Add an shm_rename syscall

Add an atomic shm rename operation, similar in spirit to a file
rename. Atomically unlink an shm from a source path and link it to a
destination path. If an existing shm is linked at the destination
path, unlink it as part of the same atomic operation. The caller needs
the same permissions as shm_unlink to the shm being renamed, and the
same permissions for the shm at the destination which is being
unlinked, if it exists. If those fail, EACCES is returned, as with the
other shm_* syscalls.

truss support is included; audit support will come later.

This commit includes only the implementation; the sysent-generated
bits will come in a follow-on commit.

Submitted by:	Matthew Bryan <matthew.bryan@isilon.com>
Reviewed by:	jilles (earlier revision)
Reviewed by:	brueffer (manpages, earlier revision)
Relnotes:	yes
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D21423
This commit is contained in:
David Bright 2019-09-26 15:32:28 +00:00
parent 0b18fb0798
commit 9afb12bab4
9 changed files with 536 additions and 29 deletions

View File

@ -477,7 +477,8 @@ MLINKS+=setuid.2 setegid.2 \
setuid.2 setgid.2
MLINKS+=shmat.2 shmdt.2
MLINKS+=shm_open.2 memfd_create.3 \
shm_open.2 shm_unlink.2
shm_open.2 shm_unlink.2 \
shm_rename.2
MLINKS+=sigwaitinfo.2 sigtimedwait.2
MLINKS+=stat.2 fstat.2 \
stat.2 fstatat.2 \

View File

@ -410,6 +410,7 @@ FBSD_1.6 {
getfhat;
funlinkat;
memfd_create;
shm_rename;
};
FBSDprivate_1.0 {

View File

@ -28,11 +28,11 @@
.\"
.\" $FreeBSD$
.\"
.Dd September 24, 2019
.Dd September 26, 2019
.Dt SHM_OPEN 2
.Os
.Sh NAME
.Nm memfd_create , shm_open , shm_unlink
.Nm memfd_create , shm_open , shm_rename, shm_unlink
.Nd "shared memory object operations"
.Sh LIBRARY
.Lb libc
@ -45,6 +45,8 @@
.Ft int
.Fn shm_open "const char *path" "int flags" "mode_t mode"
.Ft int
.Fn shm_rename "const char *path_from" "const char *path_to" "int flags"
.Ft int
.Fn shm_unlink "const char *path"
.Sh DESCRIPTION
The
@ -112,8 +114,9 @@ see
and
.Xr fcntl 2 .
.Pp
As a FreeBSD extension,
the constant
As a
.Fx
extension, the constant
.Dv SHM_ANON
may be used for the
.Fa path
@ -122,7 +125,9 @@ argument to
In this case, an anonymous, unnamed shared memory object is created.
Since the object has no name,
it cannot be removed via a subsequent call to
.Fn shm_unlink .
.Fn shm_unlink ,
or moved with a call to
.Fn shm_rename .
Instead,
the shared memory object will be garbage collected when the last reference to
the shared memory object is removed.
@ -138,6 +143,31 @@ will fail with
All other flags are ignored.
.Pp
The
.Fn shm_rename
system call atomically removes a shared memory object named
.Fa path_from
and relinks it at
.Fa path_to .
If another object is already linked at
.Fa path_to ,
that object will be unlinked, unless one of the following flags are provided:
.Bl -tag -offset indent -width Er
.It Er SHM_RENAME_EXCHANGE
Atomically exchange the shms at
.Fa path_from
and
.Fa path_to .
.It Er SHM_RENAME_NOREPLACE
Return an error if an shm exists at
.Fa path_to ,
rather than unlinking it.
.El
.Fn shm_rename
is also a
.Fx
extension.
.Pp
The
.Fn shm_unlink
system call removes a shared memory object named
.Fa path .
@ -196,15 +226,20 @@ and
.Fn shm_open
both return a non-negative integer,
and
.Fn shm_rename
and
.Fn shm_unlink
returns zero.
All three functions return -1 on failure, and set
return zero.
All functions return -1 on failure, and set
.Va errno
to indicate the error.
.Sh COMPATIBILITY
The
.Fa path
argument does not necessarily represent a pathname (although it does in
.Fa path ,
.Fa path_from ,
and
.Fa path_to
arguments do not necessarily represent a pathname (although they do in
most other implementations).
Two processes opening the same
.Fa path
@ -325,7 +360,7 @@ The
.Fa path
argument points outside the process' allocated address space.
.It Bq Er ENAMETOOLONG
The entire pathname exceeded 1023 characters.
The entire pathname exceeds 1023 characters.
.It Bq Er EINVAL
The
.Fa path
@ -344,6 +379,31 @@ are specified and the named shared memory object does exist.
The required permissions (for reading or reading and writing) are denied.
.El
.Pp
The following errors are defined for
.Fn shm_rename :
.Bl -tag -width Er
.It Bq Er EFAULT
The
.Fa path_from
or
.Fa path_to
argument points outside the process' allocated address space.
.It Bq Er ENAMETOOLONG
The entire pathname exceeds 1023 characters.
.It Bq Er ENOENT
The shared memory object at
.Fa path_from
does not exist.
.It Bq Er EACCES
The required permissions are denied.
.It Bq Er EEXIST
An shm exists at
.Fa path_to ,
and the
.Dv SHM_RENAME_NOREPLACE
flag was provided.
.El
.Pp
.Fn shm_unlink
fails with these error codes for these conditions:
.Bl -tag -width Er
@ -352,7 +412,7 @@ The
.Fa path
argument points outside the process' allocated address space.
.It Bq Er ENAMETOOLONG
The entire pathname exceeded 1023 characters.
The entire pathname exceeds 1023 characters.
.It Bq Er ENOENT
The named shared memory object does not exist.
.It Bq Er EACCES
@ -394,9 +454,19 @@ functions first appeared in
The functions were reimplemented as system calls using shared memory objects
directly rather than files in
.Fx 8.0 .
.Pp
.Fn shm_rename
first appeared in
.Fx 13.0
as a
.Fx
extension.
.Sh AUTHORS
.An Garrett A. Wollman Aq Mt wollman@FreeBSD.org
(C library support and this manual page)
.Pp
.An Matthew Dillon Aq Mt dillon@FreeBSD.org
.Pq Dv MAP_NOSYNC
.Pp
.An Matthew Bryan Aq Mt matthew.bryan@isilon.com
.Pq Dv shm_rename implementation

View File

@ -1157,5 +1157,7 @@
571 AUE_SHMOPEN NOPROTO { int shm_open2( \
const char *path, int flags, mode_t mode, \
int shmflags, const char *name); }
572 AUE_NULL NOPROTO { int shm_rename(const char *path_from, \
const char *path_to, int flags); }
; vim: syntax=off

View File

@ -3204,6 +3204,13 @@
_In_z_ const char *name
);
}
572 AUE_NULL STD {
int shm_rename(
_In_z_ const char *path_from,
_In_z_ const char *path_to,
int flags
);
}
; Please copy any additions and changes to the following compatability tables:
; sys/compat/freebsd32/syscalls.master

View File

@ -33,8 +33,9 @@
/*
* Support for shared swap-backed anonymous memory objects via
* shm_open(2) and shm_unlink(2). While most of the implementation is
* here, vm_mmap.c contains mapping logic changes.
* shm_open(2), shm_rename(2), and shm_unlink(2).
* While most of the implementation is here, vm_mmap.c contains
* mapping logic changes.
*
* posixshmcontrol(1) allows users to inspect the state of the memory
* objects. Per-uid swap resource limit controls total amount of
@ -947,6 +948,158 @@ sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
return (error);
}
int
sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
{
char *path_from = NULL, *path_to = NULL;
Fnv32_t fnv_from, fnv_to;
struct shmfd *fd_from;
struct shmfd *fd_to;
int error;
int flags;
flags = uap->flags;
/*
* Make sure the user passed only valid flags.
* If you add a new flag, please add a new term here.
*/
if ((flags & ~(
SHM_RENAME_NOREPLACE |
SHM_RENAME_EXCHANGE
)) != 0) {
error = EINVAL;
goto out;
}
/*
* EXCHANGE and NOREPLACE don't quite make sense together. Let's
* force the user to choose one or the other.
*/
if ((flags & SHM_RENAME_NOREPLACE) != 0 &&
(flags & SHM_RENAME_EXCHANGE) != 0) {
error = EINVAL;
goto out;
}
/*
* Malloc zone M_SHMFD, since this path may end up freed later from
* M_SHMFD if we end up doing an insert.
*/
path_from = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
error = copyinstr(uap->path_from, path_from, MAXPATHLEN, NULL);
if (error)
goto out;
path_to = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
error = copyinstr(uap->path_to, path_to, MAXPATHLEN, NULL);
if (error)
goto out;
/* Rename with from/to equal is a no-op */
if (strncmp(path_from, path_to, MAXPATHLEN) == 0)
goto out;
fnv_from = fnv_32_str(path_from, FNV1_32_INIT);
fnv_to = fnv_32_str(path_to, FNV1_32_INIT);
sx_xlock(&shm_dict_lock);
fd_from = shm_lookup(path_from, fnv_from);
if (fd_from == NULL) {
sx_xunlock(&shm_dict_lock);
error = ENOENT;
goto out;
}
fd_to = shm_lookup(path_to, fnv_to);
if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) {
sx_xunlock(&shm_dict_lock);
error = EEXIST;
goto out;
}
/*
* Unconditionally prevents shm_remove from invalidating the 'from'
* shm's state.
*/
shm_hold(fd_from);
error = shm_remove(path_from, fnv_from, td->td_ucred);
/*
* One of my assumptions failed if ENOENT (e.g. locking didn't
* protect us)
*/
KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s",
path_from));
if (error) {
shm_drop(fd_from);
sx_xunlock(&shm_dict_lock);
goto out;
}
/*
* If we are exchanging, we need to ensure the shm_remove below
* doesn't invalidate the dest shm's state.
*/
if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL)
shm_hold(fd_to);
/*
* NOTE: if path_to is not already in the hash, c'est la vie;
* it simply means we have nothing already at path_to to unlink.
* That is the ENOENT case.
*
* If we somehow don't have access to unlink this guy, but
* did for the shm at path_from, then relink the shm to path_from
* and abort with EACCES.
*
* All other errors: that is weird; let's relink and abort the
* operation.
*/
error = shm_remove(path_to, fnv_to, td->td_ucred);
if (error && error != ENOENT) {
shm_insert(path_from, fnv_from, fd_from);
shm_drop(fd_from);
/* Don't free path_from now, since the hash references it */
path_from = NULL;
sx_xunlock(&shm_dict_lock);
goto out;
}
shm_insert(path_to, fnv_to, fd_from);
/* Don't free path_to now, since the hash references it */
path_to = NULL;
/* We kept a ref when we removed, and incremented again in insert */
shm_drop(fd_from);
#ifdef DEBUG
KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n",
fd_from->shm_refs));
#endif
if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) {
shm_insert(path_from, fnv_from, fd_to);
path_from = NULL;
shm_drop(fd_to);
#ifdef DEBUG
KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n",
fd_to->shm_refs));
#endif
}
error = 0;
sx_xunlock(&shm_dict_lock);
out:
if (path_from != NULL)
free(path_from, M_SHMFD);
if (path_to != NULL)
free(path_to, M_SHMFD);
return(error);
}
int
shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
vm_prot_t prot, vm_prot_t cap_maxprot, int flags,

View File

@ -133,6 +133,14 @@
*/
#define MAP_FAILED ((void *)-1)
/*
* Flags provided to shm_rename
*/
/* Don't overwrite dest, if it exists */
#define SHM_RENAME_NOREPLACE (1 << 0)
/* Atomically swap src and dest */
#define SHM_RENAME_EXCHANGE (1 << 1)
/*
* msync() flags
*/
@ -313,6 +321,7 @@ int posix_madvise(void *, size_t, int);
int mlockall(int);
int munlockall(void);
int shm_open(const char *, int, mode_t);
int shm_rename(const char *, const char *, int);
int shm_unlink(const char *);
#endif
#if __BSD_VISIBLE

View File

@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
#include <sys/syscall.h>
#include <sys/wait.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
@ -46,18 +47,34 @@ __FBSDID("$FreeBSD$");
#define TEST_PATH_LEN 256
static char test_path[TEST_PATH_LEN];
static char test_path2[TEST_PATH_LEN];
static unsigned int test_path_idx = 0;
static void
gen_a_test_path(char *path)
{
snprintf(path, TEST_PATH_LEN, "%s/tmp.XXXXXX%d",
getenv("TMPDIR") == NULL ? "/tmp" : getenv("TMPDIR"),
test_path_idx);
test_path_idx++;
ATF_REQUIRE_MSG(mkstemp(path) != -1,
"mkstemp failed; errno=%d", errno);
ATF_REQUIRE_MSG(unlink(path) == 0,
"unlink failed; errno=%d", errno);
}
static void
gen_test_path(void)
{
gen_a_test_path(test_path);
}
snprintf(test_path, sizeof(test_path), "%s/tmp.XXXXXX",
getenv("TMPDIR") == NULL ? "/tmp" : getenv("TMPDIR"));
test_path[sizeof(test_path) - 1] = '\0';
ATF_REQUIRE_MSG(mkstemp(test_path) != -1,
"mkstemp failed; errno=%d", errno);
ATF_REQUIRE_MSG(unlink(test_path) == 0,
"unlink failed; errno=%d", errno);
static void
gen_test_path2(void)
{
gen_a_test_path(test_path2);
}
/*
@ -89,20 +106,18 @@ shm_unlink_should_fail(const char *path, int error)
}
/*
* Open the test object and write '1' to the first byte. Returns valid fd
* Open the test object and write a value to the first byte. Returns valid fd
* on success and -1 on failure.
*/
static int
scribble_object(void)
scribble_object(const char *path, char value)
{
char *page;
int fd, pagesize;
gen_test_path();
ATF_REQUIRE(0 < (pagesize = getpagesize()));
fd = shm_open(test_path, O_CREAT|O_EXCL|O_RDWR, 0777);
fd = shm_open(path, O_CREAT|O_EXCL|O_RDWR, 0777);
if (fd < 0 && errno == EEXIST) {
if (shm_unlink(test_path) < 0)
atf_tc_fail("shm_unlink");
@ -117,13 +132,45 @@ scribble_object(void)
if (page == MAP_FAILED)
atf_tc_fail("mmap failed; errno=%d", errno);
page[0] = '1';
page[0] = value;
ATF_REQUIRE_MSG(munmap(page, pagesize) == 0, "munmap failed; errno=%d",
errno);
return (fd);
}
/*
* Fail the test case if the 'path' does not refer to an shm whose first byte
* is equal to expected_value
*/
static void
verify_object(const char *path, char expected_value)
{
int fd;
int pagesize;
char *page;
ATF_REQUIRE(0 < (pagesize = getpagesize()));
fd = shm_open(path, O_RDONLY, 0777);
if (fd < 0)
atf_tc_fail("shm_open failed in verify_object; errno=%d, path=%s",
errno, path);
page = mmap(0, pagesize, PROT_READ, MAP_SHARED, fd, 0);
if (page == MAP_FAILED)
atf_tc_fail("mmap(1)");
if (page[0] != expected_value)
atf_tc_fail("Renamed object has incorrect value; has"
"%d (0x%x, '%c'), expected %d (0x%x, '%c')\n",
page[0], page[0], isprint(page[0]) ? page[0] : ' ',
expected_value, expected_value,
isprint(expected_value) ? expected_value : ' ');
ATF_REQUIRE_MSG(munmap(page, pagesize) == 0, "munmap failed; errno=%d",
errno);
close(fd);
}
ATF_TC_WITHOUT_HEAD(remap_object);
ATF_TC_BODY(remap_object, tc)
{
@ -132,7 +179,8 @@ ATF_TC_BODY(remap_object, tc)
ATF_REQUIRE(0 < (pagesize = getpagesize()));
fd = scribble_object();
gen_test_path();
fd = scribble_object(test_path, '1');
page = mmap(0, pagesize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (page == MAP_FAILED)
@ -149,6 +197,209 @@ ATF_TC_BODY(remap_object, tc)
"shm_unlink failed; errno=%d", errno);
}
ATF_TC_WITHOUT_HEAD(rename_from_anon);
ATF_TC_BODY(rename_from_anon, tc)
{
int rc;
gen_test_path();
rc = shm_rename(SHM_ANON, test_path, 0);
if (rc != -1)
atf_tc_fail("shm_rename from SHM_ANON succeeded unexpectedly");
}
ATF_TC_WITHOUT_HEAD(rename_bad_path_pointer);
ATF_TC_BODY(rename_bad_path_pointer, tc)
{
const char *bad_path;
int rc;
bad_path = (const char *)0x1;
gen_test_path();
rc = shm_rename(test_path, bad_path, 0);
if (rc != -1)
atf_tc_fail("shm_rename of nonexisting shm succeeded unexpectedly");
rc = shm_rename(bad_path, test_path, 0);
if (rc != -1)
atf_tc_fail("shm_rename of nonexisting shm succeeded unexpectedly");
}
ATF_TC_WITHOUT_HEAD(rename_from_nonexisting);
ATF_TC_BODY(rename_from_nonexisting, tc)
{
int rc;
gen_test_path();
rc = shm_rename(test_path, test_path2, 0);
if (rc != -1)
atf_tc_fail("shm_rename of nonexisting shm succeeded unexpectedly");
if (errno != ENOENT)
atf_tc_fail("Expected ENOENT to rename of nonexistent shm");
}
ATF_TC_WITHOUT_HEAD(rename_to_anon);
ATF_TC_BODY(rename_to_anon, tc)
{
int rc;
gen_test_path();
rc = shm_rename(test_path, SHM_ANON, 0);
if (rc != -1)
atf_tc_fail("shm_rename to SHM_ANON succeeded unexpectedly");
}
ATF_TC_WITHOUT_HEAD(rename_to_replace);
ATF_TC_BODY(rename_to_replace, tc)
{
char expected_value;
int fd;
int fd2;
// Some contents we can verify later
expected_value = 'g';
gen_test_path();
fd = scribble_object(test_path, expected_value);
close(fd);
// Give the other some different value so we can detect success
gen_test_path2();
fd2 = scribble_object(test_path2, 'h');
close(fd2);
ATF_REQUIRE_MSG(shm_rename(test_path, test_path2, 0) == 0,
"shm_rename failed; errno=%d", errno);
// Read back renamed; verify contents
verify_object(test_path2, expected_value);
}
ATF_TC_WITHOUT_HEAD(rename_to_noreplace);
ATF_TC_BODY(rename_to_noreplace, tc)
{
char expected_value_from;
char expected_value_to;
int fd_from;
int fd_to;
int rc;
// Some contents we can verify later
expected_value_from = 'g';
gen_test_path();
fd_from = scribble_object(test_path, expected_value_from);
close(fd_from);
// Give the other some different value so we can detect success
expected_value_to = 'h';
gen_test_path2();
fd_to = scribble_object(test_path2, expected_value_to);
close(fd_to);
rc = shm_rename(test_path, test_path2, SHM_RENAME_NOREPLACE);
ATF_REQUIRE_MSG((rc == -1) && (errno == EEXIST),
"shm_rename didn't fail as expected; errno: %d; return: %d", errno,
rc);
// Read back renamed; verify contents
verify_object(test_path2, expected_value_to);
}
ATF_TC_WITHOUT_HEAD(rename_to_exchange);
ATF_TC_BODY(rename_to_exchange, tc)
{
char expected_value_from;
char expected_value_to;
int fd_from;
int fd_to;
// Some contents we can verify later
expected_value_from = 'g';
gen_test_path();
fd_from = scribble_object(test_path, expected_value_from);
close(fd_from);
// Give the other some different value so we can detect success
expected_value_to = 'h';
gen_test_path2();
fd_to = scribble_object(test_path2, expected_value_to);
close(fd_to);
ATF_REQUIRE_MSG(shm_rename(test_path, test_path2,
SHM_RENAME_EXCHANGE) == 0,
"shm_rename failed; errno=%d", errno);
// Read back renamed; verify contents
verify_object(test_path, expected_value_to);
verify_object(test_path2, expected_value_from);
}
ATF_TC_WITHOUT_HEAD(rename_to_exchange_nonexisting);
ATF_TC_BODY(rename_to_exchange_nonexisting, tc)
{
char expected_value_from;
int fd_from;
// Some contents we can verify later
expected_value_from = 'g';
gen_test_path();
fd_from = scribble_object(test_path, expected_value_from);
close(fd_from);
gen_test_path2();
ATF_REQUIRE_MSG(shm_rename(test_path, test_path2,
SHM_RENAME_EXCHANGE) == 0,
"shm_rename failed; errno=%d", errno);
// Read back renamed; verify contents
verify_object(test_path2, expected_value_from);
}
ATF_TC_WITHOUT_HEAD(rename_to_self);
ATF_TC_BODY(rename_to_self, tc)
{
int fd;
char expected_value;
expected_value = 't';
gen_test_path();
fd = scribble_object(test_path, expected_value);
close(fd);
ATF_REQUIRE_MSG(shm_rename(test_path, test_path, 0) == 0,
"shm_rename failed; errno=%d", errno);
verify_object(test_path, expected_value);
}
ATF_TC_WITHOUT_HEAD(rename_bad_flag);
ATF_TC_BODY(rename_bad_flag, tc)
{
int fd;
int rc;
/* Make sure we don't fail out due to ENOENT */
gen_test_path();
gen_test_path2();
fd = scribble_object(test_path, 'd');
close(fd);
fd = scribble_object(test_path2, 'd');
close(fd);
/*
* Note: if we end up with enough flags that we use all the bits,
* then remove this test completely.
*/
rc = shm_rename(test_path, test_path2, INT_MIN);
ATF_REQUIRE_MSG((rc == -1) && (errno == EINVAL),
"shm_rename should have failed with EINVAL; got: return=%d, "
"errno=%d", rc, errno);
}
ATF_TC_WITHOUT_HEAD(reopen_object);
ATF_TC_BODY(reopen_object, tc)
{
@ -157,7 +408,8 @@ ATF_TC_BODY(reopen_object, tc)
ATF_REQUIRE(0 < (pagesize = getpagesize()));
fd = scribble_object();
gen_test_path();
fd = scribble_object(test_path, '1');
close(fd);
fd = shm_open(test_path, O_RDONLY, 0777);
@ -634,6 +886,16 @@ ATF_TP_ADD_TCS(tp)
{
ATF_TP_ADD_TC(tp, remap_object);
ATF_TP_ADD_TC(tp, rename_from_anon);
ATF_TP_ADD_TC(tp, rename_bad_path_pointer);
ATF_TP_ADD_TC(tp, rename_from_nonexisting);
ATF_TP_ADD_TC(tp, rename_to_anon);
ATF_TP_ADD_TC(tp, rename_to_replace);
ATF_TP_ADD_TC(tp, rename_to_noreplace);
ATF_TP_ADD_TC(tp, rename_to_exchange);
ATF_TP_ADD_TC(tp, rename_to_exchange_nonexisting);
ATF_TP_ADD_TC(tp, rename_to_self);
ATF_TP_ADD_TC(tp, rename_bad_flag);
ATF_TP_ADD_TC(tp, reopen_object);
ATF_TP_ADD_TC(tp, readonly_mmap_write);
ATF_TP_ADD_TC(tp, open_after_link);

View File

@ -471,6 +471,8 @@ static struct syscall decoded_syscalls[] = {
{ Ptr | IN, 3 }, { Socklent, 4 } } },
{ .name = "shm_open", .ret_type = 1, .nargs = 3,
.args = { { ShmName | IN, 0 }, { Open, 1 }, { Octal, 2 } } },
{ .name = "shm_rename", .ret_type = 1, .nargs = 3,
.args = { { Name | IN, 0 }, { Name | IN, 1 }, { Hex, 2 } } },
{ .name = "shm_unlink", .ret_type = 1, .nargs = 1,
.args = { { Name | IN, 0 } } },
{ .name = "shutdown", .ret_type = 1, .nargs = 2,