static ERL_NIF_TERM close_nif(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
enum efile_state_t previous_state;
efile_data_t *d;
ASSERT(argc == 1);
if(!get_file_data(env, argv[0], &d)) {
return enif_make_badarg(env);
}
previous_state = erts_atomic32_cmpxchg_acqb(&d->state,
EFILE_STATE_CLOSED, EFILE_STATE_IDLE);
if(previous_state == EFILE_STATE_IDLE) {
posix_errno_t error;
enif_demonitor_process(env, d, &d->monitor);
if(!efile_close(d, &error)) {
return posix_error_to_tuple(env, error);
}
return am_ok;
} else {
/* CLOSE_PENDING should be impossible at this point since it requires
* a transition from BUSY; the only valid state here is CLOSED. */
ASSERT(previous_state == EFILE_STATE_CLOSED);
return posix_error_to_tuple(env, EINVAL);
}
}
static void owner_death_callback(ErlNifEnv* env, void* obj, ErlNifPid* pid, ErlNifMonitor* mon) {
efile_data_t *d = (efile_data_t*)obj;
(void)env;
(void)pid;
(void)mon;
for(;;) {
enum efile_state_t previous_state;
previous_state = erts_atomic32_cmpxchg_acqb(&d->state,
EFILE_STATE_CLOSED, EFILE_STATE_IDLE);
switch(previous_state) {
case EFILE_STATE_IDLE:
efile_close(d);
return;
case EFILE_STATE_CLOSE_PENDING:
case EFILE_STATE_CLOSED:
/* We're either already closed or managed to mark ourselves for
* closure in the previous iteration. */
return;
case EFILE_STATE_BUSY:
/* Schedule ourselves to be closed once the current operation
* finishes, retrying the [IDLE -> CLOSED] transition in case we
* narrowly passed the [BUSY -> IDLE] one. */
erts_atomic32_cmpxchg_nob(&d->state,
EFILE_STATE_CLOSE_PENDING, EFILE_STATE_BUSY);
break;
}
}
}
static ERL_NIF_TERM read_file_nif(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
posix_errno_t posix_errno, ignored;
efile_fileinfo_t info = {0};
efile_path_t path;
efile_data_t *d;
ErlNifBinary result;
ASSERT(argc == 1);
if((posix_errno = efile_marshal_path(env, argv[0], &path))) {
return posix_error_to_tuple(env, posix_errno);
} else if((posix_errno = efile_read_info(&path, 1, &info))) {
return posix_error_to_tuple(env, posix_errno);
} else if((posix_errno = efile_open(&path, EFILE_MODE_READ, efile_resource_type, &d))) {
return posix_error_to_tuple(env, posix_errno);
}
posix_errno = read_file(d, info.size, &result);
erts_atomic32_set_acqb(&d->state, EFILE_STATE_CLOSED);
efile_close(d, &ignored);
if(posix_errno) {
return posix_error_to_tuple(env, posix_errno);
}
return enif_make_tuple2(env, am_ok, enif_make_binary(env, &result));
}
/* This is a special close operation used by the erts_prim_file process for
* cleaning up orphaned files. It differs from the ordinary close_nif in that
* it only works for files that have already entered the CLOSED state. */
static ERL_NIF_TERM delayed_close_nif(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
posix_errno_t ignored;
efile_data_t *d;
ASSERT(argc == 1);
if(!get_file_data(env, argv[0], &d)) {
return enif_make_badarg(env);
}
ASSERT(erts_atomic32_read_acqb(&d->state) == EFILE_STATE_CLOSED);
efile_close(d, &ignored);
return am_ok;
}
static ERL_NIF_TERM open_nif(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
posix_errno_t posix_errno;
efile_data_t *d;
ErlNifPid controlling_process;
enum efile_modes_t modes;
ERL_NIF_TERM result;
efile_path_t path;
ASSERT(argc == 2);
if(!enif_is_list(env, argv[1])) {
return enif_make_badarg(env);
}
modes = efile_translate_modelist(env, argv[1]);
if((posix_errno = efile_marshal_path(env, argv[0], &path))) {
return posix_error_to_tuple(env, posix_errno);
} else if((posix_errno = efile_open(&path, modes, efile_resource_type, &d))) {
return posix_error_to_tuple(env, posix_errno);
}
enif_self(env, &controlling_process);
if(enif_monitor_process(env, d, &controlling_process, &d->monitor)) {
/* We need to close the file manually as we haven't registered a
* destructor. */
posix_errno_t ignored;
erts_atomic32_set_acqb(&d->state, EFILE_STATE_CLOSED);
efile_close(d, &ignored);
return posix_error_to_tuple(env, EINVAL);
}
/* Note that we do not call enif_release_resource at this point. While it's
* normally safe to leave resource management to the GC, efile_close is a
* blocking operation which must not be done in the GC callback, and we
* can't defer it as the resource is gone as soon as it returns.
*
* We instead keep the resource alive until efile_close is called, after
* which it's safe to leave things to the GC. If the controlling process
* were to die before the user had a chance to close their file, the above
* monitor will tell the erts_prim_file process to close it for them. */
result = enif_make_resource(env, d);
return enif_make_tuple2(env, am_ok, result);
}
static void gc_callback(ErlNifEnv *env, void* data) {
efile_data_t *d = (efile_data_t*)data;
enum efile_state_t previous_state;
(void)env;
previous_state = erts_atomic32_cmpxchg_acqb(&d->state,
EFILE_STATE_CLOSED, EFILE_STATE_IDLE);
ASSERT(previous_state != EFILE_STATE_CLOSE_PENDING &&
previous_state != EFILE_STATE_BUSY);
if(previous_state == EFILE_STATE_IDLE) {
efile_close(d);
}
}
static ERL_NIF_TERM file_handle_wrapper(file_op_impl_t operation, ErlNifEnv *env,
int argc, const ERL_NIF_TERM argv[]) {
efile_data_t *d;
enum efile_state_t previous_state;
ERL_NIF_TERM result;
if(argc < 1 || !get_file_data(env, argv[0], &d)) {
return enif_make_badarg(env);
}
previous_state = erts_atomic32_cmpxchg_acqb(&d->state,
EFILE_STATE_BUSY, EFILE_STATE_IDLE);
if(previous_state == EFILE_STATE_IDLE) {
result = operation(d, env, argc - 1, &argv[1]);
previous_state = erts_atomic32_cmpxchg_relb(&d->state,
EFILE_STATE_IDLE, EFILE_STATE_BUSY);
ASSERT(previous_state != EFILE_STATE_IDLE);
if(previous_state == EFILE_STATE_CLOSE_PENDING) {
/* This is the only point where a change from CLOSE_PENDING is
* possible, and we're running synchronously, so we can't race with
* anything else here. */
posix_errno_t ignored;
erts_atomic32_set_acqb(&d->state, EFILE_STATE_CLOSED);
efile_close(d, &ignored);
}
} else {
/* CLOSE_PENDING should be impossible at this point since it requires
* a transition from BUSY; the only valid state here is CLOSED. */
ASSERT(previous_state == EFILE_STATE_CLOSED);
result = posix_error_to_tuple(env, EINVAL);
}
return result;
}
static ERL_NIF_TERM close_nif_impl(efile_data_t *d, ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
enum efile_state_t previous_state;
ASSERT(argc == 0);
previous_state = erts_atomic32_cmpxchg_acqb(&d->state,
EFILE_STATE_CLOSED, EFILE_STATE_BUSY);
ASSERT(previous_state == EFILE_STATE_CLOSE_PENDING ||
previous_state == EFILE_STATE_BUSY);
if(previous_state == EFILE_STATE_BUSY) {
enif_demonitor_process(env, d, &d->monitor);
if(!efile_close(d)) {
return posix_error_to_tuple(env, d->posix_errno);
}
}
return am_ok;
}
