From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Wed, 6 May 2026 13:22:32 +0000 (+0200)
Subject: contrib/mempattern: utilize modern attributes
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=refs%2Fheads%2Fmempattern;p=thirdparty%2Fknot-resolver.git

contrib/mempattern: utilize modern attributes

They're mostly to aid diagnostics, but some of it may even
help performance, e.g. via aiding pointer aliasing analysis.
---

diff --git a/contrib/mempattern.c b/contrib/mempattern.c
index 75c397a92..b6fcdf40a 100644
--- a/contrib/mempattern.c
+++ b/contrib/mempattern.c
@@ -70,7 +70,13 @@ void *mm_realloc(knot_mm_t *mm, void *what, size_t size, size_t prev_size)
 				memcpy(p, what,
 				       prev_size < size ? prev_size : size);
 			}
+		#pragma GCC diagnostic push
+		#ifdef __clang__
+			#pragma GCC diagnostic ignored "-Wunknown-warning-option"
+		#endif
+		#pragma GCC diagnostic ignored "-Wmismatched-dealloc"
 			mm_free(mm, what);
+		#pragma GCC diagnostic pop
 			return p;
 		}
 	} else {
@@ -80,9 +86,6 @@ void *mm_realloc(knot_mm_t *mm, void *what, size_t size, size_t prev_size)
 
 char *mm_strdup(knot_mm_t *mm, const char *s)
 {
-	if (s == NULL) {
-		return NULL;
-	}
 	if (mm) {
 		size_t len = strlen(s) + 1;
 		void *mem = mm_alloc(mm, len);
diff --git a/contrib/mempattern.h b/contrib/mempattern.h
index da299233f..fa84b550a 100644
--- a/contrib/mempattern.h
+++ b/contrib/mempattern.h
@@ -29,23 +29,39 @@
 /*! \brief Default memory block size. */
 #define MM_DEFAULT_BLKSIZE 4096
 
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wignored-attributes"
+
+// TODO: also enable for clang at some version
+#if __GNUC__ >= 11
+	#define malloc_attr(...) malloc(__VA_ARGS__)
+#else
+	#define malloc_attr(...) malloc
+#endif
+
+/*! \brief Free using 'mm' if any, uses system free() otherwise. */
+KR_EXPORT
+void mm_free(knot_mm_t *mm, const void *what);
+
 /*! \brief Allocs using 'mm' if any, uses system malloc() otherwise. */
 KR_EXPORT
-void *mm_alloc(knot_mm_t *mm, size_t size);
+void *mm_alloc(knot_mm_t *mm, size_t size)
+__attribute__ ((malloc_attr(mm_free,2),alloc_size(2),warn_unused_result));
 
 /*! \brief Callocs using 'mm' if any, uses system calloc() otherwise. */
-void *mm_calloc(knot_mm_t *mm, size_t nmemb, size_t size);
+void *mm_calloc(knot_mm_t *mm, size_t nmemb, size_t size)
+__attribute__ ((malloc_attr(mm_free,2),alloc_size(2,3),warn_unused_result));
 
 /*! \brief Reallocs using 'mm' if any, uses system realloc() otherwise. */
 KR_EXPORT
-void *mm_realloc(knot_mm_t *mm, void *what, size_t size, size_t prev_size);
+void *mm_realloc(knot_mm_t *mm, void *what, size_t size, size_t prev_size)
+__attribute__ ((alloc_size(3),warn_unused_result));
 
 /*! \brief Strdups using 'mm' if any, uses system strdup() otherwise. */
-char *mm_strdup(knot_mm_t *mm, const char *s);
-
-/*! \brief Free using 'mm' if any, uses system free() otherwise. */
-KR_EXPORT
-void mm_free(knot_mm_t *mm, const void *what);
+char *mm_strdup(knot_mm_t *mm, const char *s)
+__attribute__ ((malloc_attr(mm_free,2),nonnull(2),warn_unused_result/*additionally to strdup()*/));
+// TODO: check in knot-dns that (s != NULL) is really assumed.
 
 /*! \brief Initialize default memory allocation context. */
 void mm_ctx_init(knot_mm_t *mm);
@@ -53,6 +69,8 @@ void mm_ctx_init(knot_mm_t *mm);
 /*! \brief Memory pool context. */
 void mm_ctx_mempool(knot_mm_t *mm, size_t chunk_size);
 
+#undef malloc_attr
+#pragma GCC diagnostic pop
 
 /* API in addition to Knot's mempattern. */