feat: obtain identities from_path() or from_process() (#386)

Author: Byron

Cargo.lock

@@ -18,3 +18,10 @@ serde1 = [ "serde" ]
 
 [dependencies]
 serde = { version = "1.0.114", optional = true, default-features = false, features = ["std", "derive"] }
+
+[target.'cfg(not(windows))'.dependencies]
+libc = "0.2.123"
+
+
+[dev-dependencies]
+tempfile = "3.3.0"

git-sec/Cargo.toml

@@ -1,5 +1,4 @@
-#![forbid(unsafe_code)]
-#![deny(rust_2018_idioms, missing_docs)]
+#![deny(unsafe_code, rust_2018_idioms, missing_docs)]
 //! A shared trust model for `gitoxide` crates.
 
 /// Various types to identify entities.
@@ -22,4 +21,64 @@ pub mod identity {
         /// The user's password
         pub password: String,
     }
+
+    ///
+    pub mod user_id {
+        use crate::identity::UserId;
+        use std::borrow::Cow;
+        use std::path::Path;
+
+        /// Obtain the owner of the given `path`.
+        pub fn from_path(path: Cow<'_, Path>) -> std::io::Result<UserId> {
+            impl_::from_path(path)
+        }
+
+        /// Obtain the of the currently running process.
+        pub fn from_process() -> Result<UserId, from_process::Error> {
+            impl_::from_process()
+        }
+
+        ///
+        pub mod from_process {
+            use crate::identity::user_id::impl_;
+
+            /// The error returned by [from_process()][super::from_process()].
+            pub type Error = impl_::FromProcessError;
+        }
+
+        #[cfg(not(windows))]
+        mod impl_ {
+            use crate::identity::UserId;
+            use std::borrow::Cow;
+            use std::path::Path;
+
+            pub fn from_path(path: Cow<'_, Path>) -> std::io::Result<UserId> {
+                use std::os::unix::fs::MetadataExt;
+                let meta = std::fs::symlink_metadata(path)?;
+                Ok(meta.uid())
+            }
+
+            pub type FromProcessError = std::convert::Infallible;
+            pub fn from_process() -> Result<UserId, FromProcessError> {
+                // SAFETY: there is no documented possibility for failure
+                #[allow(unsafe_code)]
+                let uid = unsafe { libc::geteuid() };
+                Ok(uid)
+            }
+        }
+
+        #[cfg(windows)]
+        mod impl_ {
+            use crate::identity::UserId;
+            use std::borrow::Cow;
+            use std::path::Path;
+
+            pub fn from_path(path: Cow<'_, Path>) -> std::io::Result<UserId> {
+                todo!("unix")
+            }
+            pub fn from_process() -> std::io::Result<UserId> {
+                todo!("process")
+            }
+        }
+    }
 }

git-sec/src/lib.rs

@@ -0,0 +1,8 @@
+mod uid {
+    #[test]
+    fn from_path() {
+        let dir = tempfile::tempdir().unwrap();
+        let owner = git_sec::identity::user_id::from_path(dir.path().into()).unwrap();
+        assert_eq!(owner, git_sec::identity::user_id::from_process().unwrap());
+    }
+}

git-sec/tests/identity/mod.rs

@@ -0,0 +1,3 @@
+pub type Result<T = ()> = std::result::Result<T, Box<dyn std::error::Error>>;
+
+mod identity;