[09/23] fsck: unify object-name code

Commit 90cf590f53 (fsck: optionally show more helpful info for broken
links, 2016-07-17) added a system for decorating objects with names. The
code is split across builtin/fsck.c (which gives the initial names) and
fsck.c (which adds to the names as it traverses the object graph). This
leads to some duplication, where both sites have near-identical
describe_object() functions (the difference being that the one in
builtin/fsck.c uses a circular array of buffers to allow multiple calls
in a single printf).

Let's provide a unified object_name API for fsck. That lets us drop the
duplication, as well as making the interface boundaries more clear
(which will let us refactor the implementation more in a future patch).

We'll leave describe_object() in builtin/fsck.c as a thin wrapper around
the new API, as it relies on a static global to make its many callers a
bit shorter.

We'll also convert the bare add_decoration() calls in builtin/fsck.c to
put_object_name(). This fixes two minor bugs:

  1. We leak many small strings. add_decoration() has a last-one-wins
     approach: it updates the decoration to the new string and returns
     the old one. But we ignore the return value, leaking the old
     string. This is quite common to trigger, since we look at reflogs:
     the tip of any ref will be described both by looking at the actual
     ref, as well as the latest reflog entry. So we'd always end up
     leaking one of those strings.

  2. The last-one-wins approach gives us lousy names. For instance, we
     first look at all of the refs, and then all of the reflogs. So
     rather than seeing "refs/heads/master", we're likely to overwrite
     it with "HEAD@{12345678}". We're generally better off using the
     first name we find.

     And indeed, the test in t1450 expects this ugly HEAD@{} name. After
     this patch, we've switched to using fsck_put_object_name()'s
     first-one-wins semantics, and we output the more human-friendly
     "refs/tags/julius" (and the test is updated accordingly).

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/fsck.c  | 50 ++++++++----------------------
 fsck.c          | 82 ++++++++++++++++++++++++++++++-------------------
 fsck.h          | 24 +++++++++++++++
 t/t1450-fsck.sh |  2 +-
 4 files changed, 89 insertions(+), 69 deletions(-)

Message ID	20191018045613.GI17879@sigill.intra.peff.net (mailing list archive)
State	New, archived
Headers	show Return-Path: <SRS0=pBOz=YL=vger.kernel.org=git-owner@kernel.org> Date: Fri, 18 Oct 2019 00:56:13 -0400 From: Jeff King <peff@peff.net> To: git@vger.kernel.org Subject: [PATCH 09/23] fsck: unify object-name code Message-ID: <20191018045613.GI17879@sigill.intra.peff.net> References: <20191018044103.GA17625@sigill.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20191018044103.GA17625@sigill.intra.peff.net> Sender: git-owner@vger.kernel.org Precedence: bulk
Series	parsing and fsck cleanups \| expand [0/23] parsing and fsck cleanups [01/23] parse_commit_buffer(): treat lookup_commit() failure as parse error [02/23] parse_commit_buffer(): treat lookup_tree() failure as parse error [03/23] parse_tag_buffer(): treat NULL tag pointer as parse error [04/23] remember commit/tag parse failures [05/23] fsck: stop checking commit->tree value [06/23] fsck: stop checking commit->parent counts [07/23] fsck: stop checking tag->tagged [08/23] fsck: require an actual buffer for non-blobs [09/23] fsck: unify object-name code [10/23] fsck_describe_object(): build on our get_object_name() primitive [11/23] fsck: use oids rather than objects for object_name API [12/23] fsck: don't require object structs for display functions [13/23] fsck: only provide oid/type in fsck_error callback [14/23] fsck: only require an oid for skiplist functions [15/23] fsck: don't require an object struct for report() [16/23] fsck: accept an oid instead of a "struct blob" for fsck_blob() [17/23] fsck: drop blob struct from fsck_finish() [18/23] fsck: don't require an object struct for fsck_ident() [19/23] fsck: don't require an object struct in verify_headers() [20/23] fsck: rename vague "oid" local variables [21/23] fsck: accept an oid instead of a "struct tag" for fsck_tag() [22/23] fsck: accept an oid instead of a "struct commit" for fsck_commit() [23/23] fsck: accept an oid instead of a "struct tree" for fsck_tree()

[09/23] fsck: unify object-name code

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