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-rw-r--r--src/shared/binfmt-util.c55
1 files changed, 55 insertions, 0 deletions
diff --git a/src/shared/binfmt-util.c b/src/shared/binfmt-util.c
new file mode 100644
index 0000000..a261754
--- /dev/null
+++ b/src/shared/binfmt-util.c
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <sys/stat.h>
+#include <sys/statvfs.h>
+#include <sys/vfs.h>
+
+#include "binfmt-util.h"
+#include "errno-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "missing_magic.h"
+#include "stat-util.h"
+
+int binfmt_mounted(void) {
+ _cleanup_close_ int fd = -EBADF;
+ int r;
+
+ fd = RET_NERRNO(open("/proc/sys/fs/binfmt_misc", O_CLOEXEC | O_DIRECTORY | O_PATH));
+ if (fd == -ENOENT)
+ return false;
+ if (fd < 0)
+ return fd;
+
+ r = fd_is_fs_type(fd, BINFMTFS_MAGIC);
+ if (r <= 0)
+ return r;
+
+ return access_fd(fd, W_OK) >= 0;
+}
+
+int disable_binfmt(void) {
+ int r;
+
+ /* Flush out all rules. This is important during shutdown to cover for rules using "F", since those
+ * might pin a file and thus block us from unmounting stuff cleanly.
+ *
+ * We are a bit careful here, since binfmt_misc might still be an autofs which we don't want to
+ * trigger. */
+
+ r = binfmt_mounted();
+ if (r < 0)
+ return log_warning_errno(r, "Failed to determine whether binfmt_misc is mounted: %m");
+ if (r == 0) {
+ log_debug("binfmt_misc is not mounted in read-write mode, not detaching entries.");
+ return 0;
+ }
+
+ r = write_string_file("/proc/sys/fs/binfmt_misc/status", "-1", WRITE_STRING_FILE_DISABLE_BUFFER);
+ if (r < 0)
+ return log_warning_errno(r, "Failed to unregister binfmt_misc entries: %m");
+
+ log_debug("Unregistered all remaining binfmt_misc entries.");
+ return 0;
+}