Collect and send kernel crash diagnostics

kernel_collector.cc

+// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "crash-reporter/kernel_collector.h"
+
+#include "base/file_util.h"
+#include "base/logging.h"
+#include "base/string_util.h"
+#include "crash-reporter/system_logging.h"
+
+static const char kKernelExecName[] = "kernel";
+static const char kPreservedDumpPath[] = "/sys/kernel/debug/preserved/kcrash";
+const pid_t kKernelPid = 0;
+const uid_t kRootUid = 0;
+
+const char KernelCollector::kClearingSequence[] = " ";
+
+KernelCollector::KernelCollector()
+    : is_enabled_(false),
+      preserved_dump_path_(kPreservedDumpPath) {
+}
+
+KernelCollector::~KernelCollector() {
+}
+
+void KernelCollector::OverridePreservedDumpPath(const FilePath &file_path) {
+  preserved_dump_path_ = file_path;
+}
+
+bool KernelCollector::LoadPreservedDump(std::string *contents) {
+  // clear contents since ReadFileToString actually appends to the string.
+  contents->clear();
+  if (!file_util::ReadFileToString(preserved_dump_path_, contents)) {
+    logger_->LogError("Unable to read %s",
+                      preserved_dump_path_.value().c_str());
+    return false;
+  }
+  return true;
+}
+
+bool KernelCollector::Enable() {
+  if (!file_util::PathExists(preserved_dump_path_)) {
+    logger_->LogWarning("Kernel does not support crash dumping");
+    return false;
+  }
+
+  // To enable crashes, we will eventually need to set
+  // the chnv bit in BIOS, but it does not yet work.
+  logger_->LogInfo("Enabling kernel crash handling");
+  is_enabled_ = true;
+  return true;
+}
+
+bool KernelCollector::ClearPreservedDump() {
+  // It is necessary to write at least one byte to the kcrash file for
+  // the log to actually be cleared.
+  if (file_util::WriteFile(
+          preserved_dump_path_,
+          kClearingSequence,
+          strlen(kClearingSequence)) != strlen(kClearingSequence)) {
+    logger_->LogError("Failed to clear kernel crash dump");
+    return false;
+  }
+  logger_->LogInfo("Cleared kernel crash diagnostics");
+  return true;
+}
+
+FilePath KernelCollector::GetKernelCrashPath(
+    const FilePath &root_crash_path,
+    time_t timestamp) {
+  std::string dump_basename =
+      FormatDumpBasename(kKernelExecName,
+                         timestamp,
+                         kKernelPid);
+  return root_crash_path.Append(
+      StringPrintf("%s.kcrash", dump_basename.c_str()));
+}
+
+bool KernelCollector::Collect() {
+  std::string kernel_dump;
+  FilePath root_crash_directory;
+  if (!LoadPreservedDump(&kernel_dump)) {
+    return false;
+  }
+  if (kernel_dump.empty()) {
+    return false;
+  }
+  if (is_feedback_allowed_function_()) {
+    count_crash_function_();
+
+    if (!GetCreatedCrashDirectoryByEuid(kRootUid,
+                                        &root_crash_directory)) {
+      return true;
+    }
+
+    FilePath kernel_crash_path = GetKernelCrashPath(root_crash_directory,
+                                                    time(NULL));
+    if (file_util::WriteFile(kernel_crash_path,
+                             kernel_dump.data(),
+                             kernel_dump.length()) !=
+        static_cast<int>(kernel_dump.length())) {
+      logger_->LogInfo("Failed to write kernel dump to %s",
+                       kernel_crash_path.value().c_str());
+      return true;
+    }
+
+    logger_->LogInfo("Collected kernel crash diagnostics into %s",
+                     kernel_crash_path.value().c_str());
+  } else {
+    logger_->LogInfo("Crash not saved since metrics disabled");
+  }
+  if (!ClearPreservedDump()) {
+    return false;
+  }
+
+  return true;
+}