static void
shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
{
struct shm_mapping *map;
map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
map->sm_path = path;
map->sm_fnv = fnv;
map->sm_shmfd = shm_hold(shmfd);
LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
}
/* System calls. */
int
sys_shm_open(struct thread *td, struct shm_open_args *uap)
{
struct filedesc *fdp;
struct shmfd *shmfd;
struct file *fp;
char *path;
Fnv32_t fnv;
mode_t cmode;
int fd, error;
#ifdef CAPABILITY_MODE
/*
* shm_open(2) is only allowed for anonymous objects.
*/
if (IN_CAPABILITY_MODE(td) && (uap->path != SHM_ANON))
return (ECAPMODE);
#endif
if ((uap->flags & O_ACCMODE) != O_RDONLY &&
(uap->flags & O_ACCMODE) != O_RDWR)
return (EINVAL);
if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC)) != 0)
return (EINVAL);
fdp = td->td_proc->p_fd;
cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS;
error = falloc(td, &fp, &fd, 0);
if (error)
return (error);
/* A SHM_ANON path pointer creates an anonymous object. */
if (uap->path == SHM_ANON) {
/* A read-only anonymous object is pointless. */
if ((uap->flags & O_ACCMODE) == O_RDONLY) {
fdclose(fdp, fp, fd, td);
fdrop(fp, td);
return (EINVAL);
}
shmfd = shm_alloc(td->td_ucred, cmode);
} else {
path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
error = copyinstr(uap->path, path, MAXPATHLEN, NULL);
/* Require paths to start with a '/' character. */
if (error == 0 && path[0] != '/')
error = EINVAL;
if (error) {
fdclose(fdp, fp, fd, td);
fdrop(fp, td);
free(path, M_SHMFD);
return (error);
}
fnv = fnv_32_str(path, FNV1_32_INIT);
sx_xlock(&shm_dict_lock);
shmfd = shm_lookup(path, fnv);
if (shmfd == NULL) {
/* Object does not yet exist, create it if requested. */
if (uap->flags & O_CREAT) {
#ifdef MAC
error = mac_posixshm_check_create(td->td_ucred,
path);
if (error == 0) {
#endif
shmfd = shm_alloc(td->td_ucred, cmode);
shm_insert(path, fnv, shmfd);
#ifdef MAC
}
#endif
} else {
free(path, M_SHMFD);
error = ENOENT;
}
} else {
/*
* Object already exists, obtain a new
* reference if requested and permitted.
*/
free(path, M_SHMFD);
if ((uap->flags & (O_CREAT | O_EXCL)) ==
(O_CREAT | O_EXCL))
error = EEXIST;
else {
#ifdef MAC
error = mac_posixshm_check_open(td->td_ucred,
shmfd, FFLAGS(uap->flags & O_ACCMODE));
if (error == 0)
#endif
error = shm_access(shmfd, td->td_ucred,
FFLAGS(uap->flags & O_ACCMODE));
}
/*
* Truncate the file back to zero length if
* O_TRUNC was specified and the object was
* opened with read/write.
*/
if (error == 0 &&
(uap->flags & (O_ACCMODE | O_TRUNC)) ==
(O_RDWR | O_TRUNC)) {
#ifdef MAC
error = mac_posixshm_check_truncate(
td->td_ucred, fp->f_cred, shmfd);
if (error == 0)
#endif
shm_dotruncate(shmfd, 0);
}
if (error == 0)
shm_hold(shmfd);
}
sx_xunlock(&shm_dict_lock);
if (error) {
fdclose(fdp, fp, fd, td);
fdrop(fp, td);
return (error);
}
}
finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
FILEDESC_XLOCK(fdp);
if (fdp->fd_ofiles[fd] == fp)
fdp->fd_ofileflags[fd] |= UF_EXCLOSE;
FILEDESC_XUNLOCK(fdp);
td->td_retval[0] = fd;
fdrop(fp, td);
return (0);
}