third_party/llvm-project/lldb/source/Host/common/LockFileBase.cpp

//===-- LockFileBase.cpp ----------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "lldb/Host/LockFileBase.h"

using namespace lldb;
using namespace lldb_private;

namespace {

Status AlreadyLocked() { return Status("Already locked"); }

Status NotLocked() { return Status("Not locked"); }
}

LockFileBase::LockFileBase(int fd)
    : m_fd(fd), m_locked(false), m_start(0), m_len(0) {}

bool LockFileBase::IsLocked() const { return m_locked; }

Status LockFileBase::WriteLock(const uint64_t start, const uint64_t len) {
  return DoLock([&](const uint64_t start,
                    const uint64_t len) { return DoWriteLock(start, len); },
                start, len);
}

Status LockFileBase::TryWriteLock(const uint64_t start, const uint64_t len) {
  return DoLock([&](const uint64_t start,
                    const uint64_t len) { return DoTryWriteLock(start, len); },
                start, len);
}

Status LockFileBase::ReadLock(const uint64_t start, const uint64_t len) {
  return DoLock([&](const uint64_t start,
                    const uint64_t len) { return DoReadLock(start, len); },
                start, len);
}

Status LockFileBase::TryReadLock(const uint64_t start, const uint64_t len) {
  return DoLock([&](const uint64_t start,
                    const uint64_t len) { return DoTryReadLock(start, len); },
                start, len);
}

Status LockFileBase::Unlock() {
  if (!IsLocked())
    return NotLocked();

  const auto error = DoUnlock();
  if (error.Success()) {
    m_locked = false;
    m_start = 0;
    m_len = 0;
  }
  return error;
}

bool LockFileBase::IsValidFile() const { return m_fd != -1; }

Status LockFileBase::DoLock(const Locker &locker, const uint64_t start,
                            const uint64_t len) {
  if (!IsValidFile())
    return Status("File is invalid");

  if (IsLocked())
    return AlreadyLocked();

  const auto error = locker(start, len);
  if (error.Success()) {
    m_locked = true;
    m_start = start;
    m_len = len;
  }

  return error;
}