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+// Copyright (c) 2010, Google Inc.
+// 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.
+
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// test_assembler.cc: Implementation of google_breakpad::TestAssembler.
+// See test_assembler.h for details.
+
+#include "common/test_assembler.h"
+
+#include <assert.h>
+#include <stdio.h>
+
+#include <iterator>
+
+namespace google_breakpad {
+namespace test_assembler {
+
+using std::back_insert_iterator;
+
+Label::Label() : value_(new Binding()) { }
+Label::Label(uint64_t value) : value_(new Binding(value)) { }
+Label::Label(const Label &label) {
+ value_ = label.value_;
+ value_->Acquire();
+}
+Label::~Label() {
+ if (value_->Release()) delete value_;
+}
+
+Label &Label::operator=(uint64_t value) {
+ value_->Set(NULL, value);
+ return *this;
+}
+
+Label &Label::operator=(const Label &label) {
+ value_->Set(label.value_, 0);
+ return *this;
+}
+
+Label Label::operator+(uint64_t addend) const {
+ Label l;
+ l.value_->Set(this->value_, addend);
+ return l;
+}
+
+Label Label::operator-(uint64_t subtrahend) const {
+ Label l;
+ l.value_->Set(this->value_, -subtrahend);
+ return l;
+}
+
+// When NDEBUG is #defined, assert doesn't evaluate its argument. This
+// means you can't simply use assert to check the return value of a
+// function with necessary side effects.
+//
+// ALWAYS_EVALUATE_AND_ASSERT(x) evaluates x regardless of whether
+// NDEBUG is #defined; when NDEBUG is not #defined, it further asserts
+// that x is true.
+#ifdef NDEBUG
+#define ALWAYS_EVALUATE_AND_ASSERT(x) x
+#else
+#define ALWAYS_EVALUATE_AND_ASSERT(x) assert(x)
+#endif
+
+uint64_t Label::operator-(const Label &label) const {
+ uint64_t offset;
+ ALWAYS_EVALUATE_AND_ASSERT(IsKnownOffsetFrom(label, &offset));
+ return offset;
+}
+
+uint64_t Label::Value() const {
+ uint64_t v = 0;
+ ALWAYS_EVALUATE_AND_ASSERT(IsKnownConstant(&v));
+ return v;
+};
+
+bool Label::IsKnownConstant(uint64_t *value_p) const {
+ Binding *base;
+ uint64_t addend;
+ value_->Get(&base, &addend);
+ if (base != NULL) return false;
+ if (value_p) *value_p = addend;
+ return true;
+}
+
+bool Label::IsKnownOffsetFrom(const Label &label, uint64_t *offset_p) const
+{
+ Binding *label_base, *this_base;
+ uint64_t label_addend, this_addend;
+ label.value_->Get(&label_base, &label_addend);
+ value_->Get(&this_base, &this_addend);
+ // If this and label are related, Get will find their final
+ // common ancestor, regardless of how indirect the relation is. This
+ // comparison also handles the constant vs. constant case.
+ if (this_base != label_base) return false;
+ if (offset_p) *offset_p = this_addend - label_addend;
+ return true;
+}
+
+Label::Binding::Binding() : base_(this), addend_(), reference_count_(1) { }
+
+Label::Binding::Binding(uint64_t addend)
+ : base_(NULL), addend_(addend), reference_count_(1) { }
+
+Label::Binding::~Binding() {
+ assert(reference_count_ == 0);
+ if (base_ && base_ != this && base_->Release())
+ delete base_;
+}
+
+void Label::Binding::Set(Binding *binding, uint64_t addend) {
+ if (!base_ && !binding) {
+ // We're equating two constants. This could be okay.
+ assert(addend_ == addend);
+ } else if (!base_) {
+ // We are a known constant, but BINDING may not be, so turn the
+ // tables and try to set BINDING's value instead.
+ binding->Set(NULL, addend_ - addend);
+ } else {
+ if (binding) {
+ // Find binding's final value. Since the final value is always either
+ // completely unconstrained or a constant, never a reference to
+ // another variable (otherwise, it wouldn't be final), this
+ // guarantees we won't create cycles here, even for code like this:
+ // l = m, m = n, n = l;
+ uint64_t binding_addend;
+ binding->Get(&binding, &binding_addend);
+ addend += binding_addend;
+ }
+
+ // It seems likely that setting a binding to itself is a bug
+ // (although I can imagine this might turn out to be helpful to
+ // permit).
+ assert(binding != this);
+
+ if (base_ != this) {
+ // Set the other bindings on our chain as well. Note that this
+ // is sufficient even though binding relationships form trees:
+ // All binding operations traverse their chains to the end, and
+ // all bindings related to us share some tail of our chain, so
+ // they will see the changes we make here.
+ base_->Set(binding, addend - addend_);
+ // We're not going to use base_ any more.
+ if (base_->Release()) delete base_;
+ }
+
+ // Adopt BINDING as our base. Note that it should be correct to
+ // acquire here, after the release above, even though the usual
+ // reference-counting rules call for acquiring first, and then
+ // releasing: the self-reference assertion above should have
+ // complained if BINDING were 'this' or anywhere along our chain,
+ // so we didn't release BINDING.
+ if (binding) binding->Acquire();
+ base_ = binding;
+ addend_ = addend;
+ }
+}
+
+void Label::Binding::Get(Binding **base, uint64_t *addend) {
+ if (base_ && base_ != this) {
+ // Recurse to find the end of our reference chain (the root of our
+ // tree), and then rewrite every binding along the chain to refer
+ // to it directly, adjusting addends appropriately. (This is why
+ // this member function isn't this-const.)
+ Binding *final_base;
+ uint64_t final_addend;
+ base_->Get(&final_base, &final_addend);
+ if (final_base) final_base->Acquire();
+ if (base_->Release()) delete base_;
+ base_ = final_base;
+ addend_ += final_addend;
+ }
+ *base = base_;
+ *addend = addend_;
+}
+
+template<typename Inserter>
+static inline void InsertEndian(test_assembler::Endianness endianness,
+ size_t size, uint64_t number, Inserter dest) {
+ assert(size > 0);
+ if (endianness == kLittleEndian) {
+ for (size_t i = 0; i < size; i++) {
+ *dest++ = (char) (number & 0xff);
+ number >>= 8;
+ }
+ } else {
+ assert(endianness == kBigEndian);
+ // The loop condition is odd, but it's correct for size_t.
+ for (size_t i = size - 1; i < size; i--)
+ *dest++ = (char) ((number >> (i * 8)) & 0xff);
+ }
+}
+
+Section &Section::Append(Endianness endianness, size_t size, uint64_t number) {
+ InsertEndian(endianness, size, number,
+ back_insert_iterator<string>(contents_));
+ return *this;
+}
+
+Section &Section::Append(Endianness endianness, size_t size,
+ const Label &label) {
+ // If this label's value is known, there's no reason to waste an
+ // entry in references_ on it.
+ uint64_t value;
+ if (label.IsKnownConstant(&value))
+ return Append(endianness, size, value);
+
+ // This will get caught when the references are resolved, but it's
+ // nicer to find out earlier.
+ assert(endianness != kUnsetEndian);
+
+ references_.push_back(Reference(contents_.size(), endianness, size, label));
+ contents_.append(size, 0);
+ return *this;
+}
+
+#define ENDIANNESS_L kLittleEndian
+#define ENDIANNESS_B kBigEndian
+#define ENDIANNESS(e) ENDIANNESS_ ## e
+
+#define DEFINE_SHORT_APPEND_NUMBER_ENDIAN(e, bits) \
+ Section &Section::e ## bits(uint ## bits ## _t v) { \
+ InsertEndian(ENDIANNESS(e), bits / 8, v, \
+ back_insert_iterator<string>(contents_)); \
+ return *this; \
+ }
+
+#define DEFINE_SHORT_APPEND_LABEL_ENDIAN(e, bits) \
+ Section &Section::e ## bits(const Label &v) { \
+ return Append(ENDIANNESS(e), bits / 8, v); \
+ }
+
+// Define L16, B32, and friends.
+#define DEFINE_SHORT_APPEND_ENDIAN(e, bits) \
+ DEFINE_SHORT_APPEND_NUMBER_ENDIAN(e, bits) \
+ DEFINE_SHORT_APPEND_LABEL_ENDIAN(e, bits)
+
+DEFINE_SHORT_APPEND_LABEL_ENDIAN(L, 8);
+DEFINE_SHORT_APPEND_LABEL_ENDIAN(B, 8);
+DEFINE_SHORT_APPEND_ENDIAN(L, 16);
+DEFINE_SHORT_APPEND_ENDIAN(L, 32);
+DEFINE_SHORT_APPEND_ENDIAN(L, 64);
+DEFINE_SHORT_APPEND_ENDIAN(B, 16);
+DEFINE_SHORT_APPEND_ENDIAN(B, 32);
+DEFINE_SHORT_APPEND_ENDIAN(B, 64);
+
+#define DEFINE_SHORT_APPEND_NUMBER_DEFAULT(bits) \
+ Section &Section::D ## bits(uint ## bits ## _t v) { \
+ InsertEndian(endianness_, bits / 8, v, \
+ back_insert_iterator<string>(contents_)); \
+ return *this; \
+ }
+#define DEFINE_SHORT_APPEND_LABEL_DEFAULT(bits) \
+ Section &Section::D ## bits(const Label &v) { \
+ return Append(endianness_, bits / 8, v); \
+ }
+#define DEFINE_SHORT_APPEND_DEFAULT(bits) \
+ DEFINE_SHORT_APPEND_NUMBER_DEFAULT(bits) \
+ DEFINE_SHORT_APPEND_LABEL_DEFAULT(bits)
+
+DEFINE_SHORT_APPEND_LABEL_DEFAULT(8)
+DEFINE_SHORT_APPEND_DEFAULT(16);
+DEFINE_SHORT_APPEND_DEFAULT(32);
+DEFINE_SHORT_APPEND_DEFAULT(64);
+
+Section &Section::Append(const Section &section) {
+ size_t base = contents_.size();
+ contents_.append(section.contents_);
+ for (vector<Reference>::const_iterator it = section.references_.begin();
+ it != section.references_.end(); it++)
+ references_.push_back(Reference(base + it->offset, it->endianness,
+ it->size, it->label));
+ return *this;
+}
+
+Section &Section::LEB128(long long value) {
+ while (value < -0x40 || 0x3f < value) {
+ contents_ += (value & 0x7f) | 0x80;
+ if (value < 0)
+ value = (value >> 7) | ~(((unsigned long long) -1) >> 7);
+ else
+ value = (value >> 7);
+ }
+ contents_ += value & 0x7f;
+ return *this;
+}
+
+Section &Section::ULEB128(uint64_t value) {
+ while (value > 0x7f) {
+ contents_ += (value & 0x7f) | 0x80;
+ value = (value >> 7);
+ }
+ contents_ += value;
+ return *this;
+}
+
+Section &Section::Align(size_t alignment, uint8_t pad_byte) {
+ // ALIGNMENT must be a power of two.
+ assert(((alignment - 1) & alignment) == 0);
+ size_t new_size = (contents_.size() + alignment - 1) & ~(alignment - 1);
+ contents_.append(new_size - contents_.size(), pad_byte);
+ assert((contents_.size() & (alignment - 1)) == 0);
+ return *this;
+}
+
+void Section::Clear() {
+ contents_.clear();
+ references_.clear();
+}
+
+bool Section::GetContents(string *contents) {
+ // For each label reference, find the label's value, and patch it into
+ // the section's contents.
+ for (size_t i = 0; i < references_.size(); i++) {
+ Reference &r = references_[i];
+ uint64_t value;
+ if (!r.label.IsKnownConstant(&value)) {
+ fprintf(stderr, "Undefined label #%zu at offset 0x%zx\n", i, r.offset);
+ return false;
+ }
+ assert(r.offset < contents_.size());
+ assert(contents_.size() - r.offset >= r.size);
+ InsertEndian(r.endianness, r.size, value, contents_.begin() + r.offset);
+ }
+ contents->clear();
+ std::swap(contents_, *contents);
+ references_.clear();
+ return true;
+}
+
+} // namespace test_assembler
+} // namespace google_breakpad