Add opt-in internal vars to ndk-env

README.md

@@ -152,6 +152,18 @@ Rust Analyzer and anything else with JSON-based environment handling:
 
 For configuring rust-analyzer, add the `--json` flag and paste the blob into the relevant place in the config.
 
+By default, `cargo ndk-env` omits cargo-ndk's internal linker wrapper variables from its output. If you want to source
+the generated environment and then build directly with Cargo using the exported linker configuration, add
+`--include-internal` so the linker wrapper receives its required metadata. Run this in a subshell, or unset the
+`_CARGO_NDK_*` variables before running `cargo ndk` again in the same shell:
+
+```
+(
+  source <(cargo ndk-env --target arm64-v8a --include-internal)
+  cargo build --target aarch64-linux-android
+)
+```
+
 ## Troubleshooting
 
 ### The build is complaining that some compiler builtins are missing. What do I do?

src/cli/env.rs

@@ -1,4 +1,4 @@
-use std::collections::BTreeMap;
+use std::{collections::BTreeMap, ffi::OsString};
 
 use clap::Parser;
 
@@ -35,6 +35,37 @@ struct EnvArgs {
     /// Print output in JSON format
     #[arg(long)]
     json: bool,
+
+    /// Include internal cargo-ndk linker wrapper variables
+    #[arg(long)]
+    include_internal: bool,
+}
+
+fn filter_env(
+    env: BTreeMap<String, OsString>,
+    include_internal: bool,
+) -> BTreeMap<String, OsString> {
+    if include_internal {
+        env
+    } else {
+        env.into_iter()
+            .filter(|(k, _)| !k.starts_with('_'))
+            .collect()
+    }
+}
+
+fn env_value(value: &OsString) -> &str {
+    value
+        .to_str()
+        .expect("cargo-ndk environment values should be valid UTF-8")
+}
+
+fn shell_quote(value: &OsString) -> String {
+    format!("'{}'", env_value(value).replace('\'', "'\\''"))
+}
+
+fn powershell_quote(value: &OsString) -> String {
+    format!("'{}'", env_value(value).replace('\'', "''"))
 }
 
 pub fn run(args: Vec<String>) -> anyhow::Result<()> {
@@ -56,40 +87,40 @@ pub fn run(args: Vec<String>) -> anyhow::Result<()> {
     let clang_target = clang_target(args.target.triple(), args.platform);
 
     // Try command line, then config. Config falls back to defaults in any case.
-    let env = build_env(
-        args.target.triple(),
-        &ndk_home,
-        &ndk_version,
-        &clang_target,
-        args.platform,
-        &args.target.to_string(),
-        args.link_builtins,
-        args.link_libcxx_shared,
-    )
-    .into_iter()
-    .filter(|(k, _)| !k.starts_with('_'))
-    .collect::<BTreeMap<_, _>>();
+    let env = filter_env(
+        build_env(
+            args.target.triple(),
+            &ndk_home,
+            &ndk_version,
+            &clang_target,
+            args.platform,
+            &args.target.to_string(),
+            args.link_builtins,
+            args.link_libcxx_shared,
+        ),
+        args.include_internal,
+    );
 
     if args.json {
         println!(
             "{}",
             serde_json::to_string_pretty(
                 &env.into_iter()
-                    .map(|(k, v)| (k, v.to_str().unwrap().to_string()))
+                    .map(|(k, v)| (k, env_value(&v).to_string()))
                     .collect::<BTreeMap<_, _>>()
             )
             .unwrap()
         );
     } else if args.powershell {
         for (k, v) in env {
-            println!("${{env:{k}}}={v:?}");
+            println!("${{env:{k}}}={}", powershell_quote(&v));
         }
         println!();
         println!("# To import with PowerShell:");
         println!("#     cargo ndk-env --powershell | Invoke-Expression");
     } else {
         for (k, v) in env {
-            println!("export {}={:?}", k.replace('-', "_"), v);
+            println!("export {}={}", k.replace('-', "_"), shell_quote(&v));
         }
         println!();
         println!("# To import with bash/zsh/etc:");
@@ -98,3 +129,55 @@ pub fn run(args: Vec<String>) -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use std::{collections::BTreeMap, ffi::OsString};
+
+    use super::{filter_env, powershell_quote, shell_quote};
+
+    fn sample_env() -> BTreeMap<String, OsString> {
+        BTreeMap::from([
+            ("ANDROID_PLATFORM".to_string(), OsString::from("28")),
+            (
+                "_CARGO_NDK_LINK_TARGET".to_string(),
+                OsString::from("--target=aarch64-linux-android28"),
+            ),
+        ])
+    }
+
+    #[test]
+    fn filter_env_hides_internal_values_by_default() {
+        let env = filter_env(sample_env(), false);
+
+        assert!(env.contains_key("ANDROID_PLATFORM"));
+        assert!(!env.contains_key("_CARGO_NDK_LINK_TARGET"));
+    }
+
+    #[test]
+    fn filter_env_keeps_internal_values_when_requested() {
+        let env = filter_env(sample_env(), true);
+
+        assert!(env.contains_key("ANDROID_PLATFORM"));
+        assert_eq!(
+            env["_CARGO_NDK_LINK_TARGET"],
+            OsString::from("--target=aarch64-linux-android28")
+        );
+    }
+
+    #[test]
+    fn shell_quote_preserves_internal_ldflag_separator() {
+        assert_eq!(
+            shell_quote(&OsString::from("-L/path with spaces\x1f-lbuiltins's")),
+            "'-L/path with spaces\x1f-lbuiltins'\\''s'"
+        );
+    }
+
+    #[test]
+    fn powershell_quote_preserves_internal_ldflag_separator() {
+        assert_eq!(
+            powershell_quote(&OsString::from("-L/path with spaces\x1f-lbuiltins's")),
+            "'-L/path with spaces\x1f-lbuiltins''s'"
+        );
+    }
+}

tests/cli_help.rs

@@ -25,6 +25,7 @@ fn cargo_ndk_env_help_shows_env_format_options() {
         assert!(help.contains("Usage: cargo-ndk-env"));
         assert!(help.contains("--powershell"));
         assert!(help.contains("--json"));
+        assert!(help.contains("--include-internal"));
         assert!(!help.contains("--output-dir"));
     }
 }