llvm-project/lldb/source/Host/posix/LockFilePosix.cpp

//===-- LockFilePosix.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/posix/LockFilePosix.h"

#include <fcntl.h>

using namespace lldb;
using namespace lldb_private;

namespace
{

Error fileLock (int fd, int cmd, int lock_type, const uint64_t start, const uint64_t len)
{
    struct flock fl;

    fl.l_type   = lock_type;
    fl.l_whence = SEEK_SET;
    fl.l_start  = start;
    fl.l_len    = len;
    fl.l_pid    = ::getpid ();

    Error error;
    if (::fcntl (fd, cmd, &fl) == -1)
        error.SetErrorToErrno ();

    return error;
}

}  // namespace

LockFilePosix::LockFilePosix (int fd)
    : LockFileBase (fd)
{
}

LockFilePosix::~LockFilePosix ()
{
    Unlock ();
}

Error
LockFilePosix::DoWriteLock (const uint64_t start, const uint64_t len)
{
    return fileLock (m_fd, F_SETLKW, F_WRLCK, start, len);
}

Error
LockFilePosix::DoTryWriteLock (const uint64_t start, const uint64_t len)
{
    return fileLock (m_fd, F_SETLK, F_WRLCK, start, len);
}

Error
LockFilePosix::DoReadLock (const uint64_t start, const uint64_t len)
{
    return fileLock (m_fd, F_SETLKW, F_RDLCK, start, len);
}

Error
LockFilePosix::DoTryReadLock (const uint64_t start, const uint64_t len)
{
    return fileLock (m_fd, F_SETLK, F_RDLCK, start, len);
}

Error
LockFilePosix::DoUnlock ()
{
    return fileLock (m_fd, F_SETLK, F_UNLCK, m_start, m_len);
}