Add utilities for processing Linux core dump files.

This patch is part of a bigger patch that helps merging the breakpad code
with the modified version in Chromium OS.

Specifically, this patch makes the following changes:
1. Add an ElfCoreDump class for processing Linux core dump files, which will
   later be used to implement the core dump to minidump conversion.
2. Add a CrashGenerator class for generating a crash with a core dump file
   for testing the functionalities of ElfCoreDump.
3. Move some utility functions for reading/writing files to file_utils.h.

BUG=455
TEST=Tested the following:
1. Build on 32-bit and 64-bit Linux with gcc 4.4.3 and gcc 4.6.
2. Build on Mac OS X 10.6.8 with gcc 4.2 and clang 3.0 (with latest gmock).
3. All unit tests pass.
Review URL: http://breakpad.appspot.com/337001

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@900 4c0a9323-5329-0410-9bdc-e9ce6186880e

6 files changed, 890 insertions, 23 deletions

diff --git a/src/common/linux/elf_core_dump.cc b/src/common/linux/elf_core_dump.cc
new file mode 100644
index 00000000..0e7db7b1
--- /dev/null
+++ b/src/common/linux/elf_core_dump.cc
@@ -0,0 +1,179 @@
+// Copyright (c) 2011, 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.
+
+// elf_core_dump.cc: Implement google_breakpad::ElfCoreDump.
+// See elf_core_dump.h for details.
+
+#include "common/linux/elf_core_dump.h"
+
+#include <stddef.h>
+#include <string.h>
+
+namespace google_breakpad {
+
+// Implementation of ElfCoreDump::Note.
+
+ElfCoreDump::Note::Note() {}
+
+ElfCoreDump::Note::Note(const MemoryRange& content) : content_(content) {}
+
+bool ElfCoreDump::Note::IsValid() const {
+  return GetHeader() != NULL;
+}
+
+const ElfCoreDump::Nhdr* ElfCoreDump::Note::GetHeader() const {
+  return content_.GetData<Nhdr>(0);
+}
+
+ElfCoreDump::Word ElfCoreDump::Note::GetType() const {
+  const Nhdr* header = GetHeader();
+  // 0 is not being used as a NOTE type.
+  return header ? header->n_type : 0;
+}
+
+MemoryRange ElfCoreDump::Note::GetName() const {
+  const Nhdr* header = GetHeader();
+  if (header) {
+      return content_.Subrange(sizeof(Nhdr), header->n_namesz);
+  }
+  return MemoryRange();
+}
+
+MemoryRange ElfCoreDump::Note::GetDescription() const {
+  const Nhdr* header = GetHeader();
+  if (header) {
+    return content_.Subrange(AlignedSize(sizeof(Nhdr) + header->n_namesz),
+                             header->n_descsz);
+  }
+  return MemoryRange();
+}
+
+ElfCoreDump::Note ElfCoreDump::Note::GetNextNote() const {
+  MemoryRange next_content;
+  const Nhdr* header = GetHeader();
+  if (header) {
+    size_t next_offset = AlignedSize(sizeof(Nhdr) + header->n_namesz);
+    next_offset = AlignedSize(next_offset + header->n_descsz);
+    next_content =
+        content_.Subrange(next_offset, content_.length() - next_offset);
+  }
+  return Note(next_content);
+}
+
+// static
+size_t ElfCoreDump::Note::AlignedSize(size_t size) {
+  size_t mask = sizeof(Word) - 1;
+  return (size + mask) & ~mask;
+}
+
+
+// Implementation of ElfCoreDump.
+
+ElfCoreDump::ElfCoreDump() {}
+
+ElfCoreDump::ElfCoreDump(const MemoryRange& content)
+    : content_(content) {
+}
+
+void ElfCoreDump::SetContent(const MemoryRange& content) {
+  content_ = content;
+}
+
+bool ElfCoreDump::IsValid() const {
+  const Ehdr* header = GetHeader();
+  return (header &&
+          header->e_ident[0] == ELFMAG0 &&
+          header->e_ident[1] == ELFMAG1 &&
+          header->e_ident[2] == ELFMAG2 &&
+          header->e_ident[3] == ELFMAG3 &&
+          header->e_ident[4] == kClass &&
+          header->e_version == EV_CURRENT &&
+          header->e_type == ET_CORE);
+}
+
+const ElfCoreDump::Ehdr* ElfCoreDump::GetHeader() const {
+  return content_.GetData<Ehdr>(0);
+}
+
+const ElfCoreDump::Phdr* ElfCoreDump::GetProgramHeader(unsigned index) const {
+  const Ehdr* header = GetHeader();
+  if (header) {
+    return reinterpret_cast<const Phdr*>(content_.GetArrayElement(
+        header->e_phoff, header->e_phentsize, index));
+  }
+  return NULL;
+}
+
+const ElfCoreDump::Phdr* ElfCoreDump::GetFirstProgramHeaderOfType(
+    Word type) const {
+  for (unsigned i = 0, n = GetProgramHeaderCount(); i < n; ++i) {
+    const Phdr* program = GetProgramHeader(i);
+    if (program->p_type == type) {
+      return program;
+    }
+  }
+  return NULL;
+}
+
+unsigned ElfCoreDump::GetProgramHeaderCount() const {
+  const Ehdr* header = GetHeader();
+  return header ? header->e_phnum : 0;
+}
+
+bool ElfCoreDump::CopyData(void* buffer, Addr virtual_address, size_t length) {
+  for (unsigned i = 0, n = GetProgramHeaderCount(); i < n; ++i) {
+    const Phdr* program = GetProgramHeader(i);
+    if (program->p_type != PT_LOAD)
+      continue;
+
+    size_t offset_in_segment = virtual_address - program->p_vaddr;
+    if (virtual_address >= program->p_vaddr &&
+        offset_in_segment < program->p_filesz) {
+      const void* data =
+          content_.GetData(program->p_offset + offset_in_segment, length);
+      if (data) {
+        memcpy(buffer, data, length);
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+ElfCoreDump::Note ElfCoreDump::GetFirstNote() const {
+  MemoryRange note_content;
+  const Phdr* program_header = GetFirstProgramHeaderOfType(PT_NOTE);
+  if (program_header) {
+    note_content = content_.Subrange(program_header->p_offset,
+                                     program_header->p_filesz);
+  }
+  return Note(note_content);
+}
+
+}  // namespace google_breakpad
diff --git a/src/common/linux/elf_core_dump.h b/src/common/linux/elf_core_dump.h
new file mode 100644
index 00000000..dd846f09
--- /dev/null
+++ b/src/common/linux/elf_core_dump.h
@@ -0,0 +1,153 @@
+// Copyright (c) 2011, 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.
+
+// elf_core_dump.h: Define the google_breakpad::ElfCoreDump class, which
+// encapsulates an ELF core dump file mapped into memory.
+
+#ifndef COMMON_LINUX_ELF_CORE_DUMP_H_
+#define COMMON_LINUX_ELF_CORE_DUMP_H_
+
+#include <elf.h>
+#if !defined(__ANDROID__)
+#include <link.h>
+#endif
+#include <stddef.h>
+
+#include "common/memory_range.h"
+#if defined(__ANDROID__)
+#include "common/linux/android_link.h"
+#endif
+
+namespace google_breakpad {
+
+// A class encapsulating an ELF core dump file mapped into memory, which
+// provides methods for accessing program headers and the note section.
+class ElfCoreDump {
+ public:
+  // ELF types based on the value of __WORDSIZE.
+  typedef ElfW(Ehdr) Ehdr;
+  typedef ElfW(Nhdr) Nhdr;
+  typedef ElfW(Phdr) Phdr;
+  typedef ElfW(Word) Word;
+  typedef ElfW(Addr) Addr;
+#if __WORDSIZE == 32
+  static const int kClass = ELFCLASS32;
+#elif __WORDSIZE == 64
+  static const int kClass = ELFCLASS64;
+#else
+#error "Unsupported __WORDSIZE for ElfCoreDump."
+#endif
+
+  // A class encapsulating the note content in a core dump, which provides
+  // methods for accessing the name and description of a note.
+  class Note {
+   public:
+    Note();
+
+    // Constructor that takes the note content from |content|.
+    explicit Note(const MemoryRange& content);
+
+    // Returns true if this note is valid, i,e. a note header is found in
+    // |content_|, or false otherwise.
+    bool IsValid() const;
+
+    // Returns the note header, or NULL if no note header is found in
+    // |content_|.
+    const Nhdr* GetHeader() const;
+
+    // Returns the note type, or 0 if no note header is found in |content_|.
+    Word GetType() const;
+
+    // Returns a memory range covering the note name, or an empty range
+    // if no valid note name is found in |content_|.
+    MemoryRange GetName() const;
+
+    // Returns a memory range covering the note description, or an empty
+    // range if no valid note description is found in |content_|.
+    MemoryRange GetDescription() const;
+
+    // Returns the note following this note, or an empty note if no valid
+    // note is found after this note.
+    Note GetNextNote() const;
+
+   private:
+    // Returns the size in bytes round up to the word alignment, specified
+    // for the note section, of a given size in bytes.
+    static size_t AlignedSize(size_t size);
+
+    // Note content.
+    MemoryRange content_;
+  };
+
+  ElfCoreDump();
+
+  // Constructor that takes the core dump content from |content|.
+  explicit ElfCoreDump(const MemoryRange& content);
+
+  // Sets the core dump content to |content|.
+  void SetContent(const MemoryRange& content);
+
+  // Returns true if a valid ELF header in the core dump, or false otherwise.
+  bool IsValid() const;
+
+  // Returns the ELF header in the core dump, or NULL if no ELF header
+  // is found in |content_|.
+  const Ehdr* GetHeader() const;
+
+  // Returns the |index|-th program header in the core dump, or NULL if no
+  // ELF header is found in |content_| or |index| is out of bounds.
+  const Phdr* GetProgramHeader(unsigned index) const;
+
+  // Returns the first program header of |type| in the core dump, or NULL if
+  // no ELF header is found in |content_| or no program header of |type| is
+  // found.
+  const Phdr* GetFirstProgramHeaderOfType(Word type) const;
+
+  // Returns the number of program headers in the core dump, or 0 if no
+  // ELF header is found in |content_|.
+  unsigned GetProgramHeaderCount() const;
+
+  // Copies |length| bytes of data starting at |virtual_address| in the core
+  // dump to |buffer|. |buffer| should be a valid pointer to a buffer of at
+  // least |length| bytes. Returns true if the data to be copied is found in
+  // the core dump, or false otherwise.
+  bool CopyData(void* buffer, Addr virtual_address, size_t length);
+
+  // Returns the first note found in the note section of the core dump, or
+  // an empty note if no note is found.
+  Note GetFirstNote() const;
+
+ private:
+  // Core dump content.
+  MemoryRange content_;
+};
+
+}  // namespace google_breakpad
+
+#endif  // COMMON_LINUX_ELF_CORE_DUMP_H_
diff --git a/src/common/linux/elf_core_dump_unittest.cc b/src/common/linux/elf_core_dump_unittest.cc
new file mode 100644
index 00000000..324e57b6
--- /dev/null
+++ b/src/common/linux/elf_core_dump_unittest.cc
@@ -0,0 +1,238 @@
+// Copyright (c) 2011, 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.
+
+// elf_core_dump_unittest.cc: Unit tests for google_breakpad::ElfCoreDump.
+
+#include <sys/procfs.h>
+
+#include <set>
+#include <string>
+
+#include "breakpad_googletest_includes.h"
+#include "common/linux/elf_core_dump.h"
+#include "common/linux/memory_mapped_file.h"
+#include "common/tests/file_utils.h"
+#include "common/linux/tests/crash_generator.h"
+
+using google_breakpad::AutoTempDir;
+using google_breakpad::CrashGenerator;
+using google_breakpad::ElfCoreDump;
+using google_breakpad::MemoryMappedFile;
+using google_breakpad::MemoryRange;
+using google_breakpad::WriteFile;
+using std::set;
+using std::string;
+
+TEST(ElfCoreDumpTest, DefaultConstructor) {
+  ElfCoreDump core;
+  EXPECT_FALSE(core.IsValid());
+  EXPECT_EQ(NULL, core.GetHeader());
+  EXPECT_EQ(0, core.GetProgramHeaderCount());
+  EXPECT_EQ(NULL, core.GetProgramHeader(0));
+  EXPECT_EQ(NULL, core.GetFirstProgramHeaderOfType(PT_LOAD));
+  EXPECT_FALSE(core.GetFirstNote().IsValid());
+}
+
+TEST(ElfCoreDumpTest, TestElfHeader) {
+  ElfCoreDump::Ehdr header;
+  memset(&header, 0, sizeof(header));
+
+  AutoTempDir temp_dir;
+  string core_path = temp_dir.path() + "/core";
+  const char* core_file = core_path.c_str();
+  MemoryMappedFile mapped_core_file;
+  ElfCoreDump core;
+
+  ASSERT_TRUE(WriteFile(core_file, &header, sizeof(header) - 1));
+  ASSERT_TRUE(mapped_core_file.Map(core_file));
+  core.SetContent(mapped_core_file.content());
+  EXPECT_FALSE(core.IsValid());
+  EXPECT_EQ(NULL, core.GetHeader());
+  EXPECT_EQ(0, core.GetProgramHeaderCount());
+  EXPECT_EQ(NULL, core.GetProgramHeader(0));
+  EXPECT_EQ(NULL, core.GetFirstProgramHeaderOfType(PT_LOAD));
+  EXPECT_FALSE(core.GetFirstNote().IsValid());
+
+  ASSERT_TRUE(WriteFile(core_file, &header, sizeof(header)));
+  ASSERT_TRUE(mapped_core_file.Map(core_file));
+  core.SetContent(mapped_core_file.content());
+  EXPECT_FALSE(core.IsValid());
+
+  header.e_ident[0] = ELFMAG0;
+  ASSERT_TRUE(WriteFile(core_file, &header, sizeof(header)));
+  ASSERT_TRUE(mapped_core_file.Map(core_file));
+  core.SetContent(mapped_core_file.content());
+  EXPECT_FALSE(core.IsValid());
+
+  header.e_ident[1] = ELFMAG1;
+  ASSERT_TRUE(WriteFile(core_file, &header, sizeof(header)));
+  ASSERT_TRUE(mapped_core_file.Map(core_file));
+  core.SetContent(mapped_core_file.content());
+  EXPECT_FALSE(core.IsValid());
+
+  header.e_ident[2] = ELFMAG2;
+  ASSERT_TRUE(WriteFile(core_file, &header, sizeof(header)));
+  ASSERT_TRUE(mapped_core_file.Map(core_file));
+  core.SetContent(mapped_core_file.content());
+  EXPECT_FALSE(core.IsValid());
+
+  header.e_ident[3] = ELFMAG3;
+  ASSERT_TRUE(WriteFile(core_file, &header, sizeof(header)));
+  ASSERT_TRUE(mapped_core_file.Map(core_file));
+  core.SetContent(mapped_core_file.content());
+  EXPECT_FALSE(core.IsValid());
+
+  header.e_ident[4] = ElfCoreDump::kClass;
+  ASSERT_TRUE(WriteFile(core_file, &header, sizeof(header)));
+  ASSERT_TRUE(mapped_core_file.Map(core_file));
+  core.SetContent(mapped_core_file.content());
+  EXPECT_FALSE(core.IsValid());
+
+  header.e_version = EV_CURRENT;
+  ASSERT_TRUE(WriteFile(core_file, &header, sizeof(header)));
+  ASSERT_TRUE(mapped_core_file.Map(core_file));
+  core.SetContent(mapped_core_file.content());
+  EXPECT_FALSE(core.IsValid());
+
+  header.e_type = ET_CORE;
+  ASSERT_TRUE(WriteFile(core_file, &header, sizeof(header)));
+  ASSERT_TRUE(mapped_core_file.Map(core_file));
+  core.SetContent(mapped_core_file.content());
+  EXPECT_TRUE(core.IsValid());
+}
+
+TEST(ElfCoreDumpTest, ValidCoreFile) {
+  CrashGenerator crash_generator;
+  if (!crash_generator.HasDefaultCorePattern()) {
+    fprintf(stderr, "ElfCoreDumpTest.ValidCoreFile test is skipped");
+    return;
+  }
+
+  const unsigned kNumOfThreads = 3;
+  const unsigned kCrashThread = 1;
+  const int kCrashSignal = SIGABRT;
+  ASSERT_TRUE(crash_generator.CreateChildCrash(kNumOfThreads, kCrashThread,
+                                               kCrashSignal));
+  pid_t expected_crash_thread_id = crash_generator.GetThreadId(kCrashThread);
+  set<pid_t> expected_thread_ids;
+  for (unsigned i = 0; i < kNumOfThreads; ++i) {
+    expected_thread_ids.insert(crash_generator.GetThreadId(i));
+  }
+
+  MemoryMappedFile mapped_core_file;
+  ASSERT_TRUE(mapped_core_file.Map(crash_generator.GetCoreFilePath().c_str()));
+
+  ElfCoreDump core;
+  core.SetContent(mapped_core_file.content());
+  EXPECT_TRUE(core.IsValid());
+
+  // Based on write_note_info() in linux/kernel/fs/binfmt_elf.c, notes are
+  // ordered as follows (NT_PRXFPREG and NT_386_TLS are i386 specific):
+  //   Thread           Name          Type
+  //   -------------------------------------------------------------------
+  //   1st thread       CORE          NT_PRSTATUS
+  //   process-wide     CORE          NT_PRPSINFO
+  //   process-wide     CORE          NT_AUXV
+  //   1st thread       CORE          NT_FPREGSET
+  //   1st thread       LINUX         NT_PRXFPREG
+  //   1st thread       LINUX         NT_386_TLS
+  //
+  //   2nd thread       CORE          NT_PRSTATUS
+  //   2nd thread       CORE          NT_FPREGSET
+  //   2nd thread       LINUX         NT_PRXFPREG
+  //   2nd thread       LINUX         NT_386_TLS
+  //
+  //   3rd thread       CORE          NT_PRSTATUS
+  //   3rd thread       CORE          NT_FPREGSET
+  //   3rd thread       LINUX         NT_PRXFPREG
+  //   3rd thread       LINUX         NT_386_TLS
+
+  size_t num_nt_prpsinfo = 0;
+  size_t num_nt_prstatus = 0;
+  size_t num_nt_fpregset = 0;
+  size_t num_nt_prxfpreg = 0;
+  set<pid_t> actual_thread_ids;
+  ElfCoreDump::Note note = core.GetFirstNote();
+  while (note.IsValid()) {
+    MemoryRange name = note.GetName();
+    MemoryRange description = note.GetDescription();
+    EXPECT_FALSE(name.IsEmpty());
+    EXPECT_FALSE(description.IsEmpty());
+
+    switch (note.GetType()) {
+      case NT_PRPSINFO: {
+        EXPECT_TRUE(description.data() != NULL);
+        EXPECT_EQ(sizeof(elf_prpsinfo), description.length());
+        ++num_nt_prpsinfo;
+        break;
+      }
+      case NT_PRSTATUS: {
+        EXPECT_TRUE(description.data() != NULL);
+        EXPECT_EQ(sizeof(elf_prstatus), description.length());
+        const elf_prstatus* status = description.GetData<elf_prstatus>(0);
+        actual_thread_ids.insert(status->pr_pid);
+        if (num_nt_prstatus == 0) {
+          EXPECT_EQ(expected_crash_thread_id, status->pr_pid);
+          EXPECT_EQ(kCrashSignal, status->pr_info.si_signo);
+        }
+        ++num_nt_prstatus;
+        break;
+      }
+#if defined(__i386) || defined(__x86_64)
+      case NT_FPREGSET: {
+        EXPECT_TRUE(description.data() != NULL);
+        EXPECT_EQ(sizeof(user_fpregs_struct), description.length());
+        ++num_nt_fpregset;
+        break;
+      }
+#endif
+#if defined(__i386)
+      case NT_PRXFPREG: {
+        EXPECT_TRUE(description.data() != NULL);
+        EXPECT_EQ(sizeof(user_fpxregs_struct), description.length());
+        ++num_nt_prxfpreg;
+        break;
+      }
+#endif
+      default:
+        break;
+    }
+    note = note.GetNextNote();
+  }
+
+  EXPECT_TRUE(expected_thread_ids == actual_thread_ids);
+  EXPECT_EQ(1, num_nt_prpsinfo);
+  EXPECT_EQ(kNumOfThreads, num_nt_prstatus);
+#if defined(__i386) || defined(__x86_64)
+  EXPECT_EQ(kNumOfThreads, num_nt_fpregset);
+#endif
+#if defined(__i386)
+  EXPECT_EQ(kNumOfThreads, num_nt_prxfpreg);
+#endif
+}
diff --git a/src/common/linux/memory_mapped_file_unittest.cc b/src/common/linux/memory_mapped_file_unittest.cc
index 8a3129fb..cf89bca9 100644
--- a/src/common/linux/memory_mapped_file_unittest.cc
+++ b/src/common/linux/memory_mapped_file_unittest.cc
@@ -40,32 +40,15 @@
 #include "common/linux/eintr_wrapper.h"
 #include "common/linux/memory_mapped_file.h"
 #include "common/tests/auto_tempdir.h"
+#include "common/tests/file_utils.h"
 
 using google_breakpad::AutoTempDir;
 using google_breakpad::MemoryMappedFile;
+using google_breakpad::WriteFile;
 using std::string;
 
 namespace {
 
-bool WriteFile(const string& path, const void* buffer, size_t buffer_size) {
-  int fd =
-      HANDLE_EINTR(open(path.c_str(), O_CREAT | O_TRUNC | O_WRONLY, S_IRWXU));
-  if (fd == -1) {
-    perror("open");
-    return false;
-  }
-
-  bool ok = true;
-  if (buffer && buffer_size > 0) {
-    if (HANDLE_EINTR(write(fd, buffer, buffer_size) != buffer_size)) {
-      perror("write");
-      ok = false;
-    }
-  }
-  close(fd);
-  return ok;
-}
-
 class MemoryMappedFileTest : public testing::Test {
  protected:
   void ExpectNoMappedData(const MemoryMappedFile& mapped_file) {
@@ -102,7 +85,7 @@ TEST_F(MemoryMappedFileTest, MapNonexistentFile) {
 TEST_F(MemoryMappedFileTest, MapEmptyFile) {
   AutoTempDir temp_dir;
   string test_file = temp_dir.path() + "/empty_file";
-  ASSERT_TRUE(WriteFile(test_file, NULL, 0));
+  ASSERT_TRUE(WriteFile(test_file.c_str(), NULL, 0));
 
   {
     MemoryMappedFile mapped_file(test_file.c_str());
@@ -124,7 +107,7 @@ TEST_F(MemoryMappedFileTest, MapNonEmptyFile) {
 
   AutoTempDir temp_dir;
   string test_file = temp_dir.path() + "/test_file";
-  ASSERT_TRUE(WriteFile(test_file, data, data_size));
+  ASSERT_TRUE(WriteFile(test_file.c_str(), data, data_size));
 
   {
     MemoryMappedFile mapped_file(test_file.c_str());
@@ -159,8 +142,8 @@ TEST_F(MemoryMappedFileTest, RemapAfterMap) {
   AutoTempDir temp_dir;
   string test_file1 = temp_dir.path() + "/test_file1";
   string test_file2 = temp_dir.path() + "/test_file2";
-  ASSERT_TRUE(WriteFile(test_file1, data1, data1_size));
-  ASSERT_TRUE(WriteFile(test_file2, data2, data2_size));
+  ASSERT_TRUE(WriteFile(test_file1.c_str(), data1, data1_size));
+  ASSERT_TRUE(WriteFile(test_file2.c_str(), data2, data2_size));
 
   {
     MemoryMappedFile mapped_file(test_file1.c_str());
diff --git a/src/common/linux/tests/crash_generator.cc b/src/common/linux/tests/crash_generator.cc
new file mode 100644
index 00000000..3ef40dbd
--- /dev/null
+++ b/src/common/linux/tests/crash_generator.cc
@@ -0,0 +1,206 @@
+// Copyright (c) 2011, 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.
+
+// crash_generator.cc: Implement google_breakpad::CrashGenerator.
+// See crash_generator.h for details.
+
+#include "common/linux/tests/crash_generator.h"
+
+#include <pthread.h>
+#include <signal.h>
+#include <sys/mman.h>
+#include <sys/resource.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include <string>
+
+#include "common/linux/eintr_wrapper.h"
+#include "common/tests/auto_tempdir.h"
+#include "common/tests/file_utils.h"
+
+namespace {
+
+struct ThreadData {
+  pthread_t thread;
+  pthread_barrier_t* barrier;
+  pid_t* thread_id_ptr;
+};
+
+// Core file size limit set to 1 MB, which is big enough for test purposes.
+const rlim_t kCoreSizeLimit = 1024 * 1024;
+
+void *thread_function(void *data) {
+  ThreadData* thread_data = reinterpret_cast<ThreadData*>(data);
+  volatile pid_t thread_id = syscall(__NR_gettid);
+  *(thread_data->thread_id_ptr) = thread_id;
+  int result = pthread_barrier_wait(thread_data->barrier);
+  if (result != 0 && result != PTHREAD_BARRIER_SERIAL_THREAD) {
+    exit(1);
+  }
+  while (true) {
+    pthread_yield();
+  }
+}
+
+}  // namespace
+
+namespace google_breakpad {
+
+CrashGenerator::CrashGenerator()
+    : shared_memory_(NULL),
+      shared_memory_size_(0) {
+}
+
+CrashGenerator::~CrashGenerator() {
+  UnmapSharedMemory();
+}
+
+bool CrashGenerator::HasDefaultCorePattern() const {
+  char buffer[8];
+  ssize_t buffer_size = sizeof(buffer);
+  return ReadFile("/proc/sys/kernel/core_pattern", buffer, &buffer_size) &&
+         buffer_size == 5 && memcmp(buffer, "core", 4) == 0;
+}
+
+std::string CrashGenerator::GetCoreFilePath() const {
+  return temp_dir_.path() + "/core";
+}
+
+pid_t CrashGenerator::GetThreadId(unsigned index) const {
+  return reinterpret_cast<pid_t*>(shared_memory_)[index];
+}
+
+pid_t* CrashGenerator::GetThreadIdPointer(unsigned index) {
+  return reinterpret_cast<pid_t*>(shared_memory_) + index;
+}
+
+bool CrashGenerator::MapSharedMemory(size_t memory_size) {
+  if (!UnmapSharedMemory())
+    return false;
+
+  void* mapped_memory = mmap(0, memory_size, PROT_READ | PROT_WRITE,
+                             MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+  if (mapped_memory == MAP_FAILED)
+    return false;
+
+  memset(mapped_memory, 0, memory_size);
+  shared_memory_ = mapped_memory;
+  shared_memory_size_ = memory_size;
+  return true;
+}
+
+bool CrashGenerator::UnmapSharedMemory() {
+  if (!shared_memory_)
+    return true;
+
+  if (munmap(shared_memory_, shared_memory_size_) == 0) {
+    shared_memory_ = NULL;
+    shared_memory_size_ = 0;
+    return true;
+  }
+  return false;
+}
+
+bool CrashGenerator::SetCoreFileSizeLimit(rlim_t limit) const {
+  struct rlimit limits = { limit, limit };
+  return setrlimit(RLIMIT_CORE, &limits) == 0;
+}
+
+bool CrashGenerator::CreateChildCrash(
+    unsigned num_threads, unsigned crash_thread, int crash_signal) {
+  if (num_threads == 0 || crash_thread >= num_threads)
+    return false;
+
+  if (!MapSharedMemory(num_threads * sizeof(pid_t)))
+    return false;
+
+  pid_t pid = fork();
+  if (pid == 0) {
+    if (chdir(temp_dir_.path().c_str()) == 0 &&
+        SetCoreFileSizeLimit(kCoreSizeLimit)) {
+      CreateThreadsInChildProcess(num_threads);
+      kill(*GetThreadIdPointer(crash_thread), crash_signal);
+    }
+    exit(1);
+  }
+
+  int status;
+  if (HANDLE_EINTR(waitpid(pid, &status, 0)) == -1 ||
+      !WIFSIGNALED(status) || WTERMSIG(status) != crash_signal)
+    return false;
+
+  return true;
+}
+
+void CrashGenerator::CreateThreadsInChildProcess(unsigned num_threads) {
+  *GetThreadIdPointer(0) = getpid();
+
+  if (num_threads <= 1)
+    return;
+
+  // This method does not clean up any pthread resource, as the process
+  // is expected to be killed anyway.
+  ThreadData* thread_data = new ThreadData[num_threads];
+
+  // Create detached threads so that we do not worry about pthread_join()
+  // later being called or not.
+  pthread_attr_t thread_attributes;
+  if (pthread_attr_init(&thread_attributes) != 0 ||
+      pthread_attr_setdetachstate(&thread_attributes,
+                                  PTHREAD_CREATE_DETACHED) != 0) {
+    exit(1);
+  }
+
+  pthread_barrier_t thread_barrier;
+  if (pthread_barrier_init(&thread_barrier, NULL, num_threads) != 0) {
+    exit(1);
+  }
+
+  for (unsigned i = 1; i < num_threads; ++i) {
+    thread_data[i].barrier = &thread_barrier;
+    thread_data[i].thread_id_ptr = GetThreadIdPointer(i);
+    if (pthread_create(&thread_data[i].thread, &thread_attributes,
+                       thread_function, &thread_data[i]) != 0) {
+      exit(1);
+    }
+  }
+
+  int result = pthread_barrier_wait(&thread_barrier);
+  if (result != 0 && result != PTHREAD_BARRIER_SERIAL_THREAD) {
+    exit(1);
+  }
+
+  pthread_barrier_destroy(&thread_barrier);
+  pthread_attr_destroy(&thread_attributes);
+  delete[] thread_data;
+}
+
+}  // namespace google_breakpad
diff --git a/src/common/linux/tests/crash_generator.h b/src/common/linux/tests/crash_generator.h
new file mode 100644
index 00000000..c88a8920
--- /dev/null
+++ b/src/common/linux/tests/crash_generator.h
@@ -0,0 +1,108 @@
+// Copyright (c) 2011, 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.
+
+// crash_generator.h: Define the google_breakpad::CrashGenerator class,
+// which is used to generate a crash (and a core dump file) for testing.
+
+#ifndef COMMON_LINUX_TESTS_CRASH_GENERATOR_H_
+#define COMMON_LINUX_TESTS_CRASH_GENERATOR_H_
+
+#include <sys/resource.h>
+
+#include <string>
+
+#include "common/tests/auto_tempdir.h"
+
+namespace google_breakpad {
+
+// A utility class for generating a crash (and a core dump file) for
+// testing. It creates a child process with the specified number of
+// threads, which is then termainated by the specified signal. A core
+// dump file is expected to be created upon the termination of the child
+// process, which can then be used for testing code that processes core
+// dump files.
+class CrashGenerator {
+ public:
+  CrashGenerator();
+
+  ~CrashGenerator();
+
+  // Returns true if a core dump file named 'core' will be generated in
+  // the current directory for a test that produces a crash by checking
+  // if /proc/sys/kernel/core_pattern has the default value 'core'.
+  bool HasDefaultCorePattern() const;
+
+  // Sets the maximum size of core dump file (both the soft and hard limit)
+  // to |limit| bytes. Returns true on success.
+  bool SetCoreFileSizeLimit(rlim_t limit) const;
+
+  // Returns the expected path of the core dump file.
+  std::string GetCoreFilePath() const;
+
+  // Creates a crash (and a core dump file) by creating a child process with
+  // |num_threads| threads, and the terminating the child process by sending
+  // a signal with number |crash_signal| to the |crash_thread|-th thread.
+  // Returns true on success.
+  bool CreateChildCrash(unsigned num_threads, unsigned crash_thread,
+                        int crash_signal);
+
+  // Creates |num_threads| threads in the child process.
+  void CreateThreadsInChildProcess(unsigned num_threads);
+
+  // Returns the thread ID of the |index|-th thread in the child process.
+  // This method does not validate |index|.
+  pid_t GetThreadId(unsigned index) const;
+
+ private:
+  // Creates a shared memory of |memory_size| bytes for communicating thread
+  // IDs between the parent and child process. Returns true on success.
+  bool MapSharedMemory(size_t memory_size);
+
+  // Releases any shared memory created by MapSharedMemory(). Returns true on
+  // success.
+  bool UnmapSharedMemory();
+
+  // Returns the pointer to the thread ID of the |index|-th thread in the child
+  // process. This method does not validate |index|.
+  pid_t* GetThreadIdPointer(unsigned index);
+
+  // Temporary directory in which a core file is generated.
+  AutoTempDir temp_dir_;
+
+  // Shared memory for communicating thread IDs between the parent and
+  // child process.
+  void* shared_memory_;
+
+  // Number of bytes mapped for |shared_memory_|.
+  size_t shared_memory_size_;
+};
+
+}  // namespace google_breakpad
+
+#endif  // COMMON_LINUX_TESTS_CRASH_GENERATOR_H_