libchromeos: add process control library, syslog logging capability, and run unit tests

chromeos/process.cc

+// Copyright (c) 2011 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 <chromeos/process.h>
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+
+#include <base/eintr_wrapper.h>
+#include <base/file_util.h>
+#include <base/logging.h>
+#include <base/string_number_conversions.h>
+#include <base/string_util.h>
+#include <base/time.h>
+
+namespace chromeos {
+
+Process::Process() {
+}
+
+Process::~Process() {
+}
+
+bool Process::ProcessExists(pid_t pid) {
+  return file_util::DirectoryExists(FilePath(StringPrintf("/proc/%d", pid)));
+}
+
+ProcessImpl::ProcessImpl() : pid_(0) {
+}
+
+ProcessImpl::~ProcessImpl() {
+  Reset(0);
+}
+
+void ProcessImpl::AddArg(const std::string& arg) {
+  arguments_.push_back(arg);
+}
+
+void ProcessImpl::RedirectOutput(const std::string& output_file) {
+  output_file_ = output_file;
+}
+
+bool ProcessImpl::Start() {
+  // Copy off a writeable version of arguments.  Exec wants to be able
+  // to write both the array and the strings.
+  int total_args_size = 0;
+
+  for (size_t i = 0; i < arguments_.size(); ++i) {
+    total_args_size += arguments_[i].size() + 1;
+  }
+
+  scoped_array<char> buffer(new char[total_args_size]);
+  scoped_array<char*> argv(new char*[arguments_.size() + 1]);
+
+  char* buffer_pointer = &buffer[0];
+  for (size_t i = 0; i < arguments_.size(); ++i) {
+    argv[i] = buffer_pointer;
+    strcpy(buffer_pointer, arguments_[i].c_str());
+    buffer_pointer += arguments_[i].size();

[petkov, 2011/02/28 08:00:14]

+ 1 here and remove ++buffer_pointer below?

[kmixter1, 2011/03/02 01:38:07]

Done.

+    ++buffer_pointer;
+  }
+  argv[arguments_.size()] = NULL;
+
+  pid_ = fork();
+  int saved_errno = errno;
+  if (pid_ < 0) {
+    LOG(ERROR) << "Fork failed: " << saved_errno;
+    return false;
+  }
+
+  if (pid_ == 0) {
+    if (!output_file_.empty()) {
+      int output_handle = HANDLE_EINTR(
+          open(output_file_.c_str(),
+               O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0666));
+      int saved_errno = errno;
+      if (output_handle < 0) {
+        LOG(ERROR) << "Could not create " << output_file_
+                   << ": " << saved_errno;
+        // Avoid exit() to avoid atexit handlers from parent.
+        _exit(127);
+      }
+      dup2(output_handle, 1);
+      dup2(output_handle, 2);
+      close(output_handle);
+    }
+    execv(argv[0], &argv[0]);
+    saved_errno = errno;
+    LOG(ERROR) << "Exec of " << argv[0] << " failed: " << saved_errno;
+    _exit(127);
+  }
+  return true;
+}
+
+int ProcessImpl::Wait() {
+  int status = 0;
+  if (pid_ == 0) {
+    LOG(ERROR) << "Process not running";
+    return -1;
+  }
+  if (HANDLE_EINTR(waitpid(pid_, &status, 0)) < 0) {
+    int saved_errno = errno;
+    LOG(ERROR) << "Problem waiting for pid " << pid_ << ": " << saved_errno;
+    return -1;
+  }
+  pid_t old_pid = pid_;
+  pid_ = 0;
+  if (!WIFEXITED(status)) {
+    LOG(ERROR) << "Process " << old_pid << " did not exit normally: "
+               << status;
+    return -1;
+  }
+  return WEXITSTATUS(status);
+}
+
+bool ProcessImpl::HandleSigChild(pid_t pid, int status) {
+  if (pid_ == 0 || pid != pid_) return false;
+  pid_ = 0;

[petkov, 2011/02/28 08:00:14]

So is this ReleaseIfSamePID?

[kmixter1, 2011/03/02 01:38:07]

Conceptually it is.  It's also what you do to clean up a child process during
sigchild or a wait-based event loop.  It's also a partially formed idea.  I've
removed it.

+  return true;
+}
+
+int ProcessImpl::Run() {
+  if (!Start()) {
+    return -1;
+  }
+  return Wait();
+}
+
+pid_t ProcessImpl::GetPid() {
+  return pid_;
+}
+
+bool ProcessImpl::Kill(int signal, int timeout) {
+  if (pid_ == 0) {
+    // Passing pid == 0 to kill is committing suicide.  Check specifically.
+    LOG(ERROR) << "Process not running";
+    return false;
+  }
+  if (kill(pid_, signal) < 0) {
+    int saved_errno = errno;
+    LOG(ERROR) << "Unable to send signal to " << pid_ << " error "
+               << saved_errno;
+    return false;
+  }
+  base::TimeTicks start_signal = base::TimeTicks::Now();
+  do {
+    int status = 0;
+    pid_t w = waitpid(pid_, &status, WNOHANG);
+    int saved_errno = errno;
+    if (w < 0) {
+      if (saved_errno == ECHILD)
+        return true;
+      LOG(ERROR) << "Waitpid returned " << w << ", errno " << saved_errno;
+      return false;
+    }
+    if (w > 0) {
+      pid_ = 0;
+      return true;
+    }
+    usleep(100);
+  } while ((base::TimeTicks::Now() - start_signal).InSecondsF() <= timeout);
+  LOG(INFO) << "process " << pid_ << " did not exit from signal " << signal
+            << " in " << timeout << " seconds";
+  return false;
+}
+
+void ProcessImpl::Reset(pid_t pid) {
+  arguments_.clear();
+  if (pid_)
+    Kill(SIGKILL, 0);
+  pid_ = pid;
+}
+
+bool ProcessImpl::ResetPidByFile(const std::string& pid_file) {
+  std::string contents;
+  if (!file_util::ReadFileToString(FilePath(pid_file), &contents)) {
+    LOG(ERROR) << "Could not read pid file" << pid_file;
+    return false;
+  }
+  TrimWhitespaceASCII(contents, TRIM_TRAILING, &contents);
+  int64 pid_int64 = 0;
+  if (!base::StringToInt64(contents, &pid_int64)) {
+    LOG(ERROR) << "Unexpected pid file contents";
+    return false;
+  }
+  Reset(pid_int64);
+  return true;
+}
+
+pid_t ProcessImpl::Release() {
+  pid_t old_pid = pid_;
+  pid_ = 0;
+  return old_pid;
+}
+
+}  // namespace chromeos