6 files changed, 409 insertions, 0 deletions
diff --git a/mozglue/static/rust/Cargo.toml b/mozglue/static/rust/Cargo.toml
new file mode 100644
index 0000000000..d0307a5bda
--- /dev/null
+++ b/mozglue/static/rust/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "mozglue-static"
+version = "0.1.0"
+edition = "2018"
+license = "MPL-2.0"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+arrayvec = "0.7"
+
+[build-dependencies]
+mozbuild = "0.1"
+cc = "1"
+rustc_version = "0.4"
+
+[features]
+moz_memory = []
diff --git a/mozglue/static/rust/build.rs b/mozglue/static/rust/build.rs
new file mode 100644
index 0000000000..e44419fb16
--- /dev/null
+++ b/mozglue/static/rust/build.rs
@@ -0,0 +1,32 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use rustc_version::{version, Version};
+
+fn main() {
+    let mut build = cc::Build::new();
+    build.cpp(true);
+    // For js-confdefs.h, see wrappers.cpp.
+    build.include(mozbuild::TOPOBJDIR.join("js").join("src"));
+    build.include(mozbuild::TOPOBJDIR.join("dist").join("include"));
+    build.define("MOZ_HAS_MOZGLUE", None);
+    build.file("wrappers.cpp");
+    build.compile("wrappers");
+    println!("cargo:rerun-if-changed=wrappers.cpp");
+
+    let ver = version().unwrap();
+    let max_oom_hook_version = Version::parse("1.77.0-alpha").unwrap();
+    // The new alloc error panic feature was temporarily reverted. We kept the
+    // code in tree, but the version here is such that it's effectively never used.
+    let max_alloc_error_panic_version = Version::parse("1.77.0-alpha").unwrap();
+
+    if ver < max_oom_hook_version {
+        println!("cargo:rustc-cfg=feature=\"oom_with_hook\"");
+    } else if ver < max_alloc_error_panic_version {
+        println!("cargo:rustc-cfg=feature=\"oom_with_alloc_error_panic\"");
+    } else if std::env::var("MOZ_AUTOMATION").is_ok() {
+        panic!("Builds on automation must use a version of rust for which we know how to hook OOM: want < {}, have {}",
+               max_alloc_error_panic_version, ver);
+    }
+}
diff --git a/mozglue/static/rust/lib.rs b/mozglue/static/rust/lib.rs
new file mode 100644
index 0000000000..001b920766
--- /dev/null
+++ b/mozglue/static/rust/lib.rs
@@ -0,0 +1,221 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#![cfg_attr(feature = "oom_with_hook", feature(alloc_error_hook))]
+#![cfg_attr(feature = "oom_with_alloc_error_panic", feature(panic_oom_payload))]
+
+use arrayvec::ArrayString;
+use std::cmp;
+use std::ops::Deref;
+use std::os::raw::c_char;
+use std::os::raw::c_int;
+use std::panic;
+
+#[link(name = "wrappers")]
+extern "C" {
+    // We can't use MOZ_Crash directly because it may be weakly linked
+    // and rust can't handle that.
+    fn RustMozCrash(filename: *const c_char, line: c_int, reason: *const c_char) -> !;
+}
+
+/// Truncate a string at the closest unicode character boundary
+/// ```
+/// assert_eq!(str_truncate_valid("éà", 3), "é");
+/// assert_eq!(str_truncate_valid("éà", 4), "éè");
+/// ```
+fn str_truncate_valid(s: &str, mut mid: usize) -> &str {
+    loop {
+        if let Some(res) = s.get(..mid) {
+            return res;
+        }
+        mid -= 1;
+    }
+}
+
+/// Similar to ArrayString, but with terminating nul character.
+#[derive(Debug, PartialEq)]
+struct ArrayCString<const CAP: usize> {
+    inner: ArrayString<CAP>,
+}
+
+impl<S: AsRef<str>, const CAP: usize> From<S> for ArrayCString<CAP> {
+    /// Contrary to ArrayString::from, truncates at the closest unicode
+    /// character boundary.
+    /// ```
+    /// assert_eq!(ArrayCString::<4>::from("éà"),
+    ///            ArrayCString::<4>::from("é"));
+    /// assert_eq!(&*ArrayCString::<4>::from("éà"), "é\0");
+    /// ```
+    fn from(s: S) -> Self {
+        let s = s.as_ref();
+        let len = cmp::min(s.len(), CAP - 1);
+        let mut result = Self {
+            inner: ArrayString::from(str_truncate_valid(s, len)).unwrap(),
+        };
+        result.inner.push('\0');
+        result
+    }
+}
+
+impl<const CAP: usize> Deref for ArrayCString<CAP> {
+    type Target = str;
+
+    fn deref(&self) -> &str {
+        self.inner.as_str()
+    }
+}
+
+fn panic_hook(info: &panic::PanicInfo) {
+    // Try to handle &str/String payloads, which should handle 99% of cases.
+    let payload = info.payload();
+    let message = if let Some(layout) = oom_hook::oom_layout(payload) {
+        unsafe {
+            oom_hook::RustHandleOOM(layout.size());
+        }
+    } else if let Some(s) = payload.downcast_ref::<&str>() {
+        s
+    } else if let Some(s) = payload.downcast_ref::<String>() {
+        s.as_str()
+    } else {
+        // Not the most helpful thing, but seems unlikely to happen
+        // in practice.
+        "Unhandled rust panic payload!"
+    };
+    let (filename, line) = if let Some(loc) = info.location() {
+        (loc.file(), loc.line())
+    } else {
+        ("unknown.rs", 0)
+    };
+    // Copy the message and filename to the stack in order to safely add
+    // a terminating nul character (since rust strings don't come with one
+    // and RustMozCrash wants one).
+    let message = ArrayCString::<512>::from(message);
+    let filename = ArrayCString::<512>::from(filename);
+    unsafe {
+        RustMozCrash(
+            filename.as_ptr() as *const c_char,
+            line as c_int,
+            message.as_ptr() as *const c_char,
+        );
+    }
+}
+
+/// Configure a panic hook to redirect rust panics to MFBT's MOZ_Crash.
+#[no_mangle]
+pub extern "C" fn install_rust_hooks() {
+    panic::set_hook(Box::new(panic_hook));
+    #[cfg(feature = "oom_with_hook")]
+    use std::alloc::set_alloc_error_hook;
+    #[cfg(feature = "oom_with_hook")]
+    set_alloc_error_hook(oom_hook::hook);
+}
+
+mod oom_hook {
+    #[cfg(feature = "oom_with_alloc_error_panic")]
+    use std::alloc::AllocErrorPanicPayload;
+    use std::alloc::Layout;
+    use std::any::Any;
+
+    #[inline(always)]
+    pub fn oom_layout(_payload: &dyn Any) -> Option<Layout> {
+        #[cfg(feature = "oom_with_alloc_error_panic")]
+        return _payload
+            .downcast_ref::<AllocErrorPanicPayload>()
+            .map(|p| p.layout());
+        #[cfg(not(feature = "oom_with_alloc_error_panic"))]
+        return None;
+    }
+
+    extern "C" {
+        pub fn RustHandleOOM(size: usize) -> !;
+    }
+
+    #[cfg(feature = "oom_with_hook")]
+    pub fn hook(layout: Layout) {
+        unsafe {
+            RustHandleOOM(layout.size());
+        }
+    }
+}
+
+#[cfg(feature = "moz_memory")]
+mod moz_memory {
+    use std::alloc::{GlobalAlloc, Layout};
+    use std::os::raw::c_void;
+
+    extern "C" {
+        fn malloc(size: usize) -> *mut c_void;
+
+        fn free(ptr: *mut c_void);
+
+        fn calloc(nmemb: usize, size: usize) -> *mut c_void;
+
+        fn realloc(ptr: *mut c_void, size: usize) -> *mut c_void;
+
+        #[cfg(windows)]
+        fn _aligned_malloc(size: usize, align: usize) -> *mut c_void;
+
+        #[cfg(not(windows))]
+        fn memalign(align: usize, size: usize) -> *mut c_void;
+    }
+
+    #[cfg(windows)]
+    unsafe fn memalign(align: usize, size: usize) -> *mut c_void {
+        _aligned_malloc(size, align)
+    }
+
+    pub struct GeckoAlloc;
+
+    #[inline(always)]
+    fn need_memalign(layout: Layout) -> bool {
+        // mozjemalloc guarantees a minimum alignment of 16 for all sizes, except
+        // for size classes below 16 (4 and 8).
+        layout.align() > layout.size() || layout.align() > 16
+    }
+
+    unsafe impl GlobalAlloc for GeckoAlloc {
+        unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+            if need_memalign(layout) {
+                memalign(layout.align(), layout.size()) as *mut u8
+            } else {
+                malloc(layout.size()) as *mut u8
+            }
+        }
+
+        unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
+            free(ptr as *mut c_void)
+        }
+
+        unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+            if need_memalign(layout) {
+                let ptr = self.alloc(layout);
+                if !ptr.is_null() {
+                    std::ptr::write_bytes(ptr, 0, layout.size());
+                }
+                ptr
+            } else {
+                calloc(1, layout.size()) as *mut u8
+            }
+        }
+
+        unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+            let new_layout = Layout::from_size_align_unchecked(new_size, layout.align());
+            if need_memalign(new_layout) {
+                let new_ptr = self.alloc(new_layout);
+                if !new_ptr.is_null() {
+                    let size = std::cmp::min(layout.size(), new_size);
+                    std::ptr::copy_nonoverlapping(ptr, new_ptr, size);
+                    self.dealloc(ptr, layout);
+                }
+                new_ptr
+            } else {
+                realloc(ptr as *mut c_void, new_size) as *mut u8
+            }
+        }
+    }
+}
+
+#[cfg(feature = "moz_memory")]
+#[global_allocator]
+static A: moz_memory::GeckoAlloc = moz_memory::GeckoAlloc;
diff --git a/mozglue/static/rust/moz_asserts/Cargo.toml b/mozglue/static/rust/moz_asserts/Cargo.toml
new file mode 100644
index 0000000000..27e336f7c7
--- /dev/null
+++ b/mozglue/static/rust/moz_asserts/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "moz_asserts"
+version = "0.1.0"
+edition = "2018"
+license = "MPL-2.0"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+mozbuild = "0.1"
diff --git a/mozglue/static/rust/moz_asserts/lib.rs b/mozglue/static/rust/moz_asserts/lib.rs
new file mode 100644
index 0000000000..f4b00a5ad2
--- /dev/null
+++ b/mozglue/static/rust/moz_asserts/lib.rs
@@ -0,0 +1,103 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// Implementation note: It seems tempting to use if cfg!(feature = ...) directly
+// in the macro, but that doesn't work, as the feature would be evaluated
+// against the dependent crate.
+//
+// It'd also seem tempting to export different macros depending on the features
+// enabled, but that's also not great because it causes warnings when the
+// features are enabled, e.g.:
+//
+//   nightly_panic!("foo");
+//   return SAFE_VALUE;
+//
+// would cause an unreachable code warning for Nightly builds. So instead we
+// choose an exported constant to guard the condition. (For reference, this
+// is also how rust's `debug_assert!` is implemented)
+
+/// Whether Nightly-only assertions are enabled.
+pub use mozbuild::config::NIGHTLY_BUILD;
+
+/// Whether diagnostic assertions are enabled.
+pub use mozbuild::config::MOZ_DIAGNOSTIC_ASSERT_ENABLED;
+
+/// assert! on Nightly, gets compiled out otherwise.
+#[macro_export]
+macro_rules! nightly_assert {
+    ($($arg:tt)*) => (if $crate::NIGHTLY_BUILD { assert!($($arg)*); })
+}
+
+/// assert_eq! on Nightly, gets compiled out otherwise.
+#[macro_export]
+macro_rules! nightly_assert_eq {
+    ($($arg:tt)*) => (if $crate::NIGHTLY_BUILD { assert_eq!($($arg)*); })
+}
+
+/// assert_ne! on Nightly, gets compiled out otherwise.
+#[macro_export]
+macro_rules! nightly_assert_ne {
+    ($($arg:tt)*) => (if $crate::NIGHTLY_BUILD { assert_ne!($($arg)*); })
+}
+
+/// panic! on Nightly, gets compiled out otherwise.
+#[macro_export]
+macro_rules! nightly_panic {
+    ($($arg:tt)*) => (if $crate::NIGHTLY_BUILD { panic!($($arg)*); })
+}
+
+/// unreachable! on Nightly, `std::hint::unreachable_unchecked()` otherwise.
+///
+/// Use carefully! Consider using nightly_panic! and handling the failure
+/// gracefully if you can't prove it's really unreachable.
+///
+/// See https://doc.rust-lang.org/std/hint/fn.unreachable_unchecked.html#safety
+/// for safety details.
+#[macro_export]
+macro_rules! nightly_unreachable {
+    ($($arg:tt)*) => {
+        if $crate::NIGHTLY_BUILD {
+            unreachable!($($arg)*);
+        } else {
+            std::hint::unreachable_unchecked()
+        }
+    }
+}
+
+/// assert! when diagnostic asserts are enabled, gets compiled out otherwise.
+#[macro_export]
+macro_rules! diagnostic_assert {
+    ($($arg:tt)*) => (if $crate::MOZ_DIAGNOSTIC_ASSERT_ENABLED { assert!($($arg)*); })
+}
+
+/// assert_eq! when diagnostic asserts are enabled, gets compiled out otherwise.
+#[macro_export]
+macro_rules! diagnostic_assert_eq {
+    ($($arg:tt)*) => (if $crate::MOZ_DIAGNOSTIC_ASSERT_ENABLED { assert_eq!($($arg)*); })
+}
+
+/// assert_ne! when diagnostic asserts are enabled, gets compiled out otherwise.
+#[macro_export]
+macro_rules! diagnostic_assert_ne {
+    ($($arg:tt)*) => (if $crate::MOZ_DIAGNOSTIC_ASSERT_ENABLED { assert_ne!($($arg)*); })
+}
+
+/// unreachable! when diagnostic asserts are enabled,
+/// `std::hint::unreachable_unchecked()` otherwise.
+///
+/// Use carefully! Consider using diagnostic_panic! and handling the failure
+/// gracefully if you can't prove it's really unreachable.
+///
+/// See https://doc.rust-lang.org/std/hint/fn.unreachable_unchecked.html#safety
+/// for safety details.
+#[macro_export]
+macro_rules! diagnostic_unreachable {
+    ($($arg:tt)*) => {
+        if $crate::MOZ_DIAGNOSTIC_ASSERT_ENABLED {
+            unreachable!($($arg)*);
+        } else {
+            std::hint::unreachable_unchecked()
+        }
+    }
+}
diff --git a/mozglue/static/rust/wrappers.cpp b/mozglue/static/rust/wrappers.cpp
new file mode 100644
index 0000000000..926593f871
--- /dev/null
+++ b/mozglue/static/rust/wrappers.cpp
@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This ensures the right configuration for e.g. MOZ_GLUE_IN_PROGRAM,
+// used in the MFBT headers included further below. We use js-confdefs.h
+// instead of mozilla-config.h because the latter is not present in
+// spidermonkey standalone builds while the former is always present.
+#include "js-confdefs.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Types.h"
+#include "mozilla/mozalloc_oom.h"
+
+// MOZ_Crash wrapper for use by rust, since MOZ_Crash is an inline function.
+extern "C" void RustMozCrash(const char* aFilename, int aLine,
+                             const char* aReason) {
+  MOZ_Crash(aFilename, aLine, aReason);
+}
+
+// mozalloc_handle_oom wrapper for use by rust, because mozalloc_handle_oom is
+// MFBT_API, that rust can't respect.
+extern "C" void RustHandleOOM(size_t size) { mozalloc_handle_oom(size); }