fix stderr logging #23

e.g:
    cmd_info!("Memory usage (free -m):");
    run_cmd!(free -m >&2)?;
to logs:
INFO - memory usage (free -m):
INFO -               total        used        free      shared  buff/cache   available
INFO - Mem:           7709        2003        1070         656        4635        4675
INFO - Swap:          8191          11        8180

Author: tao-guo

src/child.rs

@@ -6,10 +6,12 @@ use std::process::{Child, ExitStatus};
 use std::thread::JoinHandle;
 use CmdChild::{ProcChild, SyncChild, ThreadChild};
 
+#[derive(Debug)]
 pub enum CmdChild {
     ProcChild {
         child: Child,
         cmd: String,
+        stderr: Option<PipeReader>,
     },
     ThreadChild {
         child: JoinHandle<CmdResult>,
@@ -35,9 +37,13 @@ impl CmdChild {
             Ok(())
         };
         match self {
-            ProcChild { mut child, cmd } => {
+            ProcChild {
+                mut child,
+                stderr,
+                cmd,
+            } => {
+                Self::log_stderr_output(stderr);
                 let status = child.wait()?;
-                Self::log_stderr_output(child.stderr);
                 if !status.success() && (is_last || pipefail) {
                     return Err(Self::status_to_io_error(
                         status,
@@ -76,9 +82,9 @@ impl CmdChild {
 
     pub fn wait_with_output(self) -> Result<Vec<u8>> {
         match self {
-            ProcChild { child, cmd } => {
+            ProcChild { child, cmd, stderr } => {
+                Self::log_stderr_output(stderr);
                 let output = child.wait_with_output()?;
-                Self::log_stderr_output(Some(&output.stderr[..]));
                 if !output.status.success() {
                     return Err(Self::status_to_io_error(
                         output.status,

src/io.rs

@@ -3,6 +3,7 @@ use std::fs::File;
 use std::io::{Read, Result, Write};
 use std::process::Stdio;
 
+#[derive(Debug)]
 pub enum CmdIn {
     CmdNull,
     CmdFile(File),
@@ -29,6 +30,7 @@ impl From<CmdIn> for Stdio {
     }
 }
 
+#[derive(Debug)]
 pub enum CmdOut {
     CmdNull,
     CmdFile(File),

src/process.rs

@@ -431,7 +431,6 @@ impl Cmd {
             let cmds: Vec<String> = self.args.to_vec();
             let mut cmd = Command::new(&cmds[0]);
             cmd.args(&cmds[1..]);
-            cmd.stderr(Stdio::piped());
             for (k, v) in self.vars.iter() {
                 cmd.env(k, v);
             }
@@ -524,6 +523,7 @@ impl Cmd {
             let child = cmd.spawn()?;
             Ok(CmdChild::ProcChild {
                 cmd: full_cmd,
+                stderr: self.stderr_logging,
                 child,
             })
         }
@@ -571,12 +571,10 @@ impl Cmd {
         pipe_in: &mut Option<PipeReader>,
         pipe_out: Option<PipeWriter>,
     ) -> CmdResult {
-        if self.in_cmd_map {
-            // set up error pipe
-            let (pipe_reader, pipe_writer) = os_pipe::pipe()?;
-            self.stderr_redirect = Some(CmdOut::CmdPipe(pipe_writer));
-            self.stderr_logging = Some(pipe_reader);
-        }
+        // set up error pipe
+        let (pipe_reader, pipe_writer) = os_pipe::pipe()?;
+        self.stderr_redirect = Some(CmdOut::CmdPipe(pipe_writer));
+        self.stderr_logging = Some(pipe_reader);
 
         if let Some(pipe) = pipe_in.take() {
             self.stdin_redirect = Some(CmdIn::CmdPipe(pipe));
@@ -598,14 +596,14 @@ impl Cmd {
                     if let Some(ref redirect) = self.stderr_redirect {
                         self.stdout_redirect = Some(redirect.try_clone()?);
                     } else {
-                        self.stdout_redirect = Some(CmdOut::CmdPipe(os_pipe::dup_stdout()?));
+                        self.stdout_redirect = Some(CmdOut::CmdPipe(os_pipe::dup_stderr()?));
                     }
                 }
                 Redirect::StderrToStdout => {
                     if let Some(ref redirect) = self.stdout_redirect {
                         self.stderr_redirect = Some(redirect.try_clone()?);
                     } else {
-                        self.stderr_redirect = Some(CmdOut::CmdPipe(os_pipe::dup_stderr()?));
+                        self.stderr_redirect = Some(CmdOut::CmdPipe(os_pipe::dup_stdout()?));
                     }
                 }
                 Redirect::StdoutToFile(path, append) => {