When fetching with the v0 protocol over ssh (or a local upload-pack with
pipes), the server closes the connection as soon as it is finished
sending the pack. So even though the client may still be operating on
the data via index-pack (e.g., resolving deltas, checking connectivity,
etc), the server has released all resources.
With the v2 protocol, however, the server considers the ssh session only
as a transport, with individual requests coming over it. After sending
the pack, it goes back to its main loop, waiting for another request to
come from the client. As a result, the ssh session hangs around until
the client process ends, which may be much later (because resolving
deltas, etc, may consume a lot of CPU).
This is bad for two reasons:
- it's consuming resources on the server to leave open a connection
that won't see any more use
- if something bad happens to the ssh connection in the meantime (say,
it gets killed by the network because it's idle, as happened in a
real-world report), then ssh will exit non-zero, and we'll propagate
the error up the stack.
The server is correct here not to hang up after serving the pack. The v2
protocol's design is meant to allow multiple requests like this, and
hanging up would be the wrong thing for a hypothetical client which was
planning to make more requests (though in practice, the git.git client
never would, and I doubt any other implementations would either).
The right thing is instead for the client to signal to the server that
it's not interested in making more requests. We can do that by closing
the pipe descriptor we use to write to ssh. This will propagate to the
server upload-pack as an EOF when it tries to read the next request (and
then it will close its half, and the whole connection will go away).
It's important to do this "half duplex" shutdown, because we have to do
it _before_ we actually receive the pack. This is an artifact of the way
fetch-pack and index-pack (or unpack-objects) interact. We hand the
connection off to index-pack (really, a sideband demuxer which feeds
it), and then wait until it returns. And it doesn't do that until it has
resolved all of the deltas in the pack, even though it was done reading
from the server long before.
So just closing the connection fully after index-pack returns would be
too late; we'd have held it open much longer than was necessary. And
teaching index-pack to close the connection is awkward. It's not even
seeing the whole conversation (the sideband demuxer is, but it doesn't
actually know what's in the packets, or when the end comes).
Note that this close() is happening deep within the transport code. It's
possible that a caller would want to perform other operations over the
same ssh transport after receiving the pack. But as of the current code,
none of the callers do, and there haven't been discussions of any plans
to change this. If we need to support that later, we can probably do so
by passing down a flag for "you're the last request on the transport;
it's OK to close" instead of the code just assuming that's true.
The description above all discusses v2 ssh, so it's worth thinking about
how this interacts with other protocols:
- in v0 protocols, we could do the same half-duplex shutdown (it just
goes into the v0 do_fetch_pack() instead). This does work, but since
it doesn't have the same persistence problem in the first place,
there's little reason to change it at this point.
- local fetches against git-upload-pack on the same machine will
behave the same as ssh (they are talking over two pipes, and see EOF
on their input pipe)
- fetches against git-daemon will run this same code, and close one of
the descriptors. In practice, this won't do anything, since there
our two descriptors are dups of each other, and not part of a
half-duplex pair. The right thing would probably be to call
shutdown(SHUT_WR) on it. I didn't bother with that here. It doesn't
face the same error-code problem (since it's just a TCP connection),
so it's really only an optimization problem. And git:// is not that
widely used these days, and has less impact on server resources than
an ssh termination.
- v2 http doesn't suffer from this problem in the first place, as our
pipes terminate at a local git-remote-https, which is passing data
along as individual requests via curl. Probably curl is keeping the
TCP/TLS connection open for more requests, and we might be able to
tell it manually "hey, we are done making requests now". But I think
that's much less important. It again doesn't suffer from the
error-code problem, and HTTP keepalive is pretty well understood
(importantly, the timeouts can be set low, because clients like curl
know how to reconnect for subsequent requests if necessary). So it's
probably not worth figuring out how to tell curl that we're done
(though if we do, this patch is probably the first step anyway;
fetch-pack closes the pipe back to remote-https, which would be the
signal that it should tell curl we're done).
The code is pretty straightforward. We close the pipe at the right
moment, and set it to -1 to mark it as invalid. I modified the later
cleanup code to avoid calling close(-1). That's not strictly necessary,
since close(-1) is a noop, but hopefully makes things a bit more obvious
to a reader.
I suspect that trying to call more transport functions after the close()
(e.g., calling transport_fetch_refs() again) would fail, as it's not
smart enough to realize we need to re-open the ssh connection. But
that's already true when v0 is in use. And no current callers want to do
that (and again, the solution is probably a flag in the transport code
to keep things open, which can be added later).
There's no test here, as the situation it covers is inherently racy (the
question is when upload-pack exits, compared to when index-pack finishes
resolving deltas and exits). The rather gross shell snippet below does
recreate the problematic situation; when run on a sufficiently-large
repository (git.git works fine), it kills an "idle" upload-pack while
the client is resolving deltas, leading to a failed clone.
(
git clone --no-local --progress . foo.git 2>&1
echo >&2 "clone exit code=$?"
) |
tr '\r' '\n' |
while read line
do
case "$done,$line" in
,Resolving*)
echo "hit resolving deltas; killing upload-pack"
killall -9 git-upload-pack
done=t
;;
esac
done
Reported-by: Greg Pflaum <greg.pflaum@pnp-hcl.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently, the packfile negotiation step within a Git fetch cannot be
done independent of sending the packfile, even though there is at least
one application wherein this is useful. Therefore, make it possible for
this negotiation step to be done independently. A subsequent commit will
use this for one such application - push negotiation.
This feature is for protocol v2 only. (An implementation for protocol v0
would require a separate implementation in the fetch, transport, and
transport helper code.)
In the protocol, the main hindrance towards independent negotiation is
that the server can unilaterally decide to send the packfile. This is
solved by a "wait-for-done" argument: the server will then wait for the
client to say "done". In practice, the client will never say it; instead
it will cease requests once it is satisfied.
In the client, the main change lies in the transport and transport
helper code. fetch_refs_via_pack() performs everything needed - protocol
version and capability checks, and the negotiation itself.
There are 2 code paths that do not go through fetch_refs_via_pack() that
needed to be individually excluded: the bundle transport (excluded
through requiring smart_options, which the bundle transport doesn't
support) and transport helpers that do not support takeover. If or when
we support independent negotiation for protocol v0, we will need to
modify these 2 code paths to support it. But for now, report failure if
independent negotiation is requested in these cases.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A subsequent commit will need this functionality independent of the rest
of send_fetch_request(), so put this into its own function.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A subsequent commit will need part, but not all, of the functionality in
add_haves(), so move some of its functionality to its sole caller
send_fetch_request().
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A subsequent commit will need part, but not all, of the functionality in
process_acks(), so move some of its functionality to its sole caller
do_fetch_pack_v2(). As a side effect, the resulting code is also
shorter.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In send_fetch_request(), "object-format" is written directly to the file
descriptor, as opposed to the other arguments, which are buffered.
Buffer "object-format" as well. "object-format" must be buffered; in
particular, it must appear after "command=fetch" in the request.
This divergence was introduced in 4b831208bb ("fetch-pack: parse and
advertise the object-format capability", 2020-05-27), perhaps as an
oversight (the surrounding code at the point of this commit has already
been using a request buffer.)
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git clone --reject-shallow" option fails the clone as soon as we
notice that we are cloning from a shallow repository.
* ll/clone-reject-shallow:
builtin/clone.c: add --reject-shallow option
Fsck API clean-up.
* ab/fsck-api-cleanup:
fetch-pack: use new fsck API to printing dangling submodules
fetch-pack: use file-scope static struct for fsck_options
fetch-pack: don't needlessly copy fsck_options
fsck.c: move gitmodules_{found,done} into fsck_options
fsck.c: add an fsck_set_msg_type() API that takes enums
fsck.c: pass along the fsck_msg_id in the fsck_error callback
fsck.[ch]: move FOREACH_FSCK_MSG_ID & fsck_msg_id from *.c to *.h
fsck.c: give "FOREACH_MSG_ID" a more specific name
fsck.c: undefine temporary STR macro after use
fsck.c: call parse_msg_type() early in fsck_set_msg_type()
fsck.h: re-order and re-assign "enum fsck_msg_type"
fsck.h: move FSCK_{FATAL,INFO,ERROR,WARN,IGNORE} into an enum
fsck.c: refactor fsck_msg_type() to limit scope of "int msg_type"
fsck.c: rename remaining fsck_msg_id "id" to "msg_id"
fsck.c: remove (mostly) redundant append_msg_id() function
fsck.c: rename variables in fsck_set_msg_type() for less confusion
fsck.h: use "enum object_type" instead of "int"
fsck.h: use designed initializers for FSCK_OPTIONS_{DEFAULT,STRICT}
fsck.c: refactor and rename common config callback
In some scenarios, users may want more history than the repository
offered for cloning, which happens to be a shallow repository, can
give them. But because users don't know it is a shallow repository
until they download it to local, we may want to refuse to clone
this kind of repository, without creating any unnecessary files.
The '--depth=x' option cannot be used as a solution; the source may
be deep enough to give us 'x' commits when cloned, but the user may
later need to deepen the history to arbitrary depth.
Teach '--reject-shallow' option to "git clone" to abort as soon as
we find out that we are cloning from a shallow repository.
Signed-off-by: Li Linchao <lilinchao@oschina.cn>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refactor the check added in 5476e1efde (fetch-pack: print and use
dangling .gitmodules, 2021-02-22) to make use of us now passing the
"msg_id" to the user defined "error_func". We can now compare against
the FSCK_MSG_GITMODULES_MISSING instead of parsing the generated
message.
Let's also replace register_found_gitmodules() with directly
manipulating the "gitmodules_found" member. A recent commit moved it
into "fsck_options" so we could do this here.
I'm sticking this callback in fsck.c. Perhaps in the future we'd like
to accumulate such callbacks into another file (maybe fsck-cb.c,
similar to parse-options-cb.c?), but while we've got just the one
let's just put it into fsck.c.
A better alternative in this case would be some library some more
obvious library shared by fetch-pack.c ad builtin/index-pack.c, but
there isn't such a thing.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change code added in 5476e1efde (fetch-pack: print and use dangling
.gitmodules, 2021-02-22) so that we use a file-scoped "static struct
fsck_options" instead of defining one in the "fsck_gitmodules_oids()"
function.
We use this pattern in all of
builtin/{fsck,index-pack,mktag,unpack-objects}.c. It's odd to see
fetch-pack be the odd one out. One might think that we're using other
fsck_options structs in fetch-pack, or doing on fsck twice there, but
we're not.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Move the gitmodules_{found,done} static variables added in
159e7b080b (fsck: detect gitmodules files, 2018-05-02) into the
fsck_options struct. It makes sense to keep all the context in the
same place.
This requires changing the recently added register_found_gitmodules()
function added in 5476e1efde (fetch-pack: print and use dangling
.gitmodules, 2021-02-22) to take fsck_options. That function will be
removed in a subsequent commit, but as it'll require the new
gitmodules_found attribute of "fsck_options" we need this intermediate
step first.
An earlier version of this patch removed the small amount of
duplication we now have between FSCK_OPTIONS_{DEFAULT,STRICT} with a
FSCK_OPTIONS_COMMON macro. I don't think such de-duplication is worth
it for this amount of copy/pasting.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add and apply a semantic patch for converting code that open-codes
CALLOC_ARRAY to use it instead. It shortens the code and infers the
element size automatically.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The code to fsck objects received across multiple packs during a
single git fetch session has been broken when the packfile URI
feature was in use. A workaround has been added by disabling the
codepath to avoid keeping a packfile that is too small.
* jt/transfer-fsck-across-packs-fix:
fetch-pack: do not mix --pack_header and packfile uri
When fetching (as opposed to cloning) from a repository with packfile
URIs enabled, an error like this may occur:
fatal: pack has bad object at offset 12: unknown object type 5
fatal: finish_http_pack_request gave result -1
fatal: fetch-pack: expected keep then TAB at start of http-fetch output
This bug was introduced in b664e9ffa1 ("fetch-pack: with packfile URIs,
use index-pack arg", 2021-02-22), when the index-pack args used when
processing the inline packfile of a fetch response and when processing
packfile URIs were unified.
This bug happens because fetch, by default, partially reads (and
consumes) the header of the inline packfile to determine if it should
store the downloaded objects as a packfile or loose objects, and thus
passes --pack_header=<...> to index-pack to inform it that some bytes
are missing. However, when it subsequently fetches the additional
packfiles linked by URIs, it reuses the same index-pack arguments, thus
wrongly passing --index-pack-arg=--pack_header=<...> when no bytes are
missing.
This does not happen when cloning because "git clone" always passes
do_keep, which instructs the fetch mechanism to always retain the
packfile, eliminating the need to read the header.
There are a few ways to fix this, including filtering out pack_header
arguments when downloading the additional packfiles, but I decided to
stick to always using index-pack throughout when packfile URIs are
present - thus, Git no longer needs to read the bytes, and no longer
needs --pack_header here.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The approach to "fsck" the incoming objects in "index-pack" is
attractive for performance reasons (we have them already in core,
inflated and ready to be inspected), but fundamentally cannot be
applied fully when we receive more than one pack stream, as a tree
object in one pack may refer to a blob object in another pack as
".gitmodules", when we want to inspect blobs that are used as
".gitmodules" file, for example. Teach "index-pack" to emit
objects that must be inspected later and check them in the calling
"fetch-pack" process.
* jt/transfer-fsck-across-packs:
fetch-pack: print and use dangling .gitmodules
fetch-pack: with packfile URIs, use index-pack arg
http-fetch: allow custom index-pack args
http: allow custom index-pack args
Teach index-pack to print dangling .gitmodules links after its "keep" or
"pack" line instead of declaring an error, and teach fetch-pack to check
such lines printed.
This allows the tree side of the .gitmodules link to be in one packfile
and the blob side to be in another without failing the fsck check,
because it is now fetch-pack which checks such objects after all
packfiles have been downloaded and indexed (and not index-pack on an
individual packfile, as it is before this commit).
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Unify the index-pack arguments used when processing the inline pack and
when downloading packfiles referenced by URIs. This is done by teaching
get_pack() to also store the index-pack arguments whenever at least one
packfile URI is given, and then when processing the packfile URI(s),
using the stored arguments.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is the next step in teaching fetch-pack to pass its index-pack
arguments when processing packfiles referenced by URIs.
The "--keep" in fetch-pack.c will be replaced with a full message in a
subsequent commit.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Let's replace the 2 different pieces of code that write a
promisor file in 'builtin/repack.c' and 'fetch-pack.c'
with a new function called 'write_promisor_file()' in
'pack-write.c' and 'pack.h'.
This might also help us in the future, if we want to put
back the ref names and associated hashes that were in
the promisor files we are repacking in 'builtin/repack.c'
as suggested by a NEEDSWORK comment just above the code
we are refactoring.
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As we are going to refactor the code that actually writes
the promisor file into a separate function in a following
commit, let's rename the current write_promisor_file()
function to create_promisor_file().
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"fetch-pack" could pass NULL pointer to unlink(2) when it sees an
invalid filename; the error checking has been tightened to make
this impossible.
* rs/fetch-pack-invalid-lockfile:
fetch-pack: disregard invalid pack lockfiles
9da69a6539 (fetch-pack: support more than one pack lockfile, 2020-06-10)
started to use a string_list for pack lockfile names instead of a single
string pointer. It removed a NULL check from transport_unlock_pack() as
well, which is the function that eventually deletes these lockfiles and
releases their name strings.
index_pack_lockfile() can return NULL if it doesn't like the contents it
reads from the file descriptor passed to it. unlink(2) is declared to
not accept NULL pointers (at least with glibc). Undefined Behavior
Sanitizer together with Address Sanitizer detects a case where a NULL
lockfile name is passed to unlink(2) by transport_unlock_pack() in t1060
(make SANITIZE=address,undefined; cd t; ./t1060-object-corruption.sh).
Reinstate the NULL check to avoid undefined behavior, but put it right
at the source, so that the number of items in the string_list reflects
the number of valid lockfiles.
Signed-off-by: René Scharfe <l.s.r@web.de>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When the server sent a session-id capability and transfer.advertiseSID
is true, advertise fetch-pack's own session ID back to the server.
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Updates to on-demand fetching code in lazily cloned repositories.
* jt/lazy-fetch:
fetch: no FETCH_HEAD display if --no-write-fetch-head
fetch-pack: remove no_dependents code
promisor-remote: lazy-fetch objects in subprocess
fetch-pack: do not lazy-fetch during ref iteration
fetch: only populate existing_refs if needed
fetch: avoid reading submodule config until needed
fetch: allow refspecs specified through stdin
negotiator/noop: add noop fetch negotiator
Bugfix for "git fetch" when the packfile URI capability is in use.
* jt/fetch-pack-loosen-validation-with-packfile-uri:
fetch-pack: make packfile URIs work with transfer.fsckobjects
fetch-pack: document only_packfile in get_pack()
(various): document from_promisor parameter
When fetching with packfile URIs and transfer.fsckobjects=1, use the
--fsck-objects instead of the --strict flag when invoking index-pack so
that links are not checked, only objects. This is because incomplete
links are expected. (A subsequent connectivity check will be done when
all the packs have been downloaded regardless of whether
transfer.fsckobjects is set.)
This is similar to 98a2ea46c2 ("fetch-pack: do not check links for
partial fetch", 2018-03-15), but for packfile URIs instead of partial
clones.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
dd4b732df7 ("upload-pack: send part of packfile response as uri",
2020-06-10) added the "only_packfile" parameter to get_pack() but did
not document it. Add documentation.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When fetching a pack from a promisor remote, the corresponding .promisor
file needs to be created. "fetch-pack" originally did this by passing
"--promisor" to "index-pack", but in 5374a290aa ("fetch-pack: write
fetched refs to .promisor", 2019-10-16), "fetch-pack" was taught to do
this itself instead, because it needed to store ref information in the
.promisor file.
This causes a problem with superprojects when transfer.fsckobjects is
set, because in the current implementation, it is "index-pack" that
calls fsck_finish() to check the objects; before 5374a290aa,
fsck_finish() would see that .gitmodules is a promisor object and
tolerate it being missing, but after, there is no .promisor file (at the
time of the invocation of fsck_finish() by "index-pack") to tell it that
.gitmodules is a promisor object, so it returns an error.
Therefore, teach "fetch-pack" to pass "--promisor" to index pack once
again. "fetch-pack" will subsequently overwrite this file with the ref
information.
An alternative is to instead move object checking to "fetch-pack", and
let "index-pack" only index the files. However, since "index-pack" has
to inflate objects in order to index them, it seems reasonable to also
let it check the objects (which also require inflated files).
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that Git has switched to using a subprocess to lazy-fetch missing
objects, remove the no_dependents code as it is no longer used.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In order to determine negotiation tips, "fetch-pack" iterates over all
refs and dereferences all annotated tags found. This causes the
existence of targets of refs and annotated tags to be checked. Avoiding
this is especially important when we use "git fetch" (which invokes
"fetch-pack") to perform lazy fetches in a partial clone because a
target of such a ref or annotated tag may need to be itself lazy-fetched
(and otherwise causing an infinite loop).
Therefore, teach "fetch-pack" not to lazy fetch whenever iterating over
refs. This is done by using the raw form of ref iteration and by
dereferencing tags ourselves.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Code which split an argv_array call across multiple lines, like:
argv_array_pushl(&args, "one argument",
"another argument", "and more",
NULL);
was recently mechanically renamed to use strvec, which results in
mis-matched indentation like:
strvec_pushl(&args, "one argument",
"another argument", "and more",
NULL);
Let's fix these up to align the arguments with the opening paren. I did
this manually by sifting through the results of:
git jump grep 'strvec_.*,$'
and liberally applying my editor's auto-format. Most of the changes are
of the form shown above, though I also normalized a few that had
originally used a single-tab indentation (rather than our usual style of
aligning with the open paren). I also rewrapped a couple of obvious
cases (e.g., where previously too-long lines became short enough to fit
on one), but I wasn't aggressive about it. In cases broken to three or
more lines, the grouping of arguments is sometimes meaningful, and it
wasn't worth my time or reviewer time to ponder each case individually.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
SHA-256 migration work continues.
* bc/sha-256-part-2: (44 commits)
remote-testgit: adapt for object-format
bundle: detect hash algorithm when reading refs
t5300: pass --object-format to git index-pack
t5704: send object-format capability with SHA-256
t5703: use object-format serve option
t5702: offer an object-format capability in the test
t/helper: initialize the repository for test-sha1-array
remote-curl: avoid truncating refs with ls-remote
t1050: pass algorithm to index-pack when outside repo
builtin/index-pack: add option to specify hash algorithm
remote-curl: detect algorithm for dumb HTTP by size
builtin/ls-remote: initialize repository based on fetch
t5500: make hash independent
serve: advertise object-format capability for protocol v2
connect: parse v2 refs with correct hash algorithm
connect: pass full packet reader when parsing v2 refs
Documentation/technical: document object-format for protocol v2
t1302: expect repo format version 1 for SHA-256
builtin/show-index: provide options to determine hash algo
t5302: modernize test formatting
...
The "fetch/clone" protocol has been updated to allow the server to
instruct the clients to grab pre-packaged packfile(s) in addition
to the packed object data coming over the wire.
* jt/cdn-offload:
upload-pack: fix a sparse '0 as NULL pointer' warning
upload-pack: send part of packfile response as uri
fetch-pack: support more than one pack lockfile
upload-pack: refactor reading of pack-objects out
Documentation: add Packfile URIs design doc
Documentation: order protocol v2 sections
http-fetch: support fetching packfiles by URL
http-fetch: refactor into function
http: refactor finish_http_pack_request()
http: use --stdin when indexing dumb HTTP pack
Teach upload-pack to send part of its packfile response as URIs.
An administrator may configure a repository with one or more
"uploadpack.blobpackfileuri" lines, each line containing an OID, a pack
hash, and a URI. A client may configure fetch.uriprotocols to be a
comma-separated list of protocols that it is willing to use to fetch
additional packfiles - this list will be sent to the server. Whenever an
object with one of those OIDs would appear in the packfile transmitted
by upload-pack, the server may exclude that object, and instead send the
URI. The client will then download the packs referred to by those URIs
before performing the connectivity check.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Whenever a fetch results in a packfile being downloaded, a .keep file is
generated, so that the packfile can be preserved (from, say, a running
"git repack") until refs are written referring to the contents of the
packfile.
In a subsequent patch, a successful fetch using protocol v2 may result
in more than one .keep file being generated. Therefore, teach
fetch_pack() and the transport mechanism to support multiple .keep
files.
Implementation notes:
- builtin/fetch-pack.c normally does not generate .keep files, and thus
is unaffected by this or future changes. However, it has an
undocumented "--lock-pack" feature, used by remote-curl.c when
implementing the "fetch" remote helper command. In keeping with the
remote helper protocol, only one "lock" line will ever be written;
the rest will result in warnings to stderr. However, in practice,
warnings will never be written because the remote-curl.c "fetch" is
only used for protocol v0/v1 (which will not generate multiple .keep
files). (Protocol v2 uses the "stateless-connect" command, not the
"fetch" command.)
- connected.c has an optimization in that connectivity checks on a ref
need not be done if the target object is in a pack known to be
self-contained and connected. If there are multiple packfiles, this
optimization can no longer be done.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Parse the server's object-format capability and respond accordingly,
dying if there is a mismatch.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Detect when the server doesn't support our hash algorithm and abort.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently, remote-curl acts as a proxy and blindly forwards packets
between an HTTP server and fetch-pack. In the case of a stateless RPC
connection where the connection is terminated before the transaction is
complete, remote-curl will blindly forward the packets before waiting on
more input from fetch-pack. Meanwhile, fetch-pack will read the
transaction and continue reading, expecting more input to continue the
transaction. This results in a deadlock between the two processes.
This can be seen in the following command which does not terminate:
$ git -c protocol.version=2 clone https://github.com/git/git.git --shallow-since=20151012
Cloning into 'git'...
whereas the v1 version does terminate as expected:
$ git -c protocol.version=1 clone https://github.com/git/git.git --shallow-since=20151012
Cloning into 'git'...
fatal: the remote end hung up unexpectedly
Instead of blindly forwarding packets, make remote-curl insert a
response end packet after proxying the responses from the remote server
when using stateless_connect(). On the RPC client side, ensure that each
response ends as described.
A separate control packet is chosen because we need to be able to
differentiate between what the remote server sends and remote-curl's
control packets. By ensuring in the remote-curl code that a server
cannot send response end packets, we prevent a malicious server from
being able to perform a denial of service attack in which they spoof a
response end packet and cause the described deadlock to happen.
Reported-by: Force Charlie <charlieio@outlook.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The upload-pack protocol v2 gave up too early before finding a
common ancestor, resulting in a wasteful fetch from a fork of a
project. This has been corrected to match the behaviour of v0
protocol.
* jt/v2-fetch-nego-fix:
fetch-pack: in protocol v2, reset in_vain upon ACK
fetch-pack: in protocol v2, in_vain only after ACK
fetch-pack: return enum from process_acks()
Fix in-core inconsistency after fetching into a shallow repository
that broke the code to write out commit-graph.
* tb/reset-shallow:
shallow.c: use '{commit,rollback}_shallow_file'
t5537: use test_write_lines and indented heredocs for readability
In previous patches, the functions 'commit_shallow_file' and
'rollback_shallow_file' were introduced to reset the shallowness
validity checks on a repository after potentially modifying
'.git/shallow'.
These functions can be made safer by wrapping the 'struct lockfile *' in
a new type, 'shallow_lock', so that they cannot be called with a raw
lock (and potentially misused by other code that happens to possess a
lockfile, but has nothing to do with shallowness).
This patch introduces that type as a thin wrapper around 'struct
lockfile', and updates the two aforementioned functions and their
callers to use it.
Suggested-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There are many functions in commit.h that are more related to shallow
repositories than they are to any sort of generic commit machinery.
Likely this began when there were only a few shallow-related functions,
and commit.h seemed a reasonable enough place to put them.
But, now there are a good number of shallow-related functions, and
placing them all in 'commit.h' doesn't make sense.
This patch extracts a 'shallow.h', which takes all of the declarations
from 'commit.h' for functions which already exist in 'shallow.c'. We
will bring the remaining shallow-related functions defined in 'commit.c'
in a subsequent patch.
For now, move only the ones that already are implemented in 'shallow.c',
and update the necessary includes.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the function process_acks() in fetch-pack.c, the variable
received_ack is meant to track that an ACK was received, but it was
never set. This results in negotiation terminating prematurely through
the in_vain counter, when the counter should have been reset upon every
ACK.
Therefore, reset the in_vain counter upon every ACK.
Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When fetching, Git stops negotiation when it has sent at least
MAX_IN_VAIN (which is 256) "have" lines without having any of them
ACK-ed. But this is supposed to trigger only after the first ACK, as
pack-protocol.txt says:
However, the 256 limit *only* turns on in the canonical client
implementation if we have received at least one "ACK %s continue"
during a prior round. This helps to ensure that at least one common
ancestor is found before we give up entirely.
The code path for protocol v0 observes this, but not protocol v2,
resulting in shorter negotiation rounds but significantly larger
packfiles. Teach the code path for protocol v2 to check this criterion
only after at least one ACK was received.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
process_acks() returns 0, 1, or 2, depending on whether "ready" was
received and if not, whether at least one commit was found to be common.
Replace these magic numbers with a documented enum.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In bd0b42aed3 (fetch-pack: do not take shallow lock unnecessarily,
2019-01-10), the author noted that 'is_repository_shallow' produces
visible side-effect(s) by setting 'is_shallow' and 'shallow_stat'.
This is a problem for e.g., fetching with '--update-shallow' in a
shallow repository with 'fetch.writeCommitGraph' enabled, since the
update to '.git/shallow' will cause Git to think that the repository
isn't shallow when it is, thereby circumventing the commit-graph
compatibility check.
This causes problems in shallow repositories with at least shallow refs
that have at least one ancestor (since the client won't have those
objects, and therefore can't take the reachability closure over commits
when writing a commit-graph).
Address this by introducing thin wrappers over 'commit_lock_file' and
'rollback_lock_file' for use specifically when the lock is held over
'.git/shallow'. These wrappers (appropriately called
'commit_shallow_file' and 'rollback_shallow_file') call into their
respective functions in 'lockfile.h', but additionally reset validity
checks used by the shallow machinery.
Replace each instance of 'commit_lock_file' and 'rollback_lock_file'
with 'commit_shallow_file' and 'rollback_shallow_file' when the lock
being held is over the '.git/shallow' file.
As a result, 'prune_shallow' can now only be called once (since
'check_shallow_file_for_update' will die after calling
'reset_repository_shallow'). But, this is OK since we only call
'prune_shallow' at most once per process.
Helped-by: Jonathan Tan <jonathantanmy@google.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
