Add a wasi target

Cargo.toml

@@ -68,5 +68,7 @@ rustc-workspace-hack = { path = 'src/tools/rustc-workspace-hack' }
 # here
 rustc-std-workspace-core = { path = 'src/tools/rustc-std-workspace-core' }
 
+libc = { git = 'https://github.com/alexcrichton/libc', branch = 'wasi' }
+
 [patch."https://github.com/rust-lang/rust-clippy"]
 clippy_lints = { path = "src/tools/clippy/clippy_lints" }

config.toml.example

@@ -477,6 +477,9 @@
 # linked binaries
 #musl-root = "..."
 
+# The root location of the `wasm32-unknown-wasi` sysroot.
+#wasi-root = "..."
+
 # Used in testing for configuring where the QEMU images are located, you
 # probably don't want to use this.
 #qemu-rootfs = "..."

src/bootstrap/bin/rustc.rs

@@ -122,8 +122,8 @@ fn main() {
             cmd.arg("-Cprefer-dynamic");
         }
 
-        // Help the libc crate compile by assisting it in finding the MUSL
-        // native libraries.
+        // Help the libc crate compile by assisting it in finding various
+        // sysroot native libraries.
         if let Some(s) = env::var_os("MUSL_ROOT") {
             if target.contains("musl") {
                 let mut root = OsString::from("native=");
@@ -132,6 +132,12 @@ fn main() {
                 cmd.arg("-L").arg(&root);
             }
         }
+        if let Some(s) = env::var_os("WASI_ROOT") {
+            let mut root = OsString::from("native=");
+            root.push(&s);
+            root.push("/lib/wasm32-wasi");
+            cmd.arg("-L").arg(&root);
+        }
 
         // Override linker if necessary.
         if let Ok(target_linker) = env::var("RUSTC_TARGET_LINKER") {

src/bootstrap/compile.rs

@@ -127,6 +127,13 @@ fn copy_third_party_objects(builder: &Builder<'_>, compiler: &Compiler, target:
                 &libdir.join(obj),
             );
         }
+    } else if target.contains("-wasi") {
+        for &obj in &["crt1.o"] {
+            builder.copy(
+                &builder.wasi_root(target).unwrap().join("lib/wasm32-wasi").join(obj),
+                &libdir.join(obj),
+            );
+        }
     }
 
     // Copies libunwind.a compiled to be linked wit x86_64-fortanix-unknown-sgx.
@@ -188,6 +195,12 @@ pub fn std_cargo(builder: &Builder<'_>,
                 cargo.env("MUSL_ROOT", p);
             }
         }
+
+        if target.contains("-wasi") {
+            if let Some(p) = builder.wasi_root(target) {
+                cargo.env("WASI_ROOT", p);
+            }
+        }
     }
 }
 

src/bootstrap/config.rs

@@ -169,6 +169,7 @@ pub struct Target {
     pub ndk: Option<PathBuf>,
     pub crt_static: Option<bool>,
     pub musl_root: Option<PathBuf>,
+    pub wasi_root: Option<PathBuf>,
     pub qemu_rootfs: Option<PathBuf>,
     pub no_std: bool,
 }
@@ -344,6 +345,7 @@ struct TomlTarget {
     android_ndk: Option<String>,
     crt_static: Option<bool>,
     musl_root: Option<String>,
+    wasi_root: Option<String>,
     qemu_rootfs: Option<String>,
 }
 
@@ -605,6 +607,7 @@ impl Config {
                 target.linker = cfg.linker.clone().map(PathBuf::from);
                 target.crt_static = cfg.crt_static.clone();
                 target.musl_root = cfg.musl_root.clone().map(PathBuf::from);
+                target.wasi_root = cfg.wasi_root.clone().map(PathBuf::from);
                 target.qemu_rootfs = cfg.qemu_rootfs.clone().map(PathBuf::from);
 
                 config.target_config.insert(INTERNER.intern_string(triple.clone()), target);

src/bootstrap/lib.rs

@@ -860,6 +860,13 @@ impl Build {
             .map(|p| &**p)
     }
 
+    /// Returns the sysroot for the wasi target, if defined
+    fn wasi_root(&self, target: Interned<String>) -> Option<&Path> {
+        self.config.target_config.get(&target)
+            .and_then(|t| t.wasi_root.as_ref())
+            .map(|p| &**p)
+    }
+
     /// Returns `true` if this is a no-std `target`, if defined
     fn no_std(&self, target: Interned<String>) -> Option<bool> {
         self.config.target_config.get(&target)

src/ci/docker/dist-various-2/Dockerfile

@@ -34,6 +34,11 @@ COPY dist-various-2/build-x86_64-fortanix-unknown-sgx-toolchain.sh /tmp/
 # Any update to the commit id here, should cause the container image to be re-built from this point on.
 RUN /tmp/build-x86_64-fortanix-unknown-sgx-toolchain.sh "53b586346f2c7870e20b170decdc30729d97c42b"
 
+COPY dist-various-2/build-wasi-toolchain.sh /tmp/
+# FIXME: remove this line and uncomment the git clone
+COPY dist-various-2/reference-sysroot-wasi/ /tmp/wut/
+RUN /tmp/build-wasi-toolchain.sh
+
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
@@ -66,6 +71,7 @@ ENV TARGETS=x86_64-fuchsia
 ENV TARGETS=$TARGETS,aarch64-fuchsia
 ENV TARGETS=$TARGETS,sparcv9-sun-solaris
 ENV TARGETS=$TARGETS,wasm32-unknown-unknown
+ENV TARGETS=$TARGETS,wasm32-unknown-wasi
 ENV TARGETS=$TARGETS,x86_64-sun-solaris
 ENV TARGETS=$TARGETS,x86_64-unknown-linux-gnux32
 ENV TARGETS=$TARGETS,x86_64-unknown-cloudabi
@@ -74,5 +80,6 @@ ENV TARGETS=$TARGETS,nvptx64-nvidia-cuda
 
 ENV X86_FORTANIX_SGX_LIBS="/x86_64-fortanix-unknown-sgx/lib/"
 
-ENV RUST_CONFIGURE_ARGS --enable-extended --enable-lld --disable-docs
+ENV RUST_CONFIGURE_ARGS --enable-extended --enable-lld --disable-docs \
+  --set target.wasm32-unknown-wasi.wasi-root=/wasm32-unknown-wasi
 ENV SCRIPT python2.7 ../x.py dist --target $TARGETS

src/ci/docker/dist-various-2/build-wasi-toolchain.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+set -ex
+
+curl http://releases.llvm.org/8.0.0/clang+llvm-8.0.0-x86_64-linux-gnu-ubuntu-14.04.tar.xz | \
+  tar xJf -
+export PATH=`pwd`/clang+llvm-8.0.0-x86_64-linux-gnu-ubuntu-14.04/bin:$PATH
+
+# FIXME: uncomment this line and remove the next
+#git clone https://github.com/cranestation/reference-sysroot-wasi
+git clone /tmp/wut reference-sysroot-wasi
+
+cd reference-sysroot-wasi
+git reset --hard d5a609fe63926533e1054e539ba5f2693d51bdf5
+make -j$(nproc) INSTALL_DIR=/wasm32-unknown-wasi
+make install INSTALL_DIR=/wasm32-unknown-wasi
+
+cd ..
+rm -rf reference-sysroot-wasi
+rm -rf clang+llvm*

src/librustc_target/spec/mod.rs

@@ -444,6 +444,7 @@ supported_targets! {
     ("asmjs-unknown-emscripten", asmjs_unknown_emscripten),
     ("wasm32-unknown-emscripten", wasm32_unknown_emscripten),
     ("wasm32-unknown-unknown", wasm32_unknown_unknown),
+    ("wasm32-unknown-wasi", wasm32_unknown_wasi),
     ("wasm32-experimental-emscripten", wasm32_experimental_emscripten),
 
     ("thumbv6m-none-eabi", thumbv6m_none_eabi),

src/librustc_target/spec/wasm32_unknown_wasi.rs

@@ -0,0 +1,113 @@
+//! The `wasm32-unknown-wasi` target is a new and still (as of March 2019)
+//! experimental target. The definition in this file is likely to be tweaked
+//! over time and shouldn't be relied on too much.
+//!
+//! The `wasi` target is a proposal to define a standardized set of syscalls
+//! that WebAssembly files can interoperate with. This set of syscalls is
+//! intended to empower WebAssembly binaries with native capabilities such as
+//! filesystem access, network access, etc.
+//!
+//! FIXME: insert link to proposal here
+//!
+//! The Rust target definition here is interesting in a few ways. We want to
+//! serve two use cases here with this target:
+//!
+//! * First, we want Rust usage of the target to be as hassle-free as possible,
+//!   ideally avoiding the need to configure and install a local
+//!   wasm32-unknown-wasi toolchain.
+//!
+//! * Second, one of the primary use cases of LLVM's new wasm backend and the
+//!   wasm support in LLD is that any compiled language can interoperate with
+//!   any other. To that the `wasm32-unknown-wasi` target is the first with a
+//!   viable C standard library and sysroot common definition, so we want Rust
+//!   and C/C++ code to interoperate when compiled to `wasm32-unknown-unknown`.
+//!
+//! You'll note, however, that the two goals above are somewhat at odds with one
+//! another. To attempt to solve both use cases in one go we define a target
+//! that (ab)uses the `crt-static` target feature to indicate which one you're
+//! in.
+//!
+//! ## No interop with C required
+//!
+//! By default the `crt-static` target feature is enabled, and when enabled
+//! this means that the the bundled version of `libc.a` found in `liblibc.rlib`
+//! is used. This isn't intended really for interoperation with a C because it
+//! may be the case that Rust's bundled C library is incompatible with a
+//! foreign-compiled C library. In this use case, though, we use `rust-lld` and
+//! some copied crt startup object files to ensure that you can download the
+//! wasi target for Rust and you're off to the races, no further configuration
+//! necessary.
+//!
+//! All in all, by default, no external dependencies are required. You can
+//! compile `wasm32-unknown-wasi` binaries straight out of the box. You can't,
+//! however, reliably interoperate with C code in this mode (yet).
+//!
+//! ## Interop with C required
+//!
+//! For the second goal we repurpose the `target-feature` flag, meaning that
+//! you'll need to do a few things to have C/Rust code interoperate.
+//!
+//! 1. All Rust code needs to be compiled with `-C target-feature=-crt-static`,
+//!    indicating that the bundled C standard library in the Rust sysroot will
+//!    not be used.
+//!
+//! 2. If you're using rustc to build a linked artifact then you'll need to
+//!    specify `-C linker` to a `clang` binary that supports
+//!    `wasm32-unknown-wasi` and is configured with the `wasm32-unknown-wasi`
+//!    sysroot. This will cause Rust code to be linked against the libc.a that
+//!    the specified `clang` provides.
+//!
+//! 3. If you're building a staticlib and integrating Rust code elsewhere, then
+//!    compiling with `-C target-feature=-crt-static` is all you need to do.
+//!
+//! You can configure the linker via Cargo using the
+//! `CARGO_TARGET_WASM32_UNKNOWN_WASI_LINKER` env var. Be sure to also set
+//! `CC_wasm32-unknown-wasi` if any crates in the dependency graph are using
+//! the `cc` crate.
+//!
+//! ## Remember, this is all in flux
+//!
+//! The wasi target is **very** new in its specification. It's likely going to
+//! be a long effort to get it standardized and stable. We'll be following it as
+//! best we can with this target. Don't start relying on too much here unless
+//! you know what you're getting in to!
+
+use super::wasm32_base;
+use super::{LinkerFlavor, LldFlavor, Target};
+
+pub fn target() -> Result<Target, String> {
+    let mut options = wasm32_base::options();
+
+    options
+        .pre_link_args
+        .entry(LinkerFlavor::Gcc)
+        .or_insert(Vec::new())
+        .push("--target=wasm32-unknown-wasi".to_string());
+
+    // When generating an executable be sure to put the startup object at the
+    // front so the main function is correctly hooked up.
+    options.pre_link_objects_exe_crt.push("crt1.o".to_string());
+
+    // Right now this is a bit of a workaround but we're currently saying that
+    // the target by default has a static crt which we're taking as a signal
+    // for "use the bundled crt". If that's turned off then the system's crt
+    // will be used, but this means that default usage of this target doesn't
+    // need an external compiler but it's still interoperable with an external
+    // compiler if configured correctly.
+    options.crt_static_default = true;
+    options.crt_static_respected = true;
+
+    Ok(Target {
+        llvm_target: "wasm32-unknown-wasi".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "32".to_string(),
+        target_c_int_width: "32".to_string(),
+        target_os: "unknown".to_string(),
+        target_env: "wasi".to_string(),
+        target_vendor: "unknown".to_string(),
+        data_layout: "e-m:e-p:32:32-i64:64-n32:64-S128".to_string(),
+        arch: "wasm32".to_string(),
+        linker_flavor: LinkerFlavor::Lld(LldFlavor::Wasm),
+        options,
+    })
+}

src/libstd/os/mod.rs

@@ -51,6 +51,7 @@ cfg_if! {
 #[cfg(target_os = "emscripten")] pub mod emscripten;
 #[cfg(target_os = "fuchsia")]    pub mod fuchsia;
 #[cfg(target_os = "hermit")]     pub mod hermit;
+#[cfg(target_env = "wasi")]      pub mod wasi;
 #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] pub mod fortanix_sgx;
 
 pub mod raw;

src/libstd/os/wasi.rs

@@ -0,0 +1,6 @@
+//! WASI-specific definitions
+
+#![stable(feature = "raw_ext", since = "1.1.0")]
+
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use crate::sys::ext::*;

src/libstd/sys/mod.rs

@@ -35,6 +35,9 @@ cfg_if! {
     } else if #[cfg(target_os = "redox")] {
         mod redox;
         pub use self::redox::*;
+    } else if #[cfg(target_env = "wasi")] {
+        mod wasi;
+        pub use self::wasi::*;
     } else if #[cfg(target_arch = "wasm32")] {
         mod wasm;
         pub use self::wasm::*;

src/libstd/sys/wasi/alloc.rs

@@ -0,0 +1,43 @@
+use crate::alloc::{GlobalAlloc, Layout, System};
+use crate::ptr;
+use crate::sys_common::alloc::{MIN_ALIGN, realloc_fallback};
+use libc;
+
+#[stable(feature = "alloc_system_type", since = "1.28.0")]
+unsafe impl GlobalAlloc for System {
+    #[inline]
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
+            libc::malloc(layout.size()) as *mut u8
+        } else {
+            libc::aligned_alloc(layout.size(), layout.align()) as *mut u8
+        }
+    }
+
+    #[inline]
+    unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+        if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
+            libc::calloc(layout.size(), 1) as *mut u8
+        } else {
+            let ptr = self.alloc(layout.clone());
+            if !ptr.is_null() {
+                ptr::write_bytes(ptr, 0, layout.size());
+            }
+            ptr
+        }
+    }
+
+    #[inline]
+    unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
+        libc::free(ptr as *mut libc::c_void)
+    }
+
+    #[inline]
+    unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+        if layout.align() <= MIN_ALIGN && layout.align() <= new_size {
+            libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8
+        } else {
+            realloc_fallback(self, ptr, layout, new_size)
+        }
+    }
+}