refactor: replace nix::libc re-exports with direct libc imports

Replace all `nix::libc::*` usages with direct `libc::*` imports
to decouple libc access from the nix crate, as preparation for
migrating from nix to rustix.

Add direct libc dependency to crates that previously relied on
nix's libc re-export: stty, env, sort, date, mknod, touch.

Cargo.lock

@@ -3543,6 +3543,7 @@ version = "0.8.0"
 dependencies = [
  "clap",
  "fluent",
+ "libc",
  "nix",
  "rust-ini",
  "thiserror 2.0.18",
@@ -3797,6 +3798,7 @@ version = "0.8.0"
 dependencies = [
  "clap",
  "fluent",
+ "libc",
  "nix",
  "uucore",
 ]
@@ -4155,6 +4157,7 @@ dependencies = [
  "fluent",
  "foldhash 0.2.0",
  "itertools 0.14.0",
+ "libc",
  "memchr",
  "nix",
  "rand 0.10.1",
@@ -4215,6 +4218,7 @@ dependencies = [
  "cfg_aliases",
  "clap",
  "fluent",
+ "libc",
  "nix",
  "uucore",
 ]

src/uu/env/Cargo.toml

@@ -26,6 +26,7 @@ uucore = { workspace = true, features = ["signals"] }
 fluent = { workspace = true }
 
 [target.'cfg(unix)'.dependencies]
+libc = { workspace = true }
 nix = { workspace = true, features = ["signal"] }
 
 [[bin]]

src/uu/env/src/env.rs

@@ -18,8 +18,6 @@ use native_int_str::{
     Convert, NCvt, NativeIntStr, NativeIntString, NativeStr, from_native_int_representation_owned,
 };
 #[cfg(unix)]
-use nix::libc;
-#[cfg(unix)]
 use nix::sys::signal::{
     SigHandler::{SigDfl, SigIgn},
     SigSet, SigmaskHow, Signal, signal, sigprocmask,

src/uu/mknod/Cargo.toml

@@ -24,6 +24,7 @@ doctest = false
 clap = { workspace = true }
 uucore = { workspace = true, features = ["mode", "fs"] }
 fluent = { workspace = true }
+libc = { workspace = true }
 nix = { workspace = true }
 
 [features]

src/uu/mknod/src/mknod.rs

@@ -6,7 +6,7 @@
 // spell-checker:ignore (ToDO) parsemode makedev sysmacros perror IFBLK IFCHR IFIFO sflag
 
 use clap::{Arg, ArgAction, Command, value_parser};
-use nix::libc::{S_IRGRP, S_IROTH, S_IRUSR, S_IWGRP, S_IWOTH, S_IWUSR, mode_t};
+use libc::{S_IRGRP, S_IROTH, S_IRUSR, S_IWGRP, S_IWOTH, S_IWUSR, mode_t};
 use nix::sys::stat::{Mode, SFlag, mknod as nix_mknod, umask as nix_umask};
 
 use uucore::display::Quotable;

src/uu/sort/Cargo.toml

@@ -51,6 +51,7 @@ foldhash = { workspace = true }
 ctrlc = { workspace = true }
 
 [target.'cfg(unix)'.dependencies]
+libc = { workspace = true }
 nix = { workspace = true, features = ["resource"] }
 
 [dev-dependencies]

src/uu/sort/src/sort.rs

@@ -1410,8 +1410,6 @@ pub(crate) fn fd_soft_limit() -> Option<usize> {
 
 #[cfg(unix)]
 pub(crate) fn current_open_fd_count() -> Option<usize> {
-    use nix::libc;
-
     fn count_dir(path: &str) -> Option<usize> {
         let entries = std::fs::read_dir(path).ok()?;
         let mut count = 0usize;
@@ -1770,7 +1768,6 @@ fn locale_failed_to_set() -> bool {
 
 #[cfg(unix)]
 fn locale_failed_to_set() -> bool {
-    use nix::libc;
     unsafe { libc::setlocale(libc::LC_COLLATE, c"".as_ptr()).is_null() }
 }
 

src/uu/stty/Cargo.toml

@@ -24,6 +24,7 @@ uucore = { workspace = true, features = ["parser"] }
 fluent = { workspace = true }
 
 [target.'cfg(unix)'.dependencies]
+libc = { workspace = true }
 nix = { workspace = true, features = ["ioctl", "term"] }
 
 [[bin]]

src/uu/stty/src/stty.rs

@@ -19,14 +19,14 @@ mod flags;
 use crate::flags::AllFlags;
 use crate::flags::COMBINATION_SETTINGS;
 use clap::{Arg, ArgAction, ArgMatches, Command};
-use nix::libc::{O_NONBLOCK, TIOCGWINSZ, TIOCSWINSZ, c_ushort};
+use libc::{O_NONBLOCK, TIOCGWINSZ, TIOCSWINSZ, c_ushort};
 
 #[cfg(all(
     target_os = "linux",
     not(target_arch = "powerpc"),
     not(target_arch = "powerpc64")
 ))]
-use nix::libc::{TCGETS2, termios2};
+use libc::{TCGETS2, termios2};
 
 use nix::sys::termios::{
     ControlFlags, InputFlags, LocalFlags, OutputFlags, SetArg, SpecialCharacterIndices as S,
@@ -520,7 +520,7 @@ fn parse_rows_cols(arg: &str) -> Option<u16> {
 /// - Returns `None` if format is invalid
 fn parse_saved_state(arg: &str) -> Option<Vec<u32>> {
     let parts: Vec<&str> = arg.split(':').collect();
-    let expected_parts = 4 + nix::libc::NCCS;
+    let expected_parts = 4 + libc::NCCS;
 
     // GNU requires exactly the right number of parts for this platform
     if parts.len() != expected_parts {
@@ -692,7 +692,7 @@ fn print_terminal_size(
     {
         // For some reason the normal nix Termios struct does not expose the line,
         // so we get the underlying libc::termios struct to get that information.
-        let libc_termios: nix::libc::termios = termios.clone().into();
+        let libc_termios: libc::termios = termios.clone().into();
         let line = libc_termios.c_line;
         printer.print(&translate!("stty-output-line", "line" => line));
     }
@@ -824,7 +824,7 @@ fn string_to_flag(option: &str) -> Option<AllFlags<'_>> {
     None
 }
 
-fn control_char_to_string(cc: nix::libc::cc_t) -> nix::Result<String> {
+fn control_char_to_string(cc: libc::cc_t) -> nix::Result<String> {
     if cc == 0 {
         return Ok(translate!("stty-output-undef"));
     }

src/uucore/src/lib/features/safe_traversal.rs

@@ -24,7 +24,6 @@ use std::path::{Path, PathBuf};
 
 use nix::dir::Dir;
 use nix::fcntl::{OFlag, openat};
-use nix::libc;
 use nix::sys::stat::{FchmodatFlags, FileStat, Mode, fchmodat, fstatat, mkdirat};
 use nix::unistd::{Gid, Uid, UnlinkatFlags, fchown, fchownat, unlinkat};
 use os_display::Quotable;

src/uucore/src/lib/features/signals.rs

@@ -12,8 +12,6 @@
 
 #[cfg(unix)]
 use nix::errno::Errno;
-#[cfg(any(target_os = "linux", target_os = "android"))]
-use nix::libc;
 #[cfg(unix)]
 use nix::sys::signal::{
     SaFlags, SigAction, SigHandler, SigHandler::SigDfl, SigHandler::SigIgn, SigSet, Signal,
@@ -548,7 +546,6 @@ static STARTUP_STATE_WAS_CAPTURED: AtomicBool = AtomicBool::new(false);
 #[cfg(unix)]
 #[allow(clippy::missing_safety_doc)]
 pub unsafe extern "C" fn capture_startup_state() {
-    use nix::libc;
     use std::mem::MaybeUninit;
     use std::ptr;
 

src/uucore/src/lib/mods/panic.rs

@@ -49,8 +49,6 @@ pub fn mute_sigpipe_panic() {
 /// variable. If set to "default", it restores SIGPIPE to SIG_DFL.
 #[cfg(unix)]
 pub fn preserve_inherited_sigpipe() {
-    use nix::libc;
-
     // Check if parent specified that SIGPIPE should be default
     if std::env::var_os("RUST_SIGPIPE").is_some_and(|v| v == "default") {
         unsafe { libc::signal(libc::SIGPIPE, libc::SIG_DFL) };

tests/by-util/test_env.rs

@@ -5,8 +5,6 @@
 // spell-checker:ignore (words) bamf chdir rlimit prlimit COMSPEC cout cerr FFFD winsize xpixel ypixel Secho sighandler
 #![allow(clippy::missing_errors_doc)]
 
-#[cfg(unix)]
-use nix::libc;
 #[cfg(unix)]
 use nix::sys::signal::Signal;
 #[cfg(feature = "echo")]