path: root/src/common/linux/stabs_reader_unittest.cc

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// stabs_reader_unittest.cc: Unit tests for StabsReader.

#include <a.out.h>
#include <cassert>
#include <cerrno>
#include <cstdarg>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <map>
#include <sstream>
#include <stab.h>

#include "breakpad_googletest_includes.h"
#include "common/linux/stabs_reader.h"

using std::istream;
using std::istringstream;
using std::map;
using std::ostream;
using std::ostringstream;
using std::string;

using ::testing::_;
using ::testing::InSequence;
using ::testing::Return;
using ::testing::Sequence;
using ::testing::StrEq;

using google_breakpad::StabsHandler;
using google_breakpad::StabsReader;

namespace {

// Mock stabs file parser
//
// In order to test StabsReader, we parse a human-readable input file
// describing STABS entries into in-memory .stab and .stabstr
// sections, and then pass those to StabsReader to look at. The
// human-readable file is called a "mock stabs file".
//
// Each line of a mock stabs file should have the following form:
//
//   TYPE OTHER DESC VALUE NAME
// 
// where all data is Latin-1 bytes and fields are separated by single
// space characters, except for NAME, which may contain spaces and
// continues to the end of the line.  The fields have the following
// meanings:
// 
// - TYPE: the name of the stabs symbol type; like SO or FUN.  These are
//   the names from /usr/include/bits/stab.def, without the leading N_.
//
// - OTHER, DESC, VALUE: numeric values for the n_other, n_desc, and
//   n_value fields of the stab.  These can be decimal or hex,
//   using C++ notation (10, 0x10)
//   
// - NAME: textual data for the entry.  STABS packs all kinds of
//   interesting data into entries' NAME fields, so calling it a NAME
//   is misleading, but that's how it is.  For SO, this may be a
//   filename; for FUN, this is the function name, plus type data; and
//   so on.

// I don't know if the whole parser/handler pattern is really worth
// the bureaucracy in this case.  But just writing it out as
// old-fashioned functions wasn't astonishingly clear either, so it
// seemed worth a try.

// A handler class for mock stabs data.
class MockStabsHandler {
 public:
  MockStabsHandler() { }
  virtual ~MockStabsHandler() { }
  // The mock stabs parser calls this member function for each entry
  // it parses, passing it the contents of the entry.  If this function
  // returns true, the parser continues; if it returns false, the parser
  // stops, and its Process member function returns false.
  virtual bool Entry(enum __stab_debug_code type, char other, short desc,
                     unsigned long value, const string &name) { return true; }
  // Report an error in parsing the mock stabs data.  If this returns true,
  // the parser continues; if it returns false, the parser stops and
  // its Process member function returns false.
  virtual bool Error(const char *format, ...) = 0;
};

// A class for parsing mock stabs files.
class MockStabsParser {
 public:
  // Create a parser reading input from STREAM and passing data to HANDLER.
  // Use FILENAME when reporting errors.
  MockStabsParser(const string &filename, istream *stream,
                  MockStabsHandler *handler);
  // Parse data from the STREAM, invoking HANDLER->Entry for each
  // entry we get.  Return true if we parsed all the data succesfully,
  // or false if we stopped early because Entry returned false, or if
  // there were any errors during parsing.
  bool Process();
 private:
  // A type for maps from stab type names ("SO", "SLINE", etc.) to
  // n_type values.
  typedef map<string, unsigned char> StabTypeNameTable;

  // Initialize the table mapping STAB type names to n_type values.
  void InitializeTypeNames();

  // Parse LINE, one line of input from a mock stabs file, and pass
  // its contents to handler_->Entry and return the boolean value that
  // returns.  If we encounter an error parsing the line, report it
  // using handler->Error.
  bool ParseLine(const string &line);

  const string &filename_;
  istream *stream_;
  MockStabsHandler *handler_;
  int line_number_;
  StabTypeNameTable type_names_;
};

MockStabsParser::MockStabsParser(const string &filename, istream *stream,
                                 MockStabsHandler *handler):
    filename_(filename), stream_(stream), handler_(handler),
    line_number_(0) {
  InitializeTypeNames();
}

bool MockStabsParser::Process() {
  // Iterate once per line, including a line at EOF without a
  // terminating newline.
  for(;;) {
    string line;
    std::getline(*stream_, line, '\n');
    if (line.empty() && stream_->eof())
      break;
    line_number_++;
    if (! ParseLine(line))
      return false;
  }
  return true;
}

void MockStabsParser::InitializeTypeNames() {
  // On GLIBC-based systems, <bits/stab.def> is a file containing a
  // call to an unspecified macro __define_stab for each stab type.
  // <stab.h> uses it to define the __stab_debug_code enum type.  We
  // use it here to initialize our mapping from type names to enum
  // values.
  //
  // This isn't portable to non-GLIBC systems.  Feel free to just
  // hard-code the values if this becomes a problem.
#  define __define_stab(name, code, str) type_names_[string(str)] = code;
#  include <bits/stab.def>
#  undef __define_stab
}

bool MockStabsParser::ParseLine(const string &line) {
  istringstream linestream(line);
  // Allow "0x" prefix for hex, and so on.
  linestream.unsetf(istringstream::basefield);
  // Parse and validate the stabs type.
  string typeName;
  linestream >> typeName;
  StabTypeNameTable::const_iterator typeIt = type_names_.find(typeName);
  if (typeIt == type_names_.end())
    return handler_->Error("%s:%d: unrecognized stab type: %s\n",
                           filename_.c_str(), line_number_, typeName.c_str());
  // These are int, not char and unsigned char, to ensure they're parsed
  // as decimal numbers, not characters.
  int otherInt, descInt;
  unsigned long value;
  linestream >> otherInt >> descInt >> value;
  if (linestream.fail())
    return handler_->Error("%s:%d: malformed mock stabs input line\n",
                           filename_.c_str(), line_number_);
  if (linestream.peek() == ' ')
    linestream.get();
  string name;
  getline(linestream, name, '\n');
  return handler_->Entry(static_cast<__stab_debug_code>(typeIt->second),
                         otherInt, descInt, value, name);
}

// A class for constructing .stab sections.
//
// A .stab section is an array of struct nlist entries.  These
// entries' n_un.n_strx fields are indices into an accompanying
// .stabstr section.
class StabSection {
 public:
  StabSection(): used_(0), size_(1) {
    entries_ = (struct nlist *) malloc(sizeof(*entries_) * size_);
  }
  ~StabSection() { free(entries_); }

  // Append a new 'struct nlist' entry to the end of the section, and
  // return a pointer to it.  This pointer is valid until the next
  // call to Append.  The caller should initialize the returned entry
  // as needed.
  struct nlist *Append();
  // Set SECTION to the contents of a .stab section holding the
  // accumulated list of entries added with Append.
  void GetSection(string *section);

 private:
  // The array of stabs entries,
  struct nlist *entries_;
  // The number of elements of entries_ that are used, and the allocated size
  // of the array.
  size_t used_, size_;
};

struct nlist *StabSection::Append() {
  if (used_ == size_) {
    size_ *= 2;
    entries_ = (struct nlist *) realloc(entries_, sizeof(*entries_) * size_);
  }
  assert(used_ < size_);
  return &entries_[used_++];
}

void StabSection::GetSection(string *section) {
  section->assign(reinterpret_cast<char *>(entries_),
                  sizeof(*entries_) * used_);
}

// A class for building .stabstr sections.
// 
// A .stabstr section is an array of characters containing a bunch of
// null-terminated strings.  A string is identified by the index of
// its initial character in the array.  The array always starts with a
// null byte, so that an index of zero refers to the empty string.
//
// This implementation also ensures that if two strings are equal, we
// assign them the same indices; most linkers do this, and some
// clients may rely upon it.  (Note that this is not quite the same as
// ensuring that a string only appears once in the section; you could
// share space when one string is a suffix of another, but we don't.)
class StabstrSection {
 public:
  StabstrSection(): next_byte_(1) { string_indices_[""] = 0; }
  // Ensure STR is present in the string section, and return its index.
  size_t Insert(const string &str);
  // Set SECTION to the contents of a .stabstr section in which the
  // strings passed to Insert appear at the indices we promised.
  void GetSection(string *section);
 private:
  // Maps from strings to .stabstr indices and back.
  typedef map<string, size_t> StringToIndex;
  typedef map<size_t, const string *> IndexToString;

  // A map from strings to the indices we've assigned them.
  StringToIndex string_indices_;

  // The next unused byte in the section.  The next string we add
  // will get this index.
  size_t next_byte_;
};

size_t StabstrSection::Insert(const string &str) {
  StringToIndex::iterator it = string_indices_.find(str);
  size_t index;
  if (it != string_indices_.end()) {
    index = it->second;
  } else {
    // This is the first time we've seen STR; add it to the table.
    string_indices_[str] = next_byte_;
    index = next_byte_;
    next_byte_ += str.size() + 1;
  }
  return index;
}

void StabstrSection::GetSection(string *section) {
  // First we have to invert the map.
  IndexToString byIndex;
  for (StringToIndex::const_iterator it = string_indices_.begin();
       it != string_indices_.end(); it++)
    byIndex[it->second] = &it->first;
  // Now we build the .stabstr section.
  section->clear();
  for (IndexToString::const_iterator it = byIndex.begin();
       it != byIndex.end(); it++) {
    // Make sure we're actually assigning it the index we claim to be.
    assert(it->first == section->size());
    *section += *(it->second);
    *section += '\0';
  }
}

// A mock stabs parser handler class that builds .stab and .stabstr
// sections.
class StabsSectionsBuilder: public MockStabsHandler {
 public:
  // Construct a handler that will receive data from a MockStabsParser
  // and construct .stab and .stabstr sections.  FILENAME should be
  // the name of the mock stabs input file; we use it in error
  // messages.
  StabsSectionsBuilder(const string &filename):
      filename_(filename), error_count_(0) { }

  // Overridden virtual member functions.
  bool Entry(enum __stab_debug_code type, char other, short desc,
             unsigned long value, const string &name);
  virtual bool Error(const char *format, ...);

  // Set SECTION to the contents of a .stab or .stabstr section
  // reflecting the entries that have been passed to us via Entry.
  void GetStab(string *section);
  void GetStabstr(string *section);

 private:
  StabSection stab_;                    // stabs entries we've seen
  StabstrSection stabstr_;              // and the strings they love
  const string &filename_;              // input filename, for error messages
  int error_count_;                     // number of errors we've seen so far
};

bool StabsSectionsBuilder::Entry(enum __stab_debug_code type, char other,
                                 short desc, unsigned long value,
                                 const string &name) {
  struct nlist *entry = stab_.Append();
  entry->n_type = type;
  entry->n_other = other;
  entry->n_desc = desc;
  entry->n_value = value;
  entry->n_un.n_strx = stabstr_.Insert(name);
  return true;
}

bool StabsSectionsBuilder::Error(const char *format, ...) {
  va_list args;
  va_start(args, format);
  vfprintf(stderr, format, args);
  va_end(args);
  error_count_++;
  if (error_count_ >= 20) {
    fprintf(stderr,
            "%s: lots of errors; is this really a mock stabs file?\n",
            filename_.c_str());
    return false;
  }
  return true;
}

void StabsSectionsBuilder::GetStab(string *section) {
  stab_.GetSection(section);
}

void StabsSectionsBuilder::GetStabstr(string *section) {
  stabstr_.GetSection(section);
}

class MockStabsReaderHandler: public StabsHandler {
 public:
  MOCK_METHOD3(StartCompilationUnit,
               bool(const char *, uint64_t, const char *));
  MOCK_METHOD1(EndCompilationUnit, bool(uint64_t));
  MOCK_METHOD2(StartFunction, bool(const std::string &, uint64_t));
  MOCK_METHOD1(EndFunction, bool(uint64_t));
  MOCK_METHOD3(Line, bool(uint64_t, const char *, int));
  void Warning(const char *format, ...) { MockWarning(format); }
  MOCK_METHOD1(MockWarning, void(const char *));
};

// Create a StabsReader to parse the mock stabs data in INPUT_FILE,
// passing the parsed information to HANDLER. If all goes well, return
// the result of calling the reader's Process member function.
// Otherwise, return false. INPUT_FILE should be relative to the top
// of the source tree.
static bool ApplyHandlerToMockStabsData(StabsHandler *handler,
                                        const string &input_file) {
  string full_input_file
      = string(getenv("srcdir") ? getenv("srcdir") : ".") + "/" + input_file;

  // Open the input file.
  std::ifstream stream(full_input_file.c_str());
  if (stream.fail()) {
    fprintf(stderr, "error opening mock stabs input file %s: %s\n",
            full_input_file.c_str(), strerror(errno));
    return false;
  }

  // Parse the mock stabs data, and produce stabs sections to use as
  // test input to the reader.
  StabsSectionsBuilder builder(full_input_file);
  MockStabsParser mock_parser(full_input_file, &stream, &builder);
  if (!mock_parser.Process())
    return false;
  string stab, stabstr;
  builder.GetStab(&stab);
  builder.GetStabstr(&stabstr);

  // Run the parser on the test input, passing whatever we find to HANDLER.
  StabsReader reader(
      reinterpret_cast<const uint8_t *>(stab.data()),    stab.size(),
      reinterpret_cast<const uint8_t *>(stabstr.data()), stabstr.size(),
      handler);
  return reader.Process();
}

TEST(StabsReaderTestCase, MockStabsInput) {
  MockStabsReaderHandler mock_handler;

  {
    InSequence s;

    EXPECT_CALL(mock_handler, StartCompilationUnit(StrEq("file1.c"), 
                                                   0x42, StrEq("builddir1/")))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, StartFunction(StrEq("fun1"), 0x62))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, Line(0xe4, StrEq("file1.c"), 91))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, Line(0x164, StrEq("header.h"), 111))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, EndFunction(0x112))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, StartFunction(StrEq("fun2"), 0x112))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, Line(0x234, StrEq("header.h"), 131))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, Line(0x254, StrEq("file1.c"), 151))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, EndFunction(0x152))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, EndCompilationUnit(0x152))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, StartCompilationUnit(StrEq("file3.c"), 
                                                   0x182, NULL))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, EndCompilationUnit(0x192))
        .WillOnce(Return(true));
  }

  ASSERT_TRUE(ApplyHandlerToMockStabsData(
                  &mock_handler, 
                  "common/linux/testdata/stabs_reader_unittest.input1"));
}

TEST(StabsReaderTestCase, AbruptCU) {
  MockStabsReaderHandler mock_handler;

  {
    InSequence s;

    EXPECT_CALL(mock_handler,
                StartCompilationUnit(StrEq("file2-1.c"), 0x12, NULL))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, EndCompilationUnit(NULL))
        .WillOnce(Return(true));
  }

  ASSERT_TRUE(ApplyHandlerToMockStabsData(
                  &mock_handler, 
                  "common/linux/testdata/stabs_reader_unittest.input2"));
}

TEST(StabsReaderTestCase, AbruptFunction) {
  MockStabsReaderHandler mock_handler;

  {
    InSequence s;

    EXPECT_CALL(mock_handler,
                StartCompilationUnit(StrEq("file3-1.c"), 0x12, NULL))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, StartFunction(StrEq("fun3_1"), 0x22))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, EndFunction(NULL))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, EndCompilationUnit(NULL))
        .WillOnce(Return(true));
  }

  ASSERT_TRUE(ApplyHandlerToMockStabsData(
                  &mock_handler, 
                  "common/linux/testdata/stabs_reader_unittest.input3"));
}

TEST(StabsReaderTestCase, NoCU) {
  MockStabsReaderHandler mock_handler;

  EXPECT_CALL(mock_handler, StartCompilationUnit(_, _, _))
      .Times(0);
  EXPECT_CALL(mock_handler, StartFunction(_, _))
      .Times(0);

  ASSERT_TRUE(ApplyHandlerToMockStabsData(
                  &mock_handler, 
                  "common/linux/testdata/stabs_reader_unittest.input4"));
  
}

TEST(StabsReaderTestCase, NoCUEnd) {
  MockStabsReaderHandler mock_handler;

  {
    InSequence s;

    EXPECT_CALL(mock_handler,
                StartCompilationUnit(StrEq("file5-1.c"), 0x12, NULL))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, EndCompilationUnit(NULL))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler,
                StartCompilationUnit(StrEq("file5-2.c"), 0x22, NULL))
        .WillOnce(Return(true));
    EXPECT_CALL(mock_handler, EndCompilationUnit(NULL))
        .WillOnce(Return(true));
  }

  ASSERT_TRUE(ApplyHandlerToMockStabsData(
                  &mock_handler, 
                  "common/linux/testdata/stabs_reader_unittest.input5"));
  
}

} // anonymous namespace