lldb/source/Host/common/LockFileBase.cpp

   1 //===-- LockFileBase.cpp --------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "lldb/Host/LockFileBase.h"
  10
  11 using namespace lldb;
  12 using namespace lldb_private;
  13
  14 static Status AlreadyLocked() { return Status("Already locked"); }
  15
  16 static Status NotLocked() { return Status("Not locked"); }
  17
  18 LockFileBase::LockFileBase(int fd)
  19     : m_fd(fd), m_locked(false), m_start(0), m_len(0) {}
  20
  21 bool LockFileBase::IsLocked() const { return m_locked; }
  22
  23 Status LockFileBase::WriteLock(const uint64_t start, const uint64_t len) {
  24   return DoLock([&](const uint64_t start,
  25                     const uint64_t len) { return DoWriteLock(start, len); },
  26                 start, len);
  27 }
  28
  29 Status LockFileBase::TryWriteLock(const uint64_t start, const uint64_t len) {
  30   return DoLock([&](const uint64_t start,
  31                     const uint64_t len) { return DoTryWriteLock(start, len); },
  32                 start, len);
  33 }
  34
  35 Status LockFileBase::ReadLock(const uint64_t start, const uint64_t len) {
  36   return DoLock([&](const uint64_t start,
  37                     const uint64_t len) { return DoReadLock(start, len); },
  38                 start, len);
  39 }
  40
  41 Status LockFileBase::TryReadLock(const uint64_t start, const uint64_t len) {
  42   return DoLock([&](const uint64_t start,
  43                     const uint64_t len) { return DoTryReadLock(start, len); },
  44                 start, len);
  45 }
  46
  47 Status LockFileBase::Unlock() {
  48   if (!IsLocked())
  49     return NotLocked();
  50
  51   const auto error = DoUnlock();
  52   if (error.Success()) {
  53     m_locked = false;
  54     m_start = 0;
  55     m_len = 0;
  56   }
  57   return error;
  58 }
  59
  60 bool LockFileBase::IsValidFile() const { return m_fd != -1; }
  61
  62 Status LockFileBase::DoLock(const Locker &locker, const uint64_t start,
  63                             const uint64_t len) {
  64   if (!IsValidFile())
  65     return Status("File is invalid");
  66
  67   if (IsLocked())
  68     return AlreadyLocked();
  69
  70   const auto error = locker(start, len);
  71   if (error.Success()) {
  72     m_locked = true;
  73     m_start = start;
  74     m_len = len;
  75   }
  76
  77   return error;
  78 }