include/android-ashmem.h

#ifdef __ANDROID__
  #ifndef _ANDROID_ASHMEM_H
    #define _ANDROID_ASHMEM_H

    #ifndef _GNU_SOURCE
      #define _GNU_SOURCE
    #endif
    #include <sys/syscall.h>
    #include <unistd.h>
    #include <fcntl.h>
    #include <linux/ashmem.h>
    #include <sys/ioctl.h>
    #include <sys/mman.h>
    #include <sys/shm.h>
    #include <stdio.h>
    #define ASHMEM_DEVICE "/dev/ashmem"

int shmdt(const void *address) {

    #if defined(SYS_shmdt)
  return syscall(SYS_shmdt, address);
    #else
  return syscall(SYS_ipc, SHMDT, 0, 0, 0, address, 0);
    #endif

}

int shmctl(int __shmid, int __cmd, struct shmid_ds *__buf) {

  int ret = 0;
  if (__cmd == IPC_RMID) {

    int               length = ioctl(__shmid, ASHMEM_GET_SIZE, NULL);
    struct ashmem_pin pin = {0, length};
    ret = ioctl(__shmid, ASHMEM_UNPIN, &pin);
    close(__shmid);

  }

  return ret;

}

int shmget(key_t __key, size_t __size, int __shmflg) {

  (void)__shmflg;
  int  fd, ret;
  char ourkey[11];

  fd = open(ASHMEM_DEVICE, O_RDWR);
  if (fd < 0) return fd;

  sprintf(ourkey, "%d", __key);
  ret = ioctl(fd, ASHMEM_SET_NAME, ourkey);
  if (ret < 0) goto error;

  ret = ioctl(fd, ASHMEM_SET_SIZE, __size);
  if (ret < 0) goto error;

  return fd;

error:
  close(fd);
  return ret;

}

void *shmat(int __shmid, const void *__shmaddr, int __shmflg) {

  (void)__shmflg;
  int   size;
  void *ptr;

  size = ioctl(__shmid, ASHMEM_GET_SIZE, NULL);
  if (size < 0) { return NULL; }

  ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, __shmid, 0);
  if (ptr == MAP_FAILED) { return NULL; }

  return ptr;

}

  #endif                                              /* !_ANDROID_ASHMEM_H */
#endif                                                      /* !__ANDROID__ */