util: don't pass invalid fd to fdopendir() on error to avoid corruption of errno

diff --git a/src/util.c b/src/util.c
index 21afdceb8cc4cf666de6d36318c1ea30be175de7..aa1f19ed69a3deec6e27259922c65a94bc0ecfe8 100644 (file)
--- a/src/util.c
+++ b/src/util.c
@@ -3436,7 +3436,18 @@ bool null_or_empty(struct stat *st) {
 }
 
 DIR *xopendirat(int fd, const char *name, int flags) {
-        return fdopendir(openat(fd, name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|flags));
+        int nfd;
+        DIR *d;
+
+        if ((nfd = openat(fd, name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|flags)) < 0)
+                return NULL;
+
+        if (!(d = fdopendir(nfd))) {
+                close_nointr_nofail(nfd);
+                return NULL;
+        }
+
+        return d;
 }
 
 int signal_from_string_try_harder(const char *s) {