| Message ID | 20181204132716.19208-3-avarab@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/3] sha1-file: test the error behavior of alt_odb_usable() | expand |
Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes: > Since 26125f6b9b ("detect broken alternates.", 2006-02-22) we've > emitted an error if the alternates directory doesn't exist, but not > for the common misstep of adding a path to another git repository as > an alternate, as opposed to its "objects" directory. > > Let's check for this, i.e. whether X/objects or X/.git/objects exists > if the user supplies X and print an error (which as a commit leading > up to this one shows doesn't change the exit code, just "warns"). I agree that "Let's check for this" is a good idea, but do not necessarily agree with "i.e.". Don't we have a helper that takes the path to an existing directory and answers "Yup, it does look like a Git repository"? Using that is a lot more in line with what you claimed to do in the title for this patch. I haven't read 3/3 yet, but as I said, I suspect it is reasonable to DWIM and use the object store associated with the directory we found to be a repository.
On Wed, Dec 05, 2018 at 12:35:08PM +0900, Junio C Hamano wrote: > Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes: > > > Since 26125f6b9b ("detect broken alternates.", 2006-02-22) we've > > emitted an error if the alternates directory doesn't exist, but not > > for the common misstep of adding a path to another git repository as > > an alternate, as opposed to its "objects" directory. > > > > Let's check for this, i.e. whether X/objects or X/.git/objects exists > > if the user supplies X and print an error (which as a commit leading > > up to this one shows doesn't change the exit code, just "warns"). > > I agree that "Let's check for this" is a good idea, but do not > necessarily agree with "i.e.". Don't we have a helper that takes > the path to an existing directory and answers "Yup, it does look > like a Git repository"? Using that is a lot more in line with what > you claimed to do in the title for this patch. Hmm. Yeah, one case this does not handle is when ".git" is a git-file pointing elsewhere, which should trigger the condition, too. I think we can afford to be a bit loose with this check if it's just generating a warning for a case that would otherwise not work (and the worst is that we might fail to correctly diagnose a broken setup). But that I think points to another issue: this kicks in even if the path is otherwise usable. So if had, say, a git repository whose worktree was full of objects and packfiles, it currently works for me to point to that as an alternate. But after this patch, we'd complain "wait, this looks like a git repo!". So I'd much rather see the logic check first for something usable, and only when we fail to find it, start doing a loose diagnosis. Something like: if !is_directory($path) complain that it does not exist, as now else if !is_directory($path/pack) /* * it doesn't look like an object directory; technically it * _could_ just have loose objects, and maybe we ought to check * for directories matching [0-9a-f]{2}, though it seems * somewhat unlikely these days. */ if is_directory($path/objects) || exists($path/.git) complain that it looks like a git dir else complain that it doesn't look like an object dir fi Hmm. I managed to write a gross mix of C and shell for my pseudocode, but hopefully you can read it. ;) > I haven't read 3/3 yet, but as I said, I suspect it is reasonable to > DWIM and use the object store associated with the directory we found > to be a repository. Yeah, I'm tempted by that, too, though I worry about corner cases. How much effort should we put into discovery? I guess the rules from enter_repo() would make sense, though the logic in that function would need some refactoring to be reused elsewhere. -Peff
diff --git a/sha1-file.c b/sha1-file.c index 5bd11c85bc..f142f81658 100644 --- a/sha1-file.c +++ b/sha1-file.c @@ -376,12 +376,20 @@ static int alt_odb_usable(struct raw_object_store *o, { struct alternate_object_database *alt; - /* Detect cases where alternate disappeared */ if (!is_directory(path->buf)) { + /* Detect cases where alternate disappeared */ error(_("object directory %s does not exist; " "check .git/objects/info/alternates"), path->buf); return 0; + } else if (is_directory(mkpath("%s/objects", path->buf)) || + is_directory(mkpath("%s/.git/objects", path->buf))) { + /* Detect cases where alternate is a git repository */ + error(_("object directory %s looks like a git repository; " + "alternates must point to the 'objects' directory. " + "check .git/objects/info/alternates"), + path->buf); + return 0; } /* diff --git a/t/t5613-info-alternate.sh b/t/t5613-info-alternate.sh index d2964c57b7..b959e21421 100755 --- a/t/t5613-info-alternate.sh +++ b/t/t5613-info-alternate.sh @@ -143,4 +143,18 @@ test_expect_success 'print "error" on non-existing alternate' ' test_i18ngrep "does not exist; check" stderr ' +test_expect_success 'print "error" on alternate that looks like a git repository' ' + git init --bare J && + git init --bare K && + + # H is bare, G is not + echo ../../H >J/objects/info/alternates && + echo ../../G >K/objects/info/alternates && + + git -C J fsck 2>stderr && + test_i18ngrep "looks like a git repository; alternates must" stderr && + git -C K fsck 2>stderr && + test_i18ngrep "looks like a git repository; alternates must" stderr +' + test_done
Since 26125f6b9b ("detect broken alternates.", 2006-02-22) we've emitted an error if the alternates directory doesn't exist, but not for the common misstep of adding a path to another git repository as an alternate, as opposed to its "objects" directory. Let's check for this, i.e. whether X/objects or X/.git/objects exists if the user supplies X and print an error (which as a commit leading up to this one shows doesn't change the exit code, just "warns"). This check is intentionally not implemented by e.g. requiring that any of X/?? exists or X/info or X/pack exists. It's a legitimate use-case to point to an existing alternate that hasn't been populated yet, but pointing to one where an "X/objects" or "X/.git/objects" directory exists is definitely a mistake we should warn the user about. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> --- sha1-file.c | 10 +++++++++- t/t5613-info-alternate.sh | 14 ++++++++++++++ 2 files changed, 23 insertions(+), 1 deletion(-)