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Refactor the "goto usage" pattern added in
cd57bc41bbc (builtin/multi-pack-index.c: display usage on unrecognized
command, 2021-03-30) and 88617d11f9d (multi-pack-index: fix potential
segfault without sub-command, 2021-07-19) to maintain the same
brevity, but in a form that doesn't run afoul of the recommendation in
CodingGuidelines about braces:
When there are multiple arms to a conditional and some of them
require braces, enclose even a single line block in braces for
consistency[...]
Let's also change "argv == 0" to juts "!argv", per:
Do not explicitly compare an integral value with constant 0 or
'\0', or a pointer value with constant NULL[...]
I'm changing this because in a subsequent commit I'll make
builtin/commit-graph.c use the same pattern, having the two similarly
structured commands match aids readability.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Make use of the parse_options_concat() so we don't need to copy/paste
common options like --object-dir.
This is inspired by a similar change to "checkout" in 2087182272
(checkout: split options[] array in three pieces, 2019-03-29), and the
same pattern in the multi-pack-index command, see
60ca94769ce (builtin/multi-pack-index.c: split sub-commands,
2021-03-30).
A minor behavior change here is that now we're going to list both
--object-dir and --progress first, before we'd list --progress along
with other options.
Co-authored-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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If we don't handle the -h option here like most parse_options() users
we'll fall through and it'll do the right thing for us.
I think this code added in 4ce58ee38d (commit-graph: create
git-commit-graph builtin, 2018-04-02) was always redundant,
parse_options() did this at the time, and the commit-graph code never
used PARSE_OPT_NO_INTERNAL_HELP.
We don't need a test for this, it's tested by the t0012-help.sh test
added in d691551192a (t0012: test "-h" with builtins, 2017-05-30).
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Share the usage message between these three variables by using a
macro. Before this new options needed to copy/paste the usage
information, see e.g. 809e0327f5 (builtin/commit-graph.c: introduce
'--max-new-filters=<n>', 2020-09-18).
See b25b727494f (builtin/multi-pack-index.c: define common usage with
a macro, 2021-03-30) for another use of this pattern (but on-list this
one came first).
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Silently skipping commits when rebasing with --no-reapply-cherry-picks
(currently the default behavior) can cause user confusion. Issue
warnings when this happens, as well as advice on how to preserve the
skipped commits.
These warnings and advice are displayed only when using the (default)
"merge" rebase backend.
Update the git-rebase docs to mention the warnings and advice.
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The most significant of this batch is of course "merge -sort".
Thanks, Elijah and everybody who helped the topic.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Update FreeBSD CI job
* cb/ci-freebsd-update:
ci: update freebsd 12 cirrus job
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Meh.
* tl/traverse-non-commits-rename:
list-objects.c: rename "traverse_trees_and_blobs" to "traverse_non_commits"
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The current implementation of GIT_TEST_FAIL_PREREQS is broken in
that checking for the lack of a prerequisite would not work. Avoid
the use of "if ! test_have_prereq X" in a test script.
* bc/t5607-avoid-broken-test-fail-prereqs:
t5607: avoid using prerequisites to select algorithm
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The userdiff pattern for "java" language has been updated.
* th/userdiff-more-java:
userdiff: improve java hunk header regex
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"git range-diff" code clean-up.
* jk/range-diff-fixes:
range-diff: use ssize_t for parsed "len" in read_patches()
range-diff: handle unterminated lines in read_patches()
range-diff: drop useless "offset" variable from read_patches()
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"git apply" miscounted the bytes and failed to read to the end of
binary hunks.
* jk/apply-binary-hunk-parsing-fix:
apply: keep buffer/size pair in sync when parsing binary hunks
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Remind developers that the userdiff patterns should be kept simple
and permissive, assuming that the contents they apply are always
syntactically correct.
* jc/userdiff-pattern-hint:
userdiff: comment on the builtin patterns
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Code clean-up.
* cb/builtin-merge-format-string-fix:
builtin/merge: avoid -Wformat-extra-args from ancient Xcode
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Debugging aid.
* js/log-protocol-version:
connect, protocol: log negotiated protocol version
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Use `ort` instead of `recursive` as the default merge strategy.
* en/ort-becomes-the-default:
Update docs for change of default merge backend
Change default merge backend from recursive to ort
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Documentation updates.
* en/merge-strategy-docs:
Update error message and code comment
merge-strategies.txt: add coverage of the `ort` merge strategy
git-rebase.txt: correct out-of-date and misleading text about renames
merge-strategies.txt: fix simple capitalization error
merge-strategies.txt: avoid giving special preference to patience algorithm
merge-strategies.txt: do not imply using copy detection is desired
merge-strategies.txt: update wording for the resolve strategy
Documentation: edit awkward references to `git merge-recursive`
directory-rename-detection.txt: small updates due to merge-ort optimizations
git-rebase.txt: correct antiquated claims about --rebase-merges
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"git pull" had various corner cases that were not well thought out
around its --rebase backend, e.g. "git pull --ff-only" did not stop
but went ahead and rebased when the history on other side is not a
descendant of our history. The series tries to fix them up.
* en/pull-conflicting-options:
pull: fix handling of multiple heads
pull: update docs & code for option compatibility with rebasing
pull: abort by default when fast-forwarding is not possible
pull: make --rebase and --no-rebase override pull.ff=only
pull: since --ff-only overrides, handle it first
pull: abort if --ff-only is given and fast-forwarding is impossible
t7601: add tests of interactions with multiple merge heads and config
t7601: test interaction of merge/rebase/fast-forward flags and options
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Based on current experience, when running git clone --recurse-submodules,
developers do not expect other commands such as pull or checkout to run
recursively into active submodules. However, setting submodule.recurse=true
at this step could make for a simpler workflow by eliminating the need for
the --recurse-submodules option in subsequent commands. To collect more
data on developers' preference in regards to making submodule.recurse=true
a default config value in the future, deploy this feature under the opt in
submodule.stickyRecursiveClone flag.
Signed-off-by: Mahi Kolla <mkolla2@illinois.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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If multiple independent patches are sent with send-email, even if the
"In-Reply-To" and "References" headers are not managed by --thread or
--in-reply-to, their values may be propagated from prior patches to
subsequent patches with no such headers defined.
To mitigate this and potential future issues, make sure all global
patch-specific variables are always either handled by
command-specific code (e.g. threading), or are reset to their default
values for every iteration.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Marvin Häuser <mhaeuser@posteo.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When fetching, Git will by default print a list of all updated refs in a
nicely formatted table. In order to come up with this table, Git needs
to iterate refs twice: first to determine the maximum column width, and
a second time to actually format these changed refs.
While this table will not be printed in case the user passes `--quiet`,
we still go out of our way and do all these steps. In fact, we even do
more work compared to not passing `--quiet`: without the flag, we will
skip all references in the column width computation which have not been
updated, but if it is set we will now compute widths for all refs.
Fix this issue by completely skipping both preparation of the format and
formatting data for display in case the user passes `--quiet`, improving
performance especially with many refs. The following benchmark shows a
nice speedup for a quiet mirror-fetch in a repository with 2.3M refs:
Benchmark #1: HEAD~: git-fetch
Time (mean ± σ): 26.929 s ± 0.145 s [User: 24.194 s, System: 4.656 s]
Range (min … max): 26.692 s … 27.068 s 5 runs
Benchmark #2: HEAD: git-fetch
Time (mean ± σ): 25.189 s ± 0.094 s [User: 22.556 s, System: 4.606 s]
Range (min … max): 25.070 s … 25.314 s 5 runs
Summary
'HEAD: git-fetch' ran
1.07 ± 0.01 times faster than 'HEAD~: git-fetch'
While at it, this patch also fixes `adjust_refcol_width()` such that it
skips unchanged refs in case the user passed `--quiet`, where verbosity
will be negative. While this function won't be called anymore if so,
this brings the comment in line with actual code. Furthermore, needless
`verbosity >= 0` checks are now removed in `store_updated_refs()`: we
never print to the `note` buffer anymore in case `verbosity < 0`, so we
won't end up in that code block anyway.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Call fspathcmp() instead of open-coding it. This shortens the code and
makes it less repetitive.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Every once in a while a test somehow manages to escape from its trash
directory and modifies the surrounding repository, whether because of
a bug in git itself, a bug in a test [1], or e.g. when trying to run
tests with a shell that is, in general, unable to run our tests [2].
Set GIT_CEILING_DIRECTORIES="$TRASH_DIRECTORY/.." as an additional
safety measure to protect the surrounding repository at least from
modifications by git commands executed in the tests (assuming that
handling of ceiling directories during repository discovery is not
broken, and, of course, it won't save us from regular shell commands,
e.g. 'cd .. && rm -f ...').
[1] e.g. https://public-inbox.org/git/20210423051255.GD2947267@szeder.dev
[2] $ git symbolic-ref HEAD
refs/heads/master
$ ksh ./t2011-checkout-invalid-head.sh
[... a lot of "not ok" ...]
$ git symbolic-ref HEAD
refs/heads/other
(In short: 'ksh' doesn't support the 'local' builtin command,
which is used by 'test_oid', causing it to return with error
whenever it's called, leaving ZERO_OID set to empty, so when the
test 'checkout main from invalid HEAD' runs 'echo $ZERO_OID
>.git/HEAD' it writes a corrupt (not invalid) HEAD, and subsequent
git commands don't recognize the repository in the trash directory
anymore, but operate on the surrounding repo.)
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Fix syntax and correct the format of printf in MyFirstObjectWalk.txt
Signed-off-by: Zoker <kaixuanguiqu@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Copy the 'index_state->dir_hash' back to the real istate after expanding
a sparse index.
A crash was observed in 'git status' during some hashmap lookups with
corrupted hashmap entries. During an index expansion, new cache-entries
are added to the 'index_state->name_hash' and the 'dir_hash' in a
temporary 'index_state' variable 'full'. However, only the 'name_hash'
hashmap from this temp variable was copied back into the real 'istate'
variable. The original copy of the 'dir_hash' was incorrectly
preserved. If the table in the 'full->dir_hash' hashmap were realloced,
the stale version (in 'istate') would be corrupted.
The test suite does not operate on index sizes sufficiently large to
trigger this reallocation, so they do not cover this behavior.
Increasing the test suite to cover such scale is fragile and likely
wasteful.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In the original code from 08cdfb1337 (pack-objects --keep-unreachable,
2007-09-16), we add each object to the packing list with type
`obj->type`, where `obj` comes from `lookup_unknown_object()`. Unless we
had already looked up and parsed the object, this will be `OBJ_NONE`.
That's fine, since oe_set_type() sets the type_valid bit to '0', and we
determine the real type later on.
So the only thing we need from the object lookup is access to the
`flags` field so that we can mark that we've added the object with
`OBJECT_ADDED` to avoid adding it again (we can just pass `OBJ_NONE`
directly instead of grabbing it from the object).
But add_object_entry() already rejects duplicates! This has been the
behavior since 7a979d99ba (Thin pack - create packfile with missing
delta base., 2006-02-19), but 08cdfb1337 didn't take advantage of it.
Moreover, to do the OBJECT_ADDED check, we have to do a hash lookup in
`obj_hash`.
So we can drop the lookup_unknown_object() call completely, *and* the
OBJECT_ADDED flag, too, since the spot we're touching here is the only
location that checks it.
In the end, we perform the same number of hash lookups, but with the
added bonus that we don't waste memory allocating an OBJ_NONE object (if
we were traversing, we'd need it eventually, but the whole point of this
code path is not to traverse).
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This function is used to implement `pack-objects`'s `--keep-unreachable`
option, but can be simplified in a couple of ways:
- add_objects_in_unpacked_packs() iterates over all packs (and then
all packed objects) itself, but could use for_each_packed_object()
instead since the missing flags necessary were added in the previous
commit
- objects are added to an in_pack array which store (off_t, object)
tuples, and then sorted in offset order when we could iterate
objects in offset order.
There is a slight behavior change here: before we would have added
objects in sorted offset order among _all_ packs. Handing objects to
create_object_entry() in pack order for each pack (instead of
feeding objects from all packs simultaneously their offset relative
to different packs) is much more reasonable, if different than how
the code currently works.
- objects in a single pack are iterated in index order and searched
for in order to discover their offsets, which is much less efficient
than using the on-disk reverse index
Simplify the function by addressing each of the above and moving the
core of the loop into a callback function that we then pass to
for_each_packed_object() instead of open-coding the latter function
ourselves.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The next patch will reimplement a function that wants to iterate over
packed objects while ignoring packs which are marked as kept (either
in-core or on-disk).
Teach for_each_packed_object() to ignore all objects from those packs by
adding a new flag for each of the "kept" states that a pack can be in.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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There are no other API docs in bundle.h, but this is at least a
start. We'll add a parameter to this function in a subsequent commit,
but let's start by documenting it.
The "/**" comment (as opposed to "/*") signifies the start of API
documentation. See [1] and bdfdaa4978d (strbuf.h: integrate
api-strbuf.txt documentation, 2015-01-16) and 6afbbdda333 (strbuf.h:
unify documentation comments beginnings, 2015-01-16) for a discussion
of that convention.
1. https://lore.kernel.org/git/874kbeecfu.fsf@evledraar.gmail.com/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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git branch only allows deleting branches that point to valid commits.
Skip that check if --force is given, as the caller is indicating with
it that they know what they are doing and accept the consequences.
This allows deleting dangling branches, which previously had to be
reset to a valid start-point using --force first.
Reported-by: Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de>
Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Pass the struct object_id on instead of just its hash member.
This is simpler and avoids the need to guess the algorithm.
Signed-off-by: René Scharfe <l.s.r@web.de>
Acked-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Only one of the callers of rev_is_head() provides two hashes to compare.
Move that check there and convert it to struct object_id.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The word "encoding" can mean a lot of things (e.g., base64 or
quoted-printable encoding in emails, HTML entities, URL encoding, and so
on). The documentation for i18n.commitEncoding and i18n.logOutputEncoding
uses the phrase "character encoding" to make this more clear.
Let's use that phrase in other places to make it clear what kind of
encoding we are talking about. This patch covers the gui.encoding
option, as well as the --encoding option for git-log, etc (in this
latter case, I word-smithed the sentence a little at the same time).
That, coupled with the mention of iconv in the --encoding description,
should make this more clear.
The other spot I looked at is the working-tree-encoding section of
gitattributes(5). But it gives specific examples of encodings that I
think make the meaning pretty clear already.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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If the user asks for a pretty-printed commit to be converted (either
explicitly with --encoding=foo, or implicitly because the commit is
non-utf8 and we want to convert it), we pass it through iconv(). If that
fails, we fall back to showing the input verbatim, but don't tell the
user that the output may be bogus.
Let's add a warning to do so, along with a mention in the documentation
for --encoding. Two things to note about the implementation:
- we could produce the warning closer to the call to iconv() in
reencode_string_len(), which would let us relay the value of errno.
But this is not actually very helpful. reencode_string_len() does
not know we are operating on a commit, and indeed does not know that
the caller won't produce an error of its own. And the errno values
from iconv() are seldom helpful (iconv_open() only ever produces
EINVAL; perhaps EILSEQ from iconv() might be illuminating, but it
can also return EINVAL for incomplete sequences).
- if the reason for the failure is that the output charset is not
supported, then the user will see this warning for every commit we
try to display. That might be ugly and overwhelming, but on the
other hand it is making it clear that every one of them has not been
converted (and the likely outcome anyway is to re-try the command
with a supported output encoding).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The 'Filtering contents...' progress report from delayed checkout is
displayed even when checkout and clone are invoked with --quiet or
--no-progress. Furthermore, it is displayed unconditionally, without
first checking whether stdout is a tty. Let's fix these issues and also
add some regression tests for the two code paths that currently use
delayed checkout: unpack_trees.c:check_updates() and
builtin/checkout.c:checkout_worktree().
Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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'git column's '--nl' option can be used to specify a "string to be
printed at the end of each line" (quoting the man page), but this
option and its mandatory argument has been parsed as OPT_INTEGER since
the introduction of the command in 7e29b8254f (Add column layout
skeleton and git-column, 2012-04-21). Consequently, any non-number
argument is rejected by parse-options, and any number other than 0
leads to segfault:
$ printf "%s\n" one two |git column --mode=plain --nl=foo
error: option `nl' expects a numerical value
$ printf "%s\n" one two |git column --mode=plain --nl=42
Segmentation fault (core dumped)
$ printf "%s\n" one two |git column --mode=plain --nl=0
one
two
Parse this option as OPT_STRING.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In the initial reference advertisement, the Git server will first
announce all of its references to the client. The logic is handled in
`send_ref()`, which will allocate a new buffer for each refline it is
about to send. This is quite wasteful: instead of allocating a new
buffer each time, we can just reuse a buffer.
Improve this by passing in a buffer via the `ls_refs_data` struct which
is then reused on each reference.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Add and apply a semantic patch for using xopen() instead of calling
open(2) and die() or die_errno() explicitly. This makes the error
messages more consistent and shortens the code.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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If the flags O_CREAT and O_EXCL are both given then open(2) is supposed
to create the file and error out if it already exists. The error
message in that case looks like this:
fatal: could not open 'foo' for writing: File exists
Without further context this is confusing: Why should the existence of
the file pose a problem? Isn't that a requirement for writing to it?
Add a more specific error message for that case to tell the user that we
actually don't expect the file to preexist, so the example becomes:
fatal: unable to create 'foo': File exists
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This makes it explicit how alternative ref backends should report errors in
read_raw_ref_fn.
read_raw_ref_fn needs to supply a credible errno for a number of cases. These
are primarily:
1) The files backend calls read_raw_ref from lock_raw_ref, and uses the
resulting error codes to create/remove directories as needed.
2) ENOENT should be translated in a zero OID, optionally with REF_ISBROKEN set,
returning the last successfully resolved symref. This is necessary so
read_raw_ref("HEAD") on an empty repo returns refs/heads/main (or the default branch
du-jour), and we know on which branch to create the first commit.
Make this information flow explicit by adding a failure_errno to the signature
of read_raw_ref. All errnos from the files backend are still propagated
unchanged, even though inspection suggests only ENOTDIR, EISDIR and ENOENT are
relevant.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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refs/files-backend.c::lock_ref_oid_basic() tries to signal how it failed
to its callers using errno.
It is safe to stop setting errno here, because the callers of this
file-scope static function are
* files_copy_or_rename_ref()
* files_create_symref()
* files_reflog_expire()
None of them looks at errno after seeing a negative return from
lock_ref_oid_basic() to make any decision, and no caller of these three
functions looks at errno after they signal a failure by returning a
negative value. In particular,
* files_copy_or_rename_ref() - here, calls are followed by error()
(which performs I/O) or write_ref_to_lockfile() (which calls
parse_object() which may perform I/O)
* files_create_symref() - here, calls are followed by error() or
create_symref_locked() (which performs I/O and does not inspect
errno)
* files_reflog_expire() - here, calls are followed by error() or
refs_reflog_exists() (which calls a function in a vtable that is not
documented to use and/or preserve errno)
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This commit does not change code; it documents the fact that an alternate ref
backend does not need to return EINVAL from read_raw_ref_fn to function
properly.
This is correct, because refs_read_raw_ref is only called from;
* resolve_ref_unsafe(), which does not care for the EINVAL errno result.
* refs_verify_refname_available(), which does not inspect errno.
* files-backend.c, where errno is overwritten on failure.
* packed-backend.c (is_packed_transaction_needed), which calls it for the
packed ref backend, which never emits EINVAL.
A grep for EINVAL */*c reveals that no code checks errno against EINVAL after
reading references. In addition, the refs.h file does not mention errno at all.
A grep over resolve_ref_unsafe() turned up the following callers that inspect
errno:
* sequencer.c::print_commit_summary, which uses it for die_errno
* lock_ref_oid_basic(), which only treats EISDIR and ENOTDIR specially.
The files ref backend does use EINVAL. The files backend does not call into
the generic API (refs_read_raw), but into the files-specific function
(files_read_raw_ref), which we are not changing in this commit.
As the errno sideband is unintuitive and error-prone, remove EINVAL
value, as a step towards getting rid of the errno sideband altogether.
Spotted by Ævar Arnfjörð Bjarmason <avarab@gmail.com>.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Move the raceproof_create_file() API added to cache.h and
object-file.c in 177978f56ad (raceproof_create_file(): new function,
2017-01-06) to its only user, refs/files-backend.c.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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As a follow-up to the preceding commit where we removed the adjacent
"errno == EISDIR" condition in the same function, remove the
"last_errno != ENOTDIR" condition here.
It's not possible for us to hit this condition added in
5b2d8d6f218 (lock_ref_sha1_basic(): improve diagnostics for ref D/F
conflicts, 2015-05-11). Since a1c1d8170db (refs_resolve_ref_unsafe:
handle d/f conflicts for writes, 2017-10-06) we've explicitly caught
these in refs_resolve_ref_unsafe() before returning NULL:
if (errno != ENOENT &&
errno != EISDIR &&
errno != ENOTDIR)
return NULL;
We'd then always return the refname from refs_resolve_ref_unsafe()
even if we were in a broken state as explained in the preceding
commit. The elided context here is a call to refs_resolve_ref_unsafe().
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When we lock a reference like "foo" we need to handle the case where
"foo" exists, but is an empty directory. That's what this code added
in bc7127ef0f (ref locking: allow 'foo' when 'foo/bar' used to exist
but not anymore., 2006-09-30) seems like it should be dealing with.
Except it doesn't, and we never take this branch. The reason is that
when bc7127ef0f was written this looked like:
ref = resolve_ref([...]);
if (!ref && errno == EISDIR) {
[...]
And in resolve_ref() we had this code:
fd = open(path, O_RDONLY);
if (fd < 0)
return NULL;
I.e. we would attempt to read "foo" with open(), which would fail with
EISDIR and we'd return NULL. We'd then take this branch, call
remove_empty_directories() and continue.
Since a1c1d8170d (refs_resolve_ref_unsafe: handle d/f conflicts for
writes, 2017-10-06) we don't. E.g. in the case of
files_copy_or_rename_ref() our callstack will look something like:
[...] ->
files_copy_or_rename_ref() ->
lock_ref_oid_basic() ->
refs_resolve_ref_unsafe()
At that point the first (now only) refs_resolve_ref_unsafe() call in
lock_ref_oid_basic() would do the equivalent of this in the resulting
call to refs_read_raw_ref() in refs_resolve_ref_unsafe():
/* Via refs_read_raw_ref() */
fd = open(path, O_RDONLY);
if (fd < 0)
/* get errno == EISDIR */
/* later, in refs_resolve_ref_unsafe() */
if ([...] && errno != EISDIR)
return NULL;
[...]
/* returns the refs/heads/foo to the caller, even though it's a directory */
return refname;
I.e. even though we got an "errno == EISDIR" we won't take this
branch, since in cases of EISDIR "resolved" is always
non-NULL. I.e. we pretend at this point as though everything's OK and
there is no "foo" directory.
We then proceed with the entire ref update and don't call
remove_empty_directories() until we call commit_ref_update(). See
5387c0d883 (commit_ref(): if there is an empty dir in the way, delete
it, 2016-05-05) for the addition of that code, and
a1c1d8170db (refs_resolve_ref_unsafe: handle d/f conflicts for writes,
2017-10-06) for the commit that changed the original codepath added in
bc7127ef0f to use this "EISDIR" handling.
Further historical commentary:
Before the two preceding commits the caller in files_reflog_expire()
was the only one out of our 4 callers that would pass non-NULL as an
oid. We would then set a (now gone) "resolve_flags" to
"RESOLVE_REF_READING" and just before that "errno != EISDIR" check do:
if (resolve_flags & RESOLVE_REF_READING)
return NULL;
There may have been some case where this ended up mattering and we
couldn't safely make this change before we removed the "oid"
parameter, but I don't think there was, see [1] for some discussion on
that.
In any case, now that we've removed the "oid" parameter in a preceding
commit we can be sure that this code is redundant, so let's remove it.
1. http://lore.kernel.org/git/871r801yp6.fsf@evledraar.gmail.com
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In the preceding commit the last caller that passed a non-NULL OID was
changed to pass NULL to lock_ref_oid_basic(). As noted in preceding
commits use of this API has been going away (we should use ref
transactions, or lock_raw_ref()), so we're unlikely to gain new
callers that want to pass the "oid".
So let's remove it, doing so means we can remove the "mustexist"
condition, and therefore anything except the "flags =
RESOLVE_REF_NO_RECURSE" case.
Furthermore, since the verify_lock() function we called did most of
its work when the "oid" was passed (as "old_oid") we can inline the
trivial part of it that remains in its only remaining caller. Without
a NULL "oid" passed it was equivalent to calling refs_read_ref_full()
followed by oidclr().
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Since the the preceding commit the "oid" parameter to reflog_expire()
is always NULL, but it was not cleaned up to reduce the size of the
diff. Let's do that subsequent API and documentation cleanup now.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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During reflog expiry, the cmd_reflog_expire() function first iterates
over all reflogs in logs/*, and then one-by-one acquires the lock for
each one and expires it. This behavior has been with us since this
command was implemented in 4264dc15e1 ("git reflog expire",
2006-12-19).
Change this to stop calling lock_ref_oid_basic() with the OID we saw
when we looped over the logs, instead have it pass the OID it managed
to lock.
This mostly mitigates a race condition where e.g. "git gc" will fail
in a concurrently updated repository because the branch moved since
"git reflog expire --all" was started. I.e. with:
error: cannot lock ref '<refname>': ref '<refname>' is at <OID-A> but expected <OID-B>
This behavior of passing in an "oid" was needed for an edge-case that
I've untangled in this and preceding commits though, namely that we
needed this OID because we'd:
1. Lookup the reflog name/OID via dwim_log()
2. With that OID, lock the reflog
3. Later in builtin/reflog.c we use the OID we looked as input to
lookup_commit_reference_gently(), assured that it's equal to the
OID we got from dwim_log().
We can be sure that this change is safe to make because between
dwim_log (step #1) and lock_ref_oid_basic (step #2) there was no other
logic relevant to the OID or expiry run in the cmd_reflog_expire()
caller.
We can thus treat that code as a black box, before and after this
change it would get an OID that's been locked, the only difference is
that now we mostly won't be failing to get the lock due to the TOCTOU
race[0]. That failure was purely an implementation detail in how the
"current OID" was looked up, it was divorced from the locking
mechanism.
What do we mean with "mostly"? It mostly mitigates it because we'll
still run into cases where the ref is locked and being updated as we
want to expire it, and other git processes wanting to update the refs
will in turn race with us as we expire the reflog.
That remaining race can in turn be mitigated with the
core.filesRefLockTimeout setting, see 4ff0f01cb7 ("refs: retry
acquiring reference locks for 100ms", 2017-08-21). In practice if that
value is high enough we'll probably never have ref updates or reflog
expiry failing, since the clients involved will retry for far longer
than the time any of those operations could take.
See [1] for an initial report of how this impacted "git gc" and a
large discussion about this change in early 2019. In particular patch
looked good to Michael Haggerty, see his[2]. That message seems to not
have made it to the ML archive, its content is quoted in full in my
[3].
I'm leaving behind now-unused code the refs API etc. that takes the
now-NULL "unused_oid" argument, and other code that can be simplified now
that we never have on OID in that context, that'll be cleaned up in
subsequent commits, but for now let's narrowly focus on fixing the
"git gc" issue. As the modified assert() shows we always pass a NULL
oid to reflog_expire() now.
Unfortunately this sort of probabilistic contention is hard to turn
into a test. I've tested this by running the following three subshells
in concurrent terminals:
(
rm -rf /tmp/git &&
git init /tmp/git &&
while true
do
head -c 10 /dev/urandom | hexdump >/tmp/git/out &&
git -C /tmp/git add out &&
git -C /tmp/git commit -m"out"
done
)
(
rm -rf /tmp/git-clone &&
git clone file:///tmp/git /tmp/git-clone &&
while git -C /tmp/git-clone pull
do
date
done
)
(
while git -C /tmp/git-clone reflog expire --all
do
date
done
)
Before this change the "reflog expire" would fail really quickly with
the "but expected" error noted above.
After this change both the "pull" and "reflog expire" will run for a
while, but eventually fail because I get unlucky with
core.filesRefLockTimeout (the "reflog expire" is in a really tight
loop). As noted above that can in turn be mitigated with higher values
of core.filesRefLockTimeout than the 100ms default.
As noted in the commentary added in the preceding commit there's also
the case of branches being racily deleted, that can be tested by
adding this to the above:
(
while git -C /tmp/git-clone branch topic master &&
git -C /tmp/git-clone branch -D topic
do
date
done
)
With core.filesRefLockTimeout set to 10 seconds (it can probably be a
lot lower) I managed to run all four of these concurrently for about
an hour, and accumulated ~125k commits, auto-gc's and all, and didn't
have a single failure. The loops visibly stall while waiting for the
lock, but that's expected and desired behavior.
0. https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use
1. https://lore.kernel.org/git/87tvg7brlm.fsf@evledraar.gmail.com/
2. http://lore.kernel.org/git/b870a17d-2103-41b8-3cbc-7389d5fff33a@alum.mit.edu
3. https://lore.kernel.org/git/87pnqkco8v.fsf@evledraar.gmail.com/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Add a comment about why it is that we need to check for the the
existence of a reflog we're deleting after we've successfully acquired
the lock in files_reflog_expire(). As noted in [1] the lock protocol
for reflogs is somewhat intuitive.
This early exit code the comment applies to dates all the way back to
4264dc15e19 (git reflog expire, 2006-12-19).
1. https://lore.kernel.org/git/54DCDA42.2060800@alum.mit.edu/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Change the repo_dwim_log() function initially added as dwim_log() in
eb3a48221fd (log --reflog: use dwim_log, 2007-02-09) to accept a NULL
oid parameter. The refs_resolve_ref_unsafe() function it invokes
already deals with it, but it didn't.
This allows for a bit more clarity in a reflog-walk.c codepath added
in f2eba66d4d1 (Enable HEAD@{...} and make it independent from the
current branch, 2007-02-03). We'll shortly use this in
builtin/reflog.c as well.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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