/* 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(oom_with = "hook", feature(alloc_error_hook))]
#![cfg_attr(oom_with = "alloc_error_panic", feature(panic_oom_payload))]
use arrayvec::ArrayString;
use std::alloc::{GlobalAlloc, Layout};
use std::cmp;
use std::ops::Deref;
use std::os::raw::c_char;
use std::os::raw::c_int;
use std::os::raw::c_void;
use std::panic;
#[cfg(has_panic_hook_info)]
use std::panic::PanicHookInfo;
#[cfg(not(has_panic_hook_info))]
use std::panic::PanicInfo as PanicHookInfo;
#[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: &PanicHookInfo) {
// 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(oom_with = "hook")]
use std::alloc::set_alloc_error_hook;
#[cfg(oom_with = "hook")]
set_alloc_error_hook(oom_hook::hook);
}
mod oom_hook {
#[cfg(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(oom_with = "alloc_error_panic")]
return _payload
.downcast_ref::<AllocErrorPanicPayload>()
.map(|p| p.layout());
#[cfg(not(oom_with = "alloc_error_panic"))]
return None;
}
extern "C" {
pub fn RustHandleOOM(size: usize) -> !;
}
#[cfg(oom_with = "hook")]
pub fn hook(layout: Layout) {
unsafe {
RustHandleOOM(layout.size());
}
}
}
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(windows)]
fn _aligned_free(ptr: *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
}
}
// On Windows, _aligned_free must be used to free memory allocated with
// _aligned_malloc. Except when mozjemalloc is enabled, in which case
// _aligned_malloc-allocated memory can be freed with free.
#[cfg(all(windows, not(feature = "moz_memory")))]
unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
if need_memalign(layout) {
_aligned_free(ptr as *mut c_void)
} else {
free(ptr as *mut c_void)
}
}
#[cfg(any(not(windows), feature = "moz_memory"))]
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
}
}
}
#[global_allocator]
static A: GeckoAlloc = GeckoAlloc;
