/* Provide operations to control over shared memory segments. */
int
__shmctl (int id, int cmd, struct shmid_ds *buf)
{
error_t err = 0;
int fd;
int res;
char filename[sizeof (SHM_DIR) - 1 + SHM_NAMEMAX];
struct stat statbuf;
sprintf (filename, SHM_DIR SHM_NAMEPRI, id);
/* SysV requires read access for IPC_STAT. */
fd = __open (filename, O_NORW);
if (fd < 0)
{
if (errno == ENOENT)
errno = EINVAL;
return -1;
}
res = __fstat (fd, &statbuf);
if (res < 0)
{
err = errno;
__close (fd);
errno = err;
return -1;
}
switch (cmd)
{
case IPC_STAT:
buf->shm_perm.__key = id;
buf->shm_perm.uid = statbuf.st_uid;
buf->shm_perm.gid = statbuf.st_gid;
/* We do not support the creator. */
buf->shm_perm.cuid = statbuf.st_uid;
buf->shm_perm.cgid = statbuf.st_gid;
/* We just want the protection bits. */
buf->shm_perm.mode = statbuf.st_mode & 0777;
/* Hopeless. We do not support a sequence number. */
buf->shm_perm.__seq = statbuf.st_ino;
buf->shm_segsz = statbuf.st_size;
/* Hopeless. We do not support any of these. */
buf->shm_atime = statbuf.st_atime;
buf->shm_dtime = statbuf.st_mtime;
/* Well, this comes at least close. */
buf->shm_ctime = statbuf.st_ctime;
/* We do not support the PID. */
buf->shm_cpid = 0;
buf->shm_lpid = 0;
if (statbuf.st_mode & S_IMMAP0)
buf->shm_nattch = 0;
else
/* 42 is the answer. Of course this is bogus, but for most
applications, this should be fine. */
buf->shm_nattch = 42;
break;
case IPC_SET:
if (statbuf.st_uid != buf->shm_perm.uid
|| statbuf.st_gid != buf->shm_perm.gid)
{
res = __fchown (fd,
(statbuf.st_uid != buf->shm_perm.uid)
? buf->shm_perm.uid : -1,
(statbuf.st_gid != buf->shm_perm.gid)
? buf->shm_perm.gid : -1);
if (res < 0)
err = errno;
}
if (!err && statbuf.st_mode & 0777 != buf->shm_perm.mode & 0777)
{
res = __fchmod (fd, (statbuf.st_mode & ~0777)
| (buf->shm_perm.mode & 0777));
if (res < 0)
err = errno;
}
break;
case IPC_RMID:
res = __unlink (filename);
/* FIXME: Check error (mapping ENOENT to EINVAL). */
break;
default:
err = EINVAL;
}
__close (fd);
errno = err;
return err ? -1 : 0;
}
int
fchown(int fd, uid_t owner, gid_t group)
{
_gfs_hook_debug_v(fputs("Hooking fchown\n", stderr));
return (__fchown(fd, owner, group));
}
