[PATCH v2 1/4] hurd: Don't pass FD_CLOEXEC in CMSG_DATA

[Sergey Bugaev]

It is of no concern to the receiving process whether or not the sender
process wants to close its copy of sent file descriptor upon exec, and
it should not influence whether or not the received file descriptor gets
the FD_CLOEXEC flag set in the receiving process.

The latter should in fact be dependent on the MSG_CMSG_CLOEXEC flag
being passed to the recvmsg () call, which is going to be implemented
in the following commit.

Fixes 344e755248ce02c0f8d095d11cc49e340703d926
"hurd: Support sending file descriptors over Unix sockets"

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
---
 sysdeps/mach/hurd/recvmsg.c | 5 +++--
 sysdeps/mach/hurd/sendmsg.c | 7 +++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/sysdeps/mach/hurd/recvmsg.c b/sysdeps/mach/hurd/recvmsg.c
index 39de86f6..c08eb499 100644
--- a/sysdeps/mach/hurd/recvmsg.c
+++ b/sysdeps/mach/hurd/recvmsg.c
@@ -189,7 +189,8 @@ __libc_recvmsg (int fd, struct msghdr *message, int flags)
     if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
       {
        /* SCM_RIGHTS support.  */
-       /* The fd's flags are passed in the control data.  */
+       /* The fd's flags are passed in the control data, but there currently
+          aren't any defined other than FD_CLOEXEC which we don't respect.  */
        int *fds = (int *) CMSG_DATA (cmsg);
        nfds = (cmsg->cmsg_len - CMSG_ALIGN (sizeof (struct cmsghdr)))
               / sizeof (int);
@@ -200,7 +201,7 @@ __libc_recvmsg (int fd, struct msghdr *message, int flags)
            if (err)
              goto cleanup;
            fds[j] = opened_fds[newfds] = _hurd_intern_fd (newports[newfds],
-                                                          fds[j], 0);
+                                                          0, 0);
            if (fds[j] == -1)
              {
                err = errno;
diff --git a/sysdeps/mach/hurd/sendmsg.c b/sysdeps/mach/hurd/sendmsg.c
index 5871d1d8..2f19797b 100644
--- a/sysdeps/mach/hurd/sendmsg.c
+++ b/sysdeps/mach/hurd/sendmsg.c
@@ -138,8 +138,11 @@ __libc_sendmsg (int fd, const struct msghdr *message, int 
flags)
                                             0, 0, 0, 0);
                   if (! err)
                     nports++;
-                  /* We pass the flags in the control data.  */
-                  fds[i] = descriptor->flags;
+                  /* We pass the file descriptor flags in the control data.
+                     The only currently defined flag is FD_CLOEXEC, which we
+                     don't want to pass and so we mask it out, so this will
+                     always be 0 currently.  */
+                  fds[i] = descriptor->flags & ~FD_CLOEXEC;
                   err;
                 }));
 
-- 
2.40.0