Source code
Revision control
Copy as Markdown
Other Tools
// 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 §ion) {
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