treewide: remove nix dependency, add custom syscall wrappers & UtsName

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Ib880f4bafe9d3bbc944af4b9125256366a6a6964

Cargo.lock

@@ -143,12 +143,6 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
-[[package]]
-name = "cfg_aliases"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
-
 [[package]]
 name = "chunked_transfer"
 version = "1.5.0"
@@ -777,7 +771,6 @@ dependencies = [
  "criterion",
  "hotpath",
  "libc",
- "nix",
 ]
 
 [[package]]
@@ -790,18 +783,6 @@ dependencies = [
  "simd-adler32",
 ]
 
-[[package]]
-name = "nix"
-version = "0.30.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "74523f3a35e05aba87a1d978330aef40f67b0304ac79c1c00b294c9830543db6"
-dependencies = [
- "bitflags",
- "cfg-if",
- "cfg_aliases",
- "libc",
-]
-
 [[package]]
 name = "num-conv"
 version = "0.1.0"

Cargo.toml

@@ -14,7 +14,6 @@ path = "src/main.rs"
 [dependencies]
 hotpath = { optional = true, version = "0.6.0" }
 libc    = "0.2.177"
-nix     = { default-features = false, features = [ "fs", "hostname", "feature" ], version = "0.30.1" }
 
 [dev-dependencies]
 criterion = "0.7"

benches/benchmark.rs

@@ -1,5 +1,6 @@
 use criterion::{Criterion, criterion_group, criterion_main};
 use microfetch_lib::{
+  UtsName,
   colors::print_dots,
   desktop::get_desktop_info,
   release::{get_os_pretty_name, get_system_info},
@@ -13,7 +14,7 @@ use microfetch_lib::{
 };
 
 fn main_benchmark(c: &mut Criterion) {
-  let utsname = nix::sys::utsname::uname().expect("lol");
+  let utsname = UtsName::uname().expect("Failed to get uname");
   c.bench_function("user_info", |b| {
     b.iter(|| get_username_and_hostname(&utsname));
   });

src/lib.rs

@@ -1,5 +1,45 @@
 pub mod colors;
 pub mod desktop;
 pub mod release;
+pub mod syscall;
 pub mod system;
 pub mod uptime;
+
+use std::mem::MaybeUninit;
+
+/// Wrapper for `libc::utsname` with safe accessor methods
+pub struct UtsName(libc::utsname);
+
+impl UtsName {
+  /// Calls `uname` syscall and returns a `UtsName` wrapper
+  ///
+  /// # Errors
+  /// Returns an error if the uname syscall fails
+  pub fn uname() -> Result<Self, std::io::Error> {
+    let mut uts = MaybeUninit::uninit();
+    if unsafe { libc::uname(uts.as_mut_ptr()) } != 0 {
+      return Err(std::io::Error::last_os_error());
+    }
+    Ok(Self(unsafe { uts.assume_init() }))
+  }
+
+  #[must_use]
+  pub const fn nodename(&self) -> &std::ffi::CStr {
+    unsafe { std::ffi::CStr::from_ptr(self.0.nodename.as_ptr()) }
+  }
+
+  #[must_use]
+  pub const fn sysname(&self) -> &std::ffi::CStr {
+    unsafe { std::ffi::CStr::from_ptr(self.0.sysname.as_ptr()) }
+  }
+
+  #[must_use]
+  pub const fn release(&self) -> &std::ffi::CStr {
+    unsafe { std::ffi::CStr::from_ptr(self.0.release.as_ptr()) }
+  }
+
+  #[must_use]
+  pub const fn machine(&self) -> &std::ffi::CStr {
+    unsafe { std::ffi::CStr::from_ptr(self.0.machine.as_ptr()) }
+  }
+}

src/main.rs

@@ -1,11 +1,14 @@
 mod colors;
 mod desktop;
 mod release;
+mod syscall;
 mod system;
 mod uptime;
 
 use std::io::{Write, stdout};
 
+pub use microfetch_lib::UtsName;
+
 use crate::{
   colors::print_dots,
   desktop::get_desktop_info,
@@ -24,7 +27,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
   if Some("--version") == std::env::args().nth(1).as_deref() {
     println!("Microfetch {}", env!("CARGO_PKG_VERSION"));
   } else {
-    let utsname = nix::sys::utsname::uname()?;
+    let utsname = UtsName::uname()?;
     let fields = Fields {
       user_info:      get_username_and_hostname(&utsname),
       os_name:        get_os_pretty_name()?,

src/release.rs

@@ -1,10 +1,6 @@
-use std::{
-  fmt::Write as _,
-  fs::File,
-  io::{self, Read},
-};
+use std::{fmt::Write as _, io};
 
-use nix::sys::utsname::UtsName;
+use crate::{UtsName, syscall::read_file_fast};
 
 #[must_use]
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
@@ -28,21 +24,46 @@ pub fn get_system_info(utsname: &UtsName) -> String {
 /// Returns an error if `/etc/os-release` cannot be read.
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
 pub fn get_os_pretty_name() -> Result<String, io::Error> {
-  // We use a stack-allocated buffer here, which seems to perform MUCH better
-  // than `BufReader`. In hindsight, I should've seen this coming.
-  let mut buffer = String::with_capacity(1024);
-  File::open("/etc/os-release")?.read_to_string(&mut buffer)?;
+  // Fast byte-level scanning for PRETTY_NAME=
+  const PREFIX: &[u8] = b"PRETTY_NAME=";
 
-  for line in buffer.lines() {
-    if let Some(pretty_name) = line.strip_prefix("PRETTY_NAME=") {
-      if let Some(trimmed) = pretty_name
-        .strip_prefix('"')
-        .and_then(|s| s.strip_suffix('"'))
+  let mut buffer = [0u8; 1024];
+
+  // Use fast syscall-based file reading
+  let bytes_read = read_file_fast("/etc/os-release", &mut buffer)?;
+  let content = &buffer[..bytes_read];
+
+  let mut offset = 0;
+
+  while offset < content.len() {
+    let remaining = &content[offset..];
+
+    // Find newline or end
+    let line_end = remaining
+      .iter()
+      .position(|&b| b == b'\n')
+      .unwrap_or(remaining.len());
+    let line = &remaining[..line_end];
+
+    if line.starts_with(PREFIX) {
+      let value = &line[PREFIX.len()..];
+
+      // Strip quotes if present
+      let trimmed = if value.len() >= 2
+        && value[0] == b'"'
+        && value[value.len() - 1] == b'"'
       {
-        return Ok(trimmed.to_owned());
-      }
-      return Ok(pretty_name.to_owned());
+        &value[1..value.len() - 1]
+      } else {
+        value
+      };
+
+      // Convert to String - should be valid UTF-8
+      return Ok(String::from_utf8_lossy(trimmed).into_owned());
     }
+
+    offset += line_end + 1;
   }
+
   Ok("Unknown".to_owned())
 }

src/syscall.rs

@@ -0,0 +1,203 @@
+//! Incredibly fast syscall wrappers for using inline assembly. Serves the
+//! purposes of completely bypassing Rust's standard library in favor of
+//! handwritten Assembly. Is this a good idea? No. Is it fast? Yeah, but only
+//! marginally. Either way it serves a purpose and I will NOT accept criticism.
+//! What do you mean I wasted two whole hours to make the program only 100µs
+//! faster?
+//!
+//! Supports `x86_64` and `aarch64` architectures. Riscv support will be
+//! implemented when and ONLY WHEN I can be bothered to work on it.
+
+use std::io;
+
+/// Direct syscall to open a file
+/// Returns file descriptor or -1 on error
+///
+/// # Safety
+///
+/// The caller must ensure:
+/// - `path` points to a valid null-terminated C string
+/// - The pointer remains valid for the duration of the syscall
+#[inline]
+#[must_use]
+pub unsafe fn sys_open(path: *const u8, flags: i32) -> i32 {
+  #[cfg(target_arch = "x86_64")]
+  unsafe {
+    let fd: i64;
+    std::arch::asm!(
+      "syscall",
+      in("rax") 2i64,  // SYS_open
+      in("rdi") path,
+      in("rsi") flags,
+      in("rdx") 0i32,  // mode (not used for reading)
+      lateout("rax") fd,
+      lateout("rcx") _,
+      lateout("r11") _,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      fd as i32
+    }
+  }
+  #[cfg(target_arch = "aarch64")]
+  unsafe {
+    let fd: i64;
+    std::arch::asm!(
+      "svc #0",
+      in("x8") 56i64,  // SYS_openat
+      in("x0") -100i32,  // AT_FDCWD
+      in("x1") path,
+      in("x2") flags,
+      in("x3") 0i32,  // mode
+      lateout("x0") fd,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      fd as i32
+    }
+  }
+  #[cfg(not(any(target_arch = "x86_64", target_arch = "aarch64")))]
+  {
+    compile_error!("Unsupported architecture for inline assembly syscalls");
+  }
+}
+
+/// Direct syscall to read from a file descriptor
+/// Returns number of bytes read or -1 on error
+///
+/// # Safety
+///
+/// The caller must ensure:
+/// - `buf` points to a valid writable buffer of at least `count` bytes
+/// - `fd` is a valid open file descriptor
+#[inline]
+pub unsafe fn sys_read(fd: i32, buf: *mut u8, count: usize) -> isize {
+  #[cfg(target_arch = "x86_64")]
+  unsafe {
+    let ret: i64;
+    std::arch::asm!(
+      "syscall",
+      in("rax") 0i64,  // SYS_read
+      in("rdi") fd,
+      in("rsi") buf,
+      in("rdx") count,
+      lateout("rax") ret,
+      lateout("rcx") _,
+      lateout("r11") _,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      ret as isize
+    }
+  }
+  #[cfg(target_arch = "aarch64")]
+  unsafe {
+    let ret: i64;
+    std::arch::asm!(
+      "svc #0",
+      in("x8") 63i64,  // SYS_read
+      in("x0") fd,
+      in("x1") buf,
+      in("x2") count,
+      lateout("x0") ret,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      ret as isize
+    }
+  }
+  #[cfg(not(any(target_arch = "x86_64", target_arch = "aarch64")))]
+  {
+    compile_error!("Unsupported architecture for inline assembly syscalls");
+  }
+}
+
+/// Direct syscall to close a file descriptor
+///
+/// # Safety
+///
+/// The caller must ensure `fd` is a valid open file descriptor
+#[inline]
+#[must_use]
+pub unsafe fn sys_close(fd: i32) -> i32 {
+  #[cfg(target_arch = "x86_64")]
+  unsafe {
+    let ret: i64;
+    std::arch::asm!(
+      "syscall",
+      in("rax") 3i64,  // SYS_close
+      in("rdi") fd,
+      lateout("rax") ret,
+      lateout("rcx") _,
+      lateout("r11") _,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      ret as i32
+    }
+  }
+  #[cfg(target_arch = "aarch64")]
+  unsafe {
+    let ret: i64;
+    std::arch::asm!(
+      "svc #0",
+      in("x8") 57i64,  // SYS_close
+      in("x0") fd,
+      lateout("x0") ret,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      ret as i32
+    }
+  }
+  #[cfg(not(any(target_arch = "x86_64", target_arch = "aarch64")))]
+  {
+    compile_error!("Unsupported architecture for inline assembly syscalls");
+  }
+}
+
+/// Read entire file using direct syscalls. This avoids libc overhead and can be
+/// significantly faster for small files.
+///
+/// # Errors
+///
+/// Returns an error if the file cannot be opened or read
+#[inline]
+pub fn read_file_fast(path: &str, buffer: &mut [u8]) -> io::Result<usize> {
+  const O_RDONLY: i32 = 0;
+
+  // Use stack-allocated buffer for null-terminated path (max 256 bytes)
+  let path_bytes = path.as_bytes();
+  if path_bytes.len() >= 256 {
+    return Err(io::Error::new(io::ErrorKind::InvalidInput, "Path too long"));
+  }
+
+  let mut path_buf = [0u8; 256];
+  path_buf[..path_bytes.len()].copy_from_slice(path_bytes);
+  // XXX: Already zero-terminated since array is initialized to zeros
+
+  unsafe {
+    let fd = sys_open(path_buf.as_ptr(), O_RDONLY);
+    if fd < 0 {
+      return Err(io::Error::last_os_error());
+    }
+
+    let bytes_read = sys_read(fd, buffer.as_mut_ptr(), buffer.len());
+    let _ = sys_close(fd);
+
+    if bytes_read < 0 {
+      return Err(io::Error::last_os_error());
+    }
+
+    #[allow(clippy::cast_sign_loss)]
+    {
+      Ok(bytes_read as usize)
+    }
+  }
+}

src/system.rs

@@ -1,13 +1,6 @@
-use std::{
-  env,
-  fmt::Write as _,
-  fs::File,
-  io::{self, Read},
-};
+use std::{env, fmt::Write as _, io, mem::MaybeUninit};
 
-use nix::sys::{statvfs::statvfs, utsname::UtsName};
-
-use crate::colors::COLORS;
+use crate::{UtsName, colors::COLORS, syscall::read_file_fast};
 
 #[must_use]
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
@@ -57,10 +50,17 @@ 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 vfs = statvfs("/")?;
-  let block_size = vfs.block_size() as u64;
-  let total_blocks = vfs.blocks();
-  let available_blocks = vfs.blocks_available();
+  let mut vfs = MaybeUninit::uninit();
+  let path = b"/\0";
+
+  if unsafe { libc::statvfs(path.as_ptr().cast(), vfs.as_mut_ptr()) } != 0 {
+    return Err(io::Error::last_os_error());
+  }
+
+  let vfs = unsafe { vfs.assume_init() };
+  let block_size = vfs.f_bsize;
+  let total_blocks = vfs.f_blocks;
+  let available_blocks = vfs.f_bavail;
 
   let total_size = block_size * total_blocks;
   let used_size = total_size - (block_size * available_blocks);
@@ -81,6 +81,20 @@ pub fn get_root_disk_usage() -> Result<String, io::Error> {
   Ok(result)
 }
 
+/// Fast integer parsing without stdlib overhead
+#[inline]
+fn parse_u64_fast(s: &[u8]) -> u64 {
+  let mut result = 0u64;
+  for &byte in s {
+    if byte.is_ascii_digit() {
+      result = result * 10 + u64::from(byte - b'0');
+    } else {
+      break;
+    }
+  }
+  result
+}
+
 /// Gets the system memory usage information.
 ///
 /// # Errors
@@ -90,30 +104,54 @@ pub fn get_root_disk_usage() -> Result<String, io::Error> {
 pub fn get_memory_usage() -> Result<String, io::Error> {
   #[cfg_attr(feature = "hotpath", hotpath::measure)]
   fn parse_memory_info() -> Result<(f64, f64), io::Error> {
-    let mut total_memory_kb = 0.0;
-    let mut available_memory_kb = 0.0;
-    let mut meminfo = String::with_capacity(2048);
+    let mut total_memory_kb = 0u64;
+    let mut available_memory_kb = 0u64;
+    let mut buffer = [0u8; 2048];
 
-    File::open("/proc/meminfo")?.read_to_string(&mut meminfo)?;
+    // Use fast syscall-based file reading
+    let bytes_read = read_file_fast("/proc/meminfo", &mut buffer)?;
+    let meminfo = &buffer[..bytes_read];
 
-    for line in meminfo.lines() {
-      let mut split = line.split_whitespace();
-      match split.next().unwrap_or_default() {
-        "MemTotal:" => {
-          total_memory_kb = split.next().unwrap_or("0").parse().unwrap_or(0.0);
-        },
-        "MemAvailable:" => {
-          available_memory_kb =
-            split.next().unwrap_or("0").parse().unwrap_or(0.0);
-          // MemTotal comes before MemAvailable, stop parsing
-          break;
-        },
-        _ => (),
+    // Fast scanning for MemTotal and MemAvailable
+    let mut offset = 0;
+    let mut found_total = false;
+    let mut found_available = false;
+
+    while offset < meminfo.len() && (!found_total || !found_available) {
+      let remaining = &meminfo[offset..];
+
+      // Find newline or end
+      let line_end = remaining
+        .iter()
+        .position(|&b| b == b'\n')
+        .unwrap_or(remaining.len());
+      let line = &remaining[..line_end];
+
+      if line.starts_with(b"MemTotal:") {
+        // Skip "MemTotal:" and whitespace
+        let mut pos = 9;
+        while pos < line.len() && line[pos].is_ascii_whitespace() {
+          pos += 1;
         }
+        total_memory_kb = parse_u64_fast(&line[pos..]);
+        found_total = true;
+      } else if line.starts_with(b"MemAvailable:") {
+        // Skip "MemAvailable:" and whitespace
+        let mut pos = 13;
+        while pos < line.len() && line[pos].is_ascii_whitespace() {
+          pos += 1;
+        }
+        available_memory_kb = parse_u64_fast(&line[pos..]);
+        found_available = true;
       }
 
-    let total_memory_gb = total_memory_kb / 1024.0 / 1024.0;
-    let available_memory_gb = available_memory_kb / 1024.0 / 1024.0;
+      offset += line_end + 1;
+    }
+
+    #[allow(clippy::cast_precision_loss)]
+    let total_memory_gb = total_memory_kb as f64 / 1024.0 / 1024.0;
+    #[allow(clippy::cast_precision_loss)]
+    let available_memory_gb = available_memory_kb as f64 / 1024.0 / 1024.0;
     let used_memory_gb = total_memory_gb - available_memory_gb;
 
     Ok((used_memory_gb, total_memory_gb))