install: allow paths like LookupPath.generator to be NULL

Fixes #3047.

3 files changed, 24 insertions, 14 deletions

diff --git a/src/basic/path-util.h b/src/basic/path-util.h
index f43d477eb9..34d5cd1570 100644
--- a/src/basic/path-util.h
+++ b/src/basic/path-util.h
@@ -48,6 +48,10 @@ bool path_equal(const char *a, const char *b) _pure_;
 bool path_equal_or_files_same(const char *a, const char *b);
 char* path_join(const char *root, const char *path, const char *rest);
 
+static inline bool path_equal_ptr(const char *a, const char *b) {
+        return !!a == !!b && (!a || path_equal(a, b));
+}
+
 /* Note: the search terminates on the first NULL item. */
 #define PATH_IN_SET(p, ...)                                     \
         ({                                                      \
diff --git a/src/shared/install.c b/src/shared/install.c
index 74de8141f1..10c724edbd 100644
--- a/src/shared/install.c
+++ b/src/shared/install.c
@@ -119,9 +119,9 @@ static int path_is_generator(const LookupPaths *p, const char *path) {
         if (!parent)
                 return -ENOMEM;
 
-        return path_equal(p->generator, parent) ||
-                path_equal(p->generator_early, parent) ||
-                path_equal(p->generator_late, parent);
+        return path_equal_ptr(parent, p->generator) ||
+               path_equal_ptr(parent, p->generator_early) ||
+               path_equal_ptr(parent, p->generator_late);
 }
 
 static int path_is_transient(const LookupPaths *p, const char *path) {
@@ -134,7 +134,7 @@ static int path_is_transient(const LookupPaths *p, const char *path) {
         if (!parent)
                 return -ENOMEM;
 
-        return path_equal(p->transient, parent);
+        return path_equal_ptr(parent, p->transient);
 }
 
 static int path_is_control(const LookupPaths *p, const char *path) {
@@ -147,8 +147,8 @@ static int path_is_control(const LookupPaths *p, const char *path) {
         if (!parent)
                 return -ENOMEM;
 
-        return path_equal(parent, p->persistent_control) ||
-                path_equal(parent, p->runtime_control);
+        return path_equal_ptr(parent, p->persistent_control) ||
+               path_equal_ptr(parent, p->runtime_control);
 }
 
 static int path_is_config(const LookupPaths *p, const char *path) {
@@ -164,8 +164,8 @@ static int path_is_config(const LookupPaths *p, const char *path) {
         if (!parent)
                 return -ENOMEM;
 
-        return path_equal(parent, p->persistent_config) ||
-               path_equal(parent, p->runtime_config);
+        return path_equal_ptr(parent, p->persistent_config) ||
+               path_equal_ptr(parent, p->runtime_config);
 }
 
 static int path_is_runtime(const LookupPaths *p, const char *path) {
@@ -186,12 +186,12 @@ static int path_is_runtime(const LookupPaths *p, const char *path) {
         if (!parent)
                 return -ENOMEM;
 
-        return path_equal(parent, p->runtime_config) ||
-               path_equal(parent, p->generator) ||
-               path_equal(parent, p->generator_early) ||
-               path_equal(parent, p->generator_late) ||
-               path_equal(parent, p->transient) ||
-               path_equal(parent, p->runtime_control);
+        return path_equal_ptr(parent, p->runtime_config) ||
+               path_equal_ptr(parent, p->generator) ||
+               path_equal_ptr(parent, p->generator_early) ||
+               path_equal_ptr(parent, p->generator_late) ||
+               path_equal_ptr(parent, p->transient) ||
+               path_equal_ptr(parent, p->runtime_control);
 }
 
 static int path_is_vendor(const LookupPaths *p, const char *path) {
diff --git a/src/test/test-path-util.c b/src/test/test-path-util.c
index 7ce2695c5c..5d77e2959c 100644
--- a/src/test/test-path-util.c
+++ b/src/test/test-path-util.c
@@ -96,6 +96,12 @@ static void test_path(void) {
         assert_se(PATH_IN_SET("/bin", "/foo/bar", "/bin"));
         assert_se(PATH_IN_SET("/", "/", "/", "/foo/bar"));
         assert_se(!PATH_IN_SET("/", "/abc", "/def"));
+
+        assert_se(path_equal_ptr(NULL, NULL));
+        assert_se(path_equal_ptr("/a", "/a"));
+        assert_se(!path_equal_ptr("/a", "/b"));
+        assert_se(!path_equal_ptr("/a", NULL));
+        assert_se(!path_equal_ptr(NULL, "/a"));
 }
 
 static void test_find_binary(const char *self) {