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Abuse Vec as an allocator in gfx

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This commit is contained in:
Simon Sapin 2017-10-12 01:50:03 +02:00
parent d6d772eba0
commit ff23a8536e
2 changed files with 31 additions and 19 deletions
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1
components/gfx/lib.rs
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@ -4,7 +4,6 @@
// For SIMD
#![cfg_attr(feature = "unstable", feature(cfg_target_feature))]
#![cfg_attr(any(target_os = "linux", target_os = "android"), feature(allocator_api))]
#![deny(unsafe_code)]

49
components/gfx/platform/freetype/font_context.rs
View file

@ -9,7 +9,7 @@ use freetype::freetype::FT_Memory;
use freetype::freetype::FT_MemoryRec_;
use freetype::freetype::FT_New_Library;
use heapsize::{HeapSizeOf, heap_size_of};
use std::heap::{Heap, Alloc, Layout};
use std::mem;
use std::os::raw::{c_long, c_void};
use std::ptr;
use std::rc::Rc;
@ -25,46 +25,59 @@ pub struct User {
const FT_ALIGNMENT: usize = 1;
extern fn ft_alloc(mem: FT_Memory, req_size: c_long) -> *mut c_void {
unsafe {
let layout = Layout::from_size_align(req_size as usize, FT_ALIGNMENT).unwrap();
let ptr = Heap.alloc(layout).unwrap() as *mut c_void;
let actual_size = heap_size_of(ptr as *const _);
assert!(FT_ALIGNMENT == 1);
let mut vec = Vec::<u8>::with_capacity(req_size as usize);
let ptr = vec.as_mut_ptr() as *mut c_void;
mem::forget(vec);
unsafe {
let actual_size = heap_size_of(ptr as *const _);
let user = (*mem).user as *mut User;
(*user).size += actual_size;
ptr
}
ptr
}
extern fn ft_free(mem: FT_Memory, ptr: *mut c_void) {
unsafe {
let actual_size = heap_size_of(ptr as *const _);
let user = (*mem).user as *mut User;
(*user).size -= actual_size;
let layout = Layout::from_size_align(actual_size, FT_ALIGNMENT).unwrap();
Heap.dealloc(ptr as *mut u8, layout);
assert!(FT_ALIGNMENT == 1);
mem::drop(Vec::<u8>::from_raw_parts(ptr as *mut u8, actual_size, 0))
}
}
extern fn ft_realloc(mem: FT_Memory, _cur_size: c_long, new_req_size: c_long,
old_ptr: *mut c_void) -> *mut c_void {
let old_actual_size;
let mut vec;
unsafe {
let old_actual_size = heap_size_of(old_ptr as *const _);
let old_layout = Layout::from_size_align(old_actual_size, FT_ALIGNMENT).unwrap();
let new_layout = Layout::from_size_align(new_req_size as usize, FT_ALIGNMENT).unwrap();
let result = Heap.realloc(old_ptr as *mut u8, old_layout, new_layout);
let new_ptr = result.unwrap() as *mut c_void;
let new_actual_size = heap_size_of(new_ptr as *const _);
old_actual_size = heap_size_of(old_ptr as *const _);
vec = Vec::<u8>::from_raw_parts(old_ptr as *mut u8, old_actual_size, old_actual_size);
};
let new_req_size = new_req_size as usize;
if new_req_size > old_actual_size {
vec.reserve_exact(new_req_size - old_actual_size)
} else if new_req_size < old_actual_size {
vec.truncate(new_req_size);
vec.shrink_to_fit()
}
let new_ptr = vec.as_mut_ptr() as *mut c_void;
mem::forget(vec);
unsafe {
let new_actual_size = heap_size_of(new_ptr as *const _);
let user = (*mem).user as *mut User;
(*user).size += new_actual_size;
(*user).size -= old_actual_size;
new_ptr
}
new_ptr
}
// A |*mut User| field in a struct triggers a "use of `#[derive]` with a raw pointer" warning from