Port to rustix, drop nix

We already have rustix as a dependency; now that we don't
use IPC anymore it's trivial to port to rustix. I prefer its
API and maintainer.

Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

Cargo.lock

@@ -30,11 +30,11 @@ hex = "0.4.3"
 libc = "^0.2"
 libsystemd = ">= 0.3, < 0.8"
 log = "^0.4"
-nix = ">= 0.22.1, < 0.24.0"
 openat = "0.1.20"
 openat-ext = ">= 0.2.2, < 0.3.0"
 openssl = "^0.10"
 os-release = "0.1.0"
+rustix = { version = "0.38.34", features = ["process", "fs"] }
 serde = { version = "^1.0", features = ["derive"] }
 serde_json = "^1.0"
 tempfile = "^3.10"

Cargo.toml

@@ -142,7 +142,7 @@ fn running_in_systemd() -> bool {
 
 /// Require root permission
 fn require_root_permission() -> Result<()> {
-    if !nix::unistd::Uid::effective().is_root() {
+    if !rustix::process::getuid().is_root() {
         anyhow::bail!("This command requires root privileges")
     }
     Ok(())

src/cli/bootupctl.rs

@@ -13,6 +13,7 @@ use anyhow::{bail, Context, Result};
 use fn_error_context::context;
 use openat_ext::OpenatDirExt;
 use os_release::OsRelease;
+use rustix::fd::BorrowedFd;
 use walkdir::WalkDir;
 use widestring::U16CString;
 
@@ -82,9 +83,9 @@ impl Efi {
             if !mnt.exists() {
                 continue;
             }
-            let st = nix::sys::statfs::statfs(&mnt)
-                .with_context(|| format!("statfs failed for {mnt:?}"))?;
-            if st.filesystem_type() != nix::sys::statfs::MSDOS_SUPER_MAGIC {
+            let st =
+                rustix::fs::statfs(&mnt).with_context(|| format!("statfs failed for {mnt:?}"))?;
+            if st.f_type != libc::MSDOS_SUPER_MAGIC {
                 continue;
             }
             log::debug!("Reusing existing {mnt:?}");
@@ -454,10 +455,13 @@ impl Drop for Efi {
 }
 
 fn validate_esp(dir: &openat::Dir) -> Result<()> {
-    let stat = nix::sys::statfs::fstatfs(dir)?;
-    let fstype = stat.filesystem_type();
-    if fstype != nix::sys::statfs::MSDOS_SUPER_MAGIC {
-        bail!("EFI mount is not a msdos filesystem, but is {:?}", fstype);
+    let dir = unsafe { BorrowedFd::borrow_raw(dir.as_raw_fd()) };
+    let stat = rustix::fs::fstatfs(&dir)?;
+    if stat.f_type != libc::MSDOS_SUPER_MAGIC {
+        bail!(
+            "EFI mount is not a msdos filesystem, but is {:?}",
+            stat.f_type
+        );
     };
     Ok(())
 }

src/efi.rs

@@ -5,6 +5,7 @@ use std::process::Command;
 
 use anyhow::{Context, Result};
 use fn_error_context::context;
+use rustix::fd::BorrowedFd;
 use serde::Deserialize;
 
 #[derive(Deserialize, Debug)]
@@ -24,12 +25,12 @@ pub(crate) struct Findmnt {
 
 #[context("Inspecting filesystem {path:?}")]
 pub(crate) fn inspect_filesystem(root: &openat::Dir, path: &str) -> Result<Filesystem> {
-    let rootfd = root.as_raw_fd();
+    let rootfd = unsafe { BorrowedFd::borrow_raw(root.as_raw_fd()) };
     // SAFETY: This is unsafe just for the pre_exec, when we port to cap-std we can use cap-std-ext
     let o = unsafe {
         Command::new("findmnt")
             .args(["-J", "-v", "--output=SOURCE,FSTYPE,OPTIONS,UUID", path])
-            .pre_exec(move || nix::unistd::fchdir(rootfd).map_err(Into::into))
+            .pre_exec(move || rustix::process::fchdir(rootfd).map_err(Into::into))
             .output()?
     };
     let st = o.status;

src/filesystem.rs

@@ -17,8 +17,6 @@ use std::fmt::Display;
 #[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
 use std::os::unix::io::AsRawFd;
 #[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
-use std::os::unix::process::CommandExt;
-#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
 use std::path::Path;
 
 /// The prefix we apply to our temporary files.
@@ -274,20 +272,9 @@ pub(crate) struct ApplyUpdateOptions {
 // Let's just fork off a helper process for now.
 #[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
 pub(crate) fn syncfs(d: &openat::Dir) -> Result<()> {
-    let d = d.sub_dir(".").expect("subdir");
-    let mut c = std::process::Command::new("sync");
-    let c = c.args(["-f", "."]);
-    unsafe {
-        c.pre_exec(move || {
-            nix::unistd::fchdir(d.as_raw_fd()).expect("fchdir");
-            Ok(())
-        })
-    };
-    let r = c.status().context("syncfs failed")?;
-    if !r.success() {
-        bail!("syncfs failed");
-    }
-    Ok(())
+    use rustix::fd::BorrowedFd;
+    let d = unsafe { BorrowedFd::borrow_raw(d.as_raw_fd()) };
+    rustix::fs::syncfs(d).map_err(Into::into)
 }
 
 #[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]

src/filetree.rs

@@ -67,10 +67,9 @@ pub(crate) fn filenames(dir: &openat::Dir) -> Result<HashSet<String>> {
 }
 
 pub(crate) fn ensure_writable_mount<P: AsRef<Path>>(p: P) -> Result<()> {
-    use nix::sys::statvfs;
     let p = p.as_ref();
-    let stat = statvfs::statvfs(p)?;
-    if !stat.flags().contains(statvfs::FsFlags::ST_RDONLY) {
+    let stat = rustix::fs::statvfs(p)?;
+    if !stat.f_flag.contains(rustix::fs::StatVfsMountFlags::RDONLY) {
         return Ok(());
     }
     let status = std::process::Command::new("mount")