From bb60956b393c3534fb4960772c7fd023aa0f81d5 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Wed, 20 Apr 2022 01:40:36 +0900
Subject: [PATCH] path-util: make readlink_value() refuse O_DIRECTORY returned
 from path_extract_filename()

The function is now only used by sd-device.c and pam_systemd.c, and they
expects the result are not directory. Hence, it is safe to change the
behavior.

Addresses https://github.com/systemd/systemd/pull/23089#discussion_r853006017.
---
 src/basic/fs-util.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/basic/fs-util.c b/src/basic/fs-util.c
index 96b588a4b5..cc25222c32 100644
--- a/src/basic/fs-util.c
+++ b/src/basic/fs-util.c
@@ -155,7 +155,7 @@ int readlink_malloc(const char *p, char **ret) {
 }
 
 int readlink_value(const char *p, char **ret) {
-        _cleanup_free_ char *link = NULL;
+        _cleanup_free_ char *link = NULL, *name = NULL;
         int r;
 
         assert(p);
@@ -165,7 +165,14 @@ int readlink_value(const char *p, char **ret) {
         if (r < 0)
                 return r;
 
-        return path_extract_filename(link, ret);
+        r = path_extract_filename(link, &name);
+        if (r < 0)
+                return r;
+        if (r == O_DIRECTORY)
+                return -EINVAL;
+
+        *ret = TAKE_PTR(name);
+        return 0;
 }
 
 int readlink_and_make_absolute(const char *p, char **r) {