Re: [PATCH] Add cloexec information to fdinfo

[Linus Torvalds]

On Wed, Jun 29, 2011 at 1:15 AM, Ulrich Drepper <drepper@xxxxxxxxxxx> wrote:
>
> In this specific case I was trying to re-implement the pfiles program.
> For normal file descriptors (not sockets) this was the last piece of
> information which wasn't available.  This is all part of my "give
> Solaris users no reason to not switch" effort.  I intend to offer the
> code to the util-linux-ng maintainers.

Ok.

So the part I really dislike about the patch is how it makes O_CLOEXEC
so magically different from the other O_xyz flags.

Wouldn't it be much nicer to just show it in the "flags:" line?

Also, I don't think you need the rcu locking, since we hold the
files->file_lock here anyway.

>> Also, it's by no means the only thing not visible in /proc. Things
>> like file locking status, leases, file descriptor ownership, signal
>> number associated with the setown etc.
>
> True, and maybe that will be useful as well.
>
> I might actually have some more patches to get to socket information but
> I haven't fully checked out yet what is available.

So at least O_CLOEXEC seems to have a real reason, and fits the
existing model. I think a patch like the attached would be ok. Does
that work for you? It's entirely untested here.

                                Linus
 fs/proc/base.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index fc5bc2767692..e2a016f24d38 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1920,6 +1920,14 @@ static int proc_fd_info(struct inode *inode, struct path *path, char *info)
 		spin_lock(&files->file_lock);
 		file = fcheck_files(files, fd);
 		if (file) {
+			unsigned int f_flags;
+			struct fdtable *fdt;
+
+			fdt = files_fdtable(files);
+			f_flags = file->f_flags & ~O_CLOEXEC;
+			if (FD_ISSET(fd, fdt->close_on_exec))
+				f_flags |= O_CLOEXEC;
+
 			if (path) {
 				*path = file->f_path;
 				path_get(&file->f_path);
@@ -1929,7 +1937,7 @@ static int proc_fd_info(struct inode *inode, struct path *path, char *info)
 					 "pos:\t%lli\n"
 					 "flags:\t0%o\n",
 					 (long long) file->f_pos,
-					 file->f_flags);
+					 f_flags);
 			spin_unlock(&files->file_lock);
 			put_files_struct(files);
 			return 0;