build.rs

extern crate cc;
extern crate pkg_config;
#[cfg(target_env = "msvc")]
extern crate vcpkg;

use std::collections::HashSet;
use std::env;
use std::ffi::OsString;
use std::fs::File;
use std::io::{BufWriter, Write};
use std::path::{Path, PathBuf};
use std::panic::{self, AssertUnwindSafe};
use std::process::Command;

// The set of `OPENSSL_NO_<FOO>`s that we care about.
const DEFINES: &'static [&'static str] = &[
    "OPENSSL_NO_BUF_FREELISTS",
    "OPENSSL_NO_COMP",
    "OPENSSL_NO_EC",
    "OPENSSL_NO_EC2M",
    "OPENSSL_NO_ENGINE",
    "OPENSSL_NO_KRB5",
    "OPENSSL_NO_NEXTPROTONEG",
    "OPENSSL_NO_PSK",
    "OPENSSL_NO_RFC3779",
    "OPENSSL_NO_SHA",
    "OPENSSL_NO_SRP",
    "OPENSSL_NO_SSL3_METHOD",
    "OPENSSL_NO_TLSEXT",
];

enum Version {
    Openssl110,
    Openssl102,
    Openssl101,
    Libressl,
}

fn env(name: &str) -> Option<OsString> {
    let prefix = env::var("TARGET").unwrap().to_uppercase().replace("-", "_");
    let prefixed = format!("{}_{}", prefix, name);
    println!("cargo:rerun-if-env-changed={}", prefixed);

    if let Some(var) = env::var_os(&prefixed) {
        return Some(var);
    }

    println!("cargo:rerun-if-env-changed={}", name);
    env::var_os(name)
}

fn main() {
    let target = env::var("TARGET").unwrap();

    let lib_dir = env("OPENSSL_LIB_DIR").map(PathBuf::from);
    let include_dir = env("OPENSSL_INCLUDE_DIR").map(PathBuf::from);

    let (lib_dir, include_dir) = if lib_dir.is_none() || include_dir.is_none() {
        let openssl_dir = env("OPENSSL_DIR").unwrap_or_else(|| find_openssl_dir(&target));
        let openssl_dir = Path::new(&openssl_dir);
        let lib_dir = lib_dir.unwrap_or_else(|| openssl_dir.join("lib"));
        let include_dir = include_dir.unwrap_or_else(|| openssl_dir.join("include"));
        (lib_dir, include_dir)
    } else {
        (lib_dir.unwrap(), include_dir.unwrap())
    };

    if !Path::new(&lib_dir).exists() {
        panic!(
            "OpenSSL library directory does not exist: {}",