fix: FFI/cgo string passing (#133)

* fix: FFI/cgo string passing

* Add GOARCH and GOOS env vars to Go command

* Add CC env var

* Add LDFLAGS to cgo

* Add libresolv

* Add doc comment to cstr_ptr_to_string function

* Fix typo

Author: Techassi

Cargo.lock

@@ -17,13 +17,14 @@ repository = "https://github.com/stackabletech/stackable-cockpit/"
 async-trait = "0.1"
 axum = { version = "0.6", features = ["http2", "headers"] }
 bcrypt = "0.15"
+bindgen = "0.68.1"
+cc = "1.0.83"
 clap = { version = "4.2.1", features = ["derive", "env"] }
 clap_complete = "4.2"
 comfy-table = { version = "7.0", features = ["custom_styling"] }
 directories = "5.0"
 dotenvy = "0.15"
 futures = "0.3"
-gobuild = "0.1.0-alpha.2"
 indexmap = { version = "2.0", features = ["serde"] }
 k8s-openapi = { version = "0.19", default-features = false, features = ["v1_27"] }
 kube = { version = "0.85", default-features = false, features = ["client", "rustls-tls"] }

Cargo.toml

@@ -11,4 +11,6 @@ publish = false
 links = "helm"
 
 [build-dependencies]
-gobuild.workspace = true
+cc.workspace = true
+bindgen.workspace = true
+snafu.workspace = true

extra/completions/stackablectl.bash

@@ -1,27 +1,95 @@
-use std::env;
+use std::{
+    env::{self, VarError},
+    path::PathBuf,
+    process::Command,
+};
 
-use gobuild::BuildMode;
+use snafu::{ResultExt, Snafu};
 
-const ENV_GO_HELM_WRAPPER: &str = "GO_HELM_WRAPPER";
+#[derive(Debug, Snafu)]
+enum Error {
+    #[snafu(display("Failed to find env var"))]
+    EnvVarNotFound { source: VarError },
+
+    #[snafu(display("Unsupported GOARCH: {arch}"))]
+    UnsupportedGoArch { arch: String },
+
+    #[snafu(display("Unsupported GOOS: {os}"))]
+    UnsupportedGoOs { os: String },
+}
 
 fn main() {
-    // cgo requires an explicit dependency on libresolv on some platforms (such as Red Hat Enterprise Linux 8 and derivatives)
+    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
+
+    println!("cargo:rerun-if-changed=go-helm-wrapper/main.go");
+
+    let cc = cc::Build::new().try_get_compiler().unwrap();
+    let goarch = get_goarch().unwrap();
+    let goos = get_goos().unwrap();
+
+    let mut cmd = Command::new("go");
+    cmd.arg("build")
+        .args(["-buildmode", "c-archive"])
+        .arg("-o")
+        .arg(out_path.join("libgo-helm-wrapper.a"))
+        .arg("go-helm-wrapper/main.go")
+        .env("CGO_ENABLED", "1")
+        .env("GOARCH", goarch)
+        .env("GOOS", goos)
+        .env("CC", format!("'{}'", cc.path().display()));
+
+    cmd.status().expect("Failed to build go-helm-wrapper");
+
+    let bindings = bindgen::builder()
+        .header(out_path.join("libgo-helm-wrapper.h").to_str().unwrap())
+        .parse_callbacks(Box::new(bindgen::CargoCallbacks))
+        .generate()
+        .expect("Failed to generate Rust bindings from Go header file");
+
+    bindings
+        .write_to_file(out_path.join("bindings.rs"))
+        .expect("Failed to write bindings");
+
     println!("cargo:rustc-link-lib=resolv");
-    println!("cargo:rerun-if-env-changed={ENV_GO_HELM_WRAPPER}");
-    match env::var(ENV_GO_HELM_WRAPPER) {
-        Ok(go_helm_wrapper) => {
-            // Reuse pre-built helm wrapper if possible
-            eprintln!("Reusing pre-built go-helm-wrapper ({go_helm_wrapper:?})");
-            println!("cargo:rustc-link-lib=static:+verbatim={go_helm_wrapper}");
-        }
-        Err(env::VarError::NotPresent) => {
-            gobuild::Build::new()
-                .file("go-helm-wrapper/main.go")
-                .buildmode(BuildMode::CArchive)
-                .compile("go-helm-wrapper");
-        }
-        Err(err @ env::VarError::NotUnicode(..)) => {
-            panic!("{ENV_GO_HELM_WRAPPER} must be valid unicode: {err}");
-        }
-    }
+    println!("cargo:rustc-link-lib=static=go-helm-wrapper");
+    println!(
+        "cargo:rustc-link-search=native={}",
+        out_path.to_str().unwrap()
+    );
+}
+
+fn get_goarch() -> Result<String, Error> {
+    let arch = env::var("CARGO_CFG_TARGET_ARCH").context(EnvVarNotFoundSnafu)?;
+
+    let arch = match arch.as_str() {
+        "x86" => "386",
+        "x86_64" => "amd64",
+        "mips" => "mips",
+        "powerpc" => "ppc",
+        "powerpc64" => "ppc64",
+        "arm" => "arm",
+        "aarch64" => "arm64",
+        _ => return UnsupportedGoArchSnafu { arch }.fail(),
+    };
+
+    Ok(arch.into())
+}
+
+fn get_goos() -> Result<String, Error> {
+    let os = env::var("CARGO_CFG_TARGET_OS").context(EnvVarNotFoundSnafu)?;
+
+    let os = match os.as_str() {
+        "windows" => "windows",
+        "macos" => "darwin",
+        "ios" => "darwin",
+        "linux" => "linux",
+        "android" => "android",
+        "freebsd" => "freebsd",
+        "dragonfly" => "dragonfly",
+        "openbsd" => "openbsd",
+        "netbsd" => "netbsd",
+        _ => return UnsupportedGoOsSnafu { os }.fail(),
+    };
+
+    Ok(os.into())
 }

extra/completions/stackablectl.fish

@@ -1,11 +1,16 @@
 package main
 
+/*
+#include <stdlib.h>
+*/
+import "C"
+
 import (
-	"C"
 	"context"
 	"encoding/json"
 	"fmt"
 	"time"
+	"unsafe"
 
 	gohelm "github.com/mittwald/go-helm-client"
 	"helm.sh/helm/v3/pkg/action"
@@ -31,16 +36,16 @@ func main() {
 }
 
 //export go_install_helm_release
-func go_install_helm_release(releaseName string, chartName string, chartVersion string, valuesYaml string, namespace string, suppressOutput bool) *C.char {
+func go_install_helm_release(releaseName *C.char, chartName *C.char, chartVersion *C.char, valuesYaml *C.char, namespace *C.char, suppressOutput bool) *C.char {
 	helmClient := getHelmClient(namespace, suppressOutput)
 
 	timeout, _ := time.ParseDuration("10m")
 	chartSpec := gohelm.ChartSpec{
-		ReleaseName: releaseName,
-		ChartName:   chartName,
-		Version:     chartVersion,
-		ValuesYaml:  valuesYaml,
-		Namespace:   namespace,
+		ReleaseName: C.GoString(releaseName),
+		ChartName:   C.GoString(chartName),
+		Version:     C.GoString(chartVersion),
+		ValuesYaml:  C.GoString(valuesYaml),
+		Namespace:   C.GoString(namespace),
 		UpgradeCRDs: true,
 		Wait:        true,
 		Timeout:     timeout,
@@ -54,21 +59,21 @@ func go_install_helm_release(releaseName string, chartName string, chartVersion
 }
 
 //export go_uninstall_helm_release
-func go_uninstall_helm_release(releaseName string, namespace string, suppressOutput bool) *C.char {
+func go_uninstall_helm_release(releaseName *C.char, namespace *C.char, suppressOutput bool) *C.char {
 	helmClient := getHelmClient(namespace, suppressOutput)
 
-	if err := helmClient.UninstallReleaseByName(releaseName); err != nil {
+	if err := helmClient.UninstallReleaseByName(C.GoString(releaseName)); err != nil {
 		return C.CString(fmt.Sprintf("%s%s", HELM_ERROR_PREFIX, err))
 	}
 
 	return C.CString("")
 }
 
 //export go_helm_release_exists
-func go_helm_release_exists(releaseName string, namespace string) bool {
+func go_helm_release_exists(releaseName *C.char, namespace *C.char) bool {
 	helmClient := getHelmClient(namespace, true)
 
-	release, _ := helmClient.GetRelease(releaseName)
+	release, _ := helmClient.GetRelease(C.GoString(releaseName))
 	return release != nil
 }
 
@@ -78,7 +83,7 @@ func go_helm_release_exists(releaseName string, namespace string) bool {
 // by the Rust code and it will abort operations.
 //
 //export go_helm_list_releases
-func go_helm_list_releases(namespace string) *C.char {
+func go_helm_list_releases(namespace *C.char) *C.char {
 	helmClient := getHelmClient(namespace, true)
 
 	// List all releases, not only the deployed ones (e.g. include pending installations)
@@ -112,12 +117,12 @@ func go_helm_list_releases(namespace string) *C.char {
 // operations.
 //
 //export go_add_helm_repo
-func go_add_helm_repo(name string, url string) *C.char {
-	helmClient := getHelmClient("default", true) // Namespace doesn't matter
+func go_add_helm_repo(name *C.char, url *C.char) *C.char {
+	helmClient := getHelmClient(C.CString("default"), true) // Namespace doesn't matter
 
 	chartRepo := repo.Entry{
-		Name: name,
-		URL:  url,
+		Name: C.GoString(name),
+		URL:  C.GoString(url),
 	}
 
 	if err := helmClient.AddOrUpdateChartRepo(chartRepo); err != nil {
@@ -127,9 +132,14 @@ func go_add_helm_repo(name string, url string) *C.char {
 	return C.CString("")
 }
 
-func getHelmClient(namespace string, suppressOutput bool) gohelm.Client {
+//export free_go_string
+func free_go_string(ptr *C.char) {
+	C.free(unsafe.Pointer(ptr))
+}
+
+func getHelmClient(namespace *C.char, suppressOutput bool) gohelm.Client {
 	options := gohelm.Options{
-		Namespace: namespace,
+		Namespace: C.GoString(namespace),
 		Debug:     false,
 	}
 

rust/helm-sys/Cargo.toml

@@ -1,37 +1,112 @@
-use std::{marker::PhantomData, os::raw::c_char};
+#![allow(non_upper_case_globals)]
+#![allow(non_camel_case_types)]
+#![allow(improper_ctypes)]
+#![allow(non_snake_case)]
 
-#[repr(C)]
-pub struct GoString<'a> {
-    p: *const u8,
-    n: i64,
-    _lifetime: PhantomData<&'a str>,
+include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
+
+use std::ffi::{c_char, CStr, CString};
+
+pub const HELM_ERROR_PREFIX: &str = "ERROR:";
+
+pub fn install_helm_release(
+    release_name: &str,
+    chart_name: &str,
+    chart_version: &str,
+    values_yaml: &str,
+    namespace: &str,
+    suppress_output: bool,
+) -> String {
+    let release_name = CString::new(release_name).unwrap();
+    let chart_name = CString::new(chart_name).unwrap();
+    let chart_version = CString::new(chart_version).unwrap();
+    let values_yaml = CString::new(values_yaml).unwrap();
+    let namespace = CString::new(namespace).unwrap();
+
+    unsafe {
+        let c = go_install_helm_release(
+            release_name.as_ptr() as *mut c_char,
+            chart_name.as_ptr() as *mut c_char,
+            chart_version.as_ptr() as *mut c_char,
+            values_yaml.as_ptr() as *mut c_char,
+            namespace.as_ptr() as *mut c_char,
+            suppress_output as u8,
+        );
+
+        cstr_ptr_to_string(c)
+    }
+}
+
+pub fn uninstall_helm_release(
+    release_name: &str,
+    namespace: &str,
+    suppress_output: bool,
+) -> String {
+    let release_name = CString::new(release_name).unwrap();
+    let namespace = CString::new(namespace).unwrap();
+
+    unsafe {
+        let c = go_uninstall_helm_release(
+            release_name.as_ptr() as *mut c_char,
+            namespace.as_ptr() as *mut c_char,
+            suppress_output as u8,
+        );
+
+        cstr_ptr_to_string(c)
+    }
+}
+
+pub fn check_helm_release_exists(release_name: &str, namespace: &str) -> bool {
+    let release_name = CString::new(release_name).unwrap();
+    let namespace = CString::new(namespace).unwrap();
+
+    unsafe {
+        go_helm_release_exists(
+            release_name.as_ptr() as *mut c_char,
+            namespace.as_ptr() as *mut c_char,
+        ) != 0
+    }
 }
 
-impl<'a> From<&'a str> for GoString<'a> {
-    fn from(str: &'a str) -> Self {
-        GoString {
-            p: str.as_ptr(),
-            n: str.len() as i64,
-            _lifetime: PhantomData,
-        }
+pub fn list_helm_releases(namespace: &str) -> String {
+    let namespace = CString::new(namespace).unwrap();
+
+    unsafe {
+        let c = go_helm_list_releases(namespace.as_ptr() as *mut c_char);
+        cstr_ptr_to_string(c)
     }
 }
 
-extern "C" {
-    pub fn go_install_helm_release(
-        release_name: GoString,
-        chart_name: GoString,
-        chart_version: GoString,
-        values_yaml: GoString,
-        namespace: GoString,
-        suppress_output: bool,
-    ) -> *const c_char;
-    pub fn go_uninstall_helm_release(
-        release_name: GoString,
-        namespace: GoString,
-        suppress_output: bool,
-    ) -> *const c_char;
-    pub fn go_helm_release_exists(release_name: GoString, namespace: GoString) -> bool;
-    pub fn go_helm_list_releases(namespace: GoString) -> *const c_char;
-    pub fn go_add_helm_repo(name: GoString, url: GoString) -> *const c_char;
+pub fn add_helm_repository(repository_name: &str, repository_url: &str) -> String {
+    let repository_name = CString::new(repository_name).unwrap();
+    let repository_url = CString::new(repository_url).unwrap();
+
+    unsafe {
+        let c = go_add_helm_repo(
+            repository_name.as_ptr() as *mut c_char,
+            repository_url.as_ptr() as *mut c_char,
+        );
+
+        cstr_ptr_to_string(c)
+    }
+}
+
+/// Checks if the result string is an error, and if so, returns the error message as a string.
+pub fn to_helm_error(result: &str) -> Option<String> {
+    if !result.is_empty() && result.starts_with(HELM_ERROR_PREFIX) {
+        return Some(result.replace(HELM_ERROR_PREFIX, ""));
+    }
+
+    None
+}
+
+/// Converts a raw C string pointer into an owned Rust [`String`]. This function
+/// also makes sure, that the pointer (and underlying memory) of the Go string is
+/// freed. The pointer **cannot** be used afterwards.
+unsafe fn cstr_ptr_to_string(c: *mut c_char) -> String {
+    let cstr = CStr::from_ptr(c);
+    let s = String::from_utf8_lossy(cstr.to_bytes()).to_string();
+    free_go_string(cstr.as_ptr() as *mut c_char);
+
+    s
 }