Merge pull request #676 from sanpeqf/feat-guards

Feat guards

Author: pixclk

examples/array/simple.c

@@ -14,25 +14,21 @@
 int
 main(int argc, const char *argv[])
 {
-    BFDEV_DEFINE_ARRAY(array, NULL, TEST_SIZE);
+    BFDEV_CLASS(bfdev_array, array)(NULL, TEST_SIZE);
     unsigned int count;
 
-    bfdev_array_append(&array, 0, 0);
-
     for (count = 0; count < TEST_LOOP; ++count) {
         unsigned int num;
         void *buff;
 
         num = rand() % TEST_SIZE;
-        buff = bfdev_array_push(&array, num);
+        buff = bfdev_array_push(array, num);
         if (!buff)
             return 1;
 
         memset(buff, 0, TEST_SIZE * num);
         printf("array bfdev_array_push test: %02u: %u\n", count, num);
     }
 
-    bfdev_array_release(&array);
-
     return 0;
 }

examples/guards/CMakeLists.txt

@@ -7,15 +7,21 @@ add_executable(guards-cleanup cleanup.c)
 target_link_libraries(guards-cleanup bfdev)
 add_test(guards-cleanup guards-cleanup)
 
+add_executable(guards-class class.c)
+target_link_libraries(guards-class bfdev)
+add_test(guards-class guards-class)
+
 if(${CMAKE_PROJECT_NAME} STREQUAL "bfdev")
     install(FILES
         cleanup.c
+        class.c
         DESTINATION
         ${CMAKE_INSTALL_DOCDIR}/examples/guards
     )
 
     install(TARGETS
         guards-cleanup
+        guards-class
         DESTINATION
         ${CMAKE_INSTALL_DOCDIR}/bin
     )

examples/guards/class.c

@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright(c) 2025 John Sanpe <sanpeqf@gmail.com>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <bfdev/guards.h>
+
+static const char *
+test_ctor(void)
+{
+    return strdup("helloworld");
+}
+
+static void
+test_dtor(const char *obj)
+{
+    free((void *)obj);
+}
+
+BFDEV_DEFINE_CLASS(test, const char *,
+    test_ctor(),
+    test_dtor(_T)
+)
+
+int
+main(int argc, const char *argv[])
+{
+    BFDEV_CLASS(test, str)();
+
+    if (!str)
+        return 1;
+    printf("%s\n", str);
+
+    return 0;
+}

examples/guards/cleanup.c

@@ -7,36 +7,36 @@
 #include <stdlib.h>
 #include <bfdev/guards.h>
 
-BFDEV_CLEAN_TEMPLATE(malloc, void *,
+BFDEV_DEFINE_CLEAN(malloc, void *,
     if (_T) {
         printf("cleanup %p\n", _T);
         free(_T);
     }
 )
 
 static void
-test_gc_cleanup(void)
+test_clean_gc(void)
 {
-    bfdev_clean(malloc) void *block;
+    BFDEV_CLEAN(malloc) void *block;
     block = malloc(8);
     (void)block;
 }
 
 static void *
-test_gc_lasting(void)
+test_clean_keep(void)
 {
-    bfdev_clean(malloc) void *block;
+    BFDEV_CLEAN(malloc) void *block;
     block = malloc(8);
-    bfdev_clean_return(block);
+    bfdev_return(block);
 }
 
 int
 main(int argc, const char *argv[])
 {
     void *block;
 
-    test_gc_cleanup();
-    block = test_gc_lasting();
+    test_clean_gc();
+    block = test_clean_keep();
     free(block);
 
     return 0;

include/bfdev/allocator.h

@@ -10,6 +10,8 @@
 #include <bfdev/config.h>
 #include <bfdev/types.h>
 #include <bfdev/stddef.h>
+#include <bfdev/guards.h>
+#include <bfdev/errptr.h>
 
 BFDEV_BEGIN_DECLS
 
@@ -125,6 +127,11 @@ bfdev_realloc_array(const bfdev_alloc_t *alloc,
     return bfdev_realloc(alloc, block, size * nr);
 }
 
+BFDEV_DEFINE_CLEAN(bfdev_free, void *,
+    if (!BFDEV_IS_INVAL(_T))
+        bfdev_free(BFDEV_NULL, _T);
+)
+
 BFDEV_END_DECLS
 
 #endif /* _BFDEV_ALLOCATOR_H_ */

include/bfdev/array.h

@@ -12,6 +12,7 @@
 #include <bfdev/stddef.h>
 #include <bfdev/string.h>
 #include <bfdev/allocator.h>
+#include <bfdev/guards.h>
 
 BFDEV_BEGIN_DECLS
 
@@ -207,6 +208,32 @@ bfdev_array_reserve(bfdev_array_t *array, unsigned long num);
 extern void
 bfdev_array_release(bfdev_array_t *array);
 
+static inline bfdev_array_t *
+bfdev_array_create(const bfdev_alloc_t *alloc, bfdev_size_t cells)
+{
+    bfdev_array_t *obj;
+
+    obj = bfdev_malloc(alloc, sizeof(*obj));
+    if (bfdev_unlikely(!obj))
+        return BFDEV_NULL;
+    bfdev_array_init(obj, alloc, cells);
+
+    return obj;
+}
+
+static inline void
+bfdev_array_destroy(bfdev_array_t *obj)
+{
+    bfdev_array_release(obj);
+    bfdev_free(obj->alloc, obj);
+}
+
+BFDEV_DEFINE_CLASS(bfdev_array, bfdev_array_t *,
+    bfdev_array_create(alloc, cells),
+    bfdev_array_destroy(_T),
+    const bfdev_alloc_t *alloc, bfdev_size_t cells
+)
+
 BFDEV_END_DECLS
 
 #endif /* _BFDEV_ARRAY_H_ */

include/bfdev/guards.h

@@ -12,24 +12,55 @@
 
 BFDEV_BEGIN_DECLS
 
-#define BFDEV_CLEAN_TEMPLATE(name, type, free)  \
+/**
+ * Guards:
+ *
+ * The "goto error" pattern is notorious for introducing subtle resource
+ * leaks. It is tedious and error prone to add new resource acquisition
+ * constraints into code paths that already have several unwind
+ * conditions. The "cleanup" helpers enable the compiler to help with
+ * this tedium and can aid in maintaining LIFO (last in first out)
+ * unwind ordering to avoid unintentional leaks.
+ */
+
+#define BFDEV_DEFINE_CLEAN(name, type, free)    \
 static inline void                              \
 __bfdev_cleanup_##name(void *object)            \
 {                                               \
     type _T = *(type *)object;                  \
     free;                                       \
 }
 
-#define bfdev_clean_lasting(object) ({  \
-    __auto_type __ptr = (object);       \
-    (object) = BFDEV_NULL; __ptr;       \
-})
-
-#define bfdev_clean(name) \
+#define BFDEV_CLEAN(name) \
     __bfdev_cleanup(__bfdev_cleanup_##name)
 
-#define bfdev_clean_return(object) \
-    return bfdev_clean_lasting(object)
+#define BFDEV_DEFINE_CLASS(name, type, ctor, dtor, args...) \
+typedef type __bfdev_class_##name##_t;                      \
+static inline type                                          \
+__bfdev_class_##name##_constructor(args)                    \
+{                                                           \
+    type __tmp = ctor;                                      \
+    return __tmp;                                           \
+}                                                           \
+static inline void                                          \
+__bfdev_class_##name##_destructor(type *p)                  \
+{                                                           \
+    type _T = *p;                                           \
+    dtor;                                                   \
+}
+
+#define BFDEV_CLASS(name, var) \
+    __bfdev_class_##name##_t var \
+        __bfdev_cleanup(__bfdev_class_##name##_destructor) = \
+        __bfdev_class_##name##_constructor
+
+#define bfdev_lasting(object) ({    \
+    __auto_type __ptr = (object);   \
+    (object) = BFDEV_NULL; __ptr;   \
+})
+
+#define bfdev_return(object) \
+    return bfdev_lasting(object)
 
 BFDEV_END_DECLS