Initial pass of version checking in ctru-sys

ctru-sys/Cargo.toml

@@ -1,10 +1,13 @@
 [package]
 name = "ctru-sys"
-version = "0.4.1"
+version = "21.2.0+2.1.2-1"
 authors = ["Ronald Kinard <furyhunter600@gmail.com>"]
-license = "https://en.wikipedia.org/wiki/Zlib_License"
+license = "Zlib"
 links = "ctru"
 edition = "2021"
 
 [dependencies]
 libc = { version = "0.2.121", default-features = false }
+
+[build-dependencies]
+which = "4.4.0"

ctru-sys/build.rs

@@ -1,4 +1,6 @@
 use std::env;
+use std::error::Error;
+use std::process::{Command, Output, Stdio};
 
 fn main() {
     let dkp_path = env::var("DEVKITPRO").unwrap();
@@ -14,4 +16,69 @@ fn main() {
             _ => "ctru",
         }
     );
+
+    match check_libctru_version() {
+        Ok((maj, min, patch)) => {
+            eprintln!("using libctru version {maj}.{min}.{patch}");
+
+            // These are accessible by the crate during build with `env!()`.
+            // We might consider exporting some public constants or something.
+            println!("cargo:rustc-env=LIBCTRU_VERSION={maj}.{min}.{patch}");
+            println!("cargo:rustc-env=LIBCTRU_MAJOR={maj}");
+            println!("cargo:rustc-env=LIBCTRU_MINOR={min}");
+            println!("cargo:rustc-env=LIBCTRU_PATCH={patch}");
+
+            // It would be nice if we could rerun-if-changed on libctru itself,
+            // maybe we can write a file to OUT_DIR and check that file?
+        }
+        Err(err) => println!("cargo:warning=failed to check libctru version: {err}"),
+    }
+}
+
+fn parse_version(version: &str) -> Result<(String, String, String), &str> {
+    let versions: Vec<_> = version
+        .split(|c| c == '.' || c == '-')
+        .map(String::from)
+        .collect();
+
+    match &versions[..] {
+        [major, minor, patch, _build] => Ok((major.clone(), minor.clone(), patch.clone())),
+        _ => Err("unexpected number of version segments"),
+    }
+}
+
+fn check_libctru_version() -> Result<(String, String, String), Box<dyn Error>> {
+    let pacman = which::which("dkp-pacman").or_else(|_| which::which("pacman"))?;
+
+    let Output { stdout, .. } = Command::new(pacman)
+        .args(["--query", "libctru"])
+        .stderr(Stdio::inherit())
+        .output()?;
+
+    let output_str = String::from_utf8_lossy(&stdout);
+
+    let (_pkg, lib_version) = output_str
+        .split_once(char::is_whitespace)
+        .ok_or("unexpected output format")?;
+
+    let cargo_pkg_version = env::var("CARGO_PKG_VERSION").unwrap();
+    let (_, crate_built_version) = cargo_pkg_version
+        .split_once('+')
+        .expect("crate version should have '+' delimeter");
+
+    let (lib_major, lib_minor, lib_patch) = parse_version(lib_version)?;
+    let (crate_supported_major, crate_supported_minor, _crate_supported_patch) =
+        parse_version(crate_built_version)?;
+
+    // TODO: does == comparison make sense, or should we use >= or something?
+    if crate_supported_major != lib_major || crate_supported_minor != lib_minor {
+        // TODO: should this be a panic (i.e. induce build failure)? Maybe only for major version?
+
+        return Err(format!(
+            "libctru version is {lib_major}.{lib_minor}.{lib_patch}, \
+            but this crate only supports {crate_supported_major}.{crate_supported_minor}.x"
+        ))?;
+    }
+
+    Ok((lib_major, lib_minor, lib_patch))
 }