Breakpad Processor: Add new unit tests for google_breakpad::Minidump

src/processor/test_assembler.cc

+// 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 <cassert>
+#include <cstdio>
+#include <iterator>
+
+#include "processor/test_assembler.h"
+
+namespace google_breakpad {
+namespace TestAssembler {
+
+using std::back_insert_iterator;
+
+Label::Label() : value_(new Binding()) { }
+Label::Label(u_int64_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=(u_int64_t value) {
+  value_->Set(NULL, value);
+  return *this;
+}
+
+Label &Label::operator=(const Label &label) {
+  value_->Set(label.value_, 0);
+  return *this;
+}
+
+Label Label::operator+(u_int64_t addend) const {
+  Label l;
+  l.value_->Set(this->value_, addend);
+  return l;
+}
+
+Label Label::operator-(u_int64_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
+
+u_int64_t Label::operator-(const Label &label) const {
+  u_int64_t offset;
+  ALWAYS_EVALUATE_AND_ASSERT(IsKnownOffsetFrom(label, &offset));
+  return offset;
+}
+
+u_int64_t Label::Value() const {
+  u_int64_t v;
+  ALWAYS_EVALUATE_AND_ASSERT(IsKnownConstant(&v));
+  return v;
+};
+
+bool Label::IsKnownConstant(u_int64_t *value_p) const {
+  Binding *base;
+  u_int64_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, u_int64_t *offset_p) const
+{
+  Binding *label_base, *this_base;
+  u_int64_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(u_int64_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, u_int64_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. This avoids creating cycles for:
+      //   l = m, m = n, n = l;

[mochalatte, 2010/03/03 22:26:09]

from the test coverage, i assume this generalizes to a loop of any length(maybe
it could be clarified in the comment)

[jimb, 2010/03/16 16:14:50]

I've expanded the comment.

+      u_int64_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, u_int64_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;
+    u_int64_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(TestAssembler::Endianness endianness,
+                                size_t size, u_int64_t number, Inserter dest) {
+  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, u_int64_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.
+  u_int64_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(u_int ## 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(u_int ## bits ## _t v) {                  \
+    InsertEndian(default_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(default_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(u_int64_t value) {
+  while (value > 0x7f) {
+    contents_ += (value & 0x7f) | 0x80;
+    value = (value >> 7);
+  }
+  contents_ += value;
+  return *this;
+}
+
+Section &Section::Align(size_t alignment, u_int8_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];
+    u_int64_t value;
+    if (!r.label.IsKnownConstant(&value)) {
+      fprintf(stderr, "Undefined label #%d at offset 0x%x\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 TestAssembler
+} // namespace google_breakpad