diff options
Diffstat (limited to 'clippy_lints')
| -rw-r--r-- | clippy_lints/src/lib.rs | 5 | ||||
| -rw-r--r-- | clippy_lints/src/strlen_on_c_strings.rs | 82 |
2 files changed, 87 insertions, 0 deletions
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index 0a468ccf25a..82519a9b5b7 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -338,6 +338,7 @@ mod size_of_in_element_count; mod slow_vector_initialization; mod stable_sort_primitive; mod strings; +mod strlen_on_c_strings; mod suspicious_operation_groupings; mod suspicious_trait_impl; mod swap; @@ -914,6 +915,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: strings::STRING_LIT_AS_BYTES, strings::STRING_TO_STRING, strings::STR_TO_STRING, + strlen_on_c_strings::STRLEN_ON_C_STRINGS, suspicious_operation_groupings::SUSPICIOUS_OPERATION_GROUPINGS, suspicious_trait_impl::SUSPICIOUS_ARITHMETIC_IMPL, suspicious_trait_impl::SUSPICIOUS_OP_ASSIGN_IMPL, @@ -1410,6 +1412,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: LintId::of(slow_vector_initialization::SLOW_VECTOR_INITIALIZATION), LintId::of(stable_sort_primitive::STABLE_SORT_PRIMITIVE), LintId::of(strings::STRING_FROM_UTF8_AS_BYTES), + LintId::of(strlen_on_c_strings::STRLEN_ON_C_STRINGS), LintId::of(suspicious_trait_impl::SUSPICIOUS_ARITHMETIC_IMPL), LintId::of(suspicious_trait_impl::SUSPICIOUS_OP_ASSIGN_IMPL), LintId::of(swap::ALMOST_SWAPPED), @@ -1639,6 +1642,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: LintId::of(reference::REF_IN_DEREF), LintId::of(repeat_once::REPEAT_ONCE), LintId::of(strings::STRING_FROM_UTF8_AS_BYTES), + LintId::of(strlen_on_c_strings::STRLEN_ON_C_STRINGS), LintId::of(swap::MANUAL_SWAP), LintId::of(temporary_assignment::TEMPORARY_ASSIGNMENT), LintId::of(transmute::CROSSPOINTER_TRANSMUTE), @@ -2096,6 +2100,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: store.register_late_pass(move || box missing_enforced_import_rename::ImportRename::new(import_renames.clone())); let scripts = conf.allowed_scripts.clone(); store.register_early_pass(move || box disallowed_script_idents::DisallowedScriptIdents::new(&scripts)); + store.register_late_pass(|| box strlen_on_c_strings::StrlenOnCStrings); } #[rustfmt::skip] diff --git a/clippy_lints/src/strlen_on_c_strings.rs b/clippy_lints/src/strlen_on_c_strings.rs new file mode 100644 index 00000000000..2ccf3a3796d --- /dev/null +++ b/clippy_lints/src/strlen_on_c_strings.rs @@ -0,0 +1,82 @@ +use clippy_utils::diagnostics::span_lint_and_sugg; +use clippy_utils::in_macro; +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. + /// + /// **Known problems:** None. + /// + /// **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 in_macro(expr.span) { + 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 + ); + } + } + } +} |