Have internal/external/pipelines taken an optional InputStream. (#1182)

Primarily, this fixes an issue where we always open a stdin pipe for
external commands, which can break various interactive commands (e.g.,
editors).

src/cli.rs

@@ -607,8 +607,7 @@ async fn process_line(readline: Result<String, ReadlineError>, ctx: &mut Context
                 return LineResult::Error(line.to_string(), err);
             }
 
-            let input = InputStream::empty();
-            match run_pipeline(pipeline, ctx, input, line).await {
+            match run_pipeline(pipeline, ctx, None, line).await {
                 Ok(_) => LineResult::Success(line.to_string()),
                 Err(err) => LineResult::Error(line.to_string(), err),
             }

src/commands/classified/external.rs

@@ -51,9 +51,9 @@ impl Decoder for LinesCodec {
 pub(crate) async fn run_external_command(
     command: ExternalCommand,
     context: &mut Context,
-    input: InputStream,
+    input: Option<InputStream>,
     is_last: bool,
-) -> Result<InputStream, ShellError> {
+) -> Result<Option<InputStream>, ShellError> {
     trace!(target: "nu::run::external", "-> {}", command.name);
 
     let has_it_arg = command.args.iter().any(|arg| arg.contains("$it"));
@@ -67,13 +67,13 @@ pub(crate) async fn run_external_command(
 async fn run_with_iterator_arg(
     command: ExternalCommand,
     context: &mut Context,
-    input: InputStream,
+    input: Option<InputStream>,
     is_last: bool,
-) -> Result<InputStream, ShellError> {
+) -> Result<Option<InputStream>, ShellError> {
     let name = command.name;
     let args = command.args;
     let name_tag = command.name_tag;
-    let inputs = input.into_vec().await;
+    let inputs = input.unwrap_or_else(InputStream::empty).into_vec().await;
 
     trace!(target: "nu::run::external", "inputs = {:?}", inputs);
 
@@ -137,7 +137,7 @@ async fn run_with_iterator_arg(
     if let Ok(mut popen) = popen {
         if is_last {
             let _ = popen.wait();
-            Ok(InputStream::empty())
+            Ok(None)
         } else {
             let stdout = popen.stdout.take().ok_or_else(|| {
                 ShellError::untagged_runtime_error("Can't redirect the stdout for external command")
@@ -148,7 +148,7 @@ async fn run_with_iterator_arg(
                 line.expect("Internal error: could not read lines of text from stdin")
                     .into_value(&name_tag)
             });
-            Ok(stream.boxed().into())
+            Ok(Some(stream.boxed().into()))
         }
     } else {
         Err(ShellError::labeled_error(
@@ -162,9 +162,9 @@ async fn run_with_iterator_arg(
 async fn run_with_stdin(
     command: ExternalCommand,
     context: &mut Context,
-    mut input: InputStream,
+    input: Option<InputStream>,
     is_last: bool,
-) -> Result<InputStream, ShellError> {
+) -> Result<Option<InputStream>, ShellError> {
     let name_tag = command.name_tag;
     let home_dir = dirs::home_dir();
 
@@ -192,19 +192,22 @@ async fn run_with_stdin(
         trace!(target: "nu::run::external", "set up stdout pipe");
     }
 
+    if input.is_some() {
         process = process.stdin(subprocess::Redirection::Pipe);
         trace!(target: "nu::run::external", "set up stdin pipe");
+    }
 
     trace!(target: "nu::run::external", "built process {:?}", process);
 
     let popen = process.detached().popen();
     if let Ok(mut popen) = popen {
+        let stream = async_stream! {
+            if let Some(mut input) = input {
                 let mut stdin_write = popen
                     .stdin
                     .take()
                     .expect("Internal error: could not get stdin pipe for external command");
 
-        let stream = async_stream! {
                 while let Some(item) = input.next().await {
                     match item.value {
                         UntaggedValue::Primitive(Primitive::Nothing) => {
@@ -247,6 +250,7 @@ async fn run_with_stdin(
 
                 // Close stdin, which informs the external process that there's no more input
                 drop(stdin_write);
+            }
 
             if !is_last {
                 let stdout = if let Some(stdout) = popen.stdout.take() {
@@ -302,7 +306,7 @@ async fn run_with_stdin(
             };
         };
 
-        Ok(stream.to_input_stream())
+        Ok(Some(stream.to_input_stream()))
     } else {
         Err(ShellError::labeled_error(
             "Command not found",

src/commands/classified/internal.rs

@@ -8,16 +8,20 @@ use nu_protocol::{CommandAction, Primitive, ReturnSuccess, UntaggedValue, Value}
 pub(crate) async fn run_internal_command(
     command: InternalCommand,
     context: &mut Context,
-    input: InputStream,
+    input: Option<InputStream>,
     source: Text,
-) -> Result<InputStream, ShellError> {
+) -> Result<Option<InputStream>, ShellError> {
     if log_enabled!(log::Level::Trace) {
         trace!(target: "nu::run::internal", "->");
         trace!(target: "nu::run::internal", "{}", command.name);
         trace!(target: "nu::run::internal", "{}", command.args.debug(&source));
     }
 
-    let objects: InputStream = trace_stream!(target: "nu::trace_stream::internal", "input" = input);
+    let objects: InputStream = if let Some(input) = input {
+        trace_stream!(target: "nu::trace_stream::internal", "input" = input)
+    } else {
+        InputStream::empty()
+    };
 
     let internal_command = context.expect_command(&command.name);
 
@@ -167,5 +171,5 @@ pub(crate) async fn run_internal_command(
         }
     };
 
-    Ok(stream.to_input_stream())
+    Ok(Some(stream.to_input_stream()))
 }

src/commands/classified/pipeline.rs

@@ -11,7 +11,7 @@ use std::sync::atomic::Ordering;
 pub(crate) async fn run_pipeline(
     pipeline: ClassifiedPipeline,
     ctx: &mut Context,
-    mut input: InputStream,
+    mut input: Option<InputStream>,
     line: &str,
 ) -> Result<(), ShellError> {
     let mut iter = pipeline.commands.list.into_iter().peekable();
@@ -46,6 +46,7 @@ pub(crate) async fn run_pipeline(
     }
 
     use futures::stream::TryStreamExt;
+    if let Some(input) = input {
         let mut output_stream: OutputStream = input.into();
         loop {
             match output_stream.try_next().await {
@@ -63,6 +64,7 @@ pub(crate) async fn run_pipeline(
                 }
             }
         }
+    }
 
     Ok(())
 }