From b58174f0ebe31fb56fe891bfbcf10979079053e3 Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Fri, 18 Dec 2020 16:54:14 +0100
Subject: Add lilv_path_absolute_child()

---
 src/filesystem.c       | 10 ++++++++++
 src/filesystem.h       |  9 +++++++++
 test/test_filesystem.c | 21 +++++++++++++++++++++
 3 files changed, 40 insertions(+)

diff --git a/src/filesystem.c b/src/filesystem.c
index 0ec9802..0482336 100644
--- a/src/filesystem.c
+++ b/src/filesystem.c
@@ -134,6 +134,16 @@ lilv_path_absolute(const char* path)
 	}
 }
 
+char*
+lilv_path_absolute_child(const char* path, const char* parent)
+{
+	if (lilv_path_is_absolute(path)) {
+		return lilv_strdup(path);
+	}
+
+	return lilv_path_join(parent, path);
+}
+
 char*
 lilv_path_relative_to(const char* path, const char* base)
 {
diff --git a/src/filesystem.h b/src/filesystem.h
index 319dd49..f888f5f 100644
--- a/src/filesystem.h
+++ b/src/filesystem.h
@@ -42,6 +42,15 @@ lilv_path_current(void);
 char*
 lilv_path_absolute(const char* path);
 
+/**
+   Return `path` as an absolute path relative to `parent`.
+
+   If `path` is absolute, an identical copy of it is returned.  Otherwise, the
+   returned path is relative to `parent`.
+*/
+char*
+lilv_path_absolute_child(const char* path, const char* parent);
+
 /**
    Return `path` relative to `base` if possible.
 
diff --git a/test/test_filesystem.c b/test/test_filesystem.c
index a3288ed..01ca5ae 100644
--- a/test/test_filesystem.c
+++ b/test/test_filesystem.c
@@ -104,6 +104,26 @@ test_path_absolute(void)
 	free(cwd);
 }
 
+static void
+test_path_absolute_child(void)
+{
+	const char* const parent     = "/parent";
+	const char* const short_path = "a";
+	const char* const long_path  = "a/b/c";
+
+	char* const expected_short = lilv_path_join(parent, short_path);
+	char* const expected_long  = lilv_path_join(parent, long_path);
+
+	assert(equals(lilv_path_absolute_child(short_path, parent),
+	              expected_short));
+
+	assert(equals(lilv_path_absolute_child(long_path, parent),
+	              expected_long));
+
+	free(expected_long);
+	free(expected_short);
+}
+
 static void
 test_path_relative_to(void)
 {
@@ -478,6 +498,7 @@ main(void)
 	test_path_is_child();
 	test_path_current();
 	test_path_absolute();
+	test_path_absolute_child();
 	test_path_relative_to();
 	test_path_parent();
 	test_path_filename();
-- 
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