utmpx api for linux musl.

close rust-lang#3190

Author: devnexen

libc-test/semver/linux-gnu.txt

@@ -617,12 +617,12 @@ dlinfo
 dlmopen
 endutxent
 explicit_bzero
+fgetgrent_r
 fgetspent_r
 futimes
 getauxval
 getentropy
 getgrent_r
-fgetgrent_r
 getloadavg
 getpt
 getpwent_r

libc-test/semver/linux-musl.txt

@@ -56,13 +56,22 @@ aio_return
 aio_suspend
 aio_write
 aiocb
+asctime_r
+basename
 clock_adjtime
 copy_file_range
 ctermid
+dirname
+eaccess
+endutxent
+euidaccess
 explicit_bzero
 futimes
 getauxval
 getloadavg
+getutxent
+getutxid
+getutxline
 lio_listio
 ntptimeval
 open_wmemstream
@@ -71,14 +80,11 @@ prlimit
 prlimit64
 process_vm_readv
 process_vm_writev
+pututxline
 pwritev64
 reallocarray
-timex
-euidaccess
-eaccess
-asctime_r
+setutxent
 strftime
 strftime_l
 strptime
-dirname
-basename
+timex

src/unix/linux_like/linux/musl/mod.rs

@@ -896,6 +896,13 @@ extern "C" {
 
     pub fn dirname(path: *mut ::c_char) -> *mut ::c_char;
     pub fn basename(path: *mut ::c_char) -> *mut ::c_char;
+
+    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();
 }
 
 // Alias <foo> to <foo>64 to mimic glibc's LFS64 support