summaryrefslogtreecommitdiff
path: root/boost/interprocess/sync/posix/semaphore_wrapper.hpp
blob: ca0f519b68eb6f891d15698c89703463bc1d221b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2005-2012. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/interprocess for documentation.
//
//////////////////////////////////////////////////////////////////////////////

#ifndef BOOST_INTERPROCESS_POSIX_SEMAPHORE_WRAPPER_HPP
#define BOOST_INTERPROCESS_POSIX_SEMAPHORE_WRAPPER_HPP

#ifndef BOOST_CONFIG_HPP
#  include <boost/config.hpp>
#endif
#
#if defined(BOOST_HAS_PRAGMA_ONCE)
#  pragma once
#endif

#include <boost/interprocess/detail/posix_time_types_wrk.hpp>
#include <boost/interprocess/exceptions.hpp>
#include <boost/interprocess/creation_tags.hpp>
#include <boost/interprocess/detail/os_file_functions.hpp>
#include <boost/interprocess/detail/shared_dir_helpers.hpp>
#include <boost/interprocess/permissions.hpp>

#include <fcntl.h>      //O_CREAT, O_*...
#include <unistd.h>     //close
#include <string>       //std::string
#include <semaphore.h>  //sem_* family, SEM_VALUE_MAX
#include <sys/stat.h>   //mode_t, S_IRWXG, S_IRWXO, S_IRWXU,
#include <boost/assert.hpp>

#ifdef SEM_FAILED
#define BOOST_INTERPROCESS_POSIX_SEM_FAILED (reinterpret_cast<sem_t*>(SEM_FAILED))
#else
#define BOOST_INTERPROCESS_POSIX_SEM_FAILED (reinterpret_cast<sem_t*>(-1))
#endif

#ifdef BOOST_INTERPROCESS_POSIX_TIMEOUTS
#include <boost/interprocess/sync/posix/ptime_to_timespec.hpp>
#else
#include <boost/interprocess/detail/os_thread_functions.hpp>
#include <boost/interprocess/sync/detail/locks.hpp>
#include <boost/interprocess/sync/detail/common_algorithms.hpp>
#endif

namespace boost {
namespace interprocess {
namespace ipcdetail {

#ifdef BOOST_INTERPROCESS_POSIX_NAMED_SEMAPHORES

inline bool semaphore_open
   (sem_t *&handle, create_enum_t type, const char *origname,
    unsigned int count = 0, const permissions &perm = permissions())
{
   std::string name;
   #ifndef BOOST_INTERPROCESS_FILESYSTEM_BASED_POSIX_SEMAPHORES
   add_leading_slash(origname, name);
   #else
   create_shared_dir_cleaning_old_and_get_filepath(origname, name);
   #endif

   //Create new mapping
   int oflag = 0;
   switch(type){
      case DoOpen:
      {
         //No addition
         handle = ::sem_open(name.c_str(), oflag);
      }
      break;
      case DoOpenOrCreate:
      case DoCreate:
      {
         while(1){
            oflag = (O_CREAT | O_EXCL);
            handle = ::sem_open(name.c_str(), oflag, perm.get_permissions(), count);
            if(handle != BOOST_INTERPROCESS_POSIX_SEM_FAILED){
               //We can't change semaphore permissions!
               //::fchmod(handle, perm.get_permissions());
               break;
            }
            else if(errno == EEXIST && type == DoOpenOrCreate){
               oflag = 0;
               if( (handle = ::sem_open(name.c_str(), oflag)) != BOOST_INTERPROCESS_POSIX_SEM_FAILED
                   || (errno != ENOENT) ){
                  break;
               }
            }
            else{
               break;
            }
         }
      }
      break;
      default:
      {
         error_info err(other_error);
         throw interprocess_exception(err);
      }
   }

   //Check for error
   if(handle == BOOST_INTERPROCESS_POSIX_SEM_FAILED){
      throw interprocess_exception(error_info(errno));
   }

   return true;
}

inline void semaphore_close(sem_t *handle)
{
   int ret = sem_close(handle);
   if(ret != 0){
      BOOST_ASSERT(0);
   }
}

inline bool semaphore_unlink(const char *semname)
{
   try{
      std::string sem_str;
      #ifndef BOOST_INTERPROCESS_FILESYSTEM_BASED_POSIX_SEMAPHORES
      add_leading_slash(semname, sem_str);
      #else
      shared_filepath(semname, sem_str);
      #endif
      return 0 == sem_unlink(sem_str.c_str());
   }
   catch(...){
      return false;
   }
}

#endif   //BOOST_INTERPROCESS_POSIX_NAMED_SEMAPHORES

#ifdef BOOST_INTERPROCESS_POSIX_UNNAMED_SEMAPHORES

inline void semaphore_init(sem_t *handle, unsigned int initialCount)
{
   int ret = sem_init(handle, 1, initialCount);
   //According to SUSV3 version 2003 edition, the return value of a successful
   //sem_init call is not defined, but -1 is returned on failure.
   //In the future, a successful call might be required to return 0.
   if(ret == -1){
      error_info err = system_error_code();
      throw interprocess_exception(err);
   }
}

inline void semaphore_destroy(sem_t *handle)
{
   int ret = sem_destroy(handle);
   if(ret != 0){
      BOOST_ASSERT(0);
   }
}

#endif   //BOOST_INTERPROCESS_POSIX_UNNAMED_SEMAPHORES

inline void semaphore_post(sem_t *handle)
{
   int ret = sem_post(handle);
   if(ret != 0){
      error_info err = system_error_code();
      throw interprocess_exception(err);
   }
}

inline void semaphore_wait(sem_t *handle)
{
   int ret = sem_wait(handle);
   if(ret != 0){
      error_info err = system_error_code();
      throw interprocess_exception(err);
   }
}

inline bool semaphore_try_wait(sem_t *handle)
{
   int res = sem_trywait(handle);
   if(res == 0)
      return true;
   if(system_error_code() == EAGAIN){
      return false;
   }
   error_info err = system_error_code();
   throw interprocess_exception(err);
}

#ifndef BOOST_INTERPROCESS_POSIX_TIMEOUTS

struct semaphore_wrapper_try_wrapper
{
   explicit semaphore_wrapper_try_wrapper(sem_t *handle)
      : m_handle(handle)
   {}

   void wait()
   {  semaphore_wait(m_handle);  }

   bool try_wait()
   {  return semaphore_try_wait(m_handle);  }

   private:
   sem_t *m_handle;
};

#endif

inline bool semaphore_timed_wait(sem_t *handle, const boost::posix_time::ptime &abs_time)
{
   #ifdef BOOST_INTERPROCESS_POSIX_TIMEOUTS
   //Posix does not support infinity absolute time so handle it here
   if(abs_time == boost::posix_time::pos_infin){
      semaphore_wait(handle);
      return true;
   }

   timespec tspec = ptime_to_timespec(abs_time);
   for (;;){
      int res = sem_timedwait(handle, &tspec);
      if(res == 0)
         return true;
      if (res > 0){
         //buggy glibc, copy the returned error code to errno
         errno = res;
      }
      if(system_error_code() == ETIMEDOUT){
         return false;
      }
      error_info err = system_error_code();
      throw interprocess_exception(err);
   }
   return false;
   #else //#ifdef BOOST_INTERPROCESS_POSIX_TIMEOUTS

   semaphore_wrapper_try_wrapper swtw(handle);
   ipcdetail::lock_to_wait<semaphore_wrapper_try_wrapper> lw(swtw);
   return ipcdetail::try_based_timed_lock(lw, abs_time);

   #endif   //#ifdef BOOST_INTERPROCESS_POSIX_TIMEOUTS
}

}  //namespace ipcdetail {
}  //namespace interprocess {
}  //namespace boost {

#endif   //#ifndef BOOST_INTERPROCESS_POSIX_SEMAPHORE_WRAPPER_HPP