build.rs: Add support for finding header paths with pkg-config

This can help in cross-compilation scenarios as well as large
complex builds.

devicemapper-rs-sys/Cargo.toml

@@ -17,6 +17,9 @@ default-features = false
 features = ["runtime"]
 version = "0.69.0"
 
+[build-dependencies]
+pkg-config = "0.3.31"
+
 [lints.rust]
 warnings = { level = "deny" }
 future_incompatible = { level = "deny", priority = 1 }

devicemapper-rs-sys/build.rs

@@ -5,11 +5,27 @@
 use std::{env::var, path::PathBuf};
 
 use bindgen::Builder;
+use pkg_config::{Config, Library};
+
+fn libdevmapper_probe() -> Library {
+    match Config::new().atleast_version("1.02.151").probe("devmapper") {
+        Ok(library) => library,
+        Err(e) => panic!("Suitable version of libdevmapper not found: {}", e),
+    }
+}
 
 fn main() {
+    let libdevmapper = libdevmapper_probe();
     // Generate bindings for dm-ioctl.h and libdevmapper.h
+    // dm-ioctl.h is part of linux-headers/libc and has no pkg-config
     let bindings = Builder::default()
         .header("dm.h")
+        .clang_args(
+            libdevmapper
+                .include_paths
+                .iter()
+                .map(|include| format!("-I{}", include.display())),
+        )
         .allowlist_var("DM.*")
         .allowlist_type("__u16")
         .allowlist_type("dm_ioctl")