81 lines
3.2 KiB
Rust
81 lines
3.2 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
|
|
use clippy_utils::paths;
|
|
use clippy_utils::source::snippet_with_macro_callsite;
|
|
use clippy_utils::ty::{is_type_diagnostic_item, is_type_ref_to_diagnostic_item};
|
|
use if_chain::if_chain;
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir as hir;
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
|
use rustc_span::symbol::{sym, Symbol};
|
|
|
|
declare_clippy_lint! {
|
|
/// ### What it does
|
|
/// Checks for usage of `libc::strlen` on a `CString` or `CStr` value,
|
|
/// and suggest calling `as_bytes().len()` or `to_bytes().len()` respectively instead.
|
|
///
|
|
/// ### Why is this bad?
|
|
/// This avoids calling an unsafe `libc` function.
|
|
/// Currently, it also avoids calculating the length.
|
|
///
|
|
/// ### Example
|
|
/// ```rust, ignore
|
|
/// use std::ffi::CString;
|
|
/// let cstring = CString::new("foo").expect("CString::new failed");
|
|
/// let len = unsafe { libc::strlen(cstring.as_ptr()) };
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust, no_run
|
|
/// use std::ffi::CString;
|
|
/// let cstring = CString::new("foo").expect("CString::new failed");
|
|
/// let len = cstring.as_bytes().len();
|
|
/// ```
|
|
pub STRLEN_ON_C_STRINGS,
|
|
complexity,
|
|
"using `libc::strlen` on a `CString` or `CStr` value, while `as_bytes().len()` or `to_bytes().len()` respectively can be used instead"
|
|
}
|
|
|
|
declare_lint_pass!(StrlenOnCStrings => [STRLEN_ON_C_STRINGS]);
|
|
|
|
impl LateLintPass<'tcx> for StrlenOnCStrings {
|
|
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
|
|
if expr.span.from_expansion() {
|
|
return;
|
|
}
|
|
|
|
if_chain! {
|
|
if let hir::ExprKind::Call(func, [recv]) = expr.kind;
|
|
if let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = func.kind;
|
|
|
|
if (&paths::LIBC_STRLEN).iter().map(|x| Symbol::intern(x)).eq(
|
|
path.segments.iter().map(|seg| seg.ident.name));
|
|
if let hir::ExprKind::MethodCall(path, _, args, _) = recv.kind;
|
|
if args.len() == 1;
|
|
if !args.iter().any(|e| e.span.from_expansion());
|
|
if path.ident.name == sym::as_ptr;
|
|
then {
|
|
let cstring = &args[0];
|
|
let ty = cx.typeck_results().expr_ty(cstring);
|
|
let val_name = snippet_with_macro_callsite(cx, cstring.span, "..");
|
|
let sugg = if is_type_diagnostic_item(cx, ty, sym::cstring_type){
|
|
format!("{}.as_bytes().len()", val_name)
|
|
} else if is_type_ref_to_diagnostic_item(cx, ty, sym::CStr){
|
|
format!("{}.to_bytes().len()", val_name)
|
|
} else {
|
|
return;
|
|
};
|
|
|
|
span_lint_and_sugg(
|
|
cx,
|
|
STRLEN_ON_C_STRINGS,
|
|
expr.span,
|
|
"using `libc::strlen` on a `CString` or `CStr` value",
|
|
"try this (you might also need to get rid of `unsafe` block in some cases):",
|
|
sugg,
|
|
Applicability::Unspecified // Sometimes unnecessary `unsafe` block
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|