1 files changed, 192 insertions, 0 deletions
diff --git a/vendor/rustix/build.rs b/vendor/rustix/build.rs
new file mode 100644
index 000000000..f6fa64579
--- /dev/null
+++ b/vendor/rustix/build.rs
@@ -0,0 +1,192 @@
+#[cfg(feature = "cc")]
+use cc::Build;
+use std::env::var;
+use std::io::Write;
+
+/// The directory for out-of-line ("outline") libraries.
+const OUTLINE_PATH: &str = "src/imp/linux_raw/arch/outline";
+
+fn main() {
+    // Don't rerun this on changes other than build.rs, as we only depend on
+    // the rustc version.
+    println!("cargo:rerun-if-changed=build.rs");
+
+    use_feature_or_nothing("rustc_attrs");
+
+    // Features only used in no-std configurations.
+    #[cfg(not(feature = "std"))]
+    {
+        use_feature_or_nothing("const_raw_ptr_deref");
+        use_feature_or_nothing("core_ffi_c");
+        use_feature_or_nothing("core_c_str");
+        use_feature_or_nothing("alloc_c_string");
+    }
+
+    // Gather target information.
+    let arch = var("CARGO_CFG_TARGET_ARCH").unwrap();
+    let asm_name = format!("{}/{}.s", OUTLINE_PATH, arch);
+    let asm_name_present = std::fs::metadata(&asm_name).is_ok();
+    let os_name = var("CARGO_CFG_TARGET_OS").unwrap();
+    let pointer_width = var("CARGO_CFG_TARGET_POINTER_WIDTH").unwrap();
+    let endian = var("CARGO_CFG_TARGET_ENDIAN").unwrap();
+
+    // Check for special target variants.
+    let is_x32 = arch == "x86_64" && pointer_width == "32";
+    let is_arm64_ilp32 = arch == "aarch64" && pointer_width == "32";
+    let is_powerpc64be = arch == "powerpc64" && endian == "big";
+    let is_mipseb = arch == "mips" && endian == "big";
+    let is_mips64eb = arch == "mips64" && endian == "big";
+    let is_unsupported_abi = is_x32 || is_arm64_ilp32 || is_powerpc64be || is_mipseb || is_mips64eb;
+
+    // Check for `--features=use-libc`. This allows crate users to enable the
+    // libc backend.
+    let feature_use_libc = var("CARGO_FEATURE_USE_LIBC").is_ok();
+
+    // Check for `--features=rustc-dep-of-std`. This is used when rustix is
+    // being used to build std, in which case `can_compile` doesn't work
+    // because `core` isn't available yet, but also, we can assume we have a
+    // recent compiler.
+    let feature_rustc_dep_of_std = var("CARGO_FEATURE_RUSTC_DEP_OF_STD").is_ok();
+
+    // Check for `RUSTFLAGS=--cfg=rustix_use_libc`. This allows end users to
+    // enable the libc backend even if rustix is depended on transitively.
+    let cfg_use_libc = var("CARGO_CFG_RUSTIX_USE_LIBC").is_ok();
+
+    // Check for eg. `RUSTFLAGS=--cfg=rustix_use_experimental_asm`. This is a
+    // rustc flag rather than a cargo feature flag because it's experimental
+    // and not something we want accidentally enabled via `--all-features`.
+    let rustix_use_experimental_asm = var("CARGO_CFG_RUSTIX_USE_EXPERIMENTAL_ASM").is_ok();
+
+    // Miri doesn't support inline asm, and has builtin support for recognizing
+    // libc FFI calls, so if we're running under miri, use the libc backend.
+    let miri = var("CARGO_CFG_MIRI").is_ok();
+
+    // If the libc backend is requested, or if we're not on a platform for
+    // which we have linux_raw support, use the libc backend.
+    //
+    // For now Android uses the libc backend; in theory it could use the
+    // linux_raw backend, but to do that we'll need to figure out how to
+    // install the toolchain for it.
+    if feature_use_libc
+        || cfg_use_libc
+        || os_name != "linux"
+        || !asm_name_present
+        || is_unsupported_abi
+        || miri
+    {
+        // Use the libc backend.
+        use_feature("libc");
+    } else {
+        // Use the linux_raw backend.
+        use_feature("linux_raw");
+        use_feature_or_nothing("core_intrinsics");
+
+        // Use inline asm if we have it, or outline asm otherwise. On PowerPC
+        // and MIPS, Rust's inline asm is considered experimental, so only use
+        // it if `--cfg=rustix_use_experimental_asm` is given.
+        if (feature_rustc_dep_of_std || can_compile("use std::arch::asm;"))
+            && (arch != "x86" || has_feature("naked_functions"))
+            && ((arch != "powerpc64" && arch != "mips" && arch != "mips64")
+                || rustix_use_experimental_asm)
+        {
+            use_feature("asm");
+            if arch == "x86" {
+                use_feature("naked_functions");
+            }
+            if rustix_use_experimental_asm {
+                use_feature("asm_experimental_arch");
+            }
+        } else {
+            link_in_librustix_outline(&arch, &asm_name);
+        }
+    }
+
+    println!("cargo:rerun-if-env-changed=CARGO_CFG_RUSTIX_USE_EXPERIMENTAL_ASM");
+}
+
+/// Link in the desired version of librustix_outline_{arch}.a, containing the
+/// outline assembly code for making syscalls.
+fn link_in_librustix_outline(arch: &str, asm_name: &str) {
+    let name = format!("rustix_outline_{}", arch);
+    let profile = var("PROFILE").unwrap();
+    let to = format!("{}/{}/lib{}.a", OUTLINE_PATH, profile, name);
+    println!("cargo:rerun-if-changed={}", to);
+
+    // If "cc" is not enabled, use a pre-built library.
+    #[cfg(not(feature = "cc"))]
+    {
+        let _ = asm_name;
+        println!("cargo:rustc-link-search={}/{}", OUTLINE_PATH, profile);
+        println!("cargo:rustc-link-lib=static={}", name);
+    }
+
+    // If "cc" is enabled, build the library from source, update the pre-built
+    // version, and assert that the pre-built version is checked in.
+    #[cfg(feature = "cc")]
+    {
+        let out_dir = var("OUT_DIR").unwrap();
+        Build::new().file(&asm_name).compile(&name);
+        println!("cargo:rerun-if-changed={}", asm_name);
+        if std::fs::metadata(".git").is_ok() {
+            let from = format!("{}/lib{}.a", out_dir, name);
+            let prev_metadata = std::fs::metadata(&to);
+            std::fs::copy(&from, &to).unwrap();
+            assert!(
+                prev_metadata.is_ok(),
+                "{} didn't previously exist; please inspect the new file and `git add` it",
+                to
+            );
+            assert!(
+                std::process::Command::new("git")
+                    .arg("diff")
+                    .arg("--quiet")
+                    .arg(&to)
+                    .status()
+                    .unwrap()
+                    .success(),
+                "{} changed; please inspect the change and `git commit` it",
+                to
+            );
+        }
+    }
+}
+
+fn use_feature_or_nothing(feature: &str) {
+    if has_feature(feature) {
+        use_feature(feature);
+    }
+}
+
+fn use_feature(feature: &str) {
+    println!("cargo:rustc-cfg={}", feature);
+}
+
+/// Test whether the rustc at `var("RUSTC")` supports the given feature.
+fn has_feature(feature: &str) -> bool {
+    can_compile(&format!(
+        "#![allow(stable_features)]\n#![feature({})]",
+        feature
+    ))
+}
+
+/// Test whether the rustc at `var("RUSTC")` can compile the given code.
+fn can_compile(code: &str) -> bool {
+    use std::process::Stdio;
+    let out_dir = var("OUT_DIR").unwrap();
+    let rustc = var("RUSTC").unwrap();
+
+    let mut child = std::process::Command::new(rustc)
+        .arg("--crate-type=rlib") // Don't require `main`.
+        .arg("--emit=metadata") // Do as little as possible but still parse.
+        .arg("--out-dir")
+        .arg(out_dir) // Put the output somewhere inconsequential.
+        .arg("-") // Read from stdin.
+        .stdin(Stdio::piped()) // Stdin is a pipe.
+        .stderr(Stdio::null())
+        .spawn()
+        .unwrap();
+
+    writeln!(child.stdin.take().unwrap(), "{}", code).unwrap();
+
+    child.wait().unwrap().success()
+}