Write version to zlib.pc

build.rs

@@ -137,19 +137,31 @@ fn build_zlib(cfg: &mut cc::Build, target: &str) {
     fs::copy("src/zlib/zconf.h", dst.join("include/zconf.h")).unwrap();
 
     fs::create_dir_all(lib.join("pkgconfig")).unwrap();
-    fs::write(
-        lib.join("pkgconfig/zlib.pc"),
-        fs::read_to_string("src/zlib/zlib.pc.in")
-            .unwrap()
-            .replace("@prefix@", dst.to_str().unwrap()),
-    )
-    .unwrap();
+    let mut contents = fs::read_to_string("src/zlib/zlib.pc.in")
+        .unwrap()
+        .replace("@prefix@", dst.to_str().unwrap());
+    if let Some(version) = extract_version(dst.join("include/zlib.h")) {
+        contents = contents.replace("@VERSION@", &version);
+    }
+    fs::write(lib.join("pkgconfig/zlib.pc"), contents).unwrap();
 
     println!("cargo:root={}", dst.to_str().unwrap());
     println!("cargo:rustc-link-search=native={}", lib.to_str().unwrap());
     println!("cargo:include={}/include", dst.to_str().unwrap());
 }
 
+fn extract_version(zlib_h: PathBuf) -> Option<String> {
+    if let Ok(zlib_h_content) = fs::read_to_string(zlib_h) {
+        zlib_h_content
+            .lines()
+            .find(|l| l.contains("ZLIB_VERSION"))
+            .map(|l| l.split("\"").nth(1).map(|s| s.to_owned()))
+            .flatten()
+    } else {
+        None
+    }
+}
+
 #[cfg(not(feature = "zlib-ng"))]
 fn build_zlib_ng(_target: &str, _compat: bool) {}