env-util: refactor parsing helper for SYSTEMD_SYSEXT_HIERARCHIES out of sysext

src/basic/env-util.c

@@ -12,6 +12,7 @@
 #include "extract-word.h"
 #include "macro.h"
 #include "parse-util.h"
+#include "path-util.h"
 #include "process-util.h"
 #include "stdio-util.h"
 #include "string-util.h"
@@ -787,3 +788,44 @@ int setenv_systemd_exec_pid(bool update_only) {
 
         return 1;
 }
+
+int getenv_path_list(const char *name, char ***ret_paths) {
+        _cleanup_strv_free_ char **l = NULL;
+        const char *e;
+        char **p;
+        int r;
+
+        assert(name);
+        assert(ret_paths);
+
+        *ret_paths = NULL;
+
+        e = secure_getenv(name);
+        if (!e)
+                return 0;
+
+        r = strv_split_full(&l, e, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to parse $%s: %m", name);
+
+        STRV_FOREACH(p, l) {
+                if (!path_is_absolute(*p))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "Path '%s' is not absolute, refusing.", *p);
+
+                if (!path_is_normalized(*p))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "Path '%s' is not normalized, refusing.", *p);
+
+                if (path_equal(*p, "/"))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "Path '%s' is the root fs, refusing.", *p);
+        }
+
+        if (strv_isempty(l))
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "No paths specified, refusing.");
+
+        *ret_paths = TAKE_PTR(l);
+        return 0;
+}

src/basic/env-util.h

@@ -59,3 +59,7 @@ int getenv_bool_secure(const char *p);
 int set_unset_env(const char *name, const char *value, bool overwrite);
 
 int setenv_systemd_exec_pid(bool update_only);
+
+/* Parses and does sanity checks on an environment variable containing
+ * PATH-like colon-separated absolute paths */
+int getenv_path_list(const char *name, char ***ret_paths);