Merge branch 'unlinkat-symlinkat-linkat' into 'master'

add unlinkat(2), symlinkat(2), linkat(2) and expose openat(2)

See merge request redox-os/relibc!1212

src/header/fcntl/mod.rs

@@ -80,6 +80,17 @@ pub unsafe extern "C" fn fcntl(fildes: c_int, cmd: c_int, mut __valist: ...) ->
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/open.html>.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn open(path: *const c_char, oflag: c_int, mut __valist: ...) -> c_int {
+    unsafe { openat(AT_FDCWD, path, oflag, __valist) }
+}
+
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/openat.html>.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn openat(
+    fd: c_int,
+    path: *const c_char,
+    oflag: c_int,
+    mut __valist: ...
+) -> c_int {
     let mode = if oflag & O_CREAT == O_CREAT
     /* || oflag & O_TMPFILE == O_TMPFILE */
     {
@@ -89,7 +100,7 @@ pub unsafe extern "C" fn open(path: *const c_char, oflag: c_int, mut __valist: .
     };
 
     let path = unsafe { CStr::from_ptr(path) };
-    Sys::open(path, oflag, mode).or_minus_one_errno()
+    Sys::openat(fd, path, oflag, mode).or_minus_one_errno()
 }
 
 #[unsafe(no_mangle)]

src/header/fcntl/redox.rs

@@ -31,5 +31,6 @@ pub const O_NDELAY: c_int = O_NONBLOCK;
 // Flags for capability based "at" functions
 pub const AT_FDCWD: c_int = -100;
 pub const AT_SYMLINK_NOFOLLOW: c_int = 0x0200;
+pub const AT_SYMLINK_FOLLOW: c_int = 0x2000;
 pub const AT_EMPTY_PATH: c_int = 0x4000;
 pub const AT_REMOVEDIR: c_int = 0x200;

src/header/unistd/mod.rs

@@ -577,7 +577,7 @@ pub unsafe extern "C" fn gethostname(mut name: *mut c_char, mut len: size_t) ->
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/getlogin.html>.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn getlogin() -> *mut c_char {
-    const LOGIN_LEN: usize = 256;
+    const LOGIN_LEN: usize = limits::LOGIN_NAME_MAX as usize;
     static mut LOGIN: [c_char; LOGIN_LEN] = [0; LOGIN_LEN];
     if getlogin_r((&raw mut LOGIN).cast(), LOGIN_LEN) == 0 {
         (&raw mut LOGIN).cast()
@@ -707,6 +707,22 @@ pub unsafe extern "C" fn link(path1: *const c_char, path2: *const c_char) -> c_i
     Sys::link(path1, path2).map(|()| 0).or_minus_one_errno()
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/linkat.html>.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn linkat(
+    fd1: c_int,
+    path1: *const c_char,
+    fd2: c_int,
+    path2: *const c_char,
+    flags: c_int,
+) -> c_int {
+    let path1 = unsafe { CStr::from_ptr(path1) };
+    let path2 = unsafe { CStr::from_ptr(path2) };
+    Sys::linkat(fd1, path1, fd2, path2, flags)
+        .map(|()| 0)
+        .or_minus_one_errno()
+}
+
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/lockf.html>.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn lockf(fildes: c_int, function: c_int, size: off_t) -> c_int {
@@ -1010,6 +1026,16 @@ pub unsafe extern "C" fn symlink(path1: *const c_char, path2: *const c_char) ->
     Sys::symlink(path1, path2).map(|()| 0).or_minus_one_errno()
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/symlinkat.html>.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn symlinkat(path1: *const c_char, fd: c_int, path2: *const c_char) -> c_int {
+    let path1 = unsafe { CStr::from_ptr(path1) };
+    let path2 = unsafe { CStr::from_ptr(path2) };
+    Sys::symlinkat(path1, fd, path2)
+        .map(|()| 0)
+        .or_minus_one_errno()
+}
+
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/sync.html>.
 #[unsafe(no_mangle)]
 pub extern "C" fn sync() {
@@ -1123,6 +1149,15 @@ pub unsafe extern "C" fn unlink(path: *const c_char) -> c_int {
     Sys::unlink(path).map(|()| 0).or_minus_one_errno()
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/unlinkat.html>.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn unlinkat(fd: c_int, path: *const c_char, flags: c_int) -> c_int {
+    let path = unsafe { CStr::from_ptr(path) };
+    Sys::unlinkat(fd, path, flags)
+        .map(|()| 0)
+        .or_minus_one_errno()
+}
+
 /// See <https://pubs.opengroup.org/onlinepubs/009695399/functions/usleep.html>.
 ///
 /// # Deprecation