Simplify kernel version parsing

test/integration-test/Cargo.toml

@@ -13,6 +13,5 @@ libc = { version = "0.2.105" }
 log = "0.4"
 object = { version = "0.31", default-features = false, features = ["std", "read_core", "elf"] }
 rbpf = "0.2.0"
-regex = "1"
 tempfile = "3.3.0"
 tokio = { version = "1.24", features = ["rt", "rt-multi-thread", "sync", "time"] }

test/integration-test/tests/common.rs

@@ -1,23 +1,42 @@
-use anyhow::bail;
+use anyhow::{anyhow, Context as _};
 use libc::{uname, utsname};
-use regex::Regex;
-use std::{cell::OnceCell, ffi::CStr, mem};
+use std::{ffi::CStr, io::Error, mem};
 
 pub fn kernel_version() -> anyhow::Result<(u8, u8, u8)> {
-    static mut RE: OnceCell<Regex> = OnceCell::new();
-    let re =
-        unsafe { &mut RE }.get_or_init(|| Regex::new(r"^([0-9]+)\.([0-9]+)\.([0-9]+)").unwrap());
     let mut data: utsname = unsafe { mem::zeroed() };
     let ret = unsafe { uname(&mut data) };
-    assert!(ret >= 0, "libc::uname failed.");
-    let release_cstr = unsafe { CStr::from_ptr(data.release.as_ptr()) };
-    let release = release_cstr.to_string_lossy();
-    if let Some(caps) = re.captures(&release) {
-        let major = caps.get(1).unwrap().as_str().parse().unwrap();
-        let minor = caps.get(2).unwrap().as_str().parse().unwrap();
-        let patch = caps.get(3).unwrap().as_str().parse().unwrap();
-        Ok((major, minor, patch))
-    } else {
-        bail!("no kernel version found");
+    if ret != 0 {
+        return Err(Error::last_os_error()).context("uname failed");
     }
+    let utsname { release, .. } = data;
+    let release: &[u8] =
+        unsafe { std::slice::from_raw_parts(release.as_ptr() as _, release.len()) };
+    let s = CStr::from_bytes_until_nul(release)?;
+    let s = s.to_str()?;
+
+    // Adapted from https://github.com/eminence/procfs/blob/d7ea846/procfs/src/sys/kernel/mod.rs#L51-L70.
+    let pos = s.find(|c: char| c != '.' && !c.is_ascii_digit());
+    let kernel = if let Some(pos) = pos {
+        let (s, _) = s.split_at(pos);
+        s
+    } else {
+        s
+    };
+    let mut kernel_split = kernel.split('.');
+
+    let major = kernel_split
+        .next()
+        .ok_or(anyhow!("Missing major version component"))?;
+    let minor = kernel_split
+        .next()
+        .ok_or(anyhow!("Missing minor version component"))?;
+    let patch = kernel_split
+        .next()
+        .ok_or(anyhow!("Missing patch version component"))?;
+
+    let major = major.parse().context("Failed to parse major version")?;
+    let minor = minor.parse().context("Failed to parse minor version")?;
+    let patch = patch.parse().context("Failed to parse patch version")?;
+
+    Ok((major, minor, patch))
 }