mod.rs

// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! MSVC-specific logic for linkers and such.
//!
//! This module contains a cross-platform interface but has a blank unix
//! implementation. The Windows implementation builds on top of Windows native
//! libraries (reading registry keys), so it otherwise wouldn't link on unix.
//!
//! Note that we don't have much special logic for finding the system linker on
//! any other platforms, so it may seem a little odd to single out MSVC to have
//! a good deal of code just to find the linker. Unlike Unix systems, however,
//! the MSVC linker is not in the system PATH by default. It also additionally
//! needs a few environment variables or command line flags to be able to link
//! against system libraries.
//!
//! In order to have a nice smooth experience on Windows, the logic in this file
//! is here to find the MSVC linker and set it up in the default configuration
//! one would need to set up anyway. This means that the Rust compiler can be
//! run not only in the developer shells of MSVC but also the standard cmd.exe
//! shell or MSYS shells.
//!
//! As a high-level note, all logic in this module for looking up various
//! paths/files is based on Microsoft's logic in their vcvars bat files, but
//! comments can also be found below leading through the various code paths.

// A simple macro to make this option mess easier to read
macro_rules! otry {
    ($expr:expr) => (match $expr {
        Some(val) => val,
        None => return None,
    })
}

#[cfg(windows)]
mod registry;
#[cfg(windows)]
mod arch;

#[cfg(windows)]
mod platform {
    use std::env;
    use std::ffi::OsString;
    use std::fs;
    use std::path::{Path, PathBuf};
    use std::process::Command;
    use session::Session;
    use super::arch::{host_arch, Arch};
    use super::registry::LOCAL_MACHINE;

    // First we need to figure out whether the environment is already correctly
    // configured by vcvars. We do this by looking at the environment variable
    // `VCINSTALLDIR` which is always set by vcvars, and unlikely to be set
    // otherwise. If it is defined, then we find `link.exe` in `PATH and trust
    // that everything else is configured correctly.
    //
    // If `VCINSTALLDIR` wasn't defined (or we couldn't find the linker where
    // it claimed it should be), then we resort to finding everything
    // ourselves. First we find where the latest version of MSVC is installed
    // and what version it is. Then based on the version we find the
    // appropriate SDKs.
    //
    // If despite our best efforts we are still unable to find MSVC then we
    // just blindly call `link.exe` and hope for the best.
    //
    // This code only supports VC 11 through 15. For versions older than that
    // the user will need to manually execute the appropriate vcvars bat file
    // and it should hopefully work.
    //
    // The second member of the tuple we return is the directory for the host
    // linker toolchain, which is necessary when using the cross linkers.
    pub fn link_exe_cmd(sess: &Session) -> (Command, Option<PathBuf>) {
        let arch = &sess.target.target.arch;
        env::var_os("VCINSTALLDIR").and_then(|_| {
            debug!("Detected that vcvars was already run.");
            let path = otry!(env::var_os("PATH"));
            // Mingw has its own link which is not the link we want so we
            // look for `cl.exe` too as a precaution.
            env::split_paths(&path).find(|path| {
                path.join("cl.exe").is_file()
                    && path.join("link.exe").is_file()
            }).map(|path| {
                (Command::new(path.join("link.exe")), None)
            })
        }).or_else(|| {
            None.or_else(|| {
                find_msvc_latest(arch, "15.0")
            }).or_else(|| {
                find_msvc_latest(arch, "14.0")
            }).or_else(|| {
                find_msvc_12(arch)
            }).or_else(|| {
                find_msvc_11(arch)
            }).map(|(cmd, path)| (cmd, Some(path)))
        }).unwrap_or_else(|| {
            debug!("Failed to locate linker.");
            (Command::new("link.exe"), None)
        })
    }

    // For MSVC 14 or newer we need to find the Universal CRT as well as either
    // the Windows 10 SDK or Windows 8.1 SDK.
    fn find_msvc_latest(arch: &str, ver: &str) -> Option<(Command, PathBuf)> {
        let vcdir = otry!(get_vc_dir(ver));
        let (mut cmd, host) = otry!(get_linker(&vcdir, arch));
        let sub = otry!(lib_subdir(arch));
        let ucrt = otry!(get_ucrt_dir());
        debug!("Found Universal CRT {:?}", ucrt);
        add_lib(&mut cmd, &ucrt.join("ucrt").join(sub));
        if let Some(dir) = get_sdk10_dir() {
            debug!("Found Win10 SDK {:?}", dir);
            add_lib(&mut cmd, &dir.join("um").join(sub));
        } else if let Some(dir) = get_sdk81_dir() {
            debug!("Found Win8.1 SDK {:?}", dir);
            add_lib(&mut cmd, &dir.join("um").join(sub));
        } else {
            return None
        }
        Some((cmd, host))
    }

    // For MSVC 12 we need to find the Windows 8.1 SDK.
    fn find_msvc_12(arch: &str) -> Option<(Command, PathBuf)> {
        let vcdir = otry!(get_vc_dir("12.0"));
        let (mut cmd, host) = otry!(get_linker(&vcdir, arch));
        let sub = otry!(lib_subdir(arch));
        let sdk81 = otry!(get_sdk81_dir());
        debug!("Found Win8.1 SDK {:?}", sdk81);
        add_lib(&mut cmd, &sdk81.join("um").join(sub));
        Some((cmd, host))
    }

    // For MSVC 11 we need to find the Windows 8 SDK.
    fn find_msvc_11(arch: &str) -> Option<(Command, PathBuf)> {
        let vcdir = otry!(get_vc_dir("11.0"));
        let (mut cmd, host) = otry!(get_linker(&vcdir, arch));
        let sub = otry!(lib_subdir(arch));
        let sdk8 = otry!(get_sdk8_dir());
        debug!("Found Win8 SDK {:?}", sdk8);
        add_lib(&mut cmd, &sdk8.join("um").join(sub));
        Some((cmd, host))
    }

    // A convenience function to append library paths.
    fn add_lib(cmd: &mut Command, lib: &Path) {
        let mut arg: OsString = "/LIBPATH:".into();
        arg.push(lib);
        cmd.arg(arg);
    }

    // Given a possible MSVC installation directory, we look for the linker and
    // then add the MSVC library path.
    fn get_linker(path: &Path, arch: &str) -> Option<(Command, PathBuf)> {
        debug!("Looking for linker in {:?}", path);
        bin_subdir(arch).into_iter().map(|(sub, host)| {
            (path.join("bin").join(sub).join("link.exe"),
             path.join("bin").join(host))
        }).filter(|&(ref path, _)| {
            path.is_file()
        }).map(|(path, host)| {
            (Command::new(path), host)
        }).filter_map(|(mut cmd, host)| {
            let sub = otry!(vc_lib_subdir(arch));
            add_lib(&mut cmd, &path.join("lib").join(sub));
            Some((cmd, host))
        }).next()
    }

    // To find MSVC we look in a specific registry key for the version we are
    // trying to find.
    fn get_vc_dir(ver: &str) -> Option<PathBuf> {
        let key = otry!(LOCAL_MACHINE
            .open(r"SOFTWARE\Microsoft\VisualStudio\SxS\VC7".as_ref()).ok());
        let path = otry!(key.query_str(ver).ok());
        Some(path.into())
    }

    // To find the Universal CRT we look in a specific registry key for where
    // all the Universal CRTs are located and then sort them asciibetically to
    // find the newest version. While this sort of sorting isn't ideal,  it is
    // what vcvars does so that's good enough for us.
    fn get_ucrt_dir() -> Option<PathBuf> {
        let key = otry!(LOCAL_MACHINE
            .open(r"SOFTWARE\Microsoft\Windows Kits\Installed Roots".as_ref()).ok());
        let root = otry!(key.query_str("KitsRoot10").ok());
        let readdir = otry!(fs::read_dir(Path::new(&root).join("lib")).ok());
        readdir.filter_map(|dir| {
            dir.ok()
        }).map(|dir| {
            dir.path()
        }).filter(|dir| {
            dir.components().last().and_then(|c| {
                c.as_os_str().to_str()
            }).map(|c| {
                c.starts_with("10.") && dir.join("ucrt").is_dir()
            }).unwrap_or(false)
        }).max()
    }

    // Vcvars finds the correct version of the Windows 10 SDK by looking
    // for the include `um\Windows.h` because sometimes a given version will
    // only have UCRT bits without the rest of the SDK. Since we only care about
    // libraries and not includes, we instead look for `um\x64\kernel32.lib`.
    // Since the 32-bit and 64-bit libraries are always installed together we
    // only need to bother checking x64, making this code a tiny bit simpler.
    // Like we do for the Universal CRT, we sort the possibilities
    // asciibetically to find the newest one as that is what vcvars does.
    fn get_sdk10_dir() -> Option<PathBuf> {
        let key = otry!(LOCAL_MACHINE
            .open(r"SOFTWARE\Microsoft\Microsoft SDKs\Windows\v10.0".as_ref()).ok());
        let root = otry!(key.query_str("InstallationFolder").ok());
        let readdir = otry!(fs::read_dir(Path::new(&root).join("lib")).ok());
        let mut dirs: Vec<_> = readdir.filter_map(|dir| dir.ok())
            .map(|dir| dir.path()).collect();
        dirs.sort();
        dirs.into_iter().rev().filter(|dir| {
            dir.join("um").join("x64").join("kernel32.lib").is_file()
        }).next()
    }

    // Interestingly there are several subdirectories, `win7` `win8` and
    // `winv6.3`. Vcvars seems to only care about `winv6.3` though, so the same
    // applies to us. Note that if we were targetting kernel mode drivers
    // instead of user mode applications, we would care.
    fn get_sdk81_dir() -> Option<PathBuf> {
        let key = otry!(LOCAL_MACHINE
            .open(r"SOFTWARE\Microsoft\Microsoft SDKs\Windows\v8.1".as_ref()).ok());
        let root = otry!(key.query_str("InstallationFolder").ok());
        Some(Path::new(&root).join("lib").join("winv6.3"))
    }

    fn get_sdk8_dir() -> Option<PathBuf> {
        let key = otry!(LOCAL_MACHINE
            .open(r"SOFTWARE\Microsoft\Microsoft SDKs\Windows\v8.0".as_ref()).ok());
        let root = otry!(key.query_str("InstallationFolder").ok());
        Some(Path::new(&root).join("lib").join("win8"))
    }

    // When choosing the linker toolchain to use, we have to choose the one
    // which matches the host architecture. Otherwise we end up in situations
    // where someone on 32-bit Windows is trying to cross compile to 64-bit and
    // it tries to invoke the native 64-bit linker which won't work.
    //
    // For the return value of this function, the first member of the tuple is
    // the folder of the linker we will be invoking, while the second member
    // is the folder of the host toolchain for that linker which is essential
    // when using a cross linker. We return a Vec since on x64 there are often
    // two linkers that can target the architecture we desire. The 64-bit host
    // linker is preferred, and hence first, due to 64-bit allowing it more
    // address space to work with and potentially being faster.
    //
    // FIXME - Figure out what happens when the host architecture is arm.
    fn bin_subdir(arch: &str) -> Vec<(&'static str, &'static str)> {
        match (arch, host_arch()) {
            ("x86", Some(Arch::X86)) => vec![("", "")],
            ("x86", Some(Arch::Amd64)) => vec![("amd64_x86", "amd64"), ("", "")],
            ("x86_64", Some(Arch::X86)) => vec![("x86_amd64", "")],
            ("x86_64", Some(Arch::Amd64)) => vec![("amd64", "amd64"), ("x86_amd64", "")],
            ("arm", Some(Arch::X86)) => vec![("x86_arm", "")],
            ("arm", Some(Arch::Amd64)) => vec![("amd64_arm", "amd64"), ("x86_arm", "")],
            _ => vec![],
        }
    }

    fn lib_subdir(arch: &str) -> Option<&'static str> {
        match arch {
            "x86" => Some("x86"),
            "x86_64" => Some("x64"),
            "arm" => Some("arm"),
            _ => None,
        }
    }

    // MSVC's x86 libraries are not in a subfolder
    fn vc_lib_subdir(arch: &str) -> Option<&'static str> {
        match arch {
            "x86" => Some(""),
            "x86_64" => Some("amd64"),
            "arm" => Some("arm"),
            _ => None,
        }
    }
}

// If we're not on Windows, then there's no registry to search through and MSVC
// wouldn't be able to run, so we just call `link.exe` and hope for the best.
#[cfg(not(windows))]
mod platform {
    use std::path::PathBuf;
    use std::process::Command;
    use session::Session;
    pub fn link_exe_cmd(_sess: &Session) -> (Command, Option<PathBuf>) {
        (Command::new("link.exe"), None)
    }
}

pub use self::platform::*;