Add conversions from File and Child* handles to Stdio

`Stdio` now implements `From<ChildStdin>`, `From<ChildStdout>`,
`From<ChildStderr>`, and `From<File>`.

The `Command::stdin`/`stdout`/`stderr` methods now take any type that
implements `Into<Stdio>`.

This makes it much easier to write shell-like command chains, piping to
one another and redirecting to and from files.  Otherwise one would need
to use the unsafe and OS-specific `from_raw_fd` or `from_raw_handle`.

4 files changed, 71 insertions, 6 deletions

diff --git a/src/libstd/process.rs b/src/libstd/process.rs
index da64704efba..4c6d88c0ae8 100644
--- a/src/libstd/process.rs
+++ b/src/libstd/process.rs
@@ -59,6 +59,7 @@ use io::prelude::*;
 
 use ffi::OsStr;
 use fmt;
+use fs;
 use io;
 use path::Path;
 use str;
@@ -544,8 +545,8 @@ impl Command {
     ///         .expect("ls command failed to start");
     /// ```
     #[stable(feature = "process", since = "1.0.0")]
-    pub fn stdin(&mut self, cfg: Stdio) -> &mut Command {
-        self.inner.stdin(cfg.0);
+    pub fn stdin<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command {
+        self.inner.stdin(cfg.into().0);
         self
     }
 
@@ -564,8 +565,8 @@ impl Command {
     ///         .expect("ls command failed to start");
     /// ```
     #[stable(feature = "process", since = "1.0.0")]
-    pub fn stdout(&mut self, cfg: Stdio) -> &mut Command {
-        self.inner.stdout(cfg.0);
+    pub fn stdout<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command {
+        self.inner.stdout(cfg.into().0);
         self
     }
 
@@ -584,8 +585,8 @@ impl Command {
     ///         .expect("ls command failed to start");
     /// ```
     #[stable(feature = "process", since = "1.0.0")]
-    pub fn stderr(&mut self, cfg: Stdio) -> &mut Command {
-        self.inner.stderr(cfg.0);
+    pub fn stderr<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command {
+        self.inner.stderr(cfg.into().0);
         self
     }
 
@@ -753,6 +754,34 @@ impl fmt::Debug for Stdio {
     }
 }
 
+#[stable(feature = "stdio_from", since = "1.20.0")]
+impl From<ChildStdin> for Stdio {
+    fn from(child: ChildStdin) -> Stdio {
+        Stdio::from_inner(child.into_inner().into())
+    }
+}
+
+#[stable(feature = "stdio_from", since = "1.20.0")]
+impl From<ChildStdout> for Stdio {
+    fn from(child: ChildStdout) -> Stdio {
+        Stdio::from_inner(child.into_inner().into())
+    }
+}
+
+#[stable(feature = "stdio_from", since = "1.20.0")]
+impl From<ChildStderr> for Stdio {
+    fn from(child: ChildStderr) -> Stdio {
+        Stdio::from_inner(child.into_inner().into())
+    }
+}
+
+#[stable(feature = "stdio_from", since = "1.20.0")]
+impl From<fs::File> for Stdio {
+    fn from(file: fs::File) -> Stdio {
+        Stdio::from_inner(file.into_inner().into())
+    }
+}
+
 /// Describes the result of a process after it has terminated.
 ///
 /// This `struct` is used to represent the exit status of a child process.
diff --git a/src/libstd/sys/redox/process.rs b/src/libstd/sys/redox/process.rs
index 95e9438cd71..62d873d257d 100644
--- a/src/libstd/sys/redox/process.rs
+++ b/src/libstd/sys/redox/process.rs
@@ -400,6 +400,18 @@ impl Stdio {
     }
 }
 
+impl From<AnonPipe> for Stdio {
+    fn from(pipe: AnonPipe) -> Stdio {
+        Stdio::Fd(pipe.into_fd())
+    }
+}
+
+impl From<File> for Stdio {
+    fn from(file: File) -> Stdio {
+        Stdio::Fd(file.into_fd())
+    }
+}
+
 impl ChildStdio {
     fn fd(&self) -> Option<usize> {
         match *self {
diff --git a/src/libstd/sys/unix/process/process_common.rs b/src/libstd/sys/unix/process/process_common.rs
index e9f41009064..32fcee1e461 100644
--- a/src/libstd/sys/unix/process/process_common.rs
+++ b/src/libstd/sys/unix/process/process_common.rs
@@ -315,6 +315,18 @@ impl Stdio {
     }
 }
 
+impl From<AnonPipe> for Stdio {
+    fn from(pipe: AnonPipe) -> Stdio {
+        Stdio::Fd(pipe.into_fd())
+    }
+}
+
+impl From<File> for Stdio {
+    fn from(file: File) -> Stdio {
+        Stdio::Fd(file.into_fd())
+    }
+}
+
 impl ChildStdio {
     pub fn fd(&self) -> Option<c_int> {
         match *self {
diff --git a/src/libstd/sys/windows/process.rs b/src/libstd/sys/windows/process.rs
index 0bd0ce73138..0d1766d5aec 100644
--- a/src/libstd/sys/windows/process.rs
+++ b/src/libstd/sys/windows/process.rs
@@ -306,6 +306,18 @@ impl Stdio {
     }
 }
 
+impl From<AnonPipe> for Stdio {
+    fn from(pipe: AnonPipe) -> Stdio {
+        Stdio::Handle(pipe.into_handle())
+    }
+}
+
+impl From<File> for Stdio {
+    fn from(file: File) -> Stdio {
+        Stdio::Handle(file.into_handle())
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Processes
 ////////////////////////////////////////////////////////////////////////////////