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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use c_str::{ToCStr, CString};
use container::Container;
use iter::Iterator;
use libc::{c_char, size_t};
use option::{Option, None, Some};
use ptr::RawPtr;
use rt;
use rt::local::Local;
use rt::task::Task;
use str::OwnedStr;
use str;
use uint;
use unstable::raw;
use vec::{ImmutableVector, OwnedVector};
pub static FROZEN_BIT: uint = 1 << (uint::bits - 1);
pub static MUT_BIT: uint = 1 << (uint::bits - 2);
static ALL_BITS: uint = FROZEN_BIT | MUT_BIT;
#[deriving(Eq)]
pub struct BorrowRecord {
priv alloc: *mut raw::Box<()>,
file: *c_char,
priv line: size_t
}
fn try_take_task_borrow_list() -> Option<~[BorrowRecord]> {
let mut task = Local::borrow(None::<Task>);
task.get().borrow_list.take()
}
fn swap_task_borrow_list(f: |~[BorrowRecord]| -> ~[BorrowRecord]) {
let borrows = match try_take_task_borrow_list() {
Some(l) => l,
None => ~[]
};
let borrows = f(borrows);
let mut task = Local::borrow(None::<Task>);
task.get().borrow_list = Some(borrows)
}
pub fn clear_task_borrow_list() {
// pub because it is used by the box annihilator.
let _ = try_take_task_borrow_list();
}
#[cold]
unsafe fn fail_borrowed(alloc: *mut raw::Box<()>, file: *c_char, line: size_t)
-> ! {
debug_borrow("fail_borrowed: ", alloc, 0, 0, file, line);
match try_take_task_borrow_list() {
None => { // not recording borrows
let msg = "borrowed";
msg.with_c_str(|msg_p| rt::begin_unwind_raw(msg_p, file, line))
}
Some(borrow_list) => { // recording borrows
let mut msg = ~"borrowed";
let mut sep = " at ";
for entry in borrow_list.rev_iter() {
if entry.alloc == alloc {
msg.push_str(sep);
let filename = str::raw::from_c_str(entry.file);
msg.push_str(filename);
msg.push_str(format!(":{}", entry.line));
sep = " and at ";
}
}
msg.with_c_str(|msg_p| rt::begin_unwind_raw(msg_p, file, line))
}
}
}
/// Because this code is so perf. sensitive, use a static constant so that
/// debug printouts are compiled out most of the time.
static ENABLE_DEBUG: bool = false;
#[inline]
unsafe fn debug_borrow<T,P:RawPtr<T>>(tag: &'static str,
p: P,
old_bits: uint,
new_bits: uint,
filename: *c_char,
line: size_t) {
//! A useful debugging function that prints a pointer + tag + newline
//! without allocating memory.
if ENABLE_DEBUG && rt::env::debug_borrow() {
debug_borrow_slow(tag, p, old_bits, new_bits, filename, line);
}
unsafe fn debug_borrow_slow<T,P:RawPtr<T>>(tag: &'static str,
p: P,
old_bits: uint,
new_bits: uint,
filename: *c_char,
line: size_t) {
let filename = CString::new(filename, false);
rterrln!("{}{:#x} {:x} {:x} {}:{}",
tag, p.to_uint(), old_bits, new_bits,
filename.as_str().unwrap(), line);
}
}
#[inline]
pub unsafe fn borrow_as_imm(a: *u8, file: *c_char, line: size_t) -> uint {
let a = a as *mut raw::Box<()>;
let old_ref_count = (*a).ref_count;
let new_ref_count = old_ref_count | FROZEN_BIT;
debug_borrow("borrow_as_imm:", a, old_ref_count, new_ref_count, file, line);
if (old_ref_count & MUT_BIT) != 0 {
fail_borrowed(a, file, line);
}
(*a).ref_count = new_ref_count;
old_ref_count
}
#[inline]
pub unsafe fn borrow_as_mut(a: *u8, file: *c_char, line: size_t) -> uint {
let a = a as *mut raw::Box<()>;
let old_ref_count = (*a).ref_count;
let new_ref_count = old_ref_count | MUT_BIT | FROZEN_BIT;
debug_borrow("borrow_as_mut:", a, old_ref_count, new_ref_count, file, line);
if (old_ref_count & (MUT_BIT|FROZEN_BIT)) != 0 {
fail_borrowed(a, file, line);
}
(*a).ref_count = new_ref_count;
old_ref_count
}
pub unsafe fn record_borrow(a: *u8, old_ref_count: uint,
file: *c_char, line: size_t) {
if (old_ref_count & ALL_BITS) == 0 {
// was not borrowed before
let a = a as *mut raw::Box<()>;
debug_borrow("record_borrow:", a, old_ref_count, 0, file, line);
swap_task_borrow_list(|borrow_list| {
let mut borrow_list = borrow_list;
borrow_list.push(BorrowRecord {
alloc: a,
file: file,
line: line,
});
borrow_list
})
}
}
pub unsafe fn unrecord_borrow(a: *u8,
old_ref_count: uint,
file: *c_char,
line: size_t) {
if (old_ref_count & ALL_BITS) == 0 {
// was not borrowed before, so we should find the record at
// the end of the list
let a = a as *mut raw::Box<()>;
debug_borrow("unrecord_borrow:", a, old_ref_count, 0, file, line);
swap_task_borrow_list(|borrow_list| {
let mut borrow_list = borrow_list;
assert!(!borrow_list.is_empty());
let br = borrow_list.pop();
if br.alloc != a || br.file != file || br.line != line {
let err = format!("wrong borrow found, br={:?}", br);
err.with_c_str(|msg_p| {
rt::begin_unwind_raw(msg_p, file, line)
})
}
borrow_list
})
}
}
#[inline]
pub unsafe fn return_to_mut(a: *u8, orig_ref_count: uint,
file: *c_char, line: size_t) {
// Sometimes the box is null, if it is conditionally frozen.
// See e.g. #4904.
if !a.is_null() {
let a = a as *mut raw::Box<()>;
let old_ref_count = (*a).ref_count;
let new_ref_count =
(old_ref_count & !ALL_BITS) | (orig_ref_count & ALL_BITS);
debug_borrow("return_to_mut:",
a, old_ref_count, new_ref_count, file, line);
(*a).ref_count = new_ref_count;
}
}
#[inline]
pub unsafe fn check_not_borrowed(a: *u8,
file: *c_char,
line: size_t) {
let a = a as *mut raw::Box<()>;
let ref_count = (*a).ref_count;
debug_borrow("check_not_borrowed:", a, ref_count, 0, file, line);
if (ref_count & FROZEN_BIT) != 0 {
fail_borrowed(a, file, line);
}
}
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