From: Daan De Meyer <daan.j.demeyer@gmail.com>
Date: Thu, 23 Mar 2023 13:30:43 +0000 (+0100)
Subject: fs-util: Allow xopenat() to reopen existing file descriptors
X-Git-Tag: v254-rc1~944^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=06ca2db39dc959a5b40690b309417d66659061ad;p=thirdparty%2Fsystemd.git

fs-util: Allow xopenat() to reopen existing file descriptors
---

diff --git a/src/basic/fs-util.c b/src/basic/fs-util.c
index 06bd5705f28..257c11ad715 100644
--- a/src/basic/fs-util.c
+++ b/src/basic/fs-util.c
@@ -1104,6 +1104,11 @@ int xopenat(int dir_fd, const char *path, int flags, mode_t mode) {
         assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
         assert(path);
 
+        if (isempty(path)) {
+                assert(!FLAGS_SET(flags, O_CREAT|O_EXCL));
+                return fd_reopen(dir_fd, flags);
+        }
+
         if (FLAGS_SET(flags, O_DIRECTORY|O_CREAT)) {
                 r = RET_NERRNO(mkdirat(dir_fd, path, mode));
                 if (r == -EEXIST) {
diff --git a/src/test/test-fs-util.c b/src/test/test-fs-util.c
index 2ad9c5b565a..0f942f6dcbb 100644
--- a/src/test/test-fs-util.c
+++ b/src/test/test-fs-util.c
@@ -1223,7 +1223,7 @@ TEST(openat_report_new) {
 
 TEST(xopenat) {
         _cleanup_(rm_rf_physical_and_freep) char *t = NULL;
-        _cleanup_close_ int tfd = -EBADF, fd = -EBADF;
+        _cleanup_close_ int tfd = -EBADF, fd = -EBADF, fd2 = -EBADF;
 
         assert_se((tfd = mkdtemp_open(NULL, 0, &t)) >= 0);
 
@@ -1244,6 +1244,11 @@ TEST(xopenat) {
         assert_se((fd = xopenat(tfd, "def", O_CREAT|O_EXCL|O_CLOEXEC, 0644)) >= 0);
         assert_se(fd_verify_regular(fd) >= 0);
         fd = safe_close(fd);
+
+        /* Test that we can reopen an existing fd with xopenat() by specifying an empty path. */
+
+        assert_se((fd = xopenat(tfd, "def", O_PATH|O_CLOEXEC, 0)) >= 0);
+        assert_se((fd2 = xopenat(fd, "", O_RDWR|O_CLOEXEC, 0644)) >= 0);
 }
 
 TEST(xopenat_lock) {