stdbuf: build on Windows (depending on cygwin dll)

Author: oech3

Cargo.toml

@@ -275,6 +275,7 @@ feat_os_unix_musl = [
 # "feat_os_windows" == set of utilities which can be built/run on modern/usual windows platforms
 feat_os_windows = [
   "feat_Tier1", ## == "feat_os_windows_legacy" + "hostname"
+  "stdbuf",
 ]
 ## (secondary platforms) feature sets
 # "feat_os_unix_gnueabihf" == set of utilities which can be built/run on the "arm-unknown-linux-gnueabihf" target (ARMv6 Linux [hardfloat])

GNUmakefile

@@ -81,7 +81,7 @@ $(info Detected OS = $(OS))
 ifeq (,$(findstring windows,$(OS)))
 	FEATURE_EXTRACT_UTILS := feat_os_unix
 else
-	FEATURE_EXTRACT_UTILS := feat_Tier1
+	FEATURE_EXTRACT_UTILS := windows
 endif
 PROGS := $(shell cargo tree --depth 1 --features $(FEATURE_EXTRACT_UTILS) --format "{p}" --prefix none | sed -E -n 's/^uu_([^ ]+).*/\1/p')
 

src/uu/stdbuf/Cargo.toml

@@ -22,12 +22,14 @@ doctest = false
 
 [dependencies]
 clap = { workspace = true }
-libstdbuf = { package = "uu_stdbuf_libstdbuf", version = "0.8.0", path = "src/libstdbuf" }
 tempfile = { workspace = true }
 uucore = { workspace = true, features = ["parser-size"] }
 thiserror = { workspace = true }
 fluent = { workspace = true }
 
+[target.'cfg(unix)'.dependencies]
+libstdbuf = { package = "uu_stdbuf_libstdbuf", version = "0.8.0", path = "src/libstdbuf" }
+
 # "feat_external_libstdbuf": use an external libstdbuf.so for stdbuf instead of embedding it into
 # the stdbuf binary.
 # There are 2 use-cases:

src/uu/stdbuf/build.rs

@@ -10,6 +10,11 @@ use std::path::Path;
 use std::process::Command;
 
 fn main() {
+    // do not compile libstdbuf for windows target. The windows stdbuf.exe loads libstdbuf.dll compiled for the cygwin target.
+    if env::var("CARGO_CFG_UNIX").is_err() {
+        println!("cargo:rustc-cfg=feature=\"feat_external_libstdbuf\"");
+        return;
+    }
     println!("cargo:rerun-if-changed=build.rs");
     println!("cargo:rerun-if-changed=src/libstdbuf/src/libstdbuf.rs");
 
@@ -38,11 +43,7 @@ fn main() {
 
     let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
     let target_vendor = env::var("CARGO_CFG_TARGET_VENDOR").unwrap();
-    let target_family = env::var("CARGO_CFG_TARGET_FAMILY").unwrap();
 
-    if target_family != "unix" {
-        return;
-    }
     let dylib_ext = if target_vendor == "apple" {
         ".dylib"
     } else if target_os == "cygwin" {

src/uu/stdbuf/locales/en-US.ftl

@@ -1,4 +1,5 @@
 stdbuf-about = Run COMMAND, with modified buffering operations for its standard streams.
+stdbuf-about-windows = Run COMMAND linked against cygwin runtime, with modified buffering operations for its standard streams.
 
   Mandatory arguments to long options are mandatory for short options too.
 stdbuf-usage = stdbuf [OPTION]... COMMAND

src/uu/stdbuf/src/libstdbuf/build.rs

@@ -7,6 +7,10 @@
 use std::env;
 
 fn main() {
+    // do not compile libstdbuf for windows target. The windows stdbuf.exe loads libstdbuf.dll compiled for the cygwin target.
+    if env::var("CARGO_CFG_UNIX").is_err() {
+        return;
+    }
     // Make sure we're building position-independent code for use with LD_PRELOAD
     println!("cargo:rustc-link-arg=-fPIC");
 

src/uu/stdbuf/src/stdbuf.rs

@@ -4,8 +4,6 @@
 // file that was distributed with this source code.
 
 // spell-checker:ignore (ToDO) tempdir dyld dylib optgrps libstdbuf
-#[cfg(not(unix))]
-compile_error!("stdbuf is not supported on the target");
 
 use clap::{Arg, ArgAction, ArgMatches, Command};
 use std::ffi::OsString;
@@ -42,7 +40,10 @@ const STDBUF_INJECT: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/libstdbuf
 #[cfg(all(not(feature = "feat_external_libstdbuf"), target_vendor = "apple"))]
 const STDBUF_INJECT: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/libstdbuf.dylib"));
 
-#[cfg(all(not(feature = "feat_external_libstdbuf"), target_os = "cygwin"))]
+#[cfg(all(
+    not(feature = "feat_external_libstdbuf"),
+    any(target_os = "cygwin", target_os = "windows")
+))]
 const STDBUF_INJECT: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/libstdbuf.dll"));
 
 enum BufferType {
@@ -89,7 +90,7 @@ fn preload_strings() -> (&'static str, &'static str) {
     ("DYLD_LIBRARY_PATH", "dylib")
 }
 
-#[cfg(target_os = "cygwin")]
+#[cfg(any(target_os = "cygwin", windows))]
 fn preload_strings() -> (&'static str, &'static str) {
     ("LD_PRELOAD", "dll")
 }
@@ -211,7 +212,16 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     command.args(command_params);
 
     // Replace the current process with the target program (no fork) using exec.
+    #[cfg(unix)]
     let e = command.exec();
+    #[cfg(windows)]
+    let e = match command.spawn() {
+        Ok(mut child) => {
+            let status = child.wait().unwrap();
+            process::exit(status.code().unwrap_or(0));
+        }
+        Err(err) => err,
+    };
     // exec() only returns if there was an error
     match e.kind() {
         std::io::ErrorKind::PermissionDenied => Err(USimpleError::new(
@@ -230,10 +240,14 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
 }
 
 pub fn uu_app() -> Command {
+    #[cfg(unix)]
+    let about = translate!("stdbuf-about");
+    #[cfg(windows)]
+    let about = translate!("stdbuf-about-windows");
     Command::new("stdbuf")
         .version(uucore::crate_version!())
         .help_template(uucore::localized_help_template("stdbuf"))
-        .about(translate!("stdbuf-about"))
+        .about(about)
         .after_help(translate!("stdbuf-after-help"))
         .override_usage(format_usage(&translate!("stdbuf-usage")))
         .trailing_var_arg(true)

tests/by-util/test_stdbuf.rs

@@ -3,19 +3,19 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 // spell-checker:ignore cmdline dyld dylib PDEATHSIG setvbuf
+
 #[cfg(target_os = "linux")]
 use uutests::at_and_ucmd;
-use uutests::new_ucmd;
-#[cfg(not(target_os = "windows"))]
-use uutests::util::TestScenario;
-use uutests::util_name;
+#[cfg(unix)]
+use uutests::{new_ucmd, util::TestScenario, util_name};
 
 #[test]
+#[cfg(unix)]
 fn invalid_input() {
     new_ucmd!().arg("-/").fails_with_code(125);
 }
 
-#[cfg(not(feature = "feat_external_libstdbuf"))]
+#[cfg(all(unix, not(feature = "feat_external_libstdbuf")))]
 #[test]
 fn test_permission() {
     new_ucmd!()
@@ -28,7 +28,7 @@ fn test_permission() {
 // LD_DEBUG is not available on macOS, OpenBSD, Android, or musl
 #[cfg(all(
     feature = "feat_external_libstdbuf",
-    not(target_os = "windows"),
+    unix,
     not(target_os = "openbsd"),
     not(target_os = "macos"),
     not(target_os = "android"),
@@ -121,7 +121,7 @@ fn test_stdbuf_search_order_exe_dir_first() {
     );
 }
 
-#[cfg(not(feature = "feat_external_libstdbuf"))]
+#[cfg(all(unix, not(feature = "feat_external_libstdbuf")))]
 #[test]
 fn test_no_such() {
     new_ucmd!()
@@ -135,7 +135,7 @@ fn test_no_such() {
 // does not provide musl-compiled system utilities (like head), leading to dynamic linker errors
 // when preloading musl-compiled libstdbuf.so into glibc-compiled binaries. Same thing for FreeBSD.
 #[cfg(all(
-    not(target_os = "windows"),
+    unix,
     not(target_os = "freebsd"),
     not(target_os = "openbsd"),
     not(all(target_arch = "x86_64", target_env = "musl"))
@@ -157,7 +157,7 @@ fn test_stdbuf_unbuffered_stdout() {
 // does not provide musl-compiled system utilities (like head), leading to dynamic linker errors
 // when preloading musl-compiled libstdbuf.so into glibc-compiled binaries. Same thing for FreeBSD.
 #[cfg(all(
-    not(target_os = "windows"),
+    unix,
     not(target_os = "freebsd"),
     not(target_os = "openbsd"),
     not(all(target_arch = "x86_64", target_env = "musl"))
@@ -174,8 +174,8 @@ fn test_stdbuf_line_buffered_stdout() {
         .stdout_is("The quick brown fox jumps over the lazy dog.");
 }
 
-#[cfg(not(target_os = "windows"))]
 #[test]
+#[cfg(unix)]
 fn test_stdbuf_no_buffer_option_fails() {
     let ts = TestScenario::new(util_name!());
 
@@ -185,8 +185,8 @@ fn test_stdbuf_no_buffer_option_fails() {
         .stderr_contains("the following required arguments were not provided:");
 }
 
-#[cfg(not(target_os = "windows"))]
 #[test]
+#[cfg(unix)]
 fn test_stdbuf_no_command_fails_with_125() {
     // Test that missing command fails with exit code 125 (stdbuf error)
     // This verifies proper error handling without unwrap panic
@@ -200,7 +200,7 @@ fn test_stdbuf_no_command_fails_with_125() {
 // does not provide musl-compiled system utilities (like tail), leading to dynamic linker errors
 // when preloading musl-compiled libstdbuf.so into glibc-compiled binaries. Same thing for FreeBSD.
 #[cfg(all(
-    not(target_os = "windows"),
+    unix,
     not(target_os = "freebsd"),
     not(target_os = "openbsd"),
     not(all(target_arch = "x86_64", target_env = "musl"))
@@ -214,17 +214,17 @@ fn test_stdbuf_trailing_var_arg() {
         .stdout_is("jumps over the lazy dog.");
 }
 
-#[cfg(not(target_os = "windows"))]
 #[test]
+#[cfg(unix)]
 fn test_stdbuf_line_buffering_stdin_fails() {
     new_ucmd!()
         .args(&["-i", "L", "head"])
         .fails()
         .usage_error("line buffering stdin is meaningless");
 }
 
-#[cfg(not(target_os = "windows"))]
 #[test]
+#[cfg(unix)]
 fn test_stdbuf_invalid_mode_fails() {
     let options = ["--input", "--output", "--error"];
     for option in &options {
@@ -254,7 +254,7 @@ fn test_stdbuf_invalid_mode_fails() {
 // and is sometimes disabled. Disable test on Android for now.
 // musl libc dynamic loader does not support LD_DEBUG, so disable on musl targets as well.
 #[cfg(all(
-    not(target_os = "windows"),
+    unix,
     not(target_os = "openbsd"),
     not(target_os = "macos"),
     not(target_os = "android"),