = pos1;
var pos_old;
var pos_new;
{
for (pos_old = old_source.length - 1, pos_new = new_source.length - 1;
true;
pos_old--, pos_new--) {
if (pos_old - change_pos + 1 < 0 || pos_new - change_pos + 1 < 0) {
old_len = pos_old - change_pos + 2;
new_len = pos_new - change_pos + 2;
break find_range;
}
if (old_source[pos_old] != new_source[pos_new]) {
old_len = pos_old - change_pos + 1;
new_len = pos_new - change_pos + 1;
break find_range;
}
}
}
}
if (old_len == 0 && new_len == 0) {
// no change
return;
}
return { "change_pos": change_pos, "old_len": old_len, "new_len": new_len };
}
}