shared_mem.cpp

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/******************************************************************************
** Copyright © 2019 by J.M.McGuiness, coder@hussar.me.uk
**
** This library is free software; you can redistribute it and/or
** modify it under the terms of the GNU Lesser General Public
** License as published by the Free Software Foundation; either
** version 2.1 of the License, or (at your option) any later version.
**
** This library is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
** Lesser General Public License for more details.
**
** You should have received a copy of the GNU Lesser General Public
** License along with this library; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
 
#include "shared_mem.hpp"
 
namespace jmmcg { namespace LIBJMMCG_VER_NAMESPACE {
 
template<class>
struct failure_code_mmap {
   static inline constexpr std::int64_t value=-1;
};
 
shared_mem::handle_t
shared_mem::open_fd(std::string const &name, oflags_type oflags, mode_type mode) noexcept(false) {
   if (name.empty()) {
      info::function fun(__LINE__, __PRETTY_FUNCTION__, typeid(open_fd), info::function::argument(_T("std::string const &name"), name));
      fun.add_args(
         info::function::argument(_T("oflags_type oflags"), oflags),
         info::function::argument(_T("mode_type mode"), mode)
      );
      throw exception_type(_T("Shared-memory segment must have a non-empty name."), std::move(fun), JMMCG_REVISION_HDR(_T(LIBJMMCG_VERSION_NUMBER)));
   } else {
      return JMMCG_SYSCALL_WRAPPER("Failed to open shared-memory segment.", _T(LIBJMMCG_VERSION_NUMBER), ::shm_open, name.c_str(), oflags, mode);
   }
}
 
void *
shared_mem::map_fd(handle_t fd, std::size_t length, protection_type prot) noexcept(false) {
   if (length<=0) {
      info::function fun(__LINE__, __PRETTY_FUNCTION__, typeid(map_fd), info::function::argument(_T("handle_t fd"), fd));
      fun.add_args(
         info::function::argument(_T("std::size_t length"), length),
         info::function::argument(_T("protection_type prot"), prot)
      );
      throw exception_type(_T("Shared-memory segment must have a length greater than zero."), std::move(fun), JMMCG_REVISION_HDR(_T(LIBJMMCG_VERSION_NUMBER)));
   } else {
      assert(fd>0);
      void * const addr=JMMCG_SYSCALL_WRAPPER_FC(failure_code_mmap, "Failed to map the shared-memory segment.", _T(LIBJMMCG_VERSION_NUMBER), ::mmap, nullptr, length, prot, MAP_SHARED_VALIDATE|MAP_LOCKED, fd, 0);
      assert(addr);
      return addr;
   }
}
 
shared_mem::shared_mem(std::string const &name, std::size_t length, oflags_type oflags, mode_type mode, protection_type prot) noexcept(false)
: name_(name), length_(length), fd(open_fd(name_, oflags, mode)), addr_(map_fd(fd, length, prot)) {
   JMMCG_SYSCALL_WRAPPER("Failed to resize the shared-memory segment to the requested size.", _T(LIBJMMCG_VERSION_NUMBER), ::ftruncate, fd, length_);
}
 
shared_mem::~shared_mem() noexcept(true) {
   try {
      JMMCG_SYSCALL_WRAPPER("Failed to unmap region.", _T(LIBJMMCG_VERSION_NUMBER), ::munmap, addr_, length_);
   } catch (std::exception const &ex) {
      JMMCG_TRACE(ex.what());
   }
   try {
      JMMCG_SYSCALL_WRAPPER("Failed unlink the named region.", _T(LIBJMMCG_VERSION_NUMBER), ::shm_unlink, name_.c_str());
   } catch (std::exception const &ex) {
// TODO: This seems to fail sometimes, so just ignore it...    JMMCG_TRACE(ex.what());
   }
}
 
void
shared_mem::sync(void *addr, std::size_t length, sync_flags_t sync_flags) noexcept(false) {
   if (length>length_) {
      info::function fun(__LINE__, __PRETTY_FUNCTION__, typeid(this), info::function::argument(_T("void *addr"), addr));
      fun.add_args(
         info::function::argument(_T("std::size_t length"), length),
         info::function::argument(_T("sync_flags_t sync_flags"), sync_flags),
         info::function::argument(_T("std::size_t length_"), length_)
      );
      throw exception_type(_T("Requested size larger than configured size."), std::move(fun), JMMCG_REVISION_HDR(_T(LIBJMMCG_VERSION_NUMBER)));
   }
   if (addr<addr_) {
      info::function fun(__LINE__, __PRETTY_FUNCTION__, typeid(this), info::function::argument(_T("void *addr"), addr));
      fun.add_args(
         info::function::argument(_T("std::size_t length"), length),
         info::function::argument(_T("sync_flags_t sync_flags"), sync_flags),
         info::function::argument(_T("void *addr_"), addr_)
      );
      throw exception_type(_T("Requested address less than mapped address."), std::move(fun), JMMCG_REVISION_HDR(_T(LIBJMMCG_VERSION_NUMBER)));
   }
   if ((reinterpret_cast<std::uint8_t const *>(addr)+length)>(reinterpret_cast<std::uint8_t const *>(addr_)+length_)) {
      info::function fun(__LINE__, __PRETTY_FUNCTION__, typeid(this), info::function::argument(_T("void *addr"), addr));
      fun.add_args(
         info::function::argument(_T("std::size_t length"), length),
         info::function::argument(_T("sync_flags_t sync_flags"), sync_flags),
         info::function::argument(_T("std::size_t length_"), length_),
         info::function::argument(_T("void *addr_"), addr_)
      );
      throw exception_type(_T("Requested address plus length less than mapped address ."), std::move(fun), JMMCG_REVISION_HDR(_T(LIBJMMCG_VERSION_NUMBER)));
   }
   JMMCG_SYSCALL_WRAPPER("Unable sync the portion of the mapped memory.", _T(LIBJMMCG_VERSION_NUMBER), ::msync, addr, length, sync_flags);
}
 
} }