1  // Copyright (c) 2017-present The Bitcoin Core developers
  2  // Distributed under the MIT software license, see the accompanying
  3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  4  
  5  #include <util/fs.h>
  6  #include <util/syserror.h>
  7  
  8  #ifndef WIN32
  9  #include <cstring>
 10  #include <fcntl.h>
 11  #include <sys/file.h>
 12  #include <sys/utsname.h>
 13  #include <unistd.h>
 14  #else
 15  #include <limits>
 16  #include <windows.h>
 17  #endif
 18  
 19  #include <cassert>
 20  #include <cerrno>
 21  #include <string>
 22  
 23  namespace fsbridge {
 24  
 25  FILE *fopen(const fs::path& p, const char *mode)
 26  {
 27  #ifndef WIN32
 28      return ::fopen(p.c_str(), mode);
 29  #else
 30      return ::fopen(p.utf8string().c_str(), mode);
 31  #endif
 32  }
 33  
 34  fs::path AbsPathJoin(const fs::path& base, const fs::path& path)
 35  {
 36      assert(base.is_absolute());
 37      return path.empty() ? base : fs::path(base / path);
 38  }
 39  
 40  #ifndef WIN32
 41  
 42  static std::string GetErrorReason()
 43  {
 44      return SysErrorString(errno);
 45  }
 46  
 47  FileLock::FileLock(const fs::path& file)
 48  {
 49      fd = open(file.c_str(), O_RDWR);
 50      if (fd == -1) {
 51          reason = GetErrorReason();
 52      }
 53  }
 54  
 55  FileLock::~FileLock()
 56  {
 57      if (fd != -1) {
 58          close(fd);
 59      }
 60  }
 61  
 62  bool FileLock::TryLock()
 63  {
 64      if (fd == -1) {
 65          return false;
 66      }
 67  
 68      struct flock lock;
 69      lock.l_type = F_WRLCK;
 70      lock.l_whence = SEEK_SET;
 71      lock.l_start = 0;
 72      lock.l_len = 0;
 73      if (fcntl(fd, F_SETLK, &lock) == -1) {
 74          reason = GetErrorReason();
 75          return false;
 76      }
 77  
 78      return true;
 79  }
 80  #else
 81  
 82  static std::string GetErrorReason() {
 83      return Win32ErrorString(GetLastError());
 84  }
 85  
 86  FileLock::FileLock(const fs::path& file)
 87  {
 88      hFile = CreateFileW(file.wstring().c_str(),  GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
 89          nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
 90      if (hFile == INVALID_HANDLE_VALUE) {
 91          reason = GetErrorReason();
 92      }
 93  }
 94  
 95  FileLock::~FileLock()
 96  {
 97      if (hFile != INVALID_HANDLE_VALUE) {
 98          CloseHandle(hFile);
 99      }
100  }
101  
102  bool FileLock::TryLock()
103  {
104      if (hFile == INVALID_HANDLE_VALUE) {
105          return false;
106      }
107      _OVERLAPPED overlapped = {};
108      if (!LockFileEx(hFile, LOCKFILE_EXCLUSIVE_LOCK | LOCKFILE_FAIL_IMMEDIATELY, 0, std::numeric_limits<DWORD>::max(), std::numeric_limits<DWORD>::max(), &overlapped)) {
109          reason = GetErrorReason();
110          return false;
111      }
112      return true;
113  }
114  #endif
115  
116  } // namespace fsbridge