treewide: break into multiple crates

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Ifabe7af523ece1354b301b1a321659ee6a6a6964

crates/lib/src/uptime.rs

@@ -0,0 +1,141 @@
+use std::{io, mem::MaybeUninit};
+
+/// Faster integer to string conversion without the formatting overhead.
+#[inline]
+fn itoa(mut n: u64, buf: &mut [u8]) -> &str {
+  if n == 0 {
+    return "0";
+  }
+
+  let mut i = buf.len();
+  while n > 0 {
+    i -= 1;
+    buf[i] = b'0' + (n % 10) as u8;
+    n /= 10;
+  }
+
+  unsafe { std::str::from_utf8_unchecked(&buf[i..]) }
+}
+
+/// Raw buffer for the `sysinfo(2)` syscall.
+///
+/// In the Linux ABI `uptime` is a `long` at offset 0. The remaining fields are
+/// not needed, but are declared to give the struct its correct size (112 bytes
+/// on 64-bit Linux).
+///
+/// The layout matches the kernel's `struct sysinfo` *exactly*:
+/// `mem_unit` ends at offset 108, then 4 bytes of implicit padding to 112.
+#[repr(C)]
+struct SysInfo {
+  uptime:    i64,
+  loads:     [u64; 3],
+  totalram:  u64,
+  freeram:   u64,
+  sharedram: u64,
+  bufferram: u64,
+  totalswap: u64,
+  freeswap:  u64,
+  procs:     u16,
+  _pad:      u16,
+  _pad2:     u32, // alignment padding to reach 8-byte boundary for totalhigh
+  totalhigh: u64,
+  freehigh:  u64,
+  mem_unit:  u32,
+  // 4 bytes implicit trailing padding to reach 112 bytes total; no field
+  // needed
+}
+
+/// Direct `sysinfo(2)` syscall using inline assembly
+///
+/// # Safety
+///
+/// The caller must ensure the sysinfo pointer is valid.
+#[inline]
+unsafe fn sys_sysinfo(info: *mut SysInfo) -> i64 {
+  #[cfg(target_arch = "x86_64")]
+  {
+    let ret: i64;
+    unsafe {
+      std::arch::asm!(
+        "syscall",
+        in("rax") 99_i64, // __NR_sysinfo
+        in("rdi") info,
+        out("rcx") _,
+        out("r11") _,
+        lateout("rax") ret,
+        options(nostack)
+      );
+    }
+    ret
+  }
+
+  #[cfg(target_arch = "aarch64")]
+  {
+    let ret: i64;
+    unsafe {
+      std::arch::asm!(
+        "svc #0",
+        in("x8") 179_i64, // __NR_sysinfo
+        in("x0") info,
+        lateout("x0") ret,
+        options(nostack)
+      );
+    }
+    ret
+  }
+
+  #[cfg(not(any(target_arch = "x86_64", target_arch = "aarch64")))]
+  {
+    compile_error!("Unsupported architecture for inline assembly syscalls");
+  }
+}
+
+/// Gets the current system uptime.
+///
+/// # Errors
+///
+/// Returns an error if the system uptime cannot be retrieved.
+#[cfg_attr(feature = "hotpath", hotpath::measure)]
+pub fn get_current() -> Result<String, io::Error> {
+  let uptime_seconds = {
+    let mut info = MaybeUninit::uninit();
+    if unsafe { sys_sysinfo(info.as_mut_ptr()) } != 0 {
+      return Err(io::Error::last_os_error());
+    }
+    #[allow(clippy::cast_sign_loss)]
+    unsafe {
+      info.assume_init().uptime as u64
+    }
+  };
+
+  let days = uptime_seconds / 86400;
+  let hours = (uptime_seconds / 3600) % 24;
+  let minutes = (uptime_seconds / 60) % 60;
+
+  let mut result = String::with_capacity(32);
+  let mut buf = [0u8; 20]; // Enough for u64::MAX
+
+  if days > 0 {
+    result.push_str(itoa(days, &mut buf));
+    result.push_str(if days == 1 { " day" } else { " days" });
+  }
+  if hours > 0 {
+    if !result.is_empty() {
+      result.push_str(", ");
+    }
+    result.push_str(itoa(hours, &mut buf));
+    result.push_str(if hours == 1 { " hour" } else { " hours" });
+  }
+  if minutes > 0 {
+    if !result.is_empty() {
+      result.push_str(", ");
+    }
+    result.push_str(itoa(minutes, &mut buf));
+    result.push_str(if minutes == 1 { " minute" } else { " minutes" });
+  }
+  if result.is_empty() {
+    result.push_str("less than a minute");
+  }
+
+  Ok(result)
+}