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, 234 insertions, 0 deletions

diff --git a/src/client/linux/minidump_writer/linux_core_dumper.cc b/src/client/linux/minidump_writer/linux_core_dumper.cc
new file mode 100644
index 00000000..3e8c92fe
--- /dev/null
+++ b/src/client/linux/minidump_writer/linux_core_dumper.cc
@@ -0,0 +1,234 @@
+// Copyright (c) 2012, 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_core_dumper.cc: Implement google_breakpad::LinuxCoreDumper.
+// See linux_core_dumper.h for details.
+
+#include "client/linux/minidump_writer/linux_core_dumper.h"
+
+#include <asm/ptrace.h>
+#include <assert.h>
+#include <elf.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/procfs.h>
+
+#include "common/linux/linux_libc_support.h"
+
+namespace google_breakpad {
+
+LinuxCoreDumper::LinuxCoreDumper(pid_t pid,
+                                 const char* core_path,
+                                 const char* procfs_path)
+    : LinuxDumper(pid),
+      core_path_(core_path),
+      procfs_path_(procfs_path),
+      thread_infos_(&allocator_, 8) {
+  assert(core_path_);
+}
+
+bool LinuxCoreDumper::BuildProcPath(char* path, pid_t pid,
+                                    const char* node) const {
+  if (!path || !node)
+    return false;
+
+  size_t node_len = my_strlen(node);
+  if (node_len == 0)
+    return false;
+
+  size_t procfs_path_len = my_strlen(procfs_path_);
+  size_t total_length = procfs_path_len + 1 + node_len;
+  if (total_length >= NAME_MAX)
+    return false;
+
+  memcpy(path, procfs_path_, procfs_path_len);
+  path[procfs_path_len] = '/';
+  memcpy(path + procfs_path_len + 1, node, node_len);
+  path[total_length] = '\0';
+  return true;
+}
+
+void LinuxCoreDumper::CopyFromProcess(void* dest, pid_t child,
+                                      const void* src, size_t length) {
+  ElfCoreDump::Addr virtual_address = reinterpret_cast<ElfCoreDump::Addr>(src);
+  // TODO(benchan): Investigate whether the data to be copied could span
+  // across multiple segments in the core dump file. ElfCoreDump::CopyData
+  // and this method do not handle that case yet.
+  if (!core_.CopyData(dest, virtual_address, length)) {
+    // If the data segment is not found in the core dump, fill the result
+    // with marker characters.
+    memset(dest, 0xab, length);
+  }
+}
+
+bool LinuxCoreDumper::GetThreadInfoByIndex(size_t index, ThreadInfo* info) {
+  if (index >= thread_infos_.size())
+    return false;
+
+  *info = thread_infos_[index];
+  const uint8_t* stack_pointer;
+#if defined(__i386)
+  memcpy(&stack_pointer, &info->regs.esp, sizeof(info->regs.esp));
+#elif defined(__x86_64)
+  memcpy(&stack_pointer, &info->regs.rsp, sizeof(info->regs.rsp));
+#elif defined(__ARM_EABI__)
+  memcpy(&stack_pointer, &info->regs.ARM_sp, sizeof(info->regs.ARM_sp));
+#else
+#error "This code hasn't been ported to your platform yet."
+#endif
+
+  return GetStackInfo(&info->stack, &info->stack_len,
+                      reinterpret_cast<uintptr_t>(stack_pointer));
+}
+
+bool LinuxCoreDumper::IsPostMortem() const {
+  return true;
+}
+
+bool LinuxCoreDumper::ThreadsSuspend() {
+  return true;
+}
+
+bool LinuxCoreDumper::ThreadsResume() {
+  return true;
+}
+
+bool LinuxCoreDumper::EnumerateThreads() {
+  if (!mapped_core_file_.Map(core_path_)) {
+    fprintf(stderr, "Could not map core dump file into memory\n");
+    return false;
+  }
+
+  core_.SetContent(mapped_core_file_.content());
+  if (!core_.IsValid()) {
+    fprintf(stderr, "Invalid core dump file\n");
+    return false;
+  }
+
+  ElfCoreDump::Note note = core_.GetFirstNote();
+  if (!note.IsValid()) {
+    fprintf(stderr, "PT_NOTE section not found\n");
+    return false;
+  }
+
+  bool first_thread = true;
+  do {
+    ElfCoreDump::Word type = note.GetType();
+    MemoryRange name = note.GetName();
+    MemoryRange description = note.GetDescription();
+
+    if (type == 0 || name.IsEmpty() || description.IsEmpty()) {
+      fprintf(stderr, "Could not found a valid PT_NOTE.\n");
+      return false;
+    }
+
+    // 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
+    //
+    // The following code only works if notes are ordered as expected.
+    switch (type) {
+      case NT_PRSTATUS: {
+        if (description.length() != sizeof(elf_prstatus)) {
+          fprintf(stderr, "Found NT_PRSTATUS descriptor of unexpected size\n");
+          return false;
+        }
+
+        const elf_prstatus* status =
+            reinterpret_cast<const elf_prstatus*>(description.data());
+        pid_t pid = status->pr_pid;
+        ThreadInfo info;
+        memset(&info, 0, sizeof(ThreadInfo));
+        info.tgid = status->pr_pgrp;
+        info.ppid = status->pr_ppid;
+        memcpy(&info.regs, status->pr_reg, sizeof(info.regs));
+        if (first_thread) {
+          crash_thread_ = pid;
+          crash_signal_ = status->pr_info.si_signo;
+        }
+        first_thread = false;
+        threads_.push_back(pid);
+        thread_infos_.push_back(info);
+        break;
+      }
+#if defined(__i386) || defined(__x86_64)
+      case NT_FPREGSET: {
+        if (thread_infos_.empty())
+          return false;
+
+        ThreadInfo* info = &thread_infos_.back();
+        if (description.length() != sizeof(info->fpregs)) {
+          fprintf(stderr, "Found NT_FPREGSET descriptor of unexpected size\n");
+          return false;
+        }
+
+        memcpy(&info->fpregs, description.data(), sizeof(info->fpregs));
+        break;
+      }
+#endif
+#if defined(__i386)
+      case NT_PRXFPREG: {
+        if (thread_infos_.empty())
+          return false;
+
+        ThreadInfo* info = &thread_infos_.back();
+        if (description.length() != sizeof(info->fpxregs)) {
+          fprintf(stderr, "Found NT_PRXFPREG descriptor of unexpected size\n");
+          return false;
+        }
+
+        memcpy(&info->fpxregs, description.data(), sizeof(info->fpxregs));
+        break;
+      }
+#endif
+    }
+    note = note.GetNextNote();
+  } while (note.IsValid());
+
+  return true;
+}
+
+}  // namespace google_breakpad