NetBSD: Introduce utmpx_.rs, correct utmpx definitions

Create a new module for `utmpx` and move definitions there, then correct
`_UTX_PADSIZE`. We can also just use `s!`, there is no need to manually
implement the traits.

NetBSD defines `_UTX_PADSIZE` manually but includes this comment in
their source:

    /*
     * This should be:
     * 40 - (sizeof(struct timeval) - sizeof(struct { long s; long u; })))
     * but g++ does not like it, to retain size compatibility with v1.00,
     * so we do it manually.
     */
    #ifdef _LP64
    #define _UTX_PADSIZE 36
    #else
    #define _UTX_PADSIZE 40
    #endif

I tried using the expression here:

    40 - (size_of::<crate::timeval>() - size_of::<(c_long, c_long)>());

But this returns a value of 8 which doesn't match the expected 36. So,
keep with their source and hardcode the values.

Link: https://github.com/NetBSD/src/blob/6ace5fed3bd010695a1b88ca6c1f8a5af7793ffb/include/utmpx.h#L91-L101

(backport <#4782>)
(cherry picked from commit 4055637)

Author: tgross35

src/new/mod.rs

@@ -186,6 +186,7 @@ cfg_if! {
         pub use sys::ipc::*;
         pub use sys::statvfs::*;
         pub use utmp_::*;
+        pub use utmpx_::*;
     } else if #[cfg(target_os = "openbsd")] {
         pub use sys::ipc::*;
     }

src/new/netbsd/mod.rs

@@ -7,3 +7,4 @@
 pub(crate) mod sys;
 pub(crate) mod unistd;
 pub(crate) mod utmp_;
+pub(crate) mod utmpx_;

src/new/netbsd/utmpx_.rs

@@ -0,0 +1,82 @@
+//! Header: `utmpx.h`
+//!
+//! <https://github.com/NetBSD/src/blob/master/include/utmp.h>
+
+use crate::prelude::*;
+
+// pub const _PATH_UTMPX: &[c_char; 14] = b"/var/run/utmpx";
+// pub const _PATH_WTMPX: &[c_char; 14] = b"/var/log/wtmpx";
+// pub const _PATH_LASTLOGX: &[c_char; 17] = b"/var/log/lastlogx";
+// pub const _PATH_UTMP_UPDATE: &[c_char; 24] = b"/usr/libexec/utmp_update";
+
+pub const _UTX_USERSIZE: usize = 32;
+pub const _UTX_LINESIZE: usize = 32;
+pub const _UTX_IDSIZE: usize = 4;
+pub const _UTX_HOSTSIZE: usize = 256;
+
+pub const EMPTY: u16 = 0;
+pub const RUN_LVL: u16 = 1;
+pub const BOOT_TIME: u16 = 2;
+pub const OLD_TIME: u16 = 3;
+pub const NEW_TIME: u16 = 4;
+pub const INIT_PROCESS: u16 = 5;
+pub const LOGIN_PROCESS: u16 = 6;
+pub const USER_PROCESS: u16 = 7;
+pub const DEAD_PROCESS: u16 = 8;
+pub const ACCOUNTING: u16 = 9;
+pub const SIGNATURE: u16 = 10;
+pub const DOWN_TIME: u16 = 11;
+
+// Expression based on the comment in NetBSD source.
+pub const _UTX_PADSIZE: usize = if cfg!(target_pointer_width = "64") {
+    36
+} else {
+    40
+};
+
+s! {
+    pub struct utmpx {
+        pub ut_name: [c_char; _UTX_USERSIZE],
+        pub ut_id: [c_char; _UTX_IDSIZE],
+        pub ut_line: [c_char; _UTX_LINESIZE],
+        pub ut_host: [c_char; _UTX_HOSTSIZE],
+        pub ut_session: u16,
+        pub ut_type: u16,
+        pub ut_pid: crate::pid_t,
+        pub ut_exit: __exit_status, // FIXME(netbsd): when anonymous struct are supported
+        pub ut_ss: crate::sockaddr_storage,
+        pub ut_tv: crate::timeval,
+        ut_pad: [u8; _UTX_PADSIZE],
+    }
+
+    pub struct __exit_status {
+        pub e_termination: u16,
+        pub e_exit: u16,
+    }
+
+    pub struct lastlogx {
+        pub ll_tv: crate::timeval,
+        pub ll_line: [c_char; _UTX_LINESIZE],
+        pub ll_host: [c_char; _UTX_HOSTSIZE],
+        pub ll_ss: crate::sockaddr_storage,
+    }
+}
+
+#[link(name = "util")]
+extern "C" {
+    pub fn setutxent();
+    pub fn endutxent();
+
+    pub fn getutxent() -> *mut utmpx;
+    pub fn getutxid(ut: *const utmpx) -> *mut utmpx;
+    pub fn getutxline(ut: *const utmpx) -> *mut utmpx;
+    pub fn pututxline(ut: *const utmpx) -> *mut utmpx;
+
+    pub fn updwtmpx(file: *const c_char, ut: *const utmpx) -> c_int;
+    pub fn getlastlogx(fname: *const c_char, uid: crate::uid_t, ll: *mut lastlogx)
+        -> *mut lastlogx;
+    pub fn updlastlogx(fname: *const c_char, uid: crate::uid_t, ll: *mut lastlogx) -> c_int;
+    pub fn getutmp(ux: *const utmpx, u: *mut crate::utmp);
+    pub fn getutmpx(u: *const crate::utmp, ux: *mut utmpx);
+    pub fn utmpxname(file: *const c_char) -> c_int;
+}

src/unix/bsd/netbsdlike/netbsd/mod.rs

@@ -419,11 +419,6 @@ s! {
         pub sdl_data: [c_char; 24],
     }
 
-    pub struct __exit_status {
-        pub e_termination: u16,
-        pub e_exit: u16,
-    }
-
     pub struct shmid_ds {
         pub shm_perm: crate::ipc_perm,
         pub shm_segsz: size_t,
@@ -780,27 +775,6 @@ s! {
         pub __tcpi_pad: [u32; 26],
     }
 
-    pub struct utmpx {
-        pub ut_name: [c_char; _UTX_USERSIZE],
-        pub ut_id: [c_char; _UTX_IDSIZE],
-        pub ut_line: [c_char; _UTX_LINESIZE],
-        pub ut_host: [c_char; _UTX_HOSTSIZE],
-        pub ut_session: u16,
-        pub ut_type: u16,
-        pub ut_pid: crate::pid_t,
-        pub ut_exit: __exit_status, // FIXME(netbsd): when anonymous struct are supported
-        pub ut_ss: sockaddr_storage,
-        pub ut_tv: crate::timeval,
-        pub ut_pad: [u8; _UTX_PADSIZE],
-    }
-
-    pub struct lastlogx {
-        pub ll_tv: crate::timeval,
-        pub ll_line: [c_char; _UTX_LINESIZE],
-        pub ll_host: [c_char; _UTX_HOSTSIZE],
-        pub ll_ss: sockaddr_storage,
-    }
-
     pub struct in_pktinfo {
         pub ipi_addr: crate::in_addr,
         pub ipi_ifindex: c_uint,
@@ -1799,28 +1773,6 @@ pub const ONLRET: crate::tcflag_t = 0x40;
 pub const CDTRCTS: crate::tcflag_t = 0x00020000;
 pub const CHWFLOW: crate::tcflag_t = crate::MDMBUF | crate::CRTSCTS | crate::CDTRCTS;
 
-// pub const _PATH_UTMPX: &[c_char; 14] = b"/var/run/utmpx";
-// pub const _PATH_WTMPX: &[c_char; 14] = b"/var/log/wtmpx";
-// pub const _PATH_LASTLOGX: &[c_char; 17] = b"/var/log/lastlogx";
-// pub const _PATH_UTMP_UPDATE: &[c_char; 24] = b"/usr/libexec/utmp_update";
-pub const _UTX_USERSIZE: usize = 32;
-pub const _UTX_LINESIZE: usize = 32;
-pub const _UTX_PADSIZE: usize = 40;
-pub const _UTX_IDSIZE: usize = 4;
-pub const _UTX_HOSTSIZE: usize = 256;
-pub const EMPTY: u16 = 0;
-pub const RUN_LVL: u16 = 1;
-pub const BOOT_TIME: u16 = 2;
-pub const OLD_TIME: u16 = 3;
-pub const NEW_TIME: u16 = 4;
-pub const INIT_PROCESS: u16 = 5;
-pub const LOGIN_PROCESS: u16 = 6;
-pub const USER_PROCESS: u16 = 7;
-pub const DEAD_PROCESS: u16 = 8;
-pub const ACCOUNTING: u16 = 9;
-pub const SIGNATURE: u16 = 10;
-pub const DOWN_TIME: u16 = 11;
-
 pub const SOCK_CLOEXEC: c_int = 0x10000000;
 pub const SOCK_NONBLOCK: c_int = 0x20000000;
 
@@ -2469,21 +2421,6 @@ extern "C" {
         result: *mut *mut crate::group,
     ) -> c_int;
 
-    pub fn updwtmpx(file: *const c_char, ut: *const utmpx) -> c_int;
-    pub fn getlastlogx(fname: *const c_char, uid: crate::uid_t, ll: *mut lastlogx)
-        -> *mut lastlogx;
-    pub fn updlastlogx(fname: *const c_char, uid: crate::uid_t, ll: *mut lastlogx) -> c_int;
-    pub fn utmpxname(file: *const c_char) -> c_int;
-    pub fn getutxent() -> *mut utmpx;
-    pub fn getutxid(ut: *const utmpx) -> *mut utmpx;
-    pub fn getutxline(ut: *const utmpx) -> *mut utmpx;
-    pub fn pututxline(ut: *const utmpx) -> *mut utmpx;
-    pub fn setutxent();
-    pub fn endutxent();
-
-    pub fn getutmp(ux: *const utmpx, u: *mut crate::utmp);
-    pub fn getutmpx(u: *const crate::utmp, ux: *mut utmpx);
-
     pub fn efopen(p: *const c_char, m: *const c_char) -> crate::FILE;
     pub fn emalloc(n: size_t) -> *mut c_void;
     pub fn ecalloc(n: size_t, c: size_t) -> *mut c_void;
@@ -2547,7 +2484,7 @@ extern "C" {
     #[link_name = "__login50"]
     pub fn login(ut: *const crate::utmp);
     #[link_name = "__loginx50"]
-    pub fn loginx(ut: *const utmpx);
+    pub fn loginx(ut: *const crate::utmpx);
     pub fn logout(line: *const c_char);
     pub fn logoutx(line: *const c_char, status: c_int, tpe: c_int);
     pub fn logwtmp(line: *const c_char, name: *const c_char, host: *const c_char);