shm_utils.cc

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#include "shm_utils.h"

#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>

#include <iostream>
#include <string>

namespace triton { namespace client {

Error
CreateSharedMemoryRegion(std::string shm_key, size_t byte_size, int* shm_fd)
{
  // get shared memory region descriptor
  *shm_fd = shm_open(shm_key.c_str(), O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
  if (*shm_fd == -1) {
    return Error(
        "unable to get shared memory descriptor for shared-memory key '" +
        shm_key + "'");
  }
  // extend shared memory object as by default it's initialized with size 0
  int res = ftruncate(*shm_fd, byte_size);
  if (res == -1) {
    return Error(
        "unable to initialize shared-memory key '" + shm_key +
        "' to requested size: " + std::to_string(byte_size) + " bytes");
  }

  return Error::Success;
}

Error
MapSharedMemory(int shm_fd, size_t offset, size_t byte_size, void** shm_addr)
{
  // map shared memory to process address space
  *shm_addr =
      mmap(NULL, byte_size, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, offset);
  if (*shm_addr == MAP_FAILED) {
    return Error(
        "unable to process address space or shared-memory descriptor: " +
        std::to_string(shm_fd));
  }

  return Error::Success;
}

Error
CloseSharedMemory(int shm_fd)
{
  // close shared memory descriptor
  if (close(shm_fd) == -1) {
    return Error(
        "unable to close shared-memory descriptor: " + std::to_string(shm_fd));
  }

  return Error::Success;
}

Error
UnlinkSharedMemoryRegion(std::string shm_key)
{
  int shm_fd = shm_unlink(shm_key.c_str());
  if (shm_fd == -1) {
    return Error("unable to unlink shared memory for key '" + shm_key + "'");
  }

  return Error::Success;
}

Error
UnmapSharedMemory(void* shm_addr, size_t byte_size)
{
  int tmp_fd = munmap(shm_addr, byte_size);
  if (tmp_fd == -1) {
    return Error("unable to munmap shared memory region");
  }

  return Error::Success;
}

}}  // namespace triton::client