[libgpiod][PATCH 5/5] bindings: rust: provide LineRequest::chip_path()

[Bartosz Golaszewski <brgl@bgdev.pl>]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Provide a wrapper around gpiod_line_request_get_chip_path() for Rust
bindings and add a test-case.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 bindings/rust/libgpiod/src/line_request.rs   | 12 ++++++++++++
 bindings/rust/libgpiod/tests/line_request.rs | 13 +++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/bindings/rust/libgpiod/src/line_request.rs b/bindings/rust/libgpiod/src/line_request.rs
index 1140aa9..2caab14 100644
--- a/bindings/rust/libgpiod/src/line_request.rs
+++ b/bindings/rust/libgpiod/src/line_request.rs
@@ -2,6 +2,7 @@
 // SPDX-FileCopyrightText: 2022 Linaro Ltd.
 // SPDX-FileCopyrightText: 2022 Viresh Kumar <viresh.kumar@linaro.org>
 
+use std::ffi::CStr;
 use std::os::unix::prelude::AsRawFd;
 use std::time::Duration;
 
@@ -25,6 +26,17 @@ impl Request {
         Ok(Self { request })
     }
 
+    pub fn chip_path(&self) -> Result<&str> {
+        // SAFETY: The string returned by libgpiod is guaranteed to live as long
+        // as the `struct LineRequest`.
+        let path = unsafe { gpiod::gpiod_line_request_get_chip_path(self.request) };
+
+        // SAFETY: The string is guaranteed to be valid here by the C API.
+        unsafe { CStr::from_ptr(path) }
+            .to_str()
+            .map_err(Error::StringNotUtf8)
+    }
+
     /// Get the number of lines in the request.
     pub fn num_lines(&self) -> usize {
         // SAFETY: `gpiod_line_request` is guaranteed to be valid here.
diff --git a/bindings/rust/libgpiod/tests/line_request.rs b/bindings/rust/libgpiod/tests/line_request.rs
index d49874f..e4ed9c2 100644
--- a/bindings/rust/libgpiod/tests/line_request.rs
+++ b/bindings/rust/libgpiod/tests/line_request.rs
@@ -59,6 +59,19 @@ mod line_request {
     mod verify {
         use super::*;
 
+        #[test]
+        fn chip_path() {
+            const GPIO: Offset = 2;
+            let mut config = TestConfig::new(NGPIO).unwrap();
+            config.lconfig_add_settings(&[GPIO]);
+            config.request_lines().unwrap();
+
+            let dev_path = config.sim().lock().unwrap().dev_path();
+            let s = dev_path.into_os_string().into_string().unwrap();
+
+            assert_eq!(config.request().chip_path().unwrap(), s);
+        }
+
         #[test]
         fn custom_consumer() {
             const GPIO: Offset = 2;
-- 
2.39.2