diff options
Diffstat (limited to 'mozglue/static/rust/lib.rs')
| -rw-r--r-- | mozglue/static/rust/lib.rs | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/mozglue/static/rust/lib.rs b/mozglue/static/rust/lib.rs new file mode 100644 index 0000000000..9b73b9d153 --- /dev/null +++ b/mozglue/static/rust/lib.rs @@ -0,0 +1,209 @@ +/* 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))] + +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(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_panic_hook() { + panic::set_hook(Box::new(panic_hook)); +} + +#[cfg(feature = "oom_with_hook")] +mod oom_hook { + use std::alloc::{set_alloc_error_hook, Layout}; + + extern "C" { + fn RustHandleOOM(size: usize) -> !; + } + + pub fn hook(layout: Layout) { + unsafe { + RustHandleOOM(layout.size()); + } + } + + pub fn install() { + set_alloc_error_hook(hook); + } +} + +#[no_mangle] +pub extern "C" fn install_rust_oom_hook() { + #[cfg(feature = "oom_with_hook")] + oom_hook::install(); +} + +#[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; |