system: use std::env::var_os over libc helpers

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I2747d4b065095314a1d454a204a251c96a6a6964

src/main.rs

@@ -101,12 +101,15 @@ fn print_system_info(
 
   let len = cursor.position() as usize;
   // Direct syscall to avoid stdout buffering allocation
-  let written = unsafe { libc::write(libc::STDOUT_FILENO, buf.as_ptr().cast(), len) };
+  let written = unsafe { syscall::sys_write(1, buf.as_ptr(), len) };
   if written < 0 {
     return Err(io::Error::last_os_error().into());
   }
   if written as usize != len {
-    return Err(io::Error::new(io::ErrorKind::WriteZero, "partial write to stdout").into());
+    return Err(
+      io::Error::new(io::ErrorKind::WriteZero, "partial write to stdout")
+        .into(),
+    );
   }
   Ok(())
 }

src/system.rs

@@ -1,18 +1,19 @@
-use std::{ffi::CStr, fmt::Write as _, io, mem::MaybeUninit};
+use std::{ffi::OsStr, fmt::Write as _, io, mem::MaybeUninit};
 
-use crate::{UtsName, colors::COLORS, syscall::read_file_fast};
+use crate::{
+  UtsName,
+  colors::COLORS,
+  syscall::{StatfsBuf, read_file_fast, sys_statfs},
+};
 
 #[must_use]
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
 pub fn get_username_and_hostname(utsname: &UtsName) -> String {
-  let username = unsafe {
+  let username_os = std::env::var_os("USER");
-    let ptr = libc::getenv(c"USER".as_ptr());
+  let username = username_os
-    if ptr.is_null() {
+    .as_deref()
-      "unknown_user"
+    .and_then(OsStr::to_str)
-    } else {
+    .unwrap_or("unknown_user");
-      CStr::from_ptr(ptr).to_str().unwrap_or("unknown_user")
-    }
-  };
   let hostname = utsname.nodename().to_str().unwrap_or("unknown_host");
 
   let capacity = COLORS.yellow.len()
@@ -38,16 +39,13 @@ pub fn get_username_and_hostname(utsname: &UtsName) -> String {
 #[must_use]
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
 pub fn get_shell() -> String {
-  unsafe {
+  let shell_os = std::env::var_os("SHELL");
-    let ptr = libc::getenv(c"SHELL".as_ptr());
+  let shell = shell_os.as_deref().and_then(OsStr::to_str).unwrap_or("");
-    if ptr.is_null() {
+  let start = shell.rfind('/').map_or(0, |i| i + 1);
-      return "unknown_shell".into();
+  if shell.is_empty() {
-    }
+    "unknown_shell".into()
-
+  } else {
-    let bytes = CStr::from_ptr(ptr).to_bytes();
+    shell[start..].into()
-    let start = bytes.iter().rposition(|&b| b == b'/').map_or(0, |i| i + 1);
-    let name = std::str::from_utf8_unchecked(&bytes[start..]);
-    name.into()
   }
 }
 
@@ -59,15 +57,16 @@ pub fn get_shell() -> String {
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
 #[allow(clippy::cast_precision_loss)]
 pub fn get_root_disk_usage() -> Result<String, io::Error> {
-  let mut vfs = MaybeUninit::uninit();
+  let mut vfs = MaybeUninit::<StatfsBuf>::uninit();
   let path = b"/\0";
 
-  if unsafe { libc::statvfs(path.as_ptr().cast(), vfs.as_mut_ptr()) } != 0 {
+  if unsafe { sys_statfs(path.as_ptr(), vfs.as_mut_ptr()) } != 0 {
     return Err(io::Error::last_os_error());
   }
 
   let vfs = unsafe { vfs.assume_init() };
-  let block_size = vfs.f_bsize;
+  #[allow(clippy::cast_sign_loss)]
+  let block_size = vfs.f_bsize as u64;
   let total_blocks = vfs.f_blocks;
   let available_blocks = vfs.f_bavail;