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Fix call stack limits.

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This commit is contained in:
Stephen Chung 2020-12-29 12:29:45 +08:00
parent 41c6f985f5
commit 13f5cec291
8 changed files with 70 additions and 55 deletions
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1
RELEASES.md
View File

@ -16,6 +16,7 @@ Bug fixes
* Fix bug when accessing properties in closures.
* Fix bug when accessing a deep index with a function call.
* Fix bug that sometimes allow assigning to an invalid l-value.
* Fix off-by-one error with `Engine::set_max_call_levels`.
Breaking changes
----------------

8
src/engine.rs
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@ -170,6 +170,7 @@ impl FromIterator<(ImmutableString, Shared<Module>)> for Imports {
#[cfg(not(feature = "unchecked"))]
#[cfg(debug_assertions)]
#[cfg(not(feature = "no_function"))]
pub const MAX_CALL_STACK_DEPTH: usize = 8;
#[cfg(not(feature = "unchecked"))]
#[cfg(debug_assertions)]
@ -181,6 +182,7 @@ pub const MAX_FUNCTION_EXPR_DEPTH: usize = 16;
#[cfg(not(feature = "unchecked"))]
#[cfg(not(debug_assertions))]
#[cfg(not(feature = "no_function"))]
pub const MAX_CALL_STACK_DEPTH: usize = 128;
#[cfg(not(feature = "unchecked"))]
#[cfg(not(debug_assertions))]
@ -527,8 +529,8 @@ impl State {
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub struct Limits {
/// Maximum levels of call-stack to prevent infinite recursion.
///
/// Defaults to 16 for debug builds and 128 for non-debug builds.
/// Not available under `no_function`.
#[cfg(not(feature = "no_function"))]
pub max_call_stack_depth: usize,
/// Maximum depth of statements/expressions at global level (0 = unlimited).
pub max_expr_depth: usize,
@ -809,6 +811,7 @@ impl Engine {
#[cfg(not(feature = "unchecked"))]
limits: Limits {
#[cfg(not(feature = "no_function"))]
max_call_stack_depth: MAX_CALL_STACK_DEPTH,
max_expr_depth: MAX_EXPR_DEPTH,
#[cfg(not(feature = "no_function"))]
@ -864,6 +867,7 @@ impl Engine {
#[cfg(not(feature = "unchecked"))]
limits: Limits {
#[cfg(not(feature = "no_function"))]
max_call_stack_depth: MAX_CALL_STACK_DEPTH,
max_expr_depth: MAX_EXPR_DEPTH,
#[cfg(not(feature = "no_function"))]

7
src/engine_api.rs
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@ -1453,7 +1453,7 @@ impl Engine {
) -> Result<T, Box<EvalAltResult>> {
let mods = &mut (&self.global_sub_modules).into();
let result = self.eval_ast_with_scope_raw(scope, mods, ast)?;
let result = self.eval_ast_with_scope_raw(scope, mods, ast, 0)?;
let typ = self.map_type_name(result.type_name());
@ -1473,12 +1473,13 @@ impl Engine {
scope: &mut Scope,
mods: &mut Imports,
ast: &'a AST,
level: usize,
) -> Result<Dynamic, Box<EvalAltResult>> {
let state = &mut State {
source: ast.clone_source(),
..Default::default()
};
self.eval_statements_raw(scope, mods, state, ast.statements(), &[ast.lib()])
self.eval_statements_raw(scope, mods, state, ast.statements(), &[ast.lib()], level)
}
/// Evaluate a file, but throw away the result and only return error (if any).
/// Useful for when you don't need the result, but still need to keep track of possible errors.
@ -1542,7 +1543,7 @@ impl Engine {
source: ast.clone_source(),
..Default::default()
};
self.eval_statements_raw(scope, mods, state, ast.statements(), &[ast.lib()])?;
self.eval_statements_raw(scope, mods, state, ast.statements(), &[ast.lib()], 0)?;
Ok(())
}
/// Call a script function defined in an [`AST`] with multiple arguments.

2
src/engine_settings.rs
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@ -38,6 +38,7 @@ impl Engine {
/// Set the maximum levels of function calls allowed for a script in order to avoid
/// infinite recursion and stack overflows.
#[cfg(not(feature = "unchecked"))]
#[cfg(not(feature = "no_function"))]
#[inline(always)]
pub fn set_max_call_levels(&mut self, levels: usize) -> &mut Self {
self.limits.max_call_stack_depth = levels;
@ -45,6 +46,7 @@ impl Engine {
}
/// The maximum levels of function calls allowed for a script.
#[cfg(not(feature = "unchecked"))]
#[cfg(not(feature = "no_function"))]
#[inline(always)]
pub fn max_call_levels(&self) -> usize {
self.limits.max_call_stack_depth

29
src/fn_call.rs
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@ -405,11 +405,11 @@ impl Engine {
mods.extend(fn_def.mods.iter_raw().map(|(n, m)| (n.clone(), m.clone())));
}
// Evaluate the function at one higher level of call depth
// Evaluate the function
let stmt = &fn_def.body;
let result = self
.eval_stmt(scope, mods, state, unified_lib, this_ptr, stmt, level + 1)
.eval_stmt(scope, mods, state, unified_lib, this_ptr, stmt, level)
.or_else(|err| match *err {
// Convert return statement to return value
EvalAltResult::Return(x, _) => Ok(x),
@ -586,6 +586,8 @@ impl Engine {
mem::swap(&mut state.source, &mut source);
let level = _level + 1;
let result = self.call_script_fn(
scope,
mods,
@ -595,7 +597,7 @@ impl Engine {
func,
rest,
pos,
_level,
level,
);
// Restore the original source
@ -610,8 +612,10 @@ impl Engine {
mem::swap(&mut state.source, &mut source);
let level = _level + 1;
let result = self.call_script_fn(
scope, mods, state, lib, &mut None, func, args, pos, _level,
scope, mods, state, lib, &mut None, func, args, pos, level,
);
// Restore the original source
@ -667,11 +671,12 @@ impl Engine {
state: &mut State,
statements: impl IntoIterator<Item = &'a Stmt>,
lib: &[&Module],
level: usize,
) -> Result<Dynamic, Box<EvalAltResult>> {
statements
.into_iter()
.try_fold(().into(), |_, stmt| {
self.eval_stmt(scope, mods, state, lib, &mut None, stmt, 0)
self.eval_stmt(scope, mods, state, lib, &mut None, stmt, level)
})
.or_else(|err| match *err {
EvalAltResult::Return(out, _) => Ok(out),
@ -691,7 +696,7 @@ impl Engine {
lib: &[&Module],
script: &str,
pos: Position,
_level: usize,
level: usize,
) -> Result<Dynamic, Box<EvalAltResult>> {
self.inc_operations(state, pos)?;
@ -700,13 +705,6 @@ impl Engine {
return Ok(Dynamic::UNIT);
}
// Check for stack overflow
#[cfg(not(feature = "no_function"))]
#[cfg(not(feature = "unchecked"))]
if _level > self.max_call_levels() {
return Err(Box::new(EvalAltResult::ErrorStackOverflow(pos)));
}
// Compile the script text
// No optimizations because we only run it once
let ast = self.compile_with_scope_and_optimization_level(
@ -727,7 +725,8 @@ impl Engine {
..Default::default()
};
let result = self.eval_statements_raw(scope, mods, &mut new_state, ast.statements(), lib);
let result =
self.eval_statements_raw(scope, mods, &mut new_state, ast.statements(), lib, level);
state.operations = new_state.operations;
result
@ -1208,6 +1207,8 @@ impl Engine {
let mut source = module.id_raw().clone();
mem::swap(&mut state.source, &mut source);
let level = level + 1;
let result = self.call_script_fn(
new_scope, mods, state, lib, &mut None, &fn_def, args, pos, level,
);

2
src/module/mod.rs
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@ -1720,7 +1720,7 @@ impl Module {
let orig_mods_len = mods.len();
// Run the script
engine.eval_ast_with_scope_raw(&mut scope, &mut mods, &ast)?;
engine.eval_ast_with_scope_raw(&mut scope, &mut mods, &ast, 0)?;
// Create new module
let mut module = Module::new();

19
src/parser.rs
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@ -19,7 +19,7 @@ use crate::stdlib::{
vec::Vec,
};
use crate::syntax::{CustomSyntax, MARKER_BLOCK, MARKER_EXPR, MARKER_IDENT};
use crate::token::{is_doc_comment, is_keyword_function, is_valid_identifier, Token, TokenStream};
use crate::token::{is_keyword_function, is_valid_identifier, Token, TokenStream};
use crate::utils::{get_hasher, StraightHasherBuilder};
use crate::{
calc_script_fn_hash, Dynamic, Engine, ImmutableString, LexError, ParseError, ParseErrorType,
@ -2534,17 +2534,19 @@ fn parse_stmt(
) -> Result<Stmt, ParseError> {
use AccessMode::{ReadOnly, ReadWrite};
let mut comments: Vec<String> = Default::default();
let mut _comments: Vec<String> = Default::default();
#[cfg(not(feature = "no_function"))]
{
let mut comments_pos = Position::NONE;
// Handle doc-comments.
#[cfg(not(feature = "no_function"))]
while let (Token::Comment(ref comment), comment_pos) = input.peek().unwrap() {
while let (Token::Comment(ref comment), pos) = input.peek().unwrap() {
if comments_pos.is_none() {
comments_pos = *comment_pos;
comments_pos = *pos;
}
if !is_doc_comment(comment) {
if !crate::token::is_doc_comment(comment) {
unreachable!("expecting doc-comment, but gets {:?}", comment);
}
@ -2554,7 +2556,7 @@ fn parse_stmt(
match input.next().unwrap().0 {
Token::Comment(comment) => {
comments.push(comment);
_comments.push(comment);
match input.peek().unwrap() {
(Token::Fn, _) | (Token::Private, _) => break,
@ -2565,6 +2567,7 @@ fn parse_stmt(
t => unreachable!("expecting Token::Comment, but gets {:?}", t),
}
}
}
let (token, token_pos) = match input.peek().unwrap() {
(Token::EOF, pos) => return Ok(Stmt::Noop(*pos)),
@ -2618,7 +2621,7 @@ fn parse_stmt(
pos: pos,
};
let func = parse_fn(input, &mut new_state, lib, access, settings, comments)?;
let func = parse_fn(input, &mut new_state, lib, access, settings, _comments)?;
lib.insert(
// Qualifiers (none) + function name + number of arguments.

17
tests/stack.rs
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@ -10,21 +10,24 @@ fn test_stack_overflow_fn_calls() -> Result<(), Box<EvalAltResult>> {
engine.eval::<INT>(
r"
fn foo(n) { if n <= 1 { 0 } else { n + foo(n-1) } }
foo(7)
foo(6)
",
)?,
27
20
);
let max = engine.max_call_levels();
#[cfg(not(feature = "unchecked"))]
assert!(matches!(
*engine
.eval::<()>(
.eval::<()>(&format!(
r"
fn foo(n) { if n == 0 { 0 } else { n + foo(n-1) } }
foo(1000)
"
)
fn foo(n) {{ if n == 0 {{ 0 }} else {{ n + foo(n-1) }} }}
foo({})
",
max + 1
))
.expect_err("should error"),
EvalAltResult::ErrorStackOverflow(_)
));