add guidelines type and barebone for [mem_unsafe_functions] lint

Signed-off-by: J-ZhengLi <lizheng135@huawei.com>

Author: J-ZhengLi

CHANGELOG.md

@@ -4707,6 +4707,7 @@ Released 2018-09-13
 [`mem_replace_option_with_none`]: https://rust-lang.github.io/rust-clippy/master/index.html#mem_replace_option_with_none
 [`mem_replace_with_default`]: https://rust-lang.github.io/rust-clippy/master/index.html#mem_replace_with_default
 [`mem_replace_with_uninit`]: https://rust-lang.github.io/rust-clippy/master/index.html#mem_replace_with_uninit
+[`mem_unsafe_functions`]: https://rust-lang.github.io/rust-clippy/master/index.html#mem_unsafe_functions
 [`min_max`]: https://rust-lang.github.io/rust-clippy/master/index.html#min_max
 [`misaligned_transmute`]: https://rust-lang.github.io/rust-clippy/master/index.html#misaligned_transmute
 [`mismatched_target_os`]: https://rust-lang.github.io/rust-clippy/master/index.html#mismatched_target_os

clippy_lints/src/declared_lints.rs

@@ -191,6 +191,7 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
     crate::functions::TOO_MANY_ARGUMENTS_INFO,
     crate::functions::TOO_MANY_LINES_INFO,
     crate::future_not_send::FUTURE_NOT_SEND_INFO,
+    crate::guidelines::MEM_UNSAFE_FUNCTIONS_INFO,
     crate::if_let_mutex::IF_LET_MUTEX_INFO,
     crate::if_not_else::IF_NOT_ELSE_INFO,
     crate::if_then_some_else_none::IF_THEN_SOME_ELSE_NONE_INFO,

clippy_lints/src/guidelines/mem_unsafe_functions.rs

@@ -0,0 +1,10 @@
+use clippy_utils::diagnostics::span_lint;
+use rustc_lint::LateContext;
+use rustc_span::Span;
+
+use super::MEM_UNSAFE_FUNCTIONS;
+
+// TODO: Adjust the parameters as necessary
+pub(super) fn check(cx: &LateContext<'_>, span: Span) {
+    span_lint(cx, MEM_UNSAFE_FUNCTIONS, span, "it's working!");
+}

clippy_lints/src/guidelines/mod.rs

@@ -0,0 +1,51 @@
+mod mem_unsafe_functions;
+
+use rustc_hir as hir;
+use rustc_hir::intravisit;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::def_id::LocalDefId;
+use rustc_span::Span;
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Check for direct usage of external functions that modify memory
+    /// without concerning about memory safety, such as `memcpy`, `strcpy`, `strcat` etc.
+    ///
+    /// ### Why is this bad?
+    /// These function can be dangerous when used incorrectly,
+    /// which could potentially introduce vulnerablities such as buffer overflow to the software.
+    ///
+    /// ### Example
+    /// ```rust
+    /// extern "C" {
+    ///     fn memcpy(dest: *mut c_void, src: *const c_void, n: size_t) -> *mut c_void;
+    /// }
+    /// let ptr = unsafe { memcpy(dest, src, size); }
+    /// // Or use via libc
+    /// let ptr = unsafe { libc::memcpy(dest, src, size); }
+    #[clippy::version = "1.70.0"]
+    pub MEM_UNSAFE_FUNCTIONS,
+    nursery,
+    "use of potentially dangerous external functions"
+}
+
+declare_lint_pass!(GuidelineLints => [
+    MEM_UNSAFE_FUNCTIONS,
+]);
+
+impl<'tcx> LateLintPass<'tcx> for GuidelineLints {
+    fn check_fn(
+        &mut self,
+        cx: &LateContext<'tcx>,
+        _kind: intravisit::FnKind<'tcx>,
+        _decl: &'tcx hir::FnDecl<'_>,
+        _body: &'tcx hir::Body<'_>,
+        span: Span,
+        _def_id: LocalDefId,
+    ) {
+        mem_unsafe_functions::check(cx, span);
+    }
+
+    fn check_item(&mut self, _cx: &LateContext<'tcx>, _item: &'tcx hir::Item<'_>) {}
+}

clippy_lints/src/lib.rs

@@ -138,6 +138,7 @@ mod from_raw_with_void_ptr;
 mod from_str_radix_10;
 mod functions;
 mod future_not_send;
+mod guidelines;
 mod if_let_mutex;
 mod if_not_else;
 mod if_then_some_else_none;
@@ -959,6 +960,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|_| Box::new(tests_outside_test_module::TestsOutsideTestModule));
     store.register_late_pass(|_| Box::new(manual_slice_size_calculation::ManualSliceSizeCalculation));
     store.register_early_pass(|| Box::new(suspicious_doc_comments::SuspiciousDocComments));
+    store.register_late_pass(|_| Box::new(guidelines::GuidelineLints));
     // add lints here, do not remove this comment, it's used in `new_lint`
 }
 

tests/ui/mem_unsafe_functions.rs

@@ -0,0 +1,27 @@
+#![feature(c_size_t)]
+#![warn(clippy::mem_unsafe_functions)]
+
+use core::ffi::{c_char, c_int, c_size_t, c_void};
+
+// mock libc crate
+mod libc {
+    pub use core::ffi::c_size_t as size_t;
+    pub use core::ffi::{c_char, c_int, c_void};
+    extern "C" {
+        pub fn strcpy(dst: *mut c_char, src: *const c_char) -> *mut c_char;
+        pub fn strncpy(dst: *mut c_char, src: *const c_char, n: size_t) -> *mut c_char;
+        pub fn memcpy(dest: *mut c_void, src: *const c_void, n: size_t) -> *mut c_void;
+        pub fn memmove(dest: *mut c_void, src: *const c_void, n: size_t) -> *mut c_void;
+        pub fn memset(dest: *mut c_void, c: c_int, n: size_t) -> *mut c_void;
+    }
+}
+
+extern "C" {
+    fn strcpy(dst: *mut c_char, src: *const c_char) -> *mut c_char;
+    fn strncpy(dst: *mut c_char, src: *const c_char, n: c_size_t) -> *mut c_char;
+    fn memcpy(dest: *mut c_void, src: *const c_void, n: c_size_t) -> *mut c_void;
+    fn memmove(dest: *mut c_void, src: *const c_void, n: c_size_t) -> *mut c_void;
+    fn memset(dest: *mut c_void, c: c_int, n: c_size_t) -> *mut c_void;
+}
+
+fn main() {}

tests/ui/mem_unsafe_functions.stderr

@@ -0,0 +1,10 @@
+error: it's working!
+  --> $DIR/mem_unsafe_functions.rs:27:1
+   |
+LL | fn main() {}
+   | ^^^^^^^^^^^^
+   |
+   = note: `-D clippy::mem-unsafe-functions` implied by `-D warnings`
+
+error: aborting due to previous error
+