From 882d6e17bc44db687c8de9b357e5ce6c6d501f28 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Wed, 10 Mar 2021 12:26:33 -0300 Subject: posix: Add posix_spawn_file_actions_addclosefrom_np This patch adds a way to close a range of file descriptors on posix_spawn as a new file action. The API is similar to the one provided by Solaris 11 [1], where the file action causes the all open file descriptors greater than or equal to input on to be closed when the new process is spawned. The function posix_spawn_file_actions_addclosefrom_np is safe to be implemented by iterating over /proc/self/fd, since the Linux spawni.c helper process does not use CLONE_FILES, so its has own file descriptor table and any failure (in /proc operation) aborts the process creation and returns an error to the caller. I am aware that this file action might be redundant to the current approach of POSIX in promoting O_CLOEXEC in more interfaces. However O_CLOEXEC is still not the default and for some specific usages, the caller needs to close all possible file descriptors to avoid them leaking. Some examples are CPython (discussed in BZ#10353) and OpenJDK jspawnhelper [2] (where OpenJDK spawns a helper process to exactly closes all file descriptors). Most likely any environment which calls functions that might open file descriptor under the hood and aim to use posix_spawn might face the same requirement. Checked on x86_64-linux-gnu and i686-linux-gnu on kernel 5.11 and 4.15. [1] https://docs.oracle.com/cd/E36784_01/html/E36874/posix-spawn-file-actions-addclosefrom-np-3c.html [2] https://github.com/openjdk/jdk/blob/master/src/java.base/unix/native/libjava/childproc.c#L82 --- sysdeps/posix/spawni.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'sysdeps/posix') diff --git a/sysdeps/posix/spawni.c b/sysdeps/posix/spawni.c index fe3b5bb7f6..ad1858fe4e 100644 --- a/sysdeps/posix/spawni.c +++ b/sysdeps/posix/spawni.c @@ -231,6 +231,10 @@ __spawni_child (void *arguments) if (__fchdir (action->action.fchdir_action.fd) != 0) goto fail; break; + + case spawn_do_closefrom: + __set_errno (EINVAL); + goto fail; } } } -- cgit 1.4.1