lib: fs: add library for implementing a filesystem service

lib/libfs/allocator.c

@@ -0,0 +1,35 @@
+#include <fs/allocator.h>
+
+void *fs_alloc(struct fs_allocator *alloc, size_t count)
+{
+	if (alloc->fs_alloc) {
+		return alloc->fs_alloc(alloc, count);
+	}
+
+	return NULL;
+}
+
+void *fs_calloc(struct fs_allocator *alloc, size_t count, size_t sz)
+{
+	if (alloc->fs_calloc) {
+		return alloc->fs_calloc(alloc, count, sz);
+	}
+
+	return NULL;
+}
+
+void *fs_realloc(struct fs_allocator *alloc, void *p, size_t count)
+{
+	if (alloc->fs_realloc) {
+		return alloc->fs_realloc(alloc, p, count);
+	}
+
+	return NULL;
+}
+
+void fs_free(struct fs_allocator *alloc, void *p)
+{
+	if (alloc->fs_free) {
+		alloc->fs_free(alloc, p);
+	}
+}