Treating the action as a string is a hang over from the scripted
rebase. The last commit removed the only remaining use of the action
that required a string so lets convert the other action users to use
the existing action enum instead. If we ever need the action name as a
string in the future the action_names array exists exactly for that
purpose.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When aborting a rebase the reflog message looks like
rebase (abort): updating HEAD
which is not very informative. Improve the message by mentioning the
branch that we are returning to as we do at the end of a successful
rebase so it looks like.
rebase (abort): returning to refs/heads/topic
If GIT_REFLOG_ACTION is set in the environment we no longer omit
"(abort)" from the reflog message. We don't omit "(start)" and
"(finish)" when starting and finishing a rebase in that case so we
shouldn't omit "(abort)".
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The apply backend creates slightly different reflog messages to the
merge backend when starting or finishing a rebase and when picking
commits. These differences make it harder than it needs to be to parse
the reflog (I have a script that reads the finishing messages from
rebase and it is a pain to have to accommodate two different message
formats). While it is possible to determine the backend used for a
rebase from the reflog messages, the differences are not designed for
that purpose. c2417d3af7 (rebase: drop '-i' from the reflog for
interactive-based rebases, 2020-02-15) removed the clear distinction
between the reflog messages of the two backends without complaint.
As the merge backend is the default it is likely to be the format most
common in existing reflogs. For that reason the apply backend is changed
to format its reflog messages to match the merge backend as closely as
possible. Note that there is still a difference as when committing a
conflict resolution the apply backend will use "(pick)" rather than
"(continue)" because it is not currently possible to change the message
for a single commit.
In addition to c2417d3af7 we also changed the reflog messages in
68aa495b59 (rebase: implement --merge via the interactive machinery,
2018-12-11) and 2ac0d6273f (rebase: change the default backend from "am"
to "merge", 2020-02-15). This commit makes the same change to "git
rebase --apply" that 2ac0d6273f made to "git rebase" without any backend
specific options. As the messages are changed to use an existing format
any scripts that can parse the reflog messages of the default rebase
backend should be unaffected by this change.
There are existing tests for the messages from both backends which are
adjusted to ensure that they do not get out of sync in the future.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reflog messages when finishing a rebase hard code "rebase" rather
than using GIT_REFLOG_ACTION.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reflog message for every pick after running "rebase --skip" looks
like
rebase (skip) (pick): commit subject line
Fix this by not appending " (skip)" to the reflog action.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reflog message for a conflict resolution committed by "rebase
--continue" looks like
rebase (continue): commit subject line
Unfortunately the reflog message each subsequent pick look like
rebase (continue) (pick): commit subject line
Fix this by setting the reflog message for "rebase --continue" in
sequencer_continue() so it does not affect subsequent commits. This
introduces a memory leak similar to the one leaking GIT_REFLOG_ACTION
in pick_commits(). Both of these will be fixed in a future series that
stops the sequencer calling setenv().
If we fail to commit the staged changes then we error out so
GIT_REFLOG_ACTION does not need to be reset in that case.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refactor the tests in preparation for adding more tests in the next
few commits. The reworked tests use the same function for testing both
the "merge" and "apply" backends. The test coverage for the "apply"
backend now includes setting GIT_REFLOG_ACTION.
Note that rebasing the "conflicts" branch does not create any
conflicts yet. A commit to do that will be added in the next commit
and the diff ends up smaller if we have don't rename the branch when
it is added.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use move_to_original_branch() when reattaching HEAD after a fast-forward
rather than open coding a copy of that code. move_to_original_branch()
does not call reset_head() if head_name is NULL but there should be no
user visible changes even though we currently call reset_head() in that
case. The reason for this is that the reset_head() call does not add a
message to the reflog because we're not changing the commit that HEAD
points to and so lock_ref_for_update() elides the update. When head_name
is not NULL then reset_head() behaves like "git symbolic-ref" and so the
reflog is updated.
Note that the removal of "strbuf_release(&msg)" is safe as there is an
identical call just above this hunk which can be seen by viewing the
diff with -U6.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* pw/rebase-keep-base-fixes:
rebase --keep-base: imply --no-fork-point
rebase --keep-base: imply --reapply-cherry-picks
rebase: factor out branch_base calculation
rebase: rename merge_base to branch_base
rebase: store orig_head as a commit
rebase: be stricter when reading state files containing oids
t3416: set $EDITOR in subshell
t3416: tighten two tests
Given the name of the option it is confusing if --keep-base actually
changes the base of the branch without --fork-point being explicitly
given on the command line.
The combination of --keep-base with an explicit --fork-point is still
supported even though --fork-point means we do not keep the same base
if the upstream branch has been rewound. We do this in case anyone is
relying on this behavior which is tested in t3431[1]
[1] https://lore.kernel.org/git/20200715032014.GA10818@generichostname/
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As --keep-base does not rebase the branch it is confusing if it
removes commits that have been cherry-picked to the upstream branch.
As --reapply-cherry-picks is not supported by the "apply" backend this
commit ensures that cherry-picks are reapplied by forcing the upstream
commit to match the onto commit unless --no-reapply-cherry-picks is
given.
Reported-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Separate out calculating the merge base between 'onto' and 'HEAD' from
the check for whether we can fast-forward or not. This means we can skip
the fast-forward checks when the rebase is forced and avoid calculating
the merge-base between 'HEAD' and 'onto' when --keep-base is given.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
merge_base is not a very descriptive name, the variable always holds
the merge-base of 'branch' and 'onto' which is commit at the base of
the branch being rebased so rename it to branch_base.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Using a struct commit rather than a struct oid to hold orig_head means
that we error out straight away if the branch being rebased does not
point to a commit. It also simplifies the code that handles finding
the merge base and fork point as it no longer has to convert from an
oid to a commit.
To avoid changing the behavior of "git rebase <upstream> <branch>" we
keep the existing call to read_ref() and use lookup_commit_object()
on the oid returned by that rather than calling
lookup_commit_reference_by_name() which applies the ref dwim rules to
its argument.
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The state files for 'onto' and 'orig_head' should contain a full hex
oid, change the reading functions from get_oid() to get_oid_hex() to
reflect this. They should also name commits and not tags so add and use
a function that looks up a commit from an oid like
lookup_commit_reference() but without dereferencing tags.
Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As $EDITOR is exported, setting it in one test affects all subsequent
tests. Avoid this by always setting it in a subshell. Also remove a
couple of unnecessary call to set_fake_editor where the editor does
not change the todo list.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a check for the correct error message to the tests that check we
require a single merge base so we can be sure the rebase failed for
the correct reason. Also rename the tests to reflect what they are
testing.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As the 'master' front will soon tag a preview and then release
candidates for 2.38, it is unknown if we are going to issue another
maintenance release on the 2.37.x track, but as we have accumulated
enough material there, let's prepare a draft for it.
Even if we end up not tagging 2.37.4, it would help motivated distro
packagers to maintain their slightly older and "more stable" versions.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The auto-stashed local changes created by "git merge --autostash"
was mixed into a conflicted state left in the working tree, which
has been corrected.
* en/merge-unstash-only-on-clean-merge:
merge: only apply autostash when appropriate
Update the version of Ubuntu used for GitHub Actions CI from 18.04
to 22.04.
* ds/github-actions-use-newer-ubuntu:
ci: update 'static-analysis' to Ubuntu 22.04
The preload-index codepath made copies of pathspec to give to
multiple threads, which were left leaked.
* ad/preload-plug-memleak:
preload-index: fix memleak
xcalloc(), imitating calloc(), takes "number of elements of the
array", and "size of a single element", in this order. A call that
does not follow this ordering has been corrected.
* sg/xcalloc-cocci-fix:
promisor-remote: fix xcalloc() argument order
Fix deadlocks between main Git process and subprocess spawned via
the pipe_command() API, that can kill "git add -p" that was
reimplemented in C recently.
* jk/pipe-command-nonblock:
pipe_command(): mark stdin descriptor as non-blocking
pipe_command(): handle ENOSPC when writing to a pipe
pipe_command(): avoid xwrite() for writing to pipe
git-compat-util: make MAX_IO_SIZE define globally available
nonblock: support Windows
compat: add function to enable nonblocking pipes
An earlier optimization discarded a tree-object buffer that is
still in use, which has been corrected.
* jk/is-promisor-object-keep-tree-in-use:
is_promisor_object(): fix use-after-free of tree buffer
Documentation for "git add --renormalize" has been improved.
source: <20220810144450.470-2-philipoakley@iee.email>
* po/doc-add-renormalize:
doc add: renormalize is not idempotent for CRCRLF
Fixes to sparse index compatibility work for "reset" and "checkout"
commands.
source: <pull.1312.v3.git.1659985672.gitgitgadget@gmail.com>
* vd/sparse-reset-checkout-fixes:
unpack-trees: unpack new trees as sparse directories
cache.h: create 'index_name_pos_sparse()'
oneway_diff: handle removed sparse directories
checkout: fix nested sparse directory diff in sparse index
"git fsck" reads mode from tree objects but canonicalizes the mode
before passing it to the logic to check object sanity, which has
hid broken tree objects from the checking logic. This has been
corrected, but to help exiting projects with broken tree objects
that they cannot fix retroactively, the severity of anomalies this
code detects has been demoted to "info" for now.
source: <YvQcNpizy9uOZiAz@coredump.intra.peff.net>
* jk/fsck-tree-mode-bits-fix:
fsck: downgrade tree badFilemode to "info"
fsck: actually detect bad file modes in trees
tree-walk: add a mechanism for getting non-canonicalized modes
Platform-specific code that determines if a directory is OK to use
as a repository has been taught to report more details, especially
on Windows.
source: <pull.1286.v2.git.1659965270.gitgitgadget@gmail.com>
* js/safe-directory-plus:
mingw: handle a file owned by the Administrators group correctly
mingw: be more informative when ownership check fails on FAT32
mingw: provide details about unsafe directories' ownership
setup: prepare for more detailed "dubious ownership" messages
setup: fix some formatting
Avoid repeatedly running getconf to ask libc version in the test
suite, and instead just as it once per script.
source: <pull.1311.git.1659620305757.gitgitgadget@gmail.com>
* pw/use-glibc-tunable-for-malloc-optim:
tests: cache glibc version check
A follow-up fix to a fix for a regression in 2.36.
source: <patch-1.1-2450e3e65cf-20220805T141402Z-avarab@gmail.com>
* ab/hooks-regression-fix:
hook API: don't segfault on strbuf_addf() to NULL "out"
Plug memory leaks in the failure code path in the "merge-ort" merge
strategy backend.
source: <pull.1307.v2.git.1659114727.gitgitgadget@gmail.com>
* js/ort-clean-up-after-failed-merge:
merge-ort: do leave trace2 region even if checkout fails
merge-ort: clean up after failed merge
Older gcc with -Wall complains about the universal zero initializer
"struct s = { 0 };" idiom, which makes developers' lives
inconvenient (as -Werror is enabled by DEVELOPER=YesPlease). The
build procedure has been tweaked to help these compilers.
source: <YuQ60ZUPBHAVETD7@coredump.intra.peff.net>
* jk/struct-zero-init-with-older-gcc:
config.mak.dev: squelch -Wno-missing-braces for older gcc
Conditionally allow building Python interpreter on Windows
source: <pull.1306.v2.git.1659109272.gitgitgadget@gmail.com>
* js/mingw-with-python:
mingw: remove unneeded `NO_CURL` directive
mingw: remove unneeded `NO_GETTEXT` directive
windows: include the Python bits when building Git for Windows
Fix build procedure for Windows that uses CMake so that it can pick
up the shell interpreter from local installation location.
source: <pull.1304.git.1658912756815.gitgitgadget@gmail.com>
* ca/unignore-local-installation-on-windows:
cmake: support local installations of git
GitHub Actions scheduled a brownout of Ubuntu 18.04, which canceled all
runs of the 'static-analysis' job in our CI runs. Update to 22.04 to
avoid this as the brownout later turns into a complete deprecation.
The use of 18.04 was set in d051ed77ee (.github/workflows/main.yml: run
static-analysis on bionic, 2021-02-08) due to the lack of Coccinelle
being available on 20.04 (which continues today).
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If a merge failed and we are leaving conflicts in the working directory
for the user to resolve, we should not attempt to apply any autostash.
Further, if we fail to apply the autostash (because either the merge
failed, or the user requested --no-commit), then we should instruct the
user how to apply it later.
Add a testcase verifying we have corrected this behavior.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Pass the number of elements first and their size second, as expected
by xcalloc().
Patch generated with:
make SPATCH_FLAGS=--recursive-includes contrib/coccinelle/xcalloc.cocci.patch
Our default SPATCH_FLAGS ('--all-includes') doesn't catch this
transformation by default, unless used in combination with a large-ish
SPATCH_BATCH_SIZE which happens to put 'promisor-remote.c' with a file
that includes 'repository.h' directly in the same batch.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix a memory leak occuring in case of pathspec copy in preload_index.
Direct leak of 8 byte(s) in 8 object(s) allocated from:
#0 0x7f0a353ead47 in __interceptor_malloc (/usr/lib/gcc/x86_64-pc-linux-gnu/11.3.0/libasan.so.6+0xb5d47)
#1 0x55750995e840 in do_xmalloc /home/anthony/src/c/git/wrapper.c:51
#2 0x55750995e840 in xmalloc /home/anthony/src/c/git/wrapper.c:72
#3 0x55750970f824 in copy_pathspec /home/anthony/src/c/git/pathspec.c:684
#4 0x557509717278 in preload_index /home/anthony/src/c/git/preload-index.c:135
#5 0x55750975f21e in refresh_index /home/anthony/src/c/git/read-cache.c:1633
#6 0x55750915b926 in cmd_status builtin/commit.c:1547
#7 0x5575090e1680 in run_builtin /home/anthony/src/c/git/git.c:466
#8 0x5575090e1680 in handle_builtin /home/anthony/src/c/git/git.c:720
#9 0x5575090e284a in run_argv /home/anthony/src/c/git/git.c:787
#10 0x5575090e284a in cmd_main /home/anthony/src/c/git/git.c:920
#11 0x5575090dbf82 in main /home/anthony/src/c/git/common-main.c:56
#12 0x7f0a348230ab (/lib64/libc.so.6+0x290ab)
Signed-off-by: Anthony Delannoy <anthony.2lannoy@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our pipe_command() helper lets you both write to and read from a child
process on its stdin/stdout. It's supposed to work without deadlocks
because we use poll() to check when descriptors are ready for reading or
writing. But there's a bug: if both the data to be written and the data
to be read back exceed the pipe buffer, we'll deadlock.
The issue is that the code assumes that if you have, say, a 2MB buffer
to write and poll() tells you that the pipe descriptor is ready for
writing, that calling:
write(cmd->in, buf, 2*1024*1024);
will do a partial write, filling the pipe buffer and then returning what
it did write. And that is what it would do on a socket, but not for a
pipe. When writing to a pipe, at least on Linux, it will block waiting
for the child process to read() more. And now we have a potential
deadlock, because the child may be writing back to us, waiting for us to
read() ourselves.
An easy way to trigger this is:
git -c add.interactive.useBuiltin=true \
-c interactive.diffFilter=cat \
checkout -p HEAD~200
The diff against HEAD~200 will be big, and the filter wants to write all
of it back to us (obviously this is a dummy filter, but in the real
world something like diff-highlight would similarly stream back a big
output).
If you set add.interactive.useBuiltin to false, the problem goes away,
because now we're not using pipe_command() anymore (instead, that part
happens in perl). But this isn't a bug in the interactive code at all.
It's the underlying pipe_command() code which is broken, and has been
all along.
We presumably didn't notice because most calls only do input _or_
output, not both. And the few that do both, like gpg calls, may have
large inputs or outputs, but never both at the same time (e.g., consider
signing, which has a large payload but a small signature comes back).
The obvious fix is to put the descriptor into non-blocking mode, and
indeed, that makes the problem go away. Callers shouldn't need to
care, because they never see the descriptor (they hand us a buffer to
feed into it).
The included test fails reliably on Linux without this patch. Curiously,
it doesn't fail in our Windows CI environment, but has been reported to
do so for individual developers. It should pass in any environment after
this patch (courtesy of the compat/ layers added in the last few
commits).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When write() to a non-blocking pipe fails because the buffer is full,
POSIX says we should see EAGAIN. But our mingw_write() compat layer on
Windows actually returns ENOSPC for this case. This is probably
something we want to correct, but given that we don't plan to use
non-blocking descriptors in a lot of places, we can work around it by
just catching ENOSPC alongside EAGAIN. If we ever do fix mingw_write(),
then this patch can be reverted.
We don't actually use a non-blocking pipe yet, so this is still just
preparation.
Helped-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If xwrite() sees an EAGAIN response, it will loop forever until the
write succeeds (or encounters a real error). This is due to ef1cf0167a
(xwrite: poll on non-blocking FDs, 2016-06-26), with the idea that we
won't be surprised by a descriptor unexpectedly set as non-blocking.
But that will make things awkward when we do want a non-blocking
descriptor, and a future patch will switch pipe_command() to using one.
In that case, looping on EAGAIN is bad, because the process on the other
end of the pipe may be waiting on us before doing another read() on the
pipe, which would mean we deadlock.
In practice we're not supposed to ever see EAGAIN here, since poll()
will have just told us the descriptor is ready for writing. But our
Windows emulation of poll() will always return "ready" for writing to a
pipe descriptor! This is due to 94f4d01932 (mingw: workaround for hangs
when sending STDIN, 2020-02-17).
Our best bet in that case is to keep handling other descriptors, as any
read() we do may allow the child command to make forward progress (i.e.,
its write() finishes, and then it read()s from its stdin, freeing up
space in the pipe buffer). This means we might busy-loop between poll()
and write() on Windows if the child command is slow to read our input,
but it's much better than the alternative of deadlocking.
In practice, this busy-looping should be rare:
- for small inputs, we'll just write the whole thing in a single
write() anyway, non-blocking or not
- for larger inputs where the child reads input and then processes it
before writing (e.g., gpg verifying a signature), we may make a few
extra write() calls that get EAGAIN during the initial write, but
once it has taken in the whole input, we'll correctly block waiting
to read back the data.
- for larger inputs where the child process is streaming output back
(like a diff filter), we'll likewise see some extra EAGAINs, but
most of them will be followed immediately by a read(), which will
let the child command make forward progress.
Of course it won't happen at all for now, since we don't yet use a
non-blocking pipe. This is just preparation for when we do.
Helped-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We define MAX_IO_SIZE within wrapper.c, but it's useful for any code
that wants to do a raw write() for whatever reason (say, because they
want different EAGAIN handling). Let's make it available everywhere.
The alternative would be adding xwrite_foo() variants to give callers
more options. But there's really no reason MAX_IO_SIZE needs to be
abstracted away, so this give callers the most flexibility.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Implement enable_pipe_nonblock() using the Windows API. This works only
for pipes, but that is sufficient for this limited interface. Despite
the API calls used, it handles both "named" and anonymous pipes from our
pipe() emulation.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We'd like to be able to make some of our pipes nonblocking so that
poll() can be used effectively, but O_NONBLOCK isn't portable. Let's
introduce a compat wrapper so this can be abstracted for each platform.
The interface is as narrow as possible to let platforms do what's
natural there (rather than having to implement fcntl() and a fake
O_NONBLOCK for example, or having to handle other types of descriptors).
The next commit will add Windows support, at which point we should be
covering all platforms in practice. But if we do find some other
platform without O_NONBLOCK, we'll return ENOSYS. Arguably we could just
trigger a build-time #error in this case, which would catch the problem
earlier. But since we're not planning to use this compat wrapper in many
code paths, a seldom-seen runtime error may be friendlier for such a
platform than blocking compilation completely. Our test suite would
still notice it.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Since commit fcc07e980b (is_promisor_object(): free tree buffer after
parsing, 2021-04-13), we'll always free the buffers attached to a
"struct tree" after searching them for promisor links. But there's an
important case where we don't want to do so: if somebody else is already
using the tree!
This can happen during a "rev-list --missing=allow-promisor" traversal
in a partial clone that is missing one or more trees or blobs. The
backtrace for the free looks like this:
#1 free_tree_buffer tree.c:147
#2 add_promisor_object packfile.c:2250
#3 for_each_object_in_pack packfile.c:2190
#4 for_each_packed_object packfile.c:2215
#5 is_promisor_object packfile.c:2272
#6 finish_object__ma builtin/rev-list.c:245
#7 finish_object builtin/rev-list.c:261
#8 show_object builtin/rev-list.c:274
#9 process_blob list-objects.c:63
#10 process_tree_contents list-objects.c:145
#11 process_tree list-objects.c:201
#12 traverse_trees_and_blobs list-objects.c:344
[...]
We're in the middle of walking through the entries of a tree object via
process_tree_contents(). We see a blob (or it could even be another tree
entry) that we don't have, so we call is_promisor_object() to check it.
That function loops over all of the objects in the promisor packfile,
including the tree we're currently walking. When we're done with it
there, we free the tree buffer. But as we return to the walk in
process_tree_contents(), it's still holding on to a pointer to that
buffer, via its tree_desc iterator, and it accesses the freed memory.
Even a trivial use of "--missing=allow-promisor" triggers this problem,
as the included test demonstrates (it's just a vanilla --blob:none
clone).
We can detect this case by only freeing the tree buffer if it was
allocated on our behalf. This is a little tricky since that happens
inside parse_object(), and it doesn't tell us whether the object was
already parsed, or whether it allocated the buffer itself. But by
checking for an already-parsed tree beforehand, we can distinguish the
two cases.
That feels a little hacky, and does incur an extra lookup in the
object-hash table. But that cost is fairly minimal compared to actually
loading objects (and since we're iterating the whole pack here, we're
likely to be loading most objects, rather than reusing cached results).
It may also be a good direction for this function in general, as there
are other possible optimizations that rely on doing some analysis before
parsing:
- we could detect blobs and avoid reading their contents; they can't
link to other objects, but parse_object() doesn't know that we don't
care about checking their hashes.
- we could avoid allocating object structs entirely for most objects
(since we really only need them in the oidset), which would save
some memory.
- promisor commits could use the commit-graph rather than loading the
object from disk
This commit doesn't do any of those optimizations, but I think it argues
that this direction is reasonable, rather than relying on parse_object()
and trying to teach it to give us more information about whether it
parsed.
The included test fails reliably under SANITIZE=address just when
running "rev-list --missing=allow-promisor". Checking the output isn't
strictly necessary to detect the bug, but it seems like a reasonable
addition given the general lack of coverage for "allow-promisor" in the
test suite.
Reported-by: Andrew Olsen <andrew.olsen@koordinates.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
