add support for access/faccessat

Author: Mic92

CHANGELOG.md

@@ -10,8 +10,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
   ([#611](https://github.com/nix-rust/nix/pull/609)
 - Added `AioCb::from_boxed_slice`
   ([#582](https://github.com/nix-rust/nix/pull/582)
-- Added `nix::unistd::{openat, fstatat, readlink, readlinkat, rename, renameat, mknodat, unlinkat, mkdirat, link, linkat, symlink, symlinkat}`
-  ([#497](https://github.com/nix-rust/nix/pull/551))
+- Added `nix::unistd::{openat, fstatat, readlink, readlinkat, rename, renameat, mknodat, unlinkat, mkdirat, link, linkat, symlink, symlinkat, access, faccessat}`
+  ([#552](https://github.com/nix-rust/nix/pull/552), [#561](https://github.com/nix-rust/nix/pull/561))
 - Added `nix::pty::{grantpt, posix_openpt, ptsname/ptsname_r, unlockpt}`
   ([#556](https://github.com/nix-rust/nix/pull/556)
 

src/unistd.rs

@@ -44,6 +44,15 @@ impl ForkResult {
     }
 }
 
+libc_bitflags!{
+    pub flags AccessMode: c_int {
+        R_OK,
+        W_OK,
+        X_OK,
+        F_OK
+    }
+}
+
 /// Create a new child process duplicating the parent process ([see
 /// fork(2)](http://man7.org/linux/man-pages/man2/fork.2.html)).
 ///
@@ -787,6 +796,24 @@ pub fn unlinkat<P: ?Sized + NixPath>(fd: RawFd, pathname: &P, flags: AtFlags) ->
     Errno::result(res).map(drop)
 }
 
+/// check user's permissions for a file
+/// ([see access(2)](http://man7.org/linux/man-pages/man2/access.2.html))
+pub fn access<P: ?Sized + NixPath>(pathname: &P, mode: AccessMode) -> Result<()> {
+    let res = try!(pathname.with_nix_path(|cstr| {
+        unsafe { libc::access(cstr.as_ptr(), mode.bits()) }
+    }));
+    Errno::result(res).map(drop)
+}
+
+/// check user's permissions for a file
+/// ([see faccessat(2)](http://man7.org/linux/man-pages/man2/faccessat.2.html))
+pub fn faccessat<P: ?Sized + NixPath>(dirfd: RawFd, pathname: &P, mode: AccessMode, flags: AtFlags) -> Result<()> {
+    let res = try!(pathname.with_nix_path(|cstr| {
+        unsafe { libc::faccessat(dirfd, cstr.as_ptr(), mode.bits(), flags.bits()) }
+    }));
+    Errno::result(res).map(drop)
+}
+
 #[inline]
 pub fn chroot<P: ?Sized + NixPath>(path: &P) -> Result<()> {
     let res = try!(path.with_nix_path(|cstr| {

test/test_unistd.rs

@@ -102,15 +102,33 @@ fn test_mkdirat() {
     let path = tempdir.path().join("test_path");
 
     let dirfd = fcntl::open(tempdir.path(),
-    fcntl::OFlag::empty(),
-    stat::Mode::empty());
+                            fcntl::OFlag::empty(),
+                            stat::Mode::empty());
 
     mkdirat(dirfd.unwrap(),
-    &path.file_name(),
-    stat::Mode::empty()).unwrap();
+            &path.file_name(),
+            stat::Mode::empty()).unwrap();
     assert!(path.exists());
 }
 
+#[test]
+fn test_access() {
+    let tempdir = TempDir::new("nix-test_mkdirat").unwrap();
+
+    let dirfd = fcntl::open(tempdir.path().parent().unwrap(),
+                            fcntl::OFlag::empty(),
+                            stat::Mode::empty());
+
+    // if succeed, permissions are or ok
+    access(tempdir.path(), R_OK | X_OK | W_OK).unwrap();
+
+    faccessat(dirfd.unwrap(),
+              &tempdir.path().file_name(),
+              R_OK | X_OK | W_OK,
+              fcntl::AtFlags::empty()).unwrap();
+
+}
+
 macro_rules! execve_test_factory(
     ($test_name:ident, $syscall:ident, $unix_sh:expr, $android_sh:expr) => (
     #[test]