lib: eliminate alloc and core::fmt, write directly to StackWriter

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members  = [ "crates/*", "microfetch", "crates/benchmarks" ]
+members  = [ "crates/asm", "crates/benchmarks", "crates/lib", "microfetch" ]
 resolver = "3"
 
 [workspace.package]
@@ -9,9 +9,8 @@ rust-version = "1.95.0"
 version      = "1.2.0"
 
 [workspace.dependencies]
-microfetch-alloc = { path = "./crates/alloc", version = "1.2.0" }
-microfetch-asm   = { path = "./crates/asm", version = "1.2.0" }
-microfetch-lib   = { path = "./crates/lib", version = "1.2.0" }
+microfetch-asm = { path = "./crates/asm", version = "1.2.0" }
+microfetch-lib = { path = "./crates/lib", version = "1.2.0" }
 
 criterion                 = { default-features = false, features = [ "cargo_bench_support" ], version = "0.8.2" }
 criterion-cycles-per-byte = "0.8.0"

crates/asm/src/darwin.rs

@@ -175,7 +175,7 @@ const HOST_VM_INFO64: c_int = 4;
 /// `host_statistics64` matches the kernel's expectation exactly (38 ints).
 #[repr(C)]
 #[derive(Default)]
-#[expect(dead_code, reason = "most fields exist only to fix the struct layout")]
+#[allow(dead_code, reason = "most fields exist only to fix the struct layout")]
 struct VmStatistics64 {
   free_count:                             u32,
   active_count:                           u32,
@@ -240,7 +240,7 @@ pub fn macos_meminfo() -> Option<(u64, u64)> {
 /// `struct timeval` (`time_t` is 64-bit, `suseconds_t` is 32-bit on macOS).
 #[repr(C)]
 #[derive(Default)]
-#[expect(
+#[allow(
   dead_code,
   reason = "tv_usec/_pad exist only to fix the struct layout"
 )]

crates/benchmarks/benches/microfetch.rs

@@ -1,32 +1,82 @@
 use criterion::{Criterion, criterion_group, criterion_main};
 use microfetch_lib::{
+  StackWriter,
   UtsName,
-  colors::print_dots,
-  desktop::get_desktop_info,
-  release::{get_os_pretty_name, get_system_info},
-  system::{
-    get_memory_usage,
-    get_root_disk_usage,
-    get_shell,
-    get_username_and_hostname,
-  },
-  uptime::get_current,
+  colors::{self, Colors},
+  cpu,
+  desktop,
+  release,
+  system,
+  uptime,
 };
 
 fn main_benchmark(c: &mut Criterion) {
   let utsname = UtsName::uname().expect("Failed to get uname");
+  let colors = Colors::new(false);
+
   c.bench_function("user_info", |b| {
-    b.iter(|| get_username_and_hostname(&utsname));
+    b.iter(|| {
+      let mut buf = [0u8; 256];
+      let mut w = StackWriter::new(&mut buf);
+      system::write_username_and_hostname(&mut w, &colors, &utsname);
+    });
+  });
+  c.bench_function("os_name", |b| {
+    b.iter(|| {
+      let mut buf = [0u8; 256];
+      let mut w = StackWriter::new(&mut buf);
+      let _ = release::write_os_pretty_name(&mut w);
+    });
+  });
+  c.bench_function("kernel_version", |b| {
+    b.iter(|| {
+      let mut buf = [0u8; 256];
+      let mut w = StackWriter::new(&mut buf);
+      release::write_system_info(&mut w, &utsname);
+    });
+  });
+  c.bench_function("shell", |b| {
+    b.iter(|| {
+      let mut buf = [0u8; 256];
+      let mut w = StackWriter::new(&mut buf);
+      system::write_shell(&mut w);
+    });
+  });
+  c.bench_function("desktop", |b| {
+    b.iter(|| {
+      let mut buf = [0u8; 256];
+      let mut w = StackWriter::new(&mut buf);
+      desktop::write_desktop_info(&mut w);
+    });
+  });
+  c.bench_function("uptime", |b| {
+    b.iter(|| {
+      let mut buf = [0u8; 256];
+      let mut w = StackWriter::new(&mut buf);
+      let _ = uptime::write_uptime(&mut w);
+    });
+  });
+  c.bench_function("memory_usage", |b| {
+    b.iter(|| {
+      let mut buf = [0u8; 256];
+      let mut w = StackWriter::new(&mut buf);
+      let _ = system::write_memory_usage(&mut w, &colors);
+    });
+  });
+  c.bench_function("storage", |b| {
+    b.iter(|| {
+      let mut buf = [0u8; 256];
+      let mut w = StackWriter::new(&mut buf);
+      let _ = system::write_root_disk_usage(&mut w, &colors);
+    });
+  });
+  c.bench_function("colors", |b| {
+    b.iter(|| {
+      let mut buf = [0u8; 256];
+      let mut w = StackWriter::new(&mut buf);
+      colors::write_dots(&mut w, &colors);
+    });
   });
-  c.bench_function("os_name", |b| b.iter(get_os_pretty_name));
-  c.bench_function("kernel_version", |b| b.iter(|| get_system_info(&utsname)));
-  c.bench_function("shell", |b| b.iter(get_shell));
-
-  c.bench_function("desktop", |b| b.iter(get_desktop_info));
-  c.bench_function("uptime", |b| b.iter(get_current));
-  c.bench_function("memory_usage", |b| b.iter(get_memory_usage));
-  c.bench_function("storage", |b| b.iter(get_root_disk_usage));
-  c.bench_function("colors", |b| b.iter(print_dots));
 }
 
 criterion_group!(benches, main_benchmark);

crates/lib/src/colors.rs

@@ -1,4 +1,4 @@
-use alloc::string::String;
+use crate::StackWriter;
 
 /// Color codes for terminal output
 pub struct Colors {
@@ -59,47 +59,27 @@ pub(crate) fn is_no_color() -> bool {
   is_set
 }
 
-#[must_use]
 #[cfg_attr(feature = "hotpath", hotpath::measure)]
-pub fn print_dots() -> String {
-  const GLYPH: &str = "";
+pub fn write_dots(w: &mut StackWriter, colors: &Colors) {
+  const GLYPH: &str = "●";
 
-  let colors = if is_no_color() {
-    Colors::new(true)
-  } else {
-    Colors::new(false)
-  };
-
-  // Pre-calculate capacity: 6 color codes + "  " (glyph + 2 spaces) per color
-  let capacity = colors.blue.len()
-    + colors.cyan.len()
-    + colors.green.len()
-    + colors.yellow.len()
-    + colors.red.len()
-    + colors.magenta.len()
-    + colors.reset.len()
-    + (GLYPH.len() + 2) * 6;
-
-  let mut result = String::with_capacity(capacity);
-  result.push_str(colors.blue);
-  result.push_str(GLYPH);
-  result.push_str("  ");
-  result.push_str(colors.cyan);
-  result.push_str(GLYPH);
-  result.push_str("  ");
-  result.push_str(colors.green);
-  result.push_str(GLYPH);
-  result.push_str("  ");
-  result.push_str(colors.yellow);
-  result.push_str(GLYPH);
-  result.push_str("  ");
-  result.push_str(colors.red);
-  result.push_str(GLYPH);
-  result.push_str("  ");
-  result.push_str(colors.magenta);
-  result.push_str(GLYPH);
-  result.push_str("  ");
-  result.push_str(colors.reset);
-
-  result
+  w.push_str(colors.blue);
+  w.push_str(GLYPH);
+  w.push_str("  ");
+  w.push_str(colors.cyan);
+  w.push_str(GLYPH);
+  w.push_str("  ");
+  w.push_str(colors.green);
+  w.push_str(GLYPH);
+  w.push_str("  ");
+  w.push_str(colors.yellow);
+  w.push_str(GLYPH);
+  w.push_str("  ");
+  w.push_str(colors.red);
+  w.push_str(GLYPH);
+  w.push_str("  ");
+  w.push_str(colors.magenta);
+  w.push_str(GLYPH);
+  w.push_str("  ");
+  w.push_str(colors.reset);
 }