fix build cross-platform

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "soxr"]
+	path = soxr
+	url = https://github.com/chirlu/soxr

Cargo.toml

@@ -16,3 +16,9 @@ edition = "2018"
 
 [build-dependencies]
 pkg-config = "0.3"
+cmake = "0.1"
+
+[features]
+default = ["static", "dynamic"]
+static = []
+dynamic = []

build.rs

@@ -1,19 +1,102 @@
+use std::{env, fmt::Display, path::Path};
+
 extern crate pkg_config;
 
+/// Based on the OS or target environment we are building for,
+/// this function will return an expected default library linking method.
+///
+/// If we build for Windows, MacOS, or Linux with musl, we will link statically.
+/// However, if you build for Linux without musl, we will link dynamically.
+///
+/// **Info**:
+/// This is a helper-function and may not be called if
+/// if the `static`-feature is enabled, the environment variable
+/// `LIBSOXR_STATIC` or `SOXR_STATIC` is set.
+fn default_library_linking() -> bool {
+    #[cfg(any(windows, target_os = "macos", target_env = "musl"))]
+    {
+        true
+    }
+    #[cfg(any(target_os = "freebsd", all(unix, target_env = "gnu")))]
+    {
+        false
+    }
+}
+
+fn is_static_build() -> bool {
+    if cfg!(feature = "static") && cfg!(feature = "dynamic") {
+        if env::var("LIBSOXR_STATIC").is_ok() || env::var("SOXR_STATIC").is_ok() {
+            true
+        } else {
+            default_library_linking()
+        }
+    } else if cfg!(feature = "static")
+        || env::var("LIBSOXR_STATIC").is_ok()
+        || env::var("SOXR_STATIC").is_ok()
+    {
+        println!("cargo:info=Static feature or environment variable found.");
+
+        true
+    } else if cfg!(feature = "dynamic") {
+        println!("cargo:info=Dynamic feature enabled.");
+
+        false
+    } else {
+        println!("cargo:info=No feature or environment variable found, linking by default.");
+
+        default_library_linking()
+    }
+}
+
+/// Outputs the library-file's prefix as word usable for actual arguments on
+/// commands or paths.
+const fn rustc_linking_word(is_static_link: bool) -> &'static str {
+    if is_static_link {
+        "static"
+    } else {
+        "dylib"
+    }
+}
+
+fn build_soxr(is_static: bool) {
+    let soxr_path = Path::new("soxr");
+
+    println!(
+        "cargo:info=Soxr source path used: {:?}.",
+        soxr_path
+            .canonicalize()
+            .expect("Could not canonicalise to absolute path")
+    );
+
+    println!("cargo:info=Building Soxr via CMake.");
+    let soxr_build_dir = cmake::Config::new("soxr")
+        .profile("Release")
+        .define("WITH_CR32S", "OFF")
+        .define("BUILD_SHARED_LIBS", if is_static { "OFF" } else { "ON" })
+        .define("WITH_OPENMP", "OFF")
+        .build();
+    link_soxr(is_static, soxr_build_dir.display())
+}
+
+fn link_soxr(is_static: bool, soxr_build_dir: impl Display) {
+    let is_static_text = rustc_linking_word(is_static);
+
+    println!(
+        "cargo:info=Linking Soxr as {} lib: {}",
+        is_static_text, soxr_build_dir
+    );
+    println!("cargo:rustc-link-lib={}=soxr", is_static_text);
+    println!("cargo:rustc-link-search=native={}/lib", soxr_build_dir);
+}
+
 fn main() {
     if std::env::var("DOCS_RS").is_err() {
         // do not probe for libsoxr when compiling at docs.rs
-        if let Err(e) = pkg_config::probe_library("soxr") {
-            match e {
-            pkg_config::Error::Failure { .. } => panic! (
-                "Pkg-config failed - usually this is because libsoxr development headers are not installed.\n\n\
-                For Mac users using brew: brew install libsoxr\n\n\
-                For Debian/Ubuntu users:\n# apt-get install libsoxr0-dev\n\n\
-                pkg_config details:\n{}",
-                e
-            ),
-            _ => panic!("{}", e)
-        }
+        if let Err(_e) = pkg_config::Config::new()
+            .statik(is_static_build())
+            .probe("soxr")
+        {
+            build_soxr(is_static_build());
         }
     }
 }

src/lib.rs

@@ -1,8 +1,8 @@
 //! # libsoxr-sys
-//! This crate is generated from [libsoxr](https://sourceforge.net/projects/soxr/) 
+//! This crate is generated from [libsoxr](https://sourceforge.net/projects/soxr/)
 //! using [bindgen](https://github.com/rust-lang/rust-bindgen).
 //!
-//! The documentation for this library can be found in the original C header 
+//! The documentation for this library can be found in the original C header
 //! file [`soxr.h`](https://sourceforge.net/p/soxr/code/ci/master/tree/src/soxr.h) of libsoxr.
 
 #![allow(non_camel_case_types)]