When pack-objects is given --include-tag, it peels each tag
ref down to a non-tag object, and if that non-tag object is
going to be packed, we include the tag, too. But what
happens if we have a chain of tags (e.g., tag "A" points to
tag "B", which points to commit "C")?
We'll peel down to "C" and realize that we want to include
tag "A", but we do not ever consider tag "B", leading to a
broken pack (assuming "B" was not otherwise selected).
Instead, we have to walk the whole chain, adding any tags we
find to the pack.
Interestingly, it doesn't seem possible to trigger this
problem with "git fetch", but you can with "git clone
--single-branch". The reason is that we generate the correct
pack when the client explicitly asks for "A" (because we do
a real reachability analysis there), and "fetch" is more
willing to do so. There are basically two cases:
1. If "C" is already a ref tip, then the client can deduce
that it needs "A" itself (via find_non_local_tags), and
will ask for it explicitly rather than relying on the
include-tag capability. Everything works.
2. If "C" is not already a ref tip, then we hope for
include-tag to send us the correct tag. But it doesn't;
it generates a broken pack. However, the next step is
to do a follow-up run of find_non_local_tags(),
followed by fetch_refs() to backfill any tags we
learned about.
In the normal case, fetch_refs() calls quickfetch(),
which does a connectivity check and sees we have no
new objects to fetch. We just write the refs.
But for the broken-pack case, the connectivity check
fails, and quickfetch will follow-up with the remote,
asking explicitly for each of the ref tips. This picks
up the missing object in a new pack.
For a regular "git clone", we are similarly OK, because we
explicitly request all of the tag refs, and get a correct
pack. But with "--single-branch", we kick in tag
auto-following via "include-tag", but do _not_ do a
follow-up backfill. We just take whatever the server sent us
via include-tag and write out tag refs for any tag objects
we were sent. So prior to c6807a4 (clone: open a shortcut
for connectivity check, 2013-05-26), we actually claimed the
clone was a success, but the result was silently
corrupted! Since c6807a4, index-pack's connectivity
check catches this case, and we correctly complain.
The included test directly checks that pack-objects does not
generate a broken pack, but also confirms that "clone
--single-branch" does not hit the bug.
Note that tag chains introduce another interesting question:
if we are packing the tag "B" but not the commit "C", should
"A" be included?
Both before and after this patch, we do not include "A",
because the initial peel_ref() check only knows about the
bottom-most level, "C". To realize that "B" is involved at
all, we would have to switch to an incremental peel, in
which we examine each tagged object, asking if it is being
packed (and including the outer tag if so).
But that runs contrary to the optimizations in peel_ref(),
which avoid accessing the objects at all, in favor of using
the value we pull from packed-refs. It's OK to walk the
whole chain once we know we're going to include the tag (we
have to access it anyway, so the effort is proportional to
the pack we're generating). But for the initial selection,
we have to look at every ref. If we're only packing a few
objects, we'd still have to parse every single referenced
tag object just to confirm that it isn't part of a tag
chain.
This could be addressed if packed-refs stored the complete
tag chain for each peeled ref (in most cases, this would be
the same cost as now, as each "chain" is only a single
link). But given the size of that project, it's out of scope
for this fix (and probably nobody cares enough anyway, as
it's such an obscure situation). This commit limits itself
to just avoiding the creation of a broken pack.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We generate a series of packfiles test-1-$pack,
test-2-$pack, with different properties and then examine
them. However we always store the packname generated by
pack-objects in the variable packname_1. This probably was
meant to be packname_2 in the second test, but it turns out
that it doesn't matter: once we are done with the first
pack, we can just keep using the same $packname variable.
So let's drop the confusing "_1" parameter. At the same
time, let's give test-1 and test-2 more descriptive names,
which can help keep them straight (note that we _could_
likewise overwrite the packfiles in each test, but by using
separate filenames, we are sure that test 2 does not
accidentally use the packfile from test 1).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This test unpacks objects into a separate repository, and
accesses it by setting GIT_DIR in a subshell. We can do the
same thing these days by using "git init <repo>" and "git
-C". In most cases this is shorter, though when there are
multiple commands, we may end up repeating the "-C".
However, this repetition can actually be a good thing. This
patch also fixes a bug introduced by 512477b (tests: use
"env" to run commands with temporary env-var settings,
2014-03-18). That commit essentially converted:
(GIT_DIR=...; export GIT_DIR
cmd1 &&
cmd2)
into:
(GIT_DIR=... cmd1 &&
cmd2)
which obviously loses the GIT_DIR setting for cmd2 (we never
noticed the bug because it simply runs "cmd2" in the parent
repo, which means we were simply failing to test anything
interesting). By using "git -C" rather than a subshell, it
becomes quite obvious where each command is supposed to be
running.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
For each test we do a dry-run of unpack-objects, followed by
a real run, followed by confirming that it contained the
objects we expected. The dry-run is telling us nothing, as
any errors it encounters would be found in the real run.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We usually try to avoid doing any significant actions
outside of test blocks. Although "rm -rf" is unlikely to
either fail or to generate output, moving these to the
point of use makes it more clear that they are part of the
overall setup of "clone.git".
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The Git CodingGuidelines prefer the $(...) construct for command
substitution instead of using the backquotes `...`.
The backquoted form is the traditional method for command
substitution, and is supported by POSIX. However, all but the
simplest uses become complicated quickly. In particular, embedded
command substitutions and/or the use of double quotes require
careful escaping with the backslash character.
The patch was generated by:
for _f in $(find . -name "*.sh")
do
perl -i -pe 'BEGIN{undef $/;} s/`(.+?)`/\$(\1)/smg' "${_f}"
done
and then carefully proof-read.
Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Ordinarily, we would say "VAR=VAL command" to execute a tested
command with environment variable(s) set only for that command.
This however does not work if 'command' is a shell function (most
notably 'test_must_fail'); the result of the assignment is retained
and affects later commands.
To avoid this, we used to assign and export environment variables
and run such a test in a subshell, like so:
(
VAR=VAL && export VAR &&
test_must_fail git command to be tested
)
But with "env" utility, we should be able to say:
test_must_fail env VAR=VAL git command to be tested
which is much shorter and easier to read.
Signed-off-by: David Tran <unsignedzero@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As a general principle, we should not use "git diff" to validate the
results of what git command that is being tested has done. We would not
know if we are testing the command in question, or locating a bug in the
cute hack of "git diff --no-index".
Rather use test_cmp for that purpose.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The new option "--include-tag" allows the caller to request that
any annotated tag be included into the packfile if the object the tag
references was also included as part of the packfile.
This option can be useful on the server side of a native git transport,
where the server knows what commits it is including into a packfile to
update the client. If new annotated tags have been introduced then we
can also include them in the packfile, saving the client from needing
to request them through a second connection.
This change only introduces the backend option and provides a test.
Protocol extensions to make this useful in fetch-pack/upload-pack
are still necessary to activate the logic during transport.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
