Re: [MINI-OS PATCH v2 1/2] 9pfs: add fstat file operation hook

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

Juergen Gross, le ven. 21 mars 2025 10:31:44 +0100, a ecrit:
> Add a file operations fstat hook to the 9pfs frontend.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
> ---
> V2:
> - or file access mode into st_mode (Jason Andryuk)
> ---
>  9pfront.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/9pfront.c b/9pfront.c
> index 1741d600..7257a07e 100644
> --- a/9pfront.c
> +++ b/9pfront.c
> @@ -85,6 +85,8 @@ struct file_9pfs {
>  
>  #define P9_QID_SIZE    13
>  
> +#define QID_TYPE_DIR   0x80     /* Applies to qid[0]. */
> +
>  struct p9_header {
>      uint32_t size;
>      uint8_t cmd;
> @@ -950,6 +952,32 @@ static int write_9pfs(struct file *file, const void *buf, size_t nbytes)
>      return ret;
>  }
>  
> +static int fstat_9pfs(struct file *file, struct stat *buf)
> +{
> +    struct file_9pfs *f9pfs = file->filedata;
> +    struct p9_stat stat;
> +    int ret;
> +
> +    ret = p9_stat(f9pfs->dev, f9pfs->fid, &stat);
> +    if ( ret )
> +    {
> +        errno = EIO;
> +        return -1;
> +    }
> +
> +    buf->st_mode = (stat.qid[0] == QID_TYPE_DIR) ? S_IFDIR : S_IFREG;
> +    buf->st_mode |= stat.mode & 0777;
> +    buf->st_atime = stat.atime;
> +    buf->st_mtime = stat.mtime;

Should we perhaps also fill st_ctime? Leaving it at 0 could surprise
other software layers.

> +    buf->st_size = stat.length;
> +    buf->st_uid = stat.n_uid;
> +    buf->st_gid = stat.n_gid;
> +
> +    free_stat(&stat);
> +
> +    return 0;
> +}
> +
>  static int close_9pfs(struct file *file)
>  {
>      struct file_9pfs *f9pfs = file->filedata;
> @@ -1296,6 +1324,7 @@ static const struct file_ops ops_9pfs = {
>      .read = read_9pfs,
>      .write = write_9pfs,
>      .close = close_9pfs,
> +    .fstat = fstat_9pfs,
>  };
>  
>  __attribute__((constructor))
> -- 
> 2.43.0
>