Re: [PATCH] btrfs-progs: fix fi du so it works in more cases

[Martin Volf <martin.volf.42@gmail.com>]

Works for me, thanks.

Martin Volf

On Mon, Mar 21, 2016 at 1:23 PM, Austin S. Hemmelgarn
<ahferroin7@gmail.com> wrote:
> Currently, btrfs fi du uses open_file_or_dir(), which tries to open
> it's argument with o_RDWR.  Because of POSIX semantics, this fails for
> non-root users when the file is read-only or is an executable that
> is being run currently, or for all users (including root) when the
> filesystem is read-only.  THis results in a somewhat confusing 'Unknown
> error -1' message when trying to check such files.  Switch to using
> open_file_or_dir3() with O_RDONLY passed in the flags, as this avoids
> the limitations listed above, and we have no need to write to the files
> anyway (and thus shouldn't be opening them writable).
>
> Signed-off-by: Austin S. Hemmelgarn <ahferroin7@gmail.com>
> ---
> Build and runtime tested on x86-64 with glibc.
>
> I intend to take the time at some point this week to audit all users of
> open_file_or_dir() and similarly change any that don't need to write
> to what they're opening, possibly adding a helper function to do a
> read-only open.
>
>  cmds-fi-du.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/cmds-fi-du.c b/cmds-fi-du.c
> index 2ffd917..168fc72 100644
> --- a/cmds-fi-du.c
> +++ b/cmds-fi-du.c
> @@ -438,7 +438,7 @@ static int du_add_file(const char *filename, int dirfd,
>                 ret = sprintf(pathp, "/%s", filename);
>         pathp += ret;
>
> -       fd = open_file_or_dir(path, &dirstream);
> +       fd = open_file_or_dir3(path, &dirstream, O_RDONLY);
>         if (fd < 0) {
>                 ret = fd;
>                 goto out;
> --
> 2.7.4
>
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-- 
Martin Volf