Implement core dump to minidump conversion.

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. Turn the LinuxDumper class into a base class and move ptrace related
   code into a new derived class, LinuxPtraceDumper.
2. Add a LinuxCoreDumper class, which is derived from LinuxDumper, to
   extract information from a crashed process via a core dump file instead
   of ptrace.
3. Add a WriteMinidumpFromCore function to
     src/client/linux/minidump_writer/minidump_writer.h,
   which uses LinuxCoreDumper to extract information from a core dump file.
4. Add a core2md utility, which simply wraps WriteMinidumpFromCore, for
   converting a core dump to a minidump.

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.
4. Run Chromium OS tests to test core2md.
Review URL: http://breakpad.appspot.com/343001

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@905 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 430 insertions, 0 deletions

diff --git a/src/client/linux/minidump_writer/linux_ptrace_dumper_unittest.cc b/src/client/linux/minidump_writer/linux_ptrace_dumper_unittest.cc
new file mode 100644
index 00000000..84e1974f
--- /dev/null
+++ b/src/client/linux/minidump_writer/linux_ptrace_dumper_unittest.cc
@@ -0,0 +1,430 @@
+// Copyright (c) 2009, 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.
+
+// linux_ptrace_dumper_unittest.cc:
+// Unit tests for google_breakpad::LinuxPtraceDumoer.
+//
+// This file was renamed from linux_dumper_unittest.cc and modified due
+// to LinuxDumper being splitted into two classes.
+
+#include <fcntl.h>
+#include <limits.h>
+#include <unistd.h>
+#include <signal.h>
+#include <stdint.h>
+#include <sys/mman.h>
+#include <sys/poll.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <string>
+
+#include "breakpad_googletest_includes.h"
+#include "client/linux/minidump_writer/linux_ptrace_dumper.h"
+#include "common/linux/eintr_wrapper.h"
+#include "common/linux/file_id.h"
+#include "common/linux/safe_readlink.h"
+#include "common/memory.h"
+
+using std::string;
+using namespace google_breakpad;
+
+namespace {
+
+typedef testing::Test LinuxPtraceDumperTest;
+
+string GetHelperBinary() {
+  // Locate helper binary next to the current binary.
+  char self_path[PATH_MAX];
+  if (!SafeReadLink("/proc/self/exe", self_path)) {
+    return "";
+  }
+  string helper_path(self_path);
+  size_t pos = helper_path.rfind('/');
+  if (pos == string::npos) {
+    return "";
+  }
+  helper_path.erase(pos + 1);
+  helper_path += "linux_dumper_unittest_helper";
+
+  return helper_path;
+}
+
+}  // namespace
+
+TEST(LinuxPtraceDumperTest, Setup) {
+  LinuxPtraceDumper dumper(getpid());
+}
+
+TEST(LinuxPtraceDumperTest, FindMappings) {
+  LinuxPtraceDumper dumper(getpid());
+  ASSERT_TRUE(dumper.Init());
+
+  ASSERT_TRUE(dumper.FindMapping(reinterpret_cast<void*>(getpid)));
+  ASSERT_TRUE(dumper.FindMapping(reinterpret_cast<void*>(printf)));
+  ASSERT_FALSE(dumper.FindMapping(NULL));
+}
+
+TEST(LinuxPtraceDumperTest, ThreadList) {
+  LinuxPtraceDumper dumper(getpid());
+  ASSERT_TRUE(dumper.Init());
+
+  ASSERT_GE(dumper.threads().size(), (size_t)1);
+  bool found = false;
+  for (size_t i = 0; i < dumper.threads().size(); ++i) {
+    if (dumper.threads()[i] == getpid()) {
+      found = true;
+      break;
+    }
+  }
+}
+
+// Helper stack class to close a file descriptor and unmap
+// a mmap'ed mapping.
+class StackHelper {
+ public:
+  StackHelper(int fd, char* mapping, size_t size)
+    : fd_(fd), mapping_(mapping), size_(size) {}
+  ~StackHelper() {
+    munmap(mapping_, size_);
+    close(fd_);
+  }
+
+ private:
+  int fd_;
+  char* mapping_;
+  size_t size_;
+};
+
+TEST(LinuxPtraceDumperTest, MergedMappings) {
+  string helper_path(GetHelperBinary());
+  if (helper_path.empty()) {
+    FAIL() << "Couldn't find helper binary";
+    exit(1);
+  }
+
+  // mmap two segments out of the helper binary, one
+  // enclosed in the other, but with different protections.
+  const size_t kPageSize = sysconf(_SC_PAGESIZE);
+  const size_t kMappingSize = 3 * kPageSize;
+  int fd = open(helper_path.c_str(), O_RDONLY);
+  ASSERT_NE(-1, fd);
+  char* mapping =
+    reinterpret_cast<char*>(mmap(NULL,
+                                 kMappingSize,
+                                 PROT_READ,
+                                 MAP_SHARED,
+                                 fd,
+                                 0));
+  ASSERT_TRUE(mapping);
+
+  const u_int64_t kMappingAddress = reinterpret_cast<u_int64_t>(mapping);
+
+  // Ensure that things get cleaned up.
+  StackHelper helper(fd, mapping, kMappingSize);
+
+  // Carve a page out of the first mapping with different permissions.
+  char* inside_mapping =  reinterpret_cast<char*>(
+      mmap(mapping + 2 *kPageSize,
+           kPageSize,
+           PROT_NONE,
+           MAP_SHARED | MAP_FIXED,
+           fd,
+           // Map a different offset just to
+           // better test real-world conditions.
+           kPageSize));
+  ASSERT_TRUE(inside_mapping);
+
+  // Now check that LinuxPtraceDumper interpreted the mappings properly.
+  LinuxPtraceDumper dumper(getpid());
+  ASSERT_TRUE(dumper.Init());
+  int mapping_count = 0;
+  for (unsigned i = 0; i < dumper.mappings().size(); ++i) {
+    const MappingInfo& mapping = *dumper.mappings()[i];
+    if (strcmp(mapping.name, helper_path.c_str()) == 0) {
+      // This mapping should encompass the entire original mapped
+      // range.
+      EXPECT_EQ(kMappingAddress, mapping.start_addr);
+      EXPECT_EQ(kMappingSize, mapping.size);
+      EXPECT_EQ(0, mapping.offset);
+      mapping_count++;
+    }
+  }
+  EXPECT_EQ(1, mapping_count);
+}
+
+TEST(LinuxPtraceDumperTest, VerifyStackReadWithMultipleThreads) {
+  static const int kNumberOfThreadsInHelperProgram = 5;
+  char kNumberOfThreadsArgument[2];
+  sprintf(kNumberOfThreadsArgument, "%d", kNumberOfThreadsInHelperProgram);
+
+  int fds[2];
+  ASSERT_NE(-1, pipe(fds));
+
+  pid_t child_pid = fork();
+  if (child_pid == 0) {
+    // In child process.
+    close(fds[0]);
+
+    string helper_path(GetHelperBinary());
+    if (helper_path.empty()) {
+      FAIL() << "Couldn't find helper binary";
+      exit(1);
+    }
+
+    // Pass the pipe fd and the number of threads as arguments.
+    char pipe_fd_string[8];
+    sprintf(pipe_fd_string, "%d", fds[1]);
+    execl(helper_path.c_str(),
+          "linux_dumper_unittest_helper",
+          pipe_fd_string,
+          kNumberOfThreadsArgument,
+          NULL);
+    // Kill if we get here.
+    printf("Errno from exec: %d", errno);
+    FAIL() << "Exec of " << helper_path << " failed: " << strerror(errno);
+    exit(0);
+  }
+  close(fds[1]);
+  // Wait for the child process to signal that it's ready.
+  struct pollfd pfd;
+  memset(&pfd, 0, sizeof(pfd));
+  pfd.fd = fds[0];
+  pfd.events = POLLIN | POLLERR;
+
+  const int r = HANDLE_EINTR(poll(&pfd, 1, 1000));
+  ASSERT_EQ(1, r);
+  ASSERT_TRUE(pfd.revents & POLLIN);
+  uint8_t junk;
+  read(fds[0], &junk, sizeof(junk));
+  close(fds[0]);
+
+  // Child is ready now.
+  LinuxPtraceDumper dumper(child_pid);
+  ASSERT_TRUE(dumper.Init());
+  EXPECT_EQ((size_t)kNumberOfThreadsInHelperProgram, dumper.threads().size());
+  EXPECT_TRUE(dumper.ThreadsSuspend());
+
+  ThreadInfo one_thread;
+  for (size_t i = 0; i < dumper.threads().size(); ++i) {
+    EXPECT_TRUE(dumper.GetThreadInfoByIndex(i, &one_thread));
+    // In the helper program, we stored a pointer to the thread id in a
+    // specific register. Check that we can recover its value.
+#if defined(__ARM_EABI__)
+    pid_t *process_tid_location = (pid_t *)(one_thread.regs.uregs[3]);
+#elif defined(__i386)
+    pid_t *process_tid_location = (pid_t *)(one_thread.regs.ecx);
+#elif defined(__x86_64)
+    pid_t *process_tid_location = (pid_t *)(one_thread.regs.rcx);
+#else
+#error This test has not been ported to this platform.
+#endif
+    pid_t one_thread_id;
+    dumper.CopyFromProcess(&one_thread_id,
+                           dumper.threads()[i],
+                           process_tid_location,
+                           4);
+    EXPECT_EQ(dumper.threads()[i], one_thread_id);
+  }
+  kill(child_pid, SIGKILL);
+}
+
+TEST(LinuxPtraceDumperTest, BuildProcPath) {
+  const pid_t pid = getpid();
+  LinuxPtraceDumper dumper(pid);
+
+  char maps_path[NAME_MAX] = "";
+  char maps_path_expected[NAME_MAX];
+  snprintf(maps_path_expected, sizeof(maps_path_expected),
+           "/proc/%d/maps", pid);
+  EXPECT_TRUE(dumper.BuildProcPath(maps_path, pid, "maps"));
+  EXPECT_STREQ(maps_path_expected, maps_path);
+
+  EXPECT_FALSE(dumper.BuildProcPath(NULL, pid, "maps"));
+  EXPECT_FALSE(dumper.BuildProcPath(maps_path, 0, "maps"));
+  EXPECT_FALSE(dumper.BuildProcPath(maps_path, pid, ""));
+  EXPECT_FALSE(dumper.BuildProcPath(maps_path, pid, NULL));
+
+  char long_node[NAME_MAX];
+  size_t long_node_len = NAME_MAX - strlen("/proc/123") - 1;
+  memset(long_node, 'a', long_node_len);
+  long_node[long_node_len] = '\0';
+  EXPECT_FALSE(dumper.BuildProcPath(maps_path, 123, long_node));
+}
+
+#if !defined(__ARM_EABI__)
+// Ensure that the linux-gate VDSO is included in the mapping list.
+TEST(LinuxPtraceDumperTest, MappingsIncludeLinuxGate) {
+  LinuxPtraceDumper dumper(getpid());
+  ASSERT_TRUE(dumper.Init());
+
+  void* linux_gate_loc = dumper.FindBeginningOfLinuxGateSharedLibrary(getpid());
+  ASSERT_TRUE(linux_gate_loc);
+  bool found_linux_gate = false;
+
+  const wasteful_vector<MappingInfo*> mappings = dumper.mappings();
+  const MappingInfo* mapping;
+  for (unsigned i = 0; i < mappings.size(); ++i) {
+    mapping = mappings[i];
+    if (!strcmp(mapping->name, kLinuxGateLibraryName)) {
+      found_linux_gate = true;
+      break;
+    }
+  }
+  EXPECT_TRUE(found_linux_gate);
+  EXPECT_EQ(linux_gate_loc, reinterpret_cast<void*>(mapping->start_addr));
+  EXPECT_EQ(0, memcmp(linux_gate_loc, ELFMAG, SELFMAG));
+}
+
+// Ensure that the linux-gate VDSO can generate a non-zeroed File ID.
+TEST(LinuxPtraceDumperTest, LinuxGateMappingID) {
+  LinuxPtraceDumper dumper(getpid());
+  ASSERT_TRUE(dumper.Init());
+
+  bool found_linux_gate = false;
+  const wasteful_vector<MappingInfo*> mappings = dumper.mappings();
+  unsigned index = 0;
+  for (unsigned i = 0; i < mappings.size(); ++i) {
+    if (!strcmp(mappings[i]->name, kLinuxGateLibraryName)) {
+      found_linux_gate = true;
+      index = i;
+      break;
+    }
+  }
+  ASSERT_TRUE(found_linux_gate);
+
+  uint8_t identifier[sizeof(MDGUID)];
+  ASSERT_TRUE(dumper.ElfFileIdentifierForMapping(*mappings[index],
+                                                 true,
+                                                 index,
+                                                 identifier));
+  uint8_t empty_identifier[sizeof(MDGUID)];
+  memset(empty_identifier, 0, sizeof(empty_identifier));
+  EXPECT_NE(0, memcmp(empty_identifier, identifier, sizeof(identifier)));
+}
+
+// Ensure that the linux-gate VDSO can generate a non-zeroed File ID
+// from a child process.
+TEST(LinuxPtraceDumperTest, LinuxGateMappingIDChild) {
+  int fds[2];
+  ASSERT_NE(-1, pipe(fds));
+
+  // Fork a child so ptrace works.
+  const pid_t child = fork();
+  if (child == 0) {
+    close(fds[1]);
+    // Now wait forever for the parent.
+    char b;
+    HANDLE_EINTR(read(fds[0], &b, sizeof(b)));
+    close(fds[0]);
+    syscall(__NR_exit);
+  }
+  close(fds[0]);
+
+  LinuxPtraceDumper dumper(child);
+  ASSERT_TRUE(dumper.Init());
+
+  bool found_linux_gate = false;
+  const wasteful_vector<MappingInfo*> mappings = dumper.mappings();
+  unsigned index = 0;
+  for (unsigned i = 0; i < mappings.size(); ++i) {
+    if (!strcmp(mappings[i]->name, kLinuxGateLibraryName)) {
+      found_linux_gate = true;
+      index = i;
+      break;
+    }
+  }
+  ASSERT_TRUE(found_linux_gate);
+
+  // Need to suspend the child so ptrace actually works.
+  ASSERT_TRUE(dumper.ThreadsSuspend());
+  uint8_t identifier[sizeof(MDGUID)];
+  ASSERT_TRUE(dumper.ElfFileIdentifierForMapping(*mappings[index],
+                                                 true,
+                                                 index,
+                                                 identifier));
+  uint8_t empty_identifier[sizeof(MDGUID)];
+  memset(empty_identifier, 0, sizeof(empty_identifier));
+  EXPECT_NE(0, memcmp(empty_identifier, identifier, sizeof(identifier)));
+  EXPECT_TRUE(dumper.ThreadsResume());
+  close(fds[1]);
+}
+#endif
+
+TEST(LinuxPtraceDumperTest, FileIDsMatch) {
+  // Calculate the File ID of our binary using both
+  // FileID::ElfFileIdentifier and LinuxDumper::ElfFileIdentifierForMapping
+  // and ensure that we get the same result from both.
+  char exe_name[PATH_MAX];
+  ASSERT_TRUE(SafeReadLink("/proc/self/exe", exe_name));
+
+  int fds[2];
+  ASSERT_NE(-1, pipe(fds));
+
+  // Fork a child so ptrace works.
+  const pid_t child = fork();
+  if (child == 0) {
+    close(fds[1]);
+    // Now wait forever for the parent.
+    char b;
+    HANDLE_EINTR(read(fds[0], &b, sizeof(b)));
+    close(fds[0]);
+    syscall(__NR_exit);
+  }
+  close(fds[0]);
+
+  LinuxPtraceDumper dumper(child);
+  ASSERT_TRUE(dumper.Init());
+  const wasteful_vector<MappingInfo*> mappings = dumper.mappings();
+  bool found_exe = false;
+  unsigned i;
+  for (i = 0; i < mappings.size(); ++i) {
+    const MappingInfo* mapping = mappings[i];
+    if (!strcmp(mapping->name, exe_name)) {
+      found_exe = true;
+      break;
+    }
+  }
+  ASSERT_TRUE(found_exe);
+
+  uint8_t identifier1[sizeof(MDGUID)];
+  uint8_t identifier2[sizeof(MDGUID)];
+  EXPECT_TRUE(dumper.ElfFileIdentifierForMapping(*mappings[i], true, i,
+                                                 identifier1));
+  FileID fileid(exe_name);
+  EXPECT_TRUE(fileid.ElfFileIdentifier(identifier2));
+  char identifier_string1[37];
+  char identifier_string2[37];
+  FileID::ConvertIdentifierToString(identifier1, identifier_string1,
+                                    37);
+  FileID::ConvertIdentifierToString(identifier2, identifier_string2,
+                                    37);
+  EXPECT_STREQ(identifier_string1, identifier_string2);
+  close(fds[1]);
+}