Re: [PATCH] Add cloexec information to fdinfo

Linus Torvalds
2011-06-29T16:23:02Z

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On Wed, Jun 29, 2011 at 1:15 AM, Ulrich Drepper <drepper@akkadia.org> 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

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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;