android-ashmem.h

#ifdef __ANDROID__
#ifndef _ANDROID_ASHMEM_H
#define _ANDROID_ASHMEM_H

#include <fcntl.h>
#include <linux/ashmem.h>
#include <linux/shm.h>
#include <sys/ioctl.h>
#include <sys/mman.h>

#if __ANDROID_API__ >= 26
#define shmat bionic_shmat
#define shmctl bionic_shmctl
#define shmdt bionic_shmdt
#define shmget bionic_shmget
#endif
#include <sys/shm.h>
#undef shmat
#undef shmctl
#undef shmdt
#undef shmget
#include <stdio.h>

#define ASHMEM_DEVICE "/dev/ashmem"

static inline 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;
}

static inline 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;
}

static inline 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__ */