Auto merge of #43051 - Mark-Simulacrum:rollup, r=Mark-Simulacrum

Rollup of 8 pull requests

- Successful merges: #42227, #42836, #42975, #42994, #43041, #43042, #43043, #43045
- Failed merges:

5 files changed, 27 insertions, 18 deletions

diff --git a/src/libstd/ffi/c_str.rs b/src/libstd/ffi/c_str.rs
index 1a91417ca0e..5f0b11a616e 100644
--- a/src/libstd/ffi/c_str.rs
+++ b/src/libstd/ffi/c_str.rs
@@ -585,11 +585,11 @@ impl From<Box<CStr>> for CString {
     }
 }
 
-#[stable(feature = "box_from_c_string", since = "1.18.0")]
-impl Into<Box<CStr>> for CString {
+#[stable(feature = "box_from_c_string", since = "1.20.0")]
+impl From<CString> for Box<CStr> {
     #[inline]
-    fn into(self) -> Box<CStr> {
-        self.into_boxed_c_str()
+    fn from(s: CString) -> Box<CStr> {
+        s.into_boxed_c_str()
     }
 }
 
diff --git a/src/libstd/ffi/os_str.rs b/src/libstd/ffi/os_str.rs
index 42d641706a8..02a13ed7a5a 100644
--- a/src/libstd/ffi/os_str.rs
+++ b/src/libstd/ffi/os_str.rs
@@ -540,10 +540,10 @@ impl From<Box<OsStr>> for OsString {
     }
 }
 
-#[stable(feature = "box_from_os_string", since = "1.18.0")]
-impl Into<Box<OsStr>> for OsString {
-    fn into(self) -> Box<OsStr> {
-        self.into_boxed_os_str()
+#[stable(feature = "box_from_os_string", since = "1.20.0")]
+impl From<OsString> for Box<OsStr> {
+    fn from(s: OsString) -> Box<OsStr> {
+        s.into_boxed_os_str()
     }
 }
 
diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index 472ce6bc4fe..e7c7be981d2 100644
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -1348,10 +1348,10 @@ impl From<Box<Path>> for PathBuf {
     }
 }
 
-#[stable(feature = "box_from_path_buf", since = "1.18.0")]
-impl Into<Box<Path>> for PathBuf {
-    fn into(self) -> Box<Path> {
-        self.into_boxed_path()
+#[stable(feature = "box_from_path_buf", since = "1.20.0")]
+impl From<PathBuf> for Box<Path> {
+    fn from(p: PathBuf) -> Box<Path> {
+        p.into_boxed_path()
     }
 }
 
diff --git a/src/libstd/sys/redox/fs.rs b/src/libstd/sys/redox/fs.rs
index 48d9cdcb2c9..c5a19e8debe 100644
--- a/src/libstd/sys/redox/fs.rs
+++ b/src/libstd/sys/redox/fs.rs
@@ -420,12 +420,19 @@ fn remove_dir_all_recursive(path: &Path) -> io::Result<()> {
 }
 
 pub fn readlink(p: &Path) -> io::Result<PathBuf> {
-    canonicalize(p)
-}
-
-pub fn symlink(_src: &Path, _dst: &Path) -> io::Result<()> {
-    ::sys_common::util::dumb_print(format_args!("Symlink\n"));
-    unimplemented!();
+    let fd = cvt(syscall::open(p.to_str().unwrap(), syscall::O_SYMLINK | syscall::O_RDONLY))?;
+    let mut buf: [u8; 4096] = [0; 4096];
+    let count = cvt(syscall::read(fd, &mut buf))?;
+    cvt(syscall::close(fd))?;
+    Ok(PathBuf::from(unsafe { String::from_utf8_unchecked(Vec::from(&buf[..count])) }))
+}
+
+pub fn symlink(src: &Path, dst: &Path) -> io::Result<()> {
+    let fd = cvt(syscall::open(dst.to_str().unwrap(),
+                               syscall::O_SYMLINK | syscall::O_CREAT | syscall::O_WRONLY | 0o777))?;
+    cvt(syscall::write(fd, src.to_str().unwrap().as_bytes()))?;
+    cvt(syscall::close(fd))?;
+    Ok(())
 }
 
 pub fn link(_src: &Path, _dst: &Path) -> io::Result<()> {
diff --git a/src/libstd/sys/redox/syscall/flag.rs b/src/libstd/sys/redox/syscall/flag.rs
index 9f0d3e6f779..bd603cfe6ef 100644
--- a/src/libstd/sys/redox/syscall/flag.rs
+++ b/src/libstd/sys/redox/syscall/flag.rs
@@ -33,6 +33,7 @@ pub const MAP_WRITE_COMBINE: usize = 2;
 pub const MODE_TYPE: u16 = 0xF000;
 pub const MODE_DIR: u16 = 0x4000;
 pub const MODE_FILE: u16 = 0x8000;
+pub const MODE_SYMLINK: u16 = 0xA000;
 
 pub const MODE_PERM: u16 = 0x0FFF;
 pub const MODE_SETUID: u16 = 0o4000;
@@ -53,6 +54,7 @@ pub const O_TRUNC: usize =      0x0400_0000;
 pub const O_EXCL: usize =       0x0800_0000;
 pub const O_DIRECTORY: usize =  0x1000_0000;
 pub const O_STAT: usize =       0x2000_0000;
+pub const O_SYMLINK: usize =    0x4000_0000;
 pub const O_ACCMODE: usize =    O_RDONLY | O_WRONLY | O_RDWR;
 
 pub const SEEK_SET: usize = 0;