Kernel: Implement deletion of SMO objects

libc/include/sys/banan-os.h

@@ -38,7 +38,9 @@ int load_keymap(const char* path);
 
 // Create shared memory object and return its key or -1 on error
 long smo_create(size_t size, int prot);
-// Map shared memory object defined by its key and return address or null on error
+// Delete shared memory object such that it will be no longer accessible with smo_map(). Existing mappings are still valid
+int smo_delete(long key);
+// Map shared memory object defined by its key and return address or null on error. Mappings can be unmapped using munmap()
 void* smo_map(long key);
 
 __END_DECLS

libc/include/sys/syscall.h

@@ -75,6 +75,7 @@ __BEGIN_DECLS
 	O(SYS_PSELECT,			pselect)		\
 	O(SYS_TRUNCATE,			truncate)		\
 	O(SYS_SMO_CREATE,		smo_create)		\
+	O(SYS_SMO_DELETE,		smo_delete)		\
 	O(SYS_SMO_MAP,			smo_map)		\
 
 enum Syscall

libc/sys/banan-os.cpp

@@ -22,6 +22,11 @@ long smo_create(size_t size, int prot)
 	return syscall(SYS_SMO_CREATE, size, prot);
 }
 
+int smo_delete(long key)
+{
+	return syscall(SYS_SMO_DELETE, key);
+}
+
 void* smo_map(long key)
 {
 	long ret = syscall(SYS_SMO_MAP, key);