From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2A59C7EE23 for ; Thu, 1 Jun 2023 17:43:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233049AbjFARn6 (ORCPT ); Thu, 1 Jun 2023 13:43:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233066AbjFARnz (ORCPT ); Thu, 1 Jun 2023 13:43:55 -0400 Received: from cloud.peff.net (cloud.peff.net [104.130.231.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 33523197 for ; Thu, 1 Jun 2023 10:43:53 -0700 (PDT) Received: (qmail 5954 invoked by uid 109); 1 Jun 2023 17:43:52 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with ESMTP; Thu, 01 Jun 2023 17:43:52 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 25318 invoked by uid 111); 1 Jun 2023 17:43:52 -0000 Received: from coredump.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.2) by peff.net (qpsmtpd/0.94) with (TLS_AES_256_GCM_SHA384 encrypted) ESMTPS; Thu, 01 Jun 2023 13:43:52 -0400 Authentication-Results: peff.net; auth=none Date: Thu, 1 Jun 2023 13:43:51 -0400 From: Jeff King To: Jim Pryor Cc: Junio C Hamano , git@vger.kernel.org Subject: [PATCH 3/3] diff: detect pathspec magic not supported by --follow Message-ID: <20230601174351.GC4165297@coredump.intra.peff.net> References: <20230601173724.GA4158369@coredump.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230601173724.GA4158369@coredump.intra.peff.net> Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org The --follow code doesn't handle most forms of pathspec magic. We check that no unexpected ones have made it to try_to_follow_renames() with a runtime GUARD_PATHSPEC() check, which gives behavior like this: $ git log --follow ':(icase)makefile' >/dev/null BUG: tree-diff.c:596: unsupported magic 10 Aborted The same is true of ":(glob)", ":(attr)", and so on. It's good that we notice the problem rather than continuing and producing a wrong answer. But there are two non-ideal things: 1. The idea of GUARD_PATHSPEC() is to catch programming errors where low-level code gets unexpected pathspecs. We'd usually try to catch unsupported pathspecs by passing a magic_mask to parse_pathspec(), which would give the user a much better message like: pathspec magic not supported by this command: 'icase' That doesn't happen here because git-log usually _does_ support all types of pathspec magic, and so it passes "0" for the mask (this call actually happens in setup_revisions()). It needs to distinguish the normal case from the "--follow" one but currently doesn't. 2. In addition to --follow, we have the log.follow config option. When that is set, we try to turn on --follow mode only when there is a single pathspec (since --follow doesn't handle anything else). But really, that ought to be expanded to "use --follow when the pathspec supports it". Otherwise, we'd complain any time you use an exotic pathspec: $ git config log.follow true $ git log ':(icase)makefile' >/dev/null BUG: tree-diff.c:596: unsupported magic 10 Aborted We should instead just avoid enabling follow mode if it's not supported by this particular invocation. This patch expands our diff_check_follow_pathspec() function to cover pathspec magic, solving both problems. A few final notes: - we could also solve (1) by passing the appropriate mask to parse_pathspec(). But that's not great for two reasons. One is that the error message is less precise. It says "magic not supported by this command", but really it is not the command, but rather the --follow option which is the problem. The second is that it always calls die(). But for our log.follow code, we want to speculatively ask "is this pathspec OK?" and just get a boolean result. - This is obviously the right thing to do for ':(icase)' and most other magic options. But ':(glob)' is a bit odd here. The --follow code doesn't support wildcards, but we allow them anyway. From try_to_follow_renames(): #if 0 /* * We should reject wildcards as well. Unfortunately we * haven't got a reliable way to detect that 'foo\*bar' in * fact has no wildcards. nowildcard_len is merely a hint for * optimization. Let it slip for now until wildmatch is taught * about dry-run mode and returns wildcard info. */ if (opt->pathspec.has_wildcard) BUG("wildcards are not supported"); #endif So something like "git log --follow 'Make*'" is already doing the wrong thing, since ":(glob)" behavior is already the default (it is used only to countermand an earlier --noglob-pathspecs). So we _could_ loosen the guard to allow :(glob), since it just behaves the same as pathspecs do by default. But it seems like a backwards step to do so. It already doesn't work (it hits the BUG() case currently), and given that the user took an explicit step to say "this pathspec should glob", it is reasonable for us to say "no, --follow does not support globbing" (or in the case of log.follow, avoid turning on follow mode). Which is what happens after this patch. - The set of allowed pathspec magic is obviously the same as in GUARD_PATHSPEC(). We could perhaps factor these out to avoid repetition. The point of having separate masks and GUARD calls is that we don't necessarily know which parsed pathspecs will be used where. But in this case, the two are heavily correlated. Still, there may be some value in keeping them separate; it would make anyone think twice about adding new magic to the list in diff_check_follow_pathspec(). They'd need to touch try_to_follow_renames() as well, which is the code that would actually need to be updated to handle more exotic pathspecs. - The documentation for log.follow says that it enables --follow "...when a single is given". We could possibly expand that to say "with no unsupported pathspec magic", but that raises the question of documenting which magic is supported. I think the existing wording of "single " sufficiently encompasses the idea (the forbidden magic is stuff that might match multiple entries), and the spirit remains the same. Reported-by: Jim Pryor Signed-off-by: Jeff King --- diff.c | 15 +++++++++++++++ t/t4202-log.sh | 15 +++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/diff.c b/diff.c index 9f548f3471..8ca16fefe7 100644 --- a/diff.c +++ b/diff.c @@ -4753,11 +4753,26 @@ unsigned diff_filter_bit(char status) int diff_check_follow_pathspec(struct pathspec *ps, int die_on_error) { + unsigned forbidden_magic; + if (ps->nr != 1) { if (die_on_error) die(_("--follow requires exactly one pathspec")); return 0; } + + forbidden_magic = ps->items[0].magic & ~(PATHSPEC_FROMTOP | + PATHSPEC_LITERAL); + if (forbidden_magic) { + if (die_on_error) { + struct strbuf sb = STRBUF_INIT; + pathspec_magic_names(forbidden_magic, &sb); + die(_("pathspec magic not supported by --follow: %s"), + sb.buf); + } + return 0; + } + return 1; } diff --git a/t/t4202-log.sh b/t/t4202-log.sh index ae73aef922..5b54d7928e 100755 --- a/t/t4202-log.sh +++ b/t/t4202-log.sh @@ -187,6 +187,21 @@ test_expect_success 'git config log.follow does not die with no paths' ' git log -- ' +test_expect_success 'git log --follow rejects unsupported pathspec magic' ' + test_must_fail git log --follow ":(top,glob,icase)ichi" 2>stderr && + # check full error message; we want to be sure we mention both + # of the rejected types (glob,icase), but not the allowed one (top) + echo "fatal: pathspec magic not supported by --follow: ${SQ}glob${SQ}, ${SQ}icase${SQ}" >expect && + test_cmp expect stderr +' + +test_expect_success 'log.follow disabled with unsupported pathspec magic' ' + test_config log.follow true && + git log --format=%s ":(glob,icase)ichi" >actual && + echo third >expect && + test_cmp expect actual +' + test_expect_success 'git config log.follow is overridden by --no-follow' ' test_config log.follow true && git log --no-follow --pretty="format:%s" ichi >actual && -- 2.41.0.346.g8d12207a4f