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src/shm.hh

    00001 /* shm.hh - shared memory
    00002  * Copyright 2007 Bas Wijnen <wijnen@debian.org>
    00003  *
    00004  * This program is free software: you can redistribute it and/or modify
    00005  * it under the terms of the GNU General Public License as published by
    00006  * the Free Software Foundation, either version 3 of the License, or
    00007  * (at your option) any later version.
    00008  *
    00009  * This program is distributed in the hope that it will be useful,
    00010  * but WITHOUT ANY WARRANTY; without even the implied warranty of
    00011  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00012  * GNU General Public License for more details.
    00013  *
    00014  * You should have received a copy of the GNU General Public License
    00015  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    00016  */
    00017
    00018 #ifndef SHEVEK_SHM_HH
    00019 #define SHEVEK_SHM_HH
    00020
    00021 #include "refbase.hh"
    00022 #include "error.hh"
    00023 #include <string>
    00024 #include <typeinfo>
    00025 #include <sys/mman.h>
    00026 #include <sys/stat.h>
    00027 #include <fcntl.h>
    00028 #include <unistd.h>
    00029
    00030 namespace shevek
    00031 {
    00033         template <typename T> class shm : public refbase
    00034         {
    00035                 shm (std::string const &name, bool l_create, bool writable, bool keep);
    00036                 ~shm ();
    00037                 T *m_data;
    00038                 std::string m_name;
    00039                 int m_fd;
    00040                 bool m_destroy;
    00041         public:
    00043
    00045                 static Glib::RefPtr <shm <T> > create (std::string const &name, bool keep = false) { return Glib::RefPtr <shm <T> > (new shm (name, true, true, keep)); }
    00047                 static Glib::RefPtr <shm <T> > open (std::string const &name, bool writable = true) { return Glib::RefPtr <shm <T> > (new shm (name, false, writable, true)); }
    00049                 T *data () { return m_data; }
    00051                 T const *data () const { return m_data; }
    00052         };
    00053
    00054         template <typename T> shm <T>::shm (std::string const &name, bool l_create, bool writable, bool keep)
    00055         {
    00056                 m_destroy = !keep;
    00057                 m_name = std::string ("/") + typeid (T).name () + '-' + name;
    00058                 m_fd = shm_open (m_name.c_str (), l_create ? O_CREAT | O_EXCL | O_RDWR : writable ? O_RDWR : O_RDONLY, 0666);
    00059                 if (m_fd < 0)
    00060                 {
    00061                         shevek_error_errno ("unable to open shared memory file " + m_name);
    00062                         throw "unable to open shared memory file";
    00063                 }
    00064                 if (l_create && ftruncate (m_fd, sizeof (T)) < 0)
    00065                 {
    00066                         shevek_error_errno ("unable to set size of shared memory file " + m_name);
    00067                         throw "unable to set size of shared memory file";
    00068                 }
    00069                 m_data = reinterpret_cast <T *> (mmap (NULL, sizeof (T), writable ? PROT_READ | PROT_WRITE : PROT_READ, MAP_SHARED, m_fd, 0));
    00070                 if (!m_data)
    00071                 {
    00072                         shevek_error_errno ("unable to map shared memory file " + m_name);
    00073                         throw "unable to map shared memory";
    00074                 }
    00075         }
    00076
    00077         template <typename T> shm <T>::~shm ()
    00078         {
    00079                 close (m_fd);
    00080                 munmap (m_data, sizeof (T));
    00081                 if (m_destroy)
    00082                         shm_unlink (m_name.c_str ());
    00083         }
    00084 }
    00085
    00086 #endif