Optimize openssl linkage

[gaoqiangz]

No description provided.

[gaoqiangz]

Sorry for the code formating...
Here is the change list:

• lib.rs

We should explicit import openssl_sys crate to make build.rs works.

#[cfg(feature = "ssl")]
mod __make_openssl_linkage_work {
    #[allow(unused_imports)]
    use openssl_sys::*;
}

• build.rs

Delete these lines.

paho.mqtt.rust/paho-mqtt-sys/build.rs

Lines 309 to 337 in be43ef8

	if cfg!(feature = "ssl") {
	if let Some(openssl_root_dir) = openssl_root_dir() {
	println!("cargo:rustc-link-search={}/lib", openssl_root_dir);
	}
	// See if static SSL linkage was requested
	let linkage = match env::var("OPENSSL_STATIC")
	.as_ref()
	.map(|s| s.as_str())
	{
	Ok("0") => "",
	Ok(_) => "=static",
	Err(_) => ""
	};
	let prefix = if is_msvc() { "lib" } else { "" };
	println!("cargo:rustc-link-lib{}={}ssl", linkage, prefix);
	println!("cargo:rustc-link-lib{}={}crypto", linkage, prefix);
	if is_windows() {
	if !is_msvc() {
	// required for mingw builds
	println!("cargo:rustc-link-lib{}=crypt32", linkage);
	println!("cargo:rustc-link-lib{}=rpcrt4", linkage);
	}
	println!("cargo:rustc-link-lib=User32");
	}
	}

Change openssl_root_dir

paho.mqtt.rust/paho-mqtt-sys/build.rs

Lines 242 to 248 in be43ef8

	fn openssl_root_dir() -> Option<String> {
	env::var("DEP_OPENSSL_INCLUDE").ok().and_then(|path| {
	Path::new(&path)
	.parent()
	.map(|path| path.display().to_string())
	})
	}

to

    fn openssl_root_dir() -> Option<String> {
        use std::ffi::OsString;

        fn env_inner(name: &str) -> Option<OsString> {
            let var = env::var_os(name);
            println!("cargo:rerun-if-env-changed={}", name);

            match var {
                Some(ref v) => println!("{} = {}", name, v.to_string_lossy()),
                None => println!("{} unset", name),
            }

            var
        }
        fn env(name: &str) -> Option<OsString> {
            let prefix = env::var("TARGET").unwrap().to_uppercase().replace('-', "_");
            let prefixed = format!("{}_{}", prefix, name);
            env_inner(&prefixed).or_else(|| env_inner(name))
        }

        env("OPENSSL_INCLUDE_DIR").and_then(|path| {
            Path::new(&path)
                .parent()
                .map(|path| path.display().to_string())
        })
    }

See also https://github.com/sfackler/rust-openssl/blob/979f982e067bd310a7aff1cfa5f711ed7bcf0d95/openssl-sys/build/main.rs#L49.

[fpagliughi]

Hey. Thanks for the PR! Unfortunately, since this is an Eclipse project, I won't be able to merge it unless you sign an Eclipse ECA. See here:
https://www.eclipse.org/legal/ECA.php

But also...

Please describe the specific problem which you are attempting to fix. On which platform(s).

Also:

• Did you test this update on all the major platforms? Linux, Windows (MSVC and mingw), and Mac?
• Did you test without the 'ssl' feature - when no OpenSSL library is installed?

I know the build still needs work, but so far, every attempt to update it has broken at least on of these platforms.

[gaoqiangz]

Sorry.....I have been busy recently.I haven't tested on Linux/MacOS yet.
This PR solves the issue of openssl linking by delegating to openssl-sys to avoid static link error (see: #158, #134).
I have tested on Windows MSVC it works fine.
Once I have time, I will test it on other platforms, maybe you can help me? :-)