Adding crash utilities to chromecast/crash.

chromecast/crash/minidump_manager.cc

+// Copyright 2015 The Chromium 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 "chromecast/crash/minidump_manager.h"
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <string.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "base/logging.h"
+#include "chromecast/base/path_utils.h"
+
+namespace chromecast {
+
+namespace {
+
+const mode_t kDirMode = 0770;
+const mode_t kFileMode = 0660;
+
+}  // namespace
+
+MinidumpManager::MinidumpManager() : nonblocking_(false), lockfile_fd_(-1) {
+  dump_path_ = GetHomePathASCII("minidumps").value();
+  lockfile_path_ = dump_path_ + "/" + "lockfile";
+}
+
+MinidumpManager::~MinidumpManager() {
+  // Release the lock if held.
+  ReleaseLockFile();
+}
+
+int MinidumpManager::GetNumDumps(bool delete_all_dumps) {
+  DIR* dirp;
+  struct dirent* dptr;
+  int num_dumps = 0;
+
+  // folder does not exist
+  dirp = opendir(dump_path_.c_str());
+  if (dirp == NULL) {
+    LOG(ERROR) << "Unable to open directory " << dump_path_;
+    return 0;
+  }
+
+  while ((dptr = readdir(dirp)) != NULL) {
+    struct stat buf;
+    const std::string file_fullname = dump_path_ + "/" + dptr->d_name;
+    if (lstat(file_fullname.c_str(), &buf) == -1 || !S_ISREG(buf.st_mode)) {
+      // if we cannot lstat this file, it is probably bad, so skip
+      // if the file is not regular, skip
+      continue;
+    }
+    // 'lockfile' is not counted
+    if (lockfile_path_ != file_fullname) {
+      ++num_dumps;
+      if (delete_all_dumps) {
+        LOG(INFO) << "Removing " << dptr->d_name
+                  << "which was not in the lockfile";
+        if (remove(file_fullname.c_str()) < 0) {
+          LOG(INFO) << "remove failed. error " << strerror(errno);
+        }
+      }
+    }
+  }
+
+  closedir(dirp);
+  return num_dumps;
+}
+
+int MinidumpManager::DoWorkLocked() {
+  int success = -1;
+  if (AcquireLockFile() >= 0) {
+    success = DoWork();
+    ReleaseLockFile();
+  }
+  return success;
+}
+
+int MinidumpManager::AcquireLockFile() {
+  // make the directory for the minidumps if it does not exist
+  if (mkdir(dump_path_.c_str(), kDirMode) < 0 && errno != EEXIST) {
+    LOG(ERROR) << "mkdir for " << dump_path_.c_str()
+               << " failed. error = " << strerror(errno);
+    return -1;
+  }
+
+  lockfile_fd_ = open(lockfile_path_.c_str(), O_RDWR | O_CREAT, kFileMode);
+
+  // if opening or creating the lockfile failed, we don't want to proceed
+  // with dump writing for fear of exhausting up system resources.
+  if (lockfile_fd_ < 0) {
+    LOG(ERROR) << "open lockfile failed " << lockfile_path_;
+    return -1;
+  }
+
+  // acquire the lock on the file. Whether or not we are in non-blocking mode,
+  // flock failure means that we did not acquire it and this method should fail.
+  int operation_mode = nonblocking_ ? (LOCK_EX | LOCK_NB) : LOCK_EX;
+  if (flock(lockfile_fd_, operation_mode) < 0) {
+    ReleaseLockFile();
+    LOG(INFO) << "flock lockfile failed, error = " << strerror(errno);
+    return -1;
+  }
+
+  return 0;
+}
+
+void MinidumpManager::ReleaseLockFile() {
+  // flock is associated with the fd entry in the open fd table, so closing
+  // all fd's will release the lock. To be safe, we explicitly unlock.
+  if (lockfile_fd_ >= 0) {
+    flock(lockfile_fd_, LOCK_UN);
+    close(lockfile_fd_);
+    // We may use this object again, so we should reset this.
+    lockfile_fd_ = -1;
+  }
+}
+
+}  // namespace chromecast