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-rw-r--r--mozglue/static/rust/lib.rs221
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+/* 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;