portable: move profile search helper to path-lookup

Will be used in systemd-analyze later

src/basic/path-lookup.c

@@ -8,6 +8,7 @@
 #include "fs-util.h"
 #include "log.h"
 #include "macro.h"
+#include "nulstr-util.h"
 #include "path-lookup.h"
 #include "path-util.h"
 #include "stat-util.h"
@@ -864,3 +865,30 @@ char **env_generator_binary_paths(bool is_system) {
 
         return TAKE_PTR(paths);
 }
+
+int find_portable_profile(const char *name, const char *unit, char **ret_path) {
+        const char *p, *dot;
+
+        assert(name);
+        assert(ret_path);
+
+        assert_se(dot = strrchr(unit, '.'));
+
+        NULSTR_FOREACH(p, PORTABLE_PROFILE_DIRS) {
+                _cleanup_free_ char *joined = NULL;
+
+                joined = strjoin(p, "/", name, "/", dot + 1, ".conf");
+                if (!joined)
+                        return -ENOMEM;
+
+                if (laccess(joined, F_OK) >= 0) {
+                        *ret_path = TAKE_PTR(joined);
+                        return 0;
+                }
+
+                if (errno != ENOENT)
+                        return -errno;
+        }
+
+        return -ENOENT;
+}

src/basic/path-lookup.h

@@ -72,3 +72,6 @@ char **env_generator_binary_paths(bool is_system);
 
 #define NETWORK_DIRS ((const char* const*) CONF_PATHS_STRV("systemd/network"))
 #define NETWORK_DIRS_NULSTR CONF_PATHS_NULSTR("systemd/network")
+
+#define PORTABLE_PROFILE_DIRS CONF_PATHS_NULSTR("systemd/portable/profile")
+int find_portable_profile(const char *name, const char *unit, char **ret_path);