initial commit: WIP debugging PAM module

rust-backend/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "once_cell"
+version = "1.21.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
+
+[[package]]
+name = "rust-backend"
+version = "0.1.0"
+dependencies = [
+ "once_cell",
+]

rust-backend/Cargo.toml

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+[package]
+name = "rust-backend"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["staticlib"]
+
+[dependencies]
+once_cell = "1.18"
+
+[profile.release]
+panic = "unwind"
+
+[profile.dev]
+panic = "unwind"

rust-backend/src/auth.rs

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+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2026 Suyono
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+pub fn authenticate(user: &str, password: &str) -> Result<(), ()> {
+    // Stub: always fail if user == "fail", else succeed
+    if user == "fail" {
+        Err(())
+    } else {
+        Ok(())
+    }
+}

rust-backend/src/error.rs

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+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2026 Suyono
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+pub const SUCCESS: i32 = 0;
+pub const ERR_INVALID_INPUT: i32 = -1;
+pub const ERR_AUTH_FAILED: i32 = -2;
+pub const ERR_PANIC: i32 = -99;

rust-backend/src/lib.rs

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+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2026 Suyono
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+use std::ffi::{CStr, CString};
+use std::os::raw::c_char;
+use std::panic::{catch_unwind, AssertUnwindSafe};
+
+mod auth;
+mod logging;
+mod error;
+
+#[no_mangle]
+pub extern "C" fn rust_init_logging(log_path: *const c_char) {
+    let _ = catch_unwind(AssertUnwindSafe(|| {
+        let path = unsafe {
+            if log_path.is_null() {
+                "/var/log/pam_rust_backend.log"
+            } else {
+                CStr::from_ptr(log_path).to_str().unwrap_or("/var/log/pam_rust_backend.log")
+            }
+        };
+        logging::init_logger(path);
+    }));
+}
+
+#[no_mangle]
+pub extern "C" fn rust_log_event(event: *const c_char) {
+    let _ = catch_unwind(AssertUnwindSafe(|| {
+        let msg = unsafe {
+            if event.is_null() {
+                return;
+            }
+            CStr::from_ptr(event).to_str().unwrap_or("")
+        };
+        logging::log_event(msg);
+    }));
+}
+
+#[no_mangle]
+pub extern "C" fn rust_auth_user(user: *const c_char, password: *const c_char) -> i32 {
+    catch_unwind(AssertUnwindSafe(|| {
+        let u = unsafe {
+            if user.is_null() {
+                return error::ERR_INVALID_INPUT;
+            }
+            CStr::from_ptr(user).to_str().unwrap_or("")
+        };
+        let p = unsafe {
+            if password.is_null() {
+                return error::ERR_INVALID_INPUT;
+            }
+            CStr::from_ptr(password).to_str().unwrap_or("")
+        };
+        match auth::authenticate(u, p) {
+            Ok(_) => error::SUCCESS,
+            Err(_) => error::ERR_AUTH_FAILED,
+        }
+    })).unwrap_or(error::ERR_PANIC)
+}

rust-backend/src/logging.rs

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+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2026 Suyono
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+use std::fs::{OpenOptions, File};
+use std::io::Write;
+use std::sync::Mutex;
+use once_cell::sync::OnceCell;
+
+static LOGGER: OnceCell<Mutex<File>> = OnceCell::new();
+
+pub fn init_logger(path: &str) {
+    if LOGGER.get().is_some() {
+        // Already initialized, do nothing
+        return;
+    }
+    let file = OpenOptions::new()
+        .create(true)
+        .append(true)
+        .open(path)
+        .expect("Failed to open log file");
+    LOGGER.set(Mutex::new(file)).ok();
+}
+
+pub fn log_event(event: &str) {
+    if let Some(logger) = LOGGER.get() {
+        let mut file = logger.lock().unwrap();
+        writeln!(file, "{}", event).ok();
+    }
+}