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() {
  15   return Status::FromErrorString("Already locked");
  16 }
  17
  18 static Status NotLocked() { return Status::FromErrorString("Not locked"); }
  19
  20 LockFileBase::LockFileBase(int fd)
  21     : m_fd(fd), m_locked(false), m_start(0), m_len(0) {}
  22
  23 bool LockFileBase::IsLocked() const { return m_locked; }
  24
  25 Status LockFileBase::WriteLock(const uint64_t start, const uint64_t len) {
  26   return DoLock([&](const uint64_t start,
  27                     const uint64_t len) { return DoWriteLock(start, len); },
  28                 start, len);
  29 }
  30
  31 Status LockFileBase::TryWriteLock(const uint64_t start, const uint64_t len) {
  32   return DoLock([&](const uint64_t start,
  33                     const uint64_t len) { return DoTryWriteLock(start, len); },
  34                 start, len);
  35 }
  36
  37 Status LockFileBase::ReadLock(const uint64_t start, const uint64_t len) {
  38   return DoLock([&](const uint64_t start,
  39                     const uint64_t len) { return DoReadLock(start, len); },
  40                 start, len);
  41 }
  42
  43 Status LockFileBase::TryReadLock(const uint64_t start, const uint64_t len) {
  44   return DoLock([&](const uint64_t start,
  45                     const uint64_t len) { return DoTryReadLock(start, len); },
  46                 start, len);
  47 }
  48
  49 Status LockFileBase::Unlock() {
  50   if (!IsLocked())
  51     return NotLocked();
  52
  53   Status error = DoUnlock();
  54   if (error.Success()) {
  55     m_locked = false;
  56     m_start = 0;
  57     m_len = 0;
  58   }
  59   return error;
  60 }
  61
  62 bool LockFileBase::IsValidFile() const { return m_fd != -1; }
  63
  64 Status LockFileBase::DoLock(const Locker &locker, const uint64_t start,
  65                             const uint64_t len) {
  66   if (!IsValidFile())
  67     return Status::FromErrorString("File is invalid");
  68
  69   if (IsLocked())
  70     return AlreadyLocked();
  71
  72   Status error = locker(start, len);
  73   if (error.Success()) {
  74     m_locked = true;
  75     m_start = start;
  76     m_len = len;
  77   }
  78
  79   return error;
  80 }