Source/cmFileLockUnix.cxx

   1 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
   2    file Copyright.txt or https://cmake.org/licensing for details.  */
   3 #include <cerrno> // errno
   4 #include <cstdio> // SEEK_SET
   5
   6 #include <fcntl.h>
   7 #include <unistd.h>
   8
   9 #include "cmFileLock.h"
  10 #include "cmSystemTools.h"
  11
  12 cmFileLock::cmFileLock() = default;
  13
  14 cmFileLockResult cmFileLock::Release()
  15 {
  16   if (this->Filename.empty()) {
  17     return cmFileLockResult::MakeOk();
  18   }
  19   const int lockResult = this->LockFile(F_SETLK, F_UNLCK);
  20
  21   this->Filename = "";
  22
  23   ::close(this->File);
  24   this->File = -1;
  25
  26   if (lockResult == 0) {
  27     return cmFileLockResult::MakeOk();
  28   }
  29   return cmFileLockResult::MakeSystem();
  30 }
  31
  32 cmFileLockResult cmFileLock::OpenFile()
  33 {
  34   this->File = ::open(this->Filename.c_str(), O_RDWR);
  35   if (this->File == -1) {
  36     return cmFileLockResult::MakeSystem();
  37   }
  38   return cmFileLockResult::MakeOk();
  39 }
  40
  41 cmFileLockResult cmFileLock::LockWithoutTimeout()
  42 {
  43   if (this->LockFile(F_SETLKW, F_WRLCK) == -1) {
  44     return cmFileLockResult::MakeSystem();
  45   }
  46   return cmFileLockResult::MakeOk();
  47 }
  48
  49 cmFileLockResult cmFileLock::LockWithTimeout(unsigned long seconds)
  50 {
  51   while (true) {
  52     if (this->LockFile(F_SETLK, F_WRLCK) == -1) {
  53       if (errno != EACCES && errno != EAGAIN) {
  54         return cmFileLockResult::MakeSystem();
  55       }
  56     } else {
  57       return cmFileLockResult::MakeOk();
  58     }
  59     if (seconds == 0) {
  60       return cmFileLockResult::MakeTimeout();
  61     }
  62     --seconds;
  63     cmSystemTools::Delay(1000);
  64   }
  65 }
  66
  67 int cmFileLock::LockFile(int cmd, int type) const
  68 {
  69   struct ::flock lock;
  70   lock.l_start = 0;
  71   lock.l_len = 0;                         // lock all bytes
  72   lock.l_pid = 0;                         // unused (for F_GETLK only)
  73   lock.l_type = static_cast<short>(type); // exclusive lock
  74   lock.l_whence = SEEK_SET;
  75   return ::fcntl(this->File, cmd, &lock);
  76 }