Re: [PATCH v2] procfs: set d_type on returned direntries

[Samuel Thibault]

Hello,

dnietoc@gmail.com, le lun. 20 janv. 2025 23:47:58 +0000, a ecrit:
> From: Diego Nieto Cid <dnietoc@gmail.com>
> 
> Thanks for the pointer Samuel. I managed to call procfs_lookup
> and extract from the node stat structure its type.
> 
> It mostly works except for the ".." and "self" entries:
> 
>     ./test-proc//..: d_type: 0
>     ./test-proc//self: d_type: 0
> 
> Well "self" is probably a symlink or something similar. And ".."
> probably comes from the parent translator (ext2fs), I'm not sure.
> 
> Also, I noticed procfs_lookup does a netfs_nref call for the returned
> node. So, I called netfs_nput after extracting its type. However, I
> don't think I got the locking correctly.

It seems odd indeed.

Actually, looking more into np->nn->ops->lookup, it allocates a new
node, taking locks etc. That becomes actually quite heavy. I'm now
thinking that perhaps best would be to make libgtop use lstat as readdir
says.

Sorry for the back&forth, we couldn't know before trying.

Samuel

> That are all the comments for version 2 of the patch.
> 
> Regards,
> Diego
> 
> 
> -- >8 -- >8 -- >8 --
> 
> ---
>  procfs/netfs.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/procfs/netfs.c b/procfs/netfs.c
> index 4ed5eab6..83db7517 100644
> --- a/procfs/netfs.c
> +++ b/procfs/netfs.c
> @@ -121,7 +121,7 @@ error_t netfs_attempt_readlink (struct iouser *user, 
> struct node *np,
>     DATA (if not NULL), write the number of entries processed in *AMT and
>     return the required/used space in DATACNT.  */
>  static int putentries (char *contents, size_t contents_len, int nentries,
> -                    char *data, mach_msg_type_number_t *datacnt)
> +                    char *data, mach_msg_type_number_t *datacnt, struct node 
> *dir)
>  {
>    int align = __alignof (struct dirent);
>    int i;
> @@ -138,11 +138,20 @@ static int putentries (char *contents, size_t 
> contents_len, int nentries,
>  
>        if (data)
>          {
> +          error_t err;
> +          struct node *np;
>         struct dirent *d = (struct dirent *) (data + *datacnt);
>         d->d_fileno = 42; /* XXX */
>         d->d_namlen = namlen;
>         d->d_reclen = reclen;
> -       d->d_type = DT_UNKNOWN;
> +          err = procfs_lookup(dir, contents, &np);
> +          if (err)
> +            d->d_type = DT_UNKNOWN;
> +          else
> +            {
> +              d->d_type = (np->nn_stat.st_mode & S_IFMT) == S_IFDIR ? DT_DIR 
> : DT_UNKNOWN;
> +              netfs_nput(np);
> +            }
>         memcpy (d->d_name, contents, namlen + 1);
>         if (pad)
>           memset(d->d_name + namlen + 1, 0, pad);
> @@ -190,7 +199,7 @@ error_t netfs_get_dirents (struct iouser *cred, struct 
> node *dir,
>      }
>  
>    /* Allocate a buffer if necessary. */
> -  putentries (contents, contents_len, nentries, NULL, datacnt);
> +  putentries (contents, contents_len, nentries, NULL, datacnt, NULL);
>    if (bufsize < *datacnt)
>      {
>        char *n = mmap (0, *datacnt, PROT_READ | PROT_WRITE, MAP_ANONYMOUS, 0, 
> 0);
> @@ -201,7 +210,7 @@ error_t netfs_get_dirents (struct iouser *cred, struct 
> node *dir,
>      }
>  
>    /* Do the actual conversion. */
> -  *amt = putentries (contents, contents_len, nentries, *data, datacnt);
> +  *amt = putentries (contents, contents_len, nentries, *data, datacnt, dir);
>  
>    return 0;
>  }
> -- 
> 2.47.1
> 
> 

-- 
Samuel
<m> bouhouhouh, b il m'a abandonné. Tout ca parce que je regardais plus mon 
emacs que lui !
<m> s/lui/ses messages irc/
 -+- #ens-mim esseulé -+-