Re: [PATCH v1 44/59] 9p-local.c: remove unneeded label in local_unlinkat_common()

[Greg Kurz]

On Mon,  6 Jan 2020 15:24:10 -0300
Daniel Henrique Barboza <address@hidden> wrote:

> 'err_out' can be replaced by 'return ret' in the error conditions
> the jump was being made.
> 
> CC: Greg Kurz <address@hidden>
> Signed-off-by: Daniel Henrique Barboza <address@hidden>
> ---
>  hw/9pfs/9p-local.c | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
> index ca641390fb..f9bdd2ad7c 100644
> --- a/hw/9pfs/9p-local.c
> +++ b/hw/9pfs/9p-local.c
> @@ -1094,12 +1094,12 @@ static int local_unlinkat_common(FsContext *ctx, int 
> dirfd, const char *name,
>  
>              fd = openat_dir(dirfd, name);
>              if (fd == -1) {
> -                goto err_out;
> +                return ret;
>              }
>              ret = unlinkat(fd, VIRTFS_META_DIR, AT_REMOVEDIR);
>              close_preserve_errno(fd);
>              if (ret < 0 && errno != ENOENT) {
> -                goto err_out;
> +                return ret;
>              }
>          }
>          map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
> @@ -1107,16 +1107,14 @@ static int local_unlinkat_common(FsContext *ctx, int 
> dirfd, const char *name,
>              ret = unlinkat(map_dirfd, name, 0);
>              close_preserve_errno(map_dirfd);
>              if (ret < 0 && errno != ENOENT) {
> -                goto err_out;
> +                return ret;
>              }
>          } else if (errno != ENOENT) {
> -            goto err_out;
> +            return ret;

Ouch... I now realize we can get there with ret == 0 when unlinking a
directory in mapped-file mode. The function will wrongly return success
despite the failure.... Since this function is supposed to return -1
on error, I suggest to do that instead of return ret, and to drop the
initialization of ret to -1, which wouldn't be needed anymore.

Since this would fix a bug it makes sense to post it separately from
this series. Rewrite the title/changelog accordingly and I'll merge
it via the 9p tree.

>          }
>      }
>  
> -    ret = unlinkat(dirfd, name, flags);
> -err_out:
> -    return ret;
> +    return unlinkat(dirfd, name, flags);
>  }
>  
>  static int local_remove(FsContext *ctx, const char *path)