Add macro `KERNAUX_CONTAINER_OF` (#100)

* Add macro KERNAUX_CONTAINER_OF
* Add includes
* Add "examples/macro_container_of"

.gitignore

@@ -111,6 +111,7 @@
 /examples/generic_file
 /examples/generic_malloc
 /examples/generic_mutex
+/examples/macro_container_of
 /examples/memmap
 /examples/ntoa
 /examples/panic

examples/Makefile.am

@@ -45,6 +45,14 @@ TESTS += generic_mutex
 generic_mutex_LDADD = $(top_builddir)/libkernaux.la
 generic_mutex_SOURCES = main.c generic_mutex.c
 
+######################
+# macro_container_of #
+######################
+
+TESTS += macro_container_of
+macro_container_of_LDADD = $(top_builddir)/libkernaux.la
+macro_container_of_SOURCES = main.c macro_container_of.c
+
 ##########
 # memmap #
 ##########

examples/generic_file.c

@@ -28,6 +28,9 @@ struct MyFile MyFile_create(char *ptr, size_t size);
 // my_file.c
 //===========
 
+#include <kernaux/generic/file.h>
+#include <stddef.h>
+
 static int MyFile_putc(void *file, unsigned char c);
 
 struct MyFile MyFile_create(char *const ptr, const size_t size)

examples/macro_container_of.c

@@ -0,0 +1,33 @@
+#include <kernaux/macro.h>
+
+#include <assert.h>
+
+struct Foo {
+    const char *hello;
+};
+
+struct Bar {
+    unsigned char a;
+    unsigned int b;
+    struct Foo foo;
+    unsigned short c;
+};
+
+static const struct Bar bar = {
+    .a = 143,
+    .b = 820794098,
+    .foo = {
+        .hello = "Hello, World!",
+    },
+    .c = 10981,
+};
+
+void example_main()
+{
+    const struct Bar *const bar_ptr =
+        KERNAUX_CONTAINER_OF(&bar.foo, struct Bar, foo);
+
+    assert(bar_ptr->a == 143);
+    assert(bar_ptr->b == 820794098);
+    assert(bar_ptr->c == 10981);
+}

include/kernaux/macro.h

@@ -5,6 +5,12 @@
 extern "C" {
 #endif
 
+#include <stddef.h>
+#include <stdint.h>
+
+#define KERNAUX_CONTAINER_OF(ptr, type, member) \
+    ((type*)((uintptr_t)(ptr) - offsetof(type, member)))
+
 #ifdef KERNAUX_ACCESS_PRIVATE
 #   define KERNAUX_PRIVATE_FIELD(id) id
 #   define KERNAUX_PROTECTED_FIELD(id) id

src/free_list.c

@@ -13,6 +13,7 @@
 #include <kernaux/free_list.h>
 #include <kernaux/generic/malloc.h>
 #include <kernaux/generic/mutex.h>
+#include <kernaux/macro.h>
 
 #include <stddef.h>
 #include <stdint.h>
@@ -22,8 +23,6 @@
 #define MIN_ZONE_SIZE (2 * NODE_HEADER_SIZE)
 #define MIN_SPLIT_SIZE (NODE_HEADER_SIZE + 16)
 
-#define CONTAINER_OF(ptr, type, member) ((type*)((uintptr_t)(ptr) - offsetof(type, member)))
-
 //#define ALIGN_MASK(align) ((align) - 1) // align should be a power of 2
 //#define ALIGN_UP(val, align) (((val) + ALIGN_MASK(align)) & ~ALIGN_MASK(align))
 
@@ -131,7 +130,7 @@ void KernAux_FreeList_free(void *const malloc, void *const ptr)
     LOCK(free_list);
 
     KernAux_FreeList_Node node =
-        CONTAINER_OF(ptr, struct KernAux_FreeList_Node, block);
+        KERNAUX_CONTAINER_OF(ptr, struct KernAux_FreeList_Node, block);
     KernAux_FreeList_Node last_node = NULL;
 
     for (
@@ -216,7 +215,7 @@ void *KernAux_FreeList_realloc(
     LOCK(free_list);
 
     KernAux_FreeList_Node node =
-        CONTAINER_OF(old_ptr, struct KernAux_FreeList_Node, block);
+        KERNAUX_CONTAINER_OF(old_ptr, struct KernAux_FreeList_Node, block);
     const size_t old_size = node->size - NODE_HEADER_SIZE;
 
     void *new_ptr = KernAux_FreeList_malloc(free_list, new_size);