From 2d25ea7eb25f4c6480cf0b1b53cab0cfe1e0c87d Mon Sep 17 00:00:00 2001
From: Tomasz Kramkowski <tomasz@kramkow.ski>
Date: Mon, 30 Jan 2023 20:37:26 +0000
Subject: Switch to rustix

---
 Cargo.toml |  2 +-
 src/lib.rs | 53 +++++++++++++++++++++++++++++++++--------------------
 2 files changed, 34 insertions(+), 21 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 060453e..068b732 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,5 +12,5 @@ name = "pam_usercg"
 crate-type = ["cdylib"]
 
 [dependencies]
-cap-std = "1.0.4"
 libc = "0.2.139"
+rustix = { version = "0.36.7", features = [ "use-libc", "fs" ] }
diff --git a/src/lib.rs b/src/lib.rs
index 42a9c1b..0b5fff9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,31 +5,38 @@ mod pam;
 mod passwd;
 mod syslog;
 
-use cap_std::fs::{Dir, OpenOptions};
 use pam::PAMHandle;
+use rustix::fd::{AsFd, OwnedFd};
+use rustix::fs::{self, Mode, OFlags};
+use rustix::io::{self, Errno};
+use rustix::path::Arg;
 use std::ffi::{c_char, c_int, CStr, CString};
-use std::io::{ErrorKind, Write};
 use std::panic;
-use std::path::Path;
 use std::process;
 use syslog::{Facility, Level, Priority};
 
-fn create_and_open_dir<P: AsRef<Path> + ?Sized>(
-    d: &Dir,
-    path: &P,
-) -> std::io::Result<Dir> {
-    if let Err(e) = d.create_dir(path) {
-        if e.kind() != ErrorKind::AlreadyExists {
+fn create_and_open_dir<D: AsFd, P: Arg + Copy>(
+    d: &D,
+    path: P,
+) -> rustix::io::Result<OwnedFd> {
+    if let Err(e) = fs::mkdirat(d, path, Mode::RWXU | Mode::RWXG | Mode::RWXO) {
+        if e != Errno::EXIST {
             return Err(e);
         }
     }
-    d.open_dir(path)
+    fs::openat(d, path, OFlags::DIRECTORY | OFlags::PATH, Mode::empty())
 }
 
 struct SessionError;
 
-impl From<std::io::Error> for SessionError {
-    fn from(_: std::io::Error) -> Self {
+impl From<rustix::io::Errno> for SessionError {
+    fn from(_: rustix::io::Errno) -> Self {
+        SessionError
+    }
+}
+
+impl From<std::ffi::NulError> for SessionError {
+    fn from(_: std::ffi::NulError) -> Self {
         SessionError
     }
 }
@@ -52,7 +59,7 @@ fn open_session(h: &PAMHandle, mountpoint: &str) -> Result<(), SessionError> {
         }
     };
     let uid = match passwd::get_uid_by_name(&user) {
-        Some(uid) => uid.to_string(),
+        Some(uid) => CString::new(uid.to_string())?,
         None => {
             if let Ok(message) =
                 CString::new(format!("Failure to map user {user:?} to passwd entry"))
@@ -62,16 +69,22 @@ fn open_session(h: &PAMHandle, mountpoint: &str) -> Result<(), SessionError> {
             return Err(SessionError);
         }
     };
-    let d = Dir::open_ambient_dir(mountpoint, cap_std::ambient_authority())?;
+    let d = fs::openat(
+        fs::cwd(),
+        mountpoint,
+        OFlags::DIRECTORY | OFlags::PATH,
+        Mode::empty(),
+    )?;
     let d = create_and_open_dir(&d, "user")?;
     let d = create_and_open_dir(&d, &uid)?;
     let d = create_and_open_dir(&d, "leaf")?;
-    let pid = process::id().to_string();
-    let mut options = OpenOptions::new();
-    options.write(true);
-    let mut procs = d.open_with("cgroup.procs", &options)?;
-    procs.write_all(pid.as_bytes())?;
-    Ok(())
+    let pid = CString::new(process::id().to_string())?;
+    let pid = pid.as_bytes();
+    let procs = fs::openat(d, "cgroup.procs", OFlags::WRONLY, Mode::empty())?;
+    match io::write(procs, pid) {
+        Ok(n) if n == pid.len() => Ok(()),
+        _ => Err(SessionError),
+    }
 }
 
 const CG_MOUNT: &str = "/sys/fs/cgroup";
-- 
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