On 11/07, Jakub Kicinski wrote:
> On Wed, 7 Nov 2018 14:43:55 -0800, Stanislav Fomichev wrote:
> > bpftool will use bpf_object__pin in the next commit to pin all programs
> > and maps from the file; in case of a partial failure, we need to get
> > back to the clean state (undo previous program/map pins).
> >
> > Signed-off-by: Stanislav Fomichev <s...@google.com>
> > ---
> > tools/lib/bpf/libbpf.c | 58 ++++++++++++++++++++++++++++++++++--------
> > 1 file changed, 48 insertions(+), 10 deletions(-)
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index d6e62e90e8d4..309abe7196f3 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -1803,14 +1803,17 @@ int bpf_object__pin(struct bpf_object *obj, const
> > char *path)
> >
> > len = snprintf(buf, PATH_MAX, "%s/%s", path,
> > bpf_map__name(map));
> > - if (len < 0)
> > - return -EINVAL;
> > - else if (len >= PATH_MAX)
> > - return -ENAMETOOLONG;
> > + if (len < 0) {
> > + err = -EINVAL;
> > + goto err_unpin_maps;
> > + } else if (len >= PATH_MAX) {
> > + err = -ENAMETOOLONG;
> > + goto err_unpin_maps;
> > + }
> >
> > err = bpf_map__pin(map, buf);
> > if (err)
> > - return err;
> > + goto err_unpin_maps;
> > }
> >
> > bpf_object__for_each_program(prog, obj) {
> > @@ -1819,17 +1822,52 @@ int bpf_object__pin(struct bpf_object *obj, const
> > char *path)
> >
> > len = snprintf(buf, PATH_MAX, "%s/%s", path,
> > prog->section_name);
> > - if (len < 0)
> > - return -EINVAL;
> > - else if (len >= PATH_MAX)
> > - return -ENAMETOOLONG;
> > + if (len < 0) {
> > + err = -EINVAL;
> > + goto err_unpin_programs;
> > + } else if (len >= PATH_MAX) {
> > + err = -ENAMETOOLONG;
> > + goto err_unpin_programs;
> > + }
> >
> > err = bpf_program__pin(prog, buf);
> > if (err)
> > - return err;
> > + goto err_unpin_programs;
> > }
> >
> > return 0;
> > +
> > +err_unpin_programs:
> > + bpf_object__for_each_program(prog, obj) {
> > + char buf[PATH_MAX];
> > + int len;
> > +
> > + len = snprintf(buf, PATH_MAX, "%s/%s", path,
> > + prog->section_name);
> > + if (len < 0)
> > + continue;
> > + else if (len >= PATH_MAX)
> > + continue;
> > +
> > + unlink(buf);
>
> I think that's no bueno, if pin failed because the file already exists
> you'll now remove that already existing file.
How about we check beforehand and bail early if we are going to
overwrite something?
> > + }
> > +
> > +err_unpin_maps:
> > + bpf_map__for_each(map, obj) {
> > + char buf[PATH_MAX];
> > + int len;
> > +
> > + len = snprintf(buf, PATH_MAX, "%s/%s", path,
> > + bpf_map__name(map));
> > + if (len < 0)
> > + continue;
> > + else if (len >= PATH_MAX)
> > + continue;
> > +
> > + unlink(buf);
> > + }
> > +
> > + return err;
> > }
> >
> > void bpf_object__close(struct bpf_object *obj)
>
