add support for symlink|symlinkat

Author: Mic92

CHANGELOG.md

@@ -24,6 +24,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
   ([#739](https://github.com/nix-rust/nix/pull/739))
 - Added nix::sys::ptrace::detach. 
   ([#749](https://github.com/nix-rust/nix/pull/749))
+- Added nix::unistd::{symlink,symlinkat}.
+  ([#756](https://github.com/nix-rust/nix/pull/756))
 
 ### Changed
 - Renamed existing `ptrace` wrappers to encourage namespacing ([#692](https://github.com/nix-rust/nix/pull/692))

src/unistd.rs

@@ -812,6 +812,39 @@ pub fn lseek64(fd: RawFd, offset: libc::off64_t, whence: Whence) -> Result<libc:
     Errno::result(res).map(|r| r as libc::off64_t)
 }
 
+/// Make a new name for a file
+/// ([see symlink(2)](http://man7.org/linux/man-pages/man2/symlink.2.html)).
+pub fn symlink<P1: ?Sized + NixPath, P2: ?Sized + NixPath>(target: &P1,
+                                                           linkpath: &P2) -> Result<()> {
+    let res = try!(try!(target.with_nix_path(|t|
+        linkpath.with_nix_path(|l|
+            unsafe {
+                libc::symlink(t.as_ptr() as *const c_char, l.as_ptr() as *const c_char)
+            }
+        )
+    )));
+
+    Errno::result(res).map(drop)
+}
+
+/// Make a new name for a file
+/// ([see symlinkat(2)](http://man7.org/linux/man-pages/man2/symlinkat.2.html)).
+pub fn symlinkat<P1: ?Sized + NixPath, P2: ?Sized + NixPath>(target: &P1,
+                                                             newdirfd: RawFd,
+                                                             linkpath: &P2) -> Result<()> {
+    let res = try!(try!(target.with_nix_path(|t|
+        linkpath.with_nix_path(|l|
+            unsafe {
+                libc::symlinkat(t.as_ptr() as *const c_char,
+                                newdirfd,
+                                l.as_ptr() as *const c_char)
+            }
+        )
+    )));
+
+    Errno::result(res).map(drop)
+}
+
 pub fn pipe() -> Result<(RawFd, RawFd)> {
     unsafe {
         let mut fds: [c_int; 2] = mem::uninitialized();

test/test_fcntl.rs

@@ -1,10 +1,9 @@
 use nix::fcntl::{openat, open, OFlag, O_RDONLY, readlink, readlinkat};
 use nix::sys::stat::Mode;
-use nix::unistd::{close, read};
+use nix::unistd::{close, read, symlink, symlinkat};
 use tempdir::TempDir;
 use tempfile::NamedTempFile;
 use std::io::prelude::*;
-use std::os::unix::fs;
 
 #[test]
 fn test_openat() {
@@ -30,19 +29,29 @@ fn test_openat() {
 
 #[test]
 fn test_readlink() {
-    let tempdir = TempDir::new("nix-test_readdir")
+    let tempdir = TempDir::new("nix-test_readdlink")
+        .unwrap_or_else(|e| panic!("tempdir failed: {}", e));
+    let src = tempdir.path().join("a");
+    let dst = tempdir.path().join("b");
+    symlink(src.as_path(), dst.as_path()).unwrap();
+
+    let mut buf = vec![0; src.to_str().unwrap().len() + 1];
+    assert_eq!(readlink(&dst, &mut buf).unwrap().to_str().unwrap(),
+               src.to_str().unwrap());
+}
+
+#[test]
+fn test_readlinkat() {
+    let tempdir = TempDir::new("nix-test_readlinkat")
         .unwrap_or_else(|e| panic!("tempdir failed: {}", e));
     let src = tempdir.path().join("a");
     let dst = tempdir.path().join("b");
-    println!("a: {:?}, b: {:?}", &src, &dst);
-    fs::symlink(&src.as_path(), &dst.as_path()).unwrap();
     let dirfd = open(tempdir.path(),
                      OFlag::empty(),
                      Mode::empty()).unwrap();
+    symlinkat(src.as_path(), dirfd, dst.file_name().unwrap()).unwrap();
 
     let mut buf = vec![0; src.to_str().unwrap().len() + 1];
-    assert_eq!(readlink(&dst, &mut buf).unwrap().to_str().unwrap(),
-               src.to_str().unwrap());
     assert_eq!(readlinkat(dirfd, "b", &mut buf).unwrap().to_str().unwrap(),
                src.to_str().unwrap());
 }