kea/src/lib/util/tests/interprocess_sync_file_unittest.cc

// Copyright (C) 2012  Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

#include "util/interprocess_sync_file.h"
#include <gtest/gtest.h>

using namespace std;

namespace isc {
namespace util {

namespace {
unsigned char
parentReadLockedState (int fd) {
  unsigned char locked = 0xff;

  fd_set rfds;
  FD_ZERO(&rfds);
  FD_SET(fd, &rfds);

  // We use select() here to wait for new data on the input end of
  // the pipe. We wait for 5 seconds (an arbitrary value) for input
  // data, and continue if no data is available. This is done so
  // that read() is not blocked due to some issue in the child
  // process (and the tests continue running).

  struct timeval tv;
  tv.tv_sec = 5;
  tv.tv_usec = 0;

  const int nfds = select(fd + 1, &rfds, NULL, NULL, &tv);
  EXPECT_EQ(1, nfds);

  if (nfds == 1) {
      // Read status
      read(fd, &locked, sizeof(locked));
  }

  return (locked);
}

TEST(InterprocessSyncFileTest, TestLock) {
  InterprocessSyncFile sync("test");
  InterprocessSyncLocker locker(sync);

  EXPECT_TRUE(locker.lock());

  int fds[2];

  // Here, we check that a lock has been taken by forking and
  // checking from the child that a lock exists. This has to be
  // done from a separate process as we test by trying to lock the
  // range again on the lock file. The lock attempt would pass if
  // done from the same process for the granted range. The lock
  // attempt must fail to pass our check.

  pipe(fds);

  if (fork() == 0) {
      unsigned char locked = 0;
      // Child writes to pipe
      close(fds[0]);

      InterprocessSyncFile sync2("test");
      InterprocessSyncLocker locker2(sync2);

      if (!locker2.tryLock()) {
          locked = 1;
      }

      write(fds[1], &locked, sizeof(locked));
      close(fds[1]);
      exit(0);
  } else {
      // Parent reads from pipe
      close(fds[1]);

      const unsigned char locked = parentReadLockedState(fds[0]);

      close(fds[0]);

      EXPECT_EQ(1, locked);
  }

  EXPECT_TRUE(locker.unlock());
}

TEST(InterprocessSyncFileTest, TestMultipleFilesDirect) {
  InterprocessSyncFile sync("test1");
  InterprocessSyncLocker locker(sync);

  EXPECT_TRUE(locker.lock());

  InterprocessSyncFile sync2("test2");
  InterprocessSyncLocker locker2(sync2);
  EXPECT_TRUE(locker2.lock());
  EXPECT_TRUE(locker2.unlock());

  EXPECT_TRUE(locker.unlock());
}

TEST(InterprocessSyncFileTest, TestMultipleFilesForked) {
  InterprocessSyncFile sync("test");
  InterprocessSyncLocker locker(sync);

  EXPECT_TRUE(locker.lock());

  int fds[2];

  pipe(fds);

  if (fork() == 0) {
      unsigned char locked = 0xff;
      // Child writes to pipe
      close(fds[0]);

      InterprocessSyncFile sync2("test2");
      InterprocessSyncLocker locker2(sync2);

      if (locker2.tryLock()) {
          locked = 0;
      }

      write(fds[1], &locked, sizeof(locked));
      close(fds[1]);
      exit(0);
  } else {
      // Parent reads from pipe
      close(fds[1]);

      const unsigned char locked = parentReadLockedState(fds[0]);

      close(fds[0]);

      EXPECT_EQ(0, locked);
  }

  EXPECT_TRUE(locker.unlock());
}
}

} // namespace util
} // namespace isc