[PATCH v2 05/25] prefix_ref_iterator: don't trim too much
- From
Michael Haggerty <mhagger@alum.mit.edu>
- Date
- May 22, 2017, 14:17 UTC
- Message-ID
- <f2f73adae931939e4335967872a1182bd3c8562b.1495460199.git.mhagger@alum.mit.edu>
- In-Reply-To
- <cover.1495460199.git.mhagger@alum.mit.edu>
The `trim` parameter can be set independently of `prefix`. So if some caller were to set `trim` to be greater than `strlen(prefix)`, we could end up pointing the `refname` field of the iterator past the NUL of the actual reference name string.
That can't happen currently, because `trim` is always set either to zero or to `strlen(prefix)`. But even the latter could lead to confusion, if a refname is exactly equal to the prefix, because then we would set the outgoing `refname` to the empty string.
And we're about to decouple the `prefix` and `trim` arguments even more, so let's be cautious here. Report a bug if ever asked to trim a reference whose name is not longer than `trim`.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> --- refs/iterator.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/refs/iterator.c b/refs/iterator.c index bce1f192f7..4cf449ef66 100644 --- a/refs/iterator.c +++ b/refs/iterator.c @@ -292,7 +292,23 @@ static int prefix_ref_iterator_advance(struct ref_iterator *ref_iterator) if (!starts_with(iter->iter0->refname, iter->prefix)) continue; - iter->base.refname = iter->iter0->refname + iter->trim; + if (iter->trim) { + /* + * It is nonsense to trim off characters that + * you haven't already checked for via a + * prefix check, whether via this + * `prefix_ref_iterator` or upstream in + * `iter0`). So if there wouldn't be at least + * one character left in the refname after + * trimming, report it as a bug: + */ + if (strlen(iter->iter0->refname) <= iter->trim) + die("BUG: attempt to trim too many characters"); + iter->base.refname = iter->iter0->refname + iter->trim; + } else { + iter->base.refname = iter->iter0->refname; + } + iter->base.oid = iter->iter0->oid; iter->base.flags = iter->iter0->flags; return ITER_OK;
-- 2.11.0