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Author SHA1 Message Date
Taylor Blau b3970c702c ls-refs.c: traverse prefixes of disjoint "ref-prefix" sets
ls-refs performs a single revision walk over the whole ref namespace,
and sends ones that match with one of the given ref prefixes down to the
user.

This can be expensive if there are many refs overall, but the portion of
them covered by the given prefixes is small by comparison.

To attempt to reduce the difference between the number of refs
traversed, and the number of refs sent, only traverse references which
are in the longest common prefix of the given prefixes. This is very
reminiscent of the approach taken in b31e2680c4 (ref-filter.c: find
disjoint pattern prefixes, 2019-06-26) which does an analogous thing for
multi-patterned 'git for-each-ref' invocations.

The callback 'send_ref' is resilient to ignore extra patterns by
discarding any arguments which do not begin with at least one of the
specified prefixes.

Similarly, the code introduced in b31e2680c4 is resilient to stop early
at metacharacters, but we only pass strict prefixes here. At worst we
would return too many results, but the double checking done by send_ref
will throw away anything that doesn't start with something in the prefix
list.

Finally, if no prefixes were provided, then implicitly add the empty
string (which will match all references) since this matches the existing
behavior (see the "no restrictions" comment in "ls-refs.c:ref_match()").

Original-patch-by: Jacob Vosmaer <jacob@gitlab.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-22 18:57:27 -08:00
Jacob Vosmaer 83befd3724 ls-refs.c: initialize 'prefixes' before using it
Correctly initialize the "prefixes" strvec using strvec_init() instead
of simply zeroing it via the earlier memset().

There's no way to trigger a crash, since the first 'ref-prefix' command
will initialize the strvec via the 'ALLOC_GROW' in 'strvec_push_nodup()'
(the alloc and nr variables are already zero'd, so the call to
ALLOC_GROW is valid).

If no "ref-prefix" command was given, then the call to
'ls-refs.c:ref_match()' will abort early after it reads the zero in
'prefixes->nr'. Likewise, strvec_clear() will only call free() on the
array, which is NULL, so we're safe there, too.

But, all of this is dangerous and requires more reasoning than it would
if we simply called 'strvec_init()', so do that.

Signed-off-by: Jacob Vosmaer <jacob@gitlab.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-22 18:57:27 -08:00
Jeff King d70a9eb611 strvec: rename struct fields
The "argc" and "argv" names made sense when the struct was argv_array,
but now they're just confusing. Let's rename them to "nr" (which we use
for counts elsewhere) and "v" (which is rather terse, but reads well
when combined with typical variable names like "args.v").

Note that we have to update all of the callers immediately. Playing
tricks with the preprocessor is hard here, because we wouldn't want to
rewrite unrelated tokens.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-30 19:18:06 -07:00
Jeff King ef8d7ac42a strvec: convert more callers away from argv_array name
We eventually want to drop the argv_array name and just use strvec
consistently. There's no particular reason we have to do it all at once,
or care about interactions between converted and unconverted bits.
Because of our preprocessor compat layer, the names are interchangeable
to the compiler (so even a definition and declaration using different
names is OK).

This patch converts remaining files from the first half of the alphabet,
to keep the diff to a manageable size.

The conversion was done purely mechanically with:

  git ls-files '*.c' '*.h' |
  xargs perl -i -pe '
    s/ARGV_ARRAY/STRVEC/g;
    s/argv_array/strvec/g;
  '

and then selectively staging files with "git add '[abcdefghjkl]*'".
We'll deal with any indentation/style fallouts separately.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-28 15:02:18 -07:00
Jeff King dbbcd44fb4 strvec: rename files from argv-array to strvec
This requires updating #include lines across the code-base, but that's
all fairly mechanical, and was done with:

  git ls-files '*.c' '*.h' |
  xargs perl -i -pe 's/argv-array.h/strvec.h/'

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-28 15:02:17 -07:00
Jeff King 4845b77245 upload-pack: handle unexpected delim packets
When processing the arguments list for a v2 ls-refs or fetch command, we
loop like this:

  while (packet_reader_read(request) != PACKET_READ_FLUSH) {
          const char *arg = request->line;
	  ...handle arg...
  }

to read and handle packets until we see a flush. The hidden assumption
here is that anything except PACKET_READ_FLUSH will give us valid packet
data to read. But that's not true; PACKET_READ_DELIM or PACKET_READ_EOF
will leave packet->line as NULL, and we'll segfault trying to look at
it.

Instead, we should follow the more careful model demonstrated on the
client side (e.g., in process_capabilities_v2): keep looping as long
as we get normal packets, and then make sure that we broke out of the
loop due to a real flush. That fixes the segfault and correctly
diagnoses any unexpected input from the client.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-03-27 12:18:48 -07:00
Jeff King 533e088250 upload-pack: strip namespace from symref data
Since 7171d8c15f (upload-pack: send symbolic ref information as
capability, 2013-09-17), we've sent cloning and fetching clients special
information about which branch HEAD is pointing to, so that they don't
have to guess based on matching up commit ids.

However, this feature has never worked properly with the GIT_NAMESPACE
feature.  Because upload-pack uses head_ref_namespaced(find_symref), we
do find and report on refs/namespaces/foo/HEAD instead of the actual
HEAD of the repo. This makes sense, since the branch pointed to by the
top-level HEAD may not be advertised at all. But we do two things wrong:

  1. We report the full name refs/namespaces/foo/HEAD, instead of just
     HEAD. Meaning no client is going to bother doing anything with that
     symref, since we're not otherwise advertising it.

  2. We report the symref destination using its full name (e.g.,
     refs/namespaces/foo/refs/heads/master). That's similarly useless to
     the client, who only saw "refs/heads/master" in the advertisement.

We should be stripping the namespace prefix off of both places (which
this patch fixes).

Likely nobody noticed because we tend to do the right thing anyway. Bug
(1) means that we said nothing about HEAD (just refs/namespace/foo/HEAD).
And so the client half of the code, from a45b5f0552 (connect: annotate
refs with their symref information in get_remote_head(), 2013-09-17),
does not annotate HEAD, and we use the fallback in guess_remote_head(),
matching refs by object id. Which is usually right. It only falls down
in ambiguous cases, like the one laid out in the included test.

This also means that we don't have to worry about breaking anybody who
was putting pre-stripped names into their namespace symrefs when we fix
bug (2). Because of bug (1), nobody would have been using the symref we
advertised in the first place (not to mention that those symrefs would
have appeared broken for any non-namespaced access).

Note that we have separate fixes here for the v0 and v2 protocols. The
symref advertisement moved in v2 to be a part of the ls-refs command.
This actually gets part (1) right, since the symref annotation
piggy-backs on the existing ref advertisement, which is properly
stripped. But it still needs a fix for part (2). The included tests
cover both protocols.

Reported-by: Bryan Turner <bturner@atlassian.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-05-28 10:02:00 -07:00
Junio C Hamano 9c96ab9872 Merge branch 'jt/namespaced-ls-refs-fix'
Fix namespace support in protocol v2.

* jt/namespaced-ls-refs-fix:
  ls-refs: filter refs using namespace-stripped name
2019-02-05 14:26:15 -08:00
Jonathan Tan e2f41a0a5a ls-refs: filter refs using namespace-stripped name
If a user fetches refs/heads/master from a repo with namespace "ns", the
remote is expected to (1) not send the real refs/heads/master, and (2)
send refs/namespaces/ns/refs/heads/master with the name
refs/heads/master. (1) indeed happens now, but not (2) - Git only sends
refs that have the user-given prefix, but it checks them against the
full name of the ref (the one starting with refs/namespaces), and not
the namespace-stripped one.

This is demonstrated by the patch in the test. Currently, it results in
"fatal: couldn't find remote ref refs/heads/master" despite both
unnamespaced and namespaced master being present. With the code change,
it produces the expected result.

Check the ref prefixes against the namespace-stripped name.

This bug was discovered through applying patches [1] that override
protocol.version to 2 in repositories when running tests, allowing us to
notice differences in behavior across different protocol versions.

[1] https://public-inbox.org/git/cover.1547677183.git.jonathantanmy@google.com/

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-01-18 12:48:41 -08:00
Jeff King e20b4192a3 upload-pack: support hidden refs with protocol v2
In the v2 protocol, upload-pack's advertisement has been moved to the
"ls-refs" command. That command does not respect hidden-ref config (like
transfer.hiderefs) at all, and advertises everything.

While there are some features that are not supported in v2 (e.g., v2
always allows fetching any sha1 without respect to advertisements), the
lack of this feature is not documented and is likely just a bug. Let's
make it work, as otherwise upgrading a server to a v2-capable git will
start exposing these refs that the repository admin has asked to remain
hidden.

Note that we assume we're operating on behalf of a fetch here, since
that's the only thing implemented in v2 at this point. See the in-code
comment. We'll have to figure out how this works when the v2 push
protocol is designed (both here in ls-refs, but also rejecting updates
to hidden refs).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-01-10 11:15:37 -08:00
Brandon Williams 72d0ea0056 ls-refs: introduce ls-refs server command
Introduce the ls-refs server command.  In protocol v2, the ls-refs
command is used to request the ref advertisement from the server.  Since
it is a command which can be requested (as opposed to mandatory in v1),
a client can sent a number of parameters in its request to limit the ref
advertisement based on provided ref-prefixes.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-15 12:01:08 -07:00