Skip calling Windows console api with piped stdin

appveyor.yml

@@ -3,8 +3,8 @@ environment:
   - TARGET: x86_64-pc-windows-gnu
   - TARGET: i686-pc-windows-gnu
 install:
-  - ps: Start-FileDownload "https://static.rust-lang.org/dist/rust-1.33.0-${env:TARGET}.exe"
-  - rust-1.33.0-%TARGET%.exe /VERYSILENT /NORESTART /DIR="C:\Program Files (x86)\Rust"
+  - ps: Start-FileDownload "https://static.rust-lang.org/dist/rust-1.44.0-${env:TARGET}.exe"
+  - rust-1.44.0-%TARGET%.exe /VERYSILENT /NORESTART /DIR="C:\Program Files (x86)\Rust"
   - SET PATH=%PATH%;C:\Program Files (x86)\Rust\bin
   - SET PATH=%PATH%;C:\MinGW\bin
   - rustc -V

src/lib.rs

@@ -151,9 +151,9 @@ mod windows {
     use winapi::um::winnt::{
         GENERIC_READ, GENERIC_WRITE, FILE_SHARE_READ, FILE_SHARE_WRITE,
     };
-    use winapi::um::fileapi::{CreateFileA, OPEN_EXISTING};
+    use winapi::um::fileapi::{CreateFileA, GetFileType, OPEN_EXISTING};
     use winapi::um::processenv::GetStdHandle;
-    use winapi::um::winbase::STD_INPUT_HANDLE;
+    use winapi::um::winbase::{FILE_TYPE_PIPE, STD_INPUT_HANDLE};
     use winapi::um::handleapi::INVALID_HANDLE_VALUE;
     use winapi::um::consoleapi::{GetConsoleMode, SetConsoleMode};
     use winapi::shared::minwindef::LPDWORD;
@@ -181,16 +181,21 @@ mod windows {
             return Err(::std::io::Error::last_os_error());
         }
 
-        // Get the old mode so we can reset back to it when we are done
         let mut mode = 0;
-        if unsafe { GetConsoleMode(handle, &mut mode as LPDWORD) } == 0 {
-            return Err(::std::io::Error::last_os_error());
-        }
 
-        // We want to be able to read line by line, and we still want backspace to work
-        let new_mode_flags = ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT;
-        if unsafe { SetConsoleMode(handle, new_mode_flags) } == 0 {
-            return Err(::std::io::Error::last_os_error());
+        // Console mode does not apply when stdin is piped
+        let handle_type = unsafe { GetFileType(handle) };
+        if handle_type != FILE_TYPE_PIPE {
+            // Get the old mode so we can reset back to it when we are done
+            if unsafe { GetConsoleMode(handle, &mut mode as LPDWORD) } == 0 {
+                return Err(::std::io::Error::last_os_error());
+            }
+
+            // We want to be able to read line by line, and we still want backspace to work
+            let new_mode_flags = ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT;
+            if unsafe { SetConsoleMode(handle, new_mode_flags) } == 0 {
+                return Err(::std::io::Error::last_os_error());
+            }
         }
 
         // Read the password.
@@ -201,9 +206,11 @@ mod windows {
         // Check the response.
         let _ = input?;
 
-        // Set the the mode back to normal
-        if unsafe { SetConsoleMode(handle, mode) } == 0 {
-            return Err(::std::io::Error::last_os_error());
+        if handle_type != FILE_TYPE_PIPE {
+            // Set the the mode back to normal
+            if unsafe { SetConsoleMode(handle, mode) } == 0 {
+                return Err(::std::io::Error::last_os_error());
+            }
         }
 
         super::fixes_newline(&mut password);

tests/piped.rs

@@ -0,0 +1,35 @@
+//! This test checks that piped input is handled correctly.
+
+use std::env;
+use std::io::Write;
+use std::process::{Command, Stdio};
+
+#[test]
+fn piped_password() {
+    // Find target directory
+    let target_dir = env::current_exe()
+        .unwrap()
+        .parent()
+        .unwrap()
+        .parent()
+        .unwrap()
+        .to_path_buf();
+
+    // Run an example that reads a password and prints it
+    let mut out = Command::new(target_dir.join("examples/read-password"))
+        .stdout(Stdio::piped())
+        .stdin(Stdio::piped())
+        .spawn()
+        .unwrap();
+
+    // Write "secret" as the password into stdin
+    let stdin = out.stdin.as_mut().unwrap();
+    stdin.write_all("secret".as_bytes()).unwrap();
+
+    let out = out.wait_with_output().unwrap();
+    assert!(out.status.success());
+
+    let stdout = String::from_utf8(out.stdout).unwrap();
+    println!("stdout: {}", stdout);
+    assert!(stdout.ends_with("Password: secret\n"));
+}