/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying

   file LICENSE.rst or https://cmake.org/licensing for details.  */

#include <cerrno> // errno

#include <cstdio> // SEEK_SET

#include <fcntl.h>

#include <unistd.h>

#include "cmFileLock.h"

#include "cmSystemTools.h"

cmFileLock::cmFileLock() = default;

cmFileLockResult cmFileLock::Release()

{

  if (this->Filename.empty()) {

    return cmFileLockResult::MakeOk();

  }

  int const lockResult = this->LockFile(F_SETLK, F_UNLCK);

  this->Filename = "";

  ::close(this->File);

  this->File = -1;

  if (lockResult == 0) {

    return cmFileLockResult::MakeOk();

  }

  return cmFileLockResult::MakeSystem();

}

cmFileLockResult cmFileLock::OpenFile()

{

  this->File = ::open(this->Filename.c_str(), O_RDWR);

  if (this->File == -1) {

    return cmFileLockResult::MakeSystem();

  }

  return cmFileLockResult::MakeOk();

}

cmFileLockResult cmFileLock::LockWithoutTimeout()

{

  if (this->LockFile(F_SETLKW, F_WRLCK) == -1) {

    return cmFileLockResult::MakeSystem();

  }

  return cmFileLockResult::MakeOk();

}

cmFileLockResult cmFileLock::LockWithTimeout(unsigned long seconds)

{

  while (true) {

    if (this->LockFile(F_SETLK, F_WRLCK) == -1) {

      if (errno != EACCES && errno != EAGAIN) {

        return cmFileLockResult::MakeSystem();

      }

    } else {

      return cmFileLockResult::MakeOk();

    }

    if (seconds == 0) {

      return cmFileLockResult::MakeTimeout();

    }

    --seconds;

    cmSystemTools::Delay(1000);

  }

}

int cmFileLock::LockFile(int cmd, int type) const

{

  struct ::flock lock;

  lock.l_start = 0;

  lock.l_len = 0;                         // lock all bytes

  lock.l_pid = 0;                         // unused (for F_GETLK only)

  lock.l_type = static_cast<short>(type); // exclusive lock

  lock.l_whence = SEEK_SET;

  return ::fcntl(this->File, cmd, &lock);

}