string_utils: add must_make_path_relative()

Stolen without shame from my previous implementation in LXCFS. Cc: stable-4.0 Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
lxc · Jan 26, 2021 · 9cde8a8 · 9cde8a8
1 parent d23cb29
commit 9cde8a8
Showing 1 changed file with 10 additions and 0 deletions.
diff --git a/src/lxc/string_utils.h b/src/lxc/string_utils.h
@@ -87,6 +87,16 @@ __hidden __attribute__((sentinel)) extern char *must_concat(size_t *len, const c
 __hidden __attribute__((sentinel)) extern char *must_make_path(const char *first, ...);
 __hidden __attribute__((sentinel)) extern char *must_append_path(char *first, ...);
 
+#define must_make_path_relative(__first__, ...)                                \
+	({                                                                     \
+		char *__ptr__;                                                 \
+		if (*__first__ == '/')                                         \
+			__ptr__ = must_make_path(".", __first__, __VA_ARGS__); \
+		else                                                           \
+			__ptr__ = must_make_path(__first__, __VA_ARGS__);      \
+		__ptr__;                                                       \
+	})
+
 /* Return copy of string @entry. Do not fail. */
 __hidden extern char *must_copy_string(const char *entry);