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Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Junio C Hamano <gitster@pobox.com>
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"Why would one want to run it in parallel?" I hear you ask. I am glad
you are curious, because a curious story is what it is, indeed.
The `GIT-VERSION-GEN` script is quite a pillar of Git's source code,
with most lines being unchanged for the past 15 years. Until the v2.48.0
release candidate cycle.
Its original purpose was to generate the version string and store it in
the `GIT-VERSION-FILE`.
This paradigm changed quite dramatically when support for building with
Meson was introduced. Most crucially, a38edab7c88b (Makefile: generate
doc versions via GIT-VERSION-GEN, 2024-12-06) changed the way the
documentation is built by using the `GIT-VERSION-GEN` file to write out
the `asciidocor-extensions.rb` and `asciidoc.conf` files with now
hard-coded version strings.
Crucially, the Makefile rule to generate those files needs to be run in
every build because `GIT_VERSION` could have been specified in the
`make` command-line, which would require these files to be modified.
This introduced a surprising race condition!
And this is how that race surfaces: When calling `make -j2 html man`
from the top-level directory (a variant of which is invoked in Git for
Windows' release process), two sub-processes are spawned, a `make -C
Documentation html` one and a `make -C Documentation man` one. Both run
the rule to (re-)generate `asciidoctor-extensions.rb` or
`asciidoc.conf`, invoking `GIT-VERSION-GEN` to do so. That script first
generates a temporary file (appending the `+` character to the
filename), then looks whether it contains something different than the
already existing file (if it exists, that is), and either replaces it if
needed, or removes the temporary file. If one of the two parallel
invocations removes that temporary file before the other can compare it,
or even worse: if one tries to replace the target file just after the
other _started_ writing the temporary file (but did not finish writing
it yet), that race condition now causes bad builds.
This may sound highly theoretical, but due to the design of Git's build
process, Git for Windows is forced to use a (slow) POSIX emulation layer
to run that script and in the blink of an eye it becomes very much not
theoretical at all. See Exhibit A: These GitHub workflow runs failed
because one of the two competing `make` processes tried to remove the
temporary file when the other process had already done so:
https://github.com/git-for-windows/git-sdk-32/actions/runs/12663456654
https://github.com/git-for-windows/git-sdk-32/actions/runs/12683174970
https://github.com/git-for-windows/git-sdk-64/actions/runs/12649348496
While it is undesirable to run this script over and over again,
certainly when this involves above-mentioned slow POSIX emulation layer,
the stage of the release cycle in which we are presently finding
ourselves does not lend itself to a re-design where this script could be
run once, and once only, but instead dictates that a quick and reliable
work-around be implemented that prevents the race condition without
changing the overall architecture of the build process.
This patch does that: By using a filename suffix for the temporary file
which is based on the currently-executing script's process ID, We
guarantee that the two competing invocations cannot overwrite or remove
each others' temporary files.
The filename suffix still ends in `+` to ensure that the temporary
artifacts are matched by the `*+` pattern in `.gitignore` that was added
in f9bbaa384ef (Add intermediate build products to .gitignore,
2009-11-08).
Helped-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When passing the `-b` flag to git-blame(1), then any blamed boundary
commits which were marked as uninteresting will not get their actual
commit ID printed, but will instead be replaced by a couple of spaces.
The flag can lead to an out-of-bounds write as though when combined with
`--abbrev=` when the abbreviation length is longer than `GIT_MAX_HEXSZ`
as we simply use memset(3p) on that array with the user-provided length
directly. The result is most likely that we segfault.
An obvious fix would be to cull `length` to `GIT_MAX_HEXSZ` many bytes.
But when the underlying object ID is SHA1, and if the abbreviated length
exceeds the SHA1 length, it would cause us to print more bytes than
desired, and the result would be misaligned.
Instead, fix the bug by computing the length via strlen(3p). This makes
us write as many bytes as the formatted object ID requires and thus
effectively limits the length of what we may end up printing to the
length of its hash. If `--abbrev=` asks us to abbreviate to something
shorter than the full length of the underlying hash function it would be
handled by the call to printf(3p) correctly.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In 6411a0a896 (builtin/blame: fix type of `length` variable when
emitting object ID, 2024-12-06) we have fixed the type of the `length`
variable. In order to avoid a cast from `size_t` to `int` in the call to
printf(3p) with the "%.*s" formatter we have converted the code to
instead use fwrite(3p), which accepts the length as a `size_t`.
It was reported though that this makes us read over the end of the OID
array when the provided `--abbrev=` length exceeds the length of the
object ID. This is because fwrite(3p) of course doesn't stop when it
sees a NUL byte, whereas printf(3p) does.
Fix the bug by reverting back to printf(3p) and culling the provided
length to `GIT_MAX_HEXSZ` to keep it from overflowing when cast to an
`int`.
Reported-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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As indicated by the `#undef malloc` line in `reftable/basics.h`, it is
quite common to use allocators other than the default one by defining
`malloc` constants and friends.
This pattern is used e.g. in Git for Windows, which uses the powerful
and performant `mimalloc` allocator.
Furthermore, in `reftable/basics.c` this `#undef malloc` is
_specifically_ disabled by virtue of defining the
`REFTABLE_ALLOW_BANNED_ALLOCATORS` constant before including
`reftable/basic.h`, to ensure that such a custom allocator is also used
in the reftable code.
However, in 8db127d43f5b (reftable: avoid leaks on realloc error,
2024-12-28) and in 2cca185e8517 (reftable: fix allocation count on
realloc error, 2024-12-28), `reftable_set_alloc()` function calls were
introduced that pass `malloc`, `realloc` and `free` function pointers as
parameters _after_ `reftable/basics.h` ensured that they were no longer
`#define`d. This would override the custom allocator and re-set it to
the default allocator provided by, say, libc or MSVCRT.
This causes problems because those calls happen after the initial
allocator has already been used to initialize an array, which is
subsequently resized using the overridden default `realloc()` allocator.
You cannot mix and match allocators like that, which leads to a
`STATUS_HEAP_CORRUPTION` (C0000374) on Windows, and when running this
unit test through shell and/or `prove` (which only support 7-bit status
codes), it surfaces as exit code 127.
It is actually unnecessary to use those function pointers to
`malloc`/`realloc`/`free`, though: The `reftable` code goes out of its
way to fall back to the initial allocator when passing `NULL` parameters
instead. So let's do that instead of causing heap corruptions.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Acked-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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`generate_perl_command` needs `depends: [git_version_file]` and the uses
in top-level meson.build were fine, but the ones in perl/ weren't, causing
parallel build failures in some cases as GIT-BUILD-OPTIONS wasn't yet
available.
Signed-off-by: Sam James <sam@gentoo.org>
Acked-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Correct verb tense, add missing words, avoid double blank lines,
and rephrase things that don’t read well to me like “Turn this linkage
to relative paths”.
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Prior to 0ad3d65652 (object-file: fix race in object collision check,
2024-12-30), callers could expect that a successful return from
`finalize_object_file()` means that either the file was moved into
place, or the identical bytes were already present. If neither of those
happens, we'd return an error.
Since that commit, if the destination file disappears between our
link(3p) call and the collision check, we'd return success without
actually checking the contents, and without retrying the link. This
solves the common case that the files were indeed the same, but it means
that we may corrupt the repository if they weren't (this implies a hash
collision, but the whole point of this function is protecting against
hash collisions).
We can't be pessimistic and assume they're different; that hurts the
common case that the mentioned commit was trying to fix. But after
seeing that the destination file went away, we can retry linking again.
Adapt the code to do so when we see that the destination file has racily
vanished. This should generally succeed as we have just observed that
the destination file does not exist anymore, except in the very unlikely
event that it gets recreated by another concurrent process again.
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In 0ad3d65652 (object-file: fix race in object collision check,
2024-12-30) we have started to ignore ENOENT when opening either the
source or destination file of the collision check. This was done to
handle races more gracefully in case either of the potentially-colliding
disappears.
The fix is overly broad though: while the destination file may indeed
vanish racily, this shouldn't ever happen for the source file, which is
a temporary object file (either loose or in packfile format) that we
have just created. So if any concurrent process would have removed that
temporary file it would indicate an actual issue.
Stop treating ENOENT specially for the source file so that we always
bubble up this error.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Rename variables used in `check_collision()` to clearly identify which
file is the source and which is the destination. This will make the next
step easier to reason about when we start to treat those files different
from one another.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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9e2b7005be (fetch set_head: add warn-if-not-$branch option, 2024-12-05)
tried to expand the advice message for set_head with the new option, but
unfortunately did not manage to add the right incantation. Fix the
advice message with the correct usage of warn-if-not-$branch.
Reported-by: Teng Long <dyroneteng@gmail.com>
Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Update following components:
* advice.c
* archive.c
* builtin/checkout.c
* builtin/clone.c
* builtin/config.c
* builtin/describe.c
* builtin/fetch.c
* builtin/gc.c
* builtin/index-pack.c
* builtin/notes.c
* builtin/pack-objects.c
* builtin/remote.c
* builtin/worktree.c
* commit.c
* fetch-pack.c
* hook.c
* object-name.c
* refs.c
* refs/files-backend.c
* remote.c
* worktree.c
Translate following new components:
* cache-tree.c
* daemon.c
* merge-ll.c
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
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Signed-off-by: Teng Long <dyroneteng@gmail.com>
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Co-authored-by: Kate Golovanova <kate@kgthreads.com>
Signed-off-by: Arkadii Yakovets <ark@cho.red>
Signed-off-by: Kate Golovanova <kate@kgthreads.com>
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Signed-off-by: Peter Krefting <peter@softwolves.pp.se>
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Signed-off-by: Vũ Tiến Hưng <newcomerminecraft@gmail.com>
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`test -f` and `! test -f` do not provide clear error messages when they fail.
To enhance debuggability, use `test_path_is_file` and `test_path_is_missing`,
which instead provide more informative error messages.
Note that `! test -f` checks if a path is not a file, while
`test_path_is_missing` verifies that a path does not exist. In this specific
case the tests are meant to check the absence of the path, making
`test_path_is_missing` a valid replacement.
Signed-off-by: Matteo Bagnolini <matteobagnolini2003@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Reviewed-by: Matthias Rüster <matthias.ruester@gmail.com>
Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
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Commit 1bc1e94091 (doc: option value may be separate for valid reasons,
2024-11-25) added a paragraph discussing tilde-expansion of, e.g.,
~/directory/file.
The tilde character has a special meaning to asciidoc tools. In this
particular case, AsciiDoc matches up the two tildes in "e.g.
~/directory/file or ~u/d/f" and sets the text between them using
subscript. In the manpage, where subscripting is not possible, this
renders as "e.g. /directory/file oru/d/f".
These paths are literal values, which our coding guidelines want typeset
as verbatim using backticks. Do that. One effect of this is indeed that
the asciidoc tools stop interpreting tilde and other special characters.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The two-line heading added in 8525e92886 (Document HOME environment
variable, 2024-12-09) uses too many tilde characters, so the heading
isn't detected as such. Both AsciiDoc and Asciidoctor end up
misrendering this in different ways.
Use the correct number of tilde characters to fix this.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Our CI jobs sometimes see false positive leaks like this:
=================================================================
==3904583==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 32 byte(s) in 1 object(s) allocated from:
#0 0x7fa790d01986 in __interceptor_realloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:98
#1 0x7fa790add769 in __pthread_getattr_np nptl/pthread_getattr_np.c:180
#2 0x7fa790d117c5 in __sanitizer::GetThreadStackTopAndBottom(bool, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:150
#3 0x7fa790d11957 in __sanitizer::GetThreadStackAndTls(bool, unsigned long*, unsigned long*, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:598
#4 0x7fa790d03fe8 in __lsan::ThreadStart(unsigned int, unsigned long long, __sanitizer::ThreadType) ../../../../src/libsanitizer/lsan/lsan_posix.cpp:51
#5 0x7fa790d013fd in __lsan_thread_start_func ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:440
#6 0x7fa790adc3eb in start_thread nptl/pthread_create.c:444
#7 0x7fa790b5ca5b in clone3 ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
This is not a leak in our code, but appears to be a race between one
thread calling exit() while another one is in LSan's stack setup code.
You can reproduce it easily by running t0003 or t5309 with --stress
(these trigger it because of the threading in git-grep and index-pack
respectively).
This may be a bug in LSan, but regardless of whether it is eventually
fixed, it is useful to work around it so that we stop seeing these false
positives.
We can recognize it by the mention of the sanitizer functions in the
DEDUP_TOKEN line. With this patch, the scripts mentioned above should
run with --stress indefinitely.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When we check the leak logs, our original strategy was to check for any
non-empty log file produced by LSan. We later amended that to ignore
noisy lines in 370ef7e40d (test-lib: ignore uninteresting LSan output,
2023-08-28).
This makes it hard to ignore noise which is more than a single line;
we'd have to actually parse the file to determine the meaning of each
line.
But there's an easy line-oriented solution. Because we always pass the
dedup_token_length option, the output will contain a DEDUP_TOKEN line
for each leak that has been found. So if we invert our strategy to stop
ignoring useless lines and only look for useful ones, we can just count
the number of DEDUP_TOKEN lines. If it's non-zero, then we found at
least one leak (it would even give us a count of unique leaks, but we
really only care if it is non-zero).
This should yield the same outcome, but will help us build more false
positive detection on top.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We have a function to count the number of leaks found (actually, it is
the number of processes which produced a log file). Once upon a time we
cared about seeing if this number increased between runs. But we
simplified that away in 95c679ad86 (test-lib: stop showing old leak
logs, 2024-09-24), and now we only care if it returns any results or
not.
In preparation for refactoring it further, let's drop the counting
function entirely, and roll it into the "is it empty" check. The outcome
should be the same, but we'll be free to return a boolean "did we find
anything" without worrying about somebody adding a new call to the
counting function.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When we run with sanitizers, we set abort_on_error=1 so that the tests
themselves can detect problems directly (when the buggy program exits
with SIGABRT). This has one blind spot, though: we don't always check
the exit codes for all programs (e.g., helpers like upload-pack invoked
behind the scenes).
For ASan and UBSan this is mostly fine; they exit as soon as they see an
error, so the unexpected abort of the program causes the test to fail
anyway.
But for LSan, the program runs to completion, since we can only check
for leaks at the end. And in that case we could miss leak reports. And
thus we started checking LSan logs in faececa53f (test-lib: have the
"check" mode for SANITIZE=leak consider leak logs, 2022-07-28).
Originally the logs were optional, but logs are generated (and checked)
always as of 8c1d6691bc (test-lib: GIT_TEST_SANITIZE_LEAK_LOG enabled by
default, 2024-07-11). And we even check them for each test snippet, as
of cf1464331b (test-lib: check for leak logs after every test,
2024-09-24).
So now aborting on error is superfluous for LSan! We can get everything
we need by checking the logs. And checking the logs is actually
preferable, since it gives us more control over silencing false
positives (something we do not yet do, but will soon).
So let's tell LSan to just exit normally, even if it finds leaks. We can
do so with exitcode=0, which also suppresses the abort_on_error flag.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The extra "barrier" approach was too much code whose sole purpose
was to work around a race that is not even ours (i.e. in LSan's
teardown code).
In preparation for queuing a solution taking a much-less-invasive
approach, let's revert them.
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Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Emir SARI <emir_sari@icloud.com>
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Signed-off-by: Junio C Hamano <gitster@pobox.com>
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i18n: expose substitution hint chars in functions and macros to
translators
For example (based on builtin/commit.c and shortened): the "--author"
option takes a name. In source this can be represented as:
OPT_STRING(0, "author", &force_author, N_("author"), N_("override author")),
When the command is run with "-h" (short help) option (git commit -h),
the above definition is displayed as:
--[no-]author <author> override author
Git does not use translated option names so the first part of the
above, "--[no-]author", is given as-is (it is based on the 2nd
argument of OPT_STRING). However the string "author" in the pair of
"<>", and the explanation "override author for commit" may be
translated into user's language.
The user's language may use a convention to mark a replaceable part of
the command line (called a "placeholder string") differently from
enclosing it inside a pair of "<>", but the implementation in
parse-options.c hardcodes "<%s>".
Allow translators to specify the presentation of a placeholder string
for their languages by overriding the "<%s>".
In case the translator's writing system is sufficiently different than
Latin the "<>" characters can be substituted by an empty string thus
effectively skipping them in the output. For example languages with
uppercase versions of characters can use that to deliniate
replaceability.
Alternatively a translator can decide to use characters that are
visually close to "<>" but are not interpreted by the shell.
Signed-off-by: Alexander Shopov <ash@kambanaria.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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There are a couple of backends from which the user can choose for HTTPS,
SHA1, its unsafe variant as well as SHA256. Provide a summary of the
configured values to make these more discoverable.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In 06c92dafb8 (Makefile: allow specifying a SHA-1 for non-cryptographic
uses, 2024-09-26), we have introduced a cryptographically-insecure
backend for SHA1 that can optionally be used in some contexts where the
processed data is not security relevant. This effort was in-flight with
the effort to introduce Meson, so we don't have an equivalent here.
Wire up a new build option that lets users pick an unsafe SHA1 backend.
Note that for simplicity's sake we have to drop the error condition
around an unhandled SHA1 backend. This should be fine though given that
Meson verifies the value for combo-options for us.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Most of our Meson build options end with a trailing dot, but those for
our SHA1 and SHA256 backends don't. Add it.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The conditions used to figure out whteher the Security framework or
OpenSSL library is required are a bit convoluted because they can be
pulled in via the HTTPS, SHA1 or SHA256 backends. Refactor them to be
easier to read.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The Security framework is required when we use CommonCrypto either as
HTTPS or SHA1 backend, but we only require it in case it is set up as
HTTPS backend. Fix this.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We've got a couple of repeated calls to `get_option()` for the SHA1 and
SHA256 backend options. While not an issue, it makes the code needlessly
verbose.
Fix this by consistently using a local variable.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The 'CommonCrypto' backend can be specified as HTTPS and SHA1 backends,
but the value that one needs to use is inconsistent across those two
build options. Unify it to 'CommonCrypto'.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In the preceding commit we have fixed a segfault when using an unsafe
SHA1 backend that is different from the safe one. This segfault only
went by unnoticed because we never set up an unsafe backend in our CI
systems. Fix this ommission by setting `OPENSSL_SHA1_UNSAFE` in our
TEST-vars job.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Same as with the preceding commit, git-fast-import(1) is using the safe
variant to initialize a hashfile checkpoint. This leads to a segfault
when passing the checkpoint into the hashfile subsystem because it would
use the unsafe variants instead:
++ git --git-dir=R/.git fast-import --big-file-threshold=1
AddressSanitizer:DEADLYSIGNAL
=================================================================
==577126==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000040 (pc 0x7ffff7a01a99 bp 0x5070000009c0 sp 0x7fffffff5b30 T0)
==577126==The signal is caused by a READ memory access.
==577126==Hint: address points to the zero page.
#0 0x7ffff7a01a99 in EVP_MD_CTX_copy_ex (/nix/store/h1ydpxkw9qhjdxjpic1pdc2nirggyy6f-openssl-3.3.2/lib/libcrypto.so.3+0x201a99) (BuildId: 41746a580d39075fc85e8c8065b6c07fb34e97d4)
#1 0x555555ddde56 in openssl_SHA1_Clone ../sha1/openssl.h:40:2
#2 0x555555dce2fc in git_hash_sha1_clone_unsafe ../object-file.c:123:2
#3 0x555555c2d5f8 in hashfile_checkpoint ../csum-file.c:211:2
#4 0x5555559647d1 in stream_blob ../builtin/fast-import.c:1110:2
#5 0x55555596247b in parse_and_store_blob ../builtin/fast-import.c:2031:3
#6 0x555555967f91 in file_change_m ../builtin/fast-import.c:2408:5
#7 0x55555595d8a2 in parse_new_commit ../builtin/fast-import.c:2768:4
#8 0x55555595bb7a in cmd_fast_import ../builtin/fast-import.c:3614:4
#9 0x555555b1f493 in run_builtin ../git.c:480:11
#10 0x555555b1bfef in handle_builtin ../git.c:740:9
#11 0x555555b1e6f4 in run_argv ../git.c:807:4
#12 0x555555b1b87a in cmd_main ../git.c:947:19
#13 0x5555561649e6 in main ../common-main.c:64:11
#14 0x7ffff742a1fb in __libc_start_call_main (/nix/store/65h17wjrrlsj2rj540igylrx7fqcd6vq-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: bf320110569c8ec2425e9a0c5e4eb7e97f1fb6e4)
#15 0x7ffff742a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/65h17wjrrlsj2rj540igylrx7fqcd6vq-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: bf320110569c8ec2425e9a0c5e4eb7e97f1fb6e4)
#16 0x555555772c84 in _start (git+0x21ec84)
==577126==Register values:
rax = 0x0000511000000cc0 rbx = 0x0000000000000000 rcx = 0x000000000000000c rdx = 0x0000000000000000
rdi = 0x0000000000000000 rsi = 0x00005070000009c0 rbp = 0x00005070000009c0 rsp = 0x00007fffffff5b30
r8 = 0x0000000000000000 r9 = 0x0000000000000000 r10 = 0x0000000000000000 r11 = 0x00007ffff7a01a30
r12 = 0x0000000000000000 r13 = 0x00007fffffff6b60 r14 = 0x00007ffff7ffd000 r15 = 0x00005555563b9910
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/nix/store/h1ydpxkw9qhjdxjpic1pdc2nirggyy6f-openssl-3.3.2/lib/libcrypto.so.3+0x201a99) (BuildId: 41746a580d39075fc85e8c8065b6c07fb34e97d4) in EVP_MD_CTX_copy_ex
==577126==ABORTING
./test-lib.sh: line 1039: 577126 Aborted git --git-dir=R/.git fast-import --big-file-threshold=1 < input
error: last command exited with $?=134
not ok 167 - R: blob bigger than threshold
The segfault is only exposed in case the unsafe and safe backends are
different from one another.
Fix the issue by initializing the context with the unsafe SHA1 variant.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
|
|
In 1b9e9be8b4 (csum-file.c: use unsafe SHA-1 implementation when
available, 2024-09-26) we have converted our `struct hashfile` to use
the unsafe SHA1 backend, which results in a significant speedup. One
needs to be careful with how to use that structure now though because
callers need to consistently use either the safe or unsafe variants of
SHA1, as otherwise one can easily trigger corruption.
As it turns out, we have one inconsistent usage in our tree because we
directly initialize `struct hashfile_checkpoint::ctx` with the safe
variant of SHA1, but end up writing to that context with the unsafe
ones. This went unnoticed so far because our CI systems do not exercise
different hash functions for these two backends, and consequently safe
and unsafe variants are equivalent. But when using SHA1DC as safe and
OpenSSL as unsafe backend this leads to a crash an t1050:
++ git -c core.compression=0 add large1
AddressSanitizer:DEADLYSIGNAL
=================================================================
==1367==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000040 (pc 0x7ffff7a01a99 bp 0x507000000db0 sp 0x7fffffff5690 T0)
==1367==The signal is caused by a READ memory access.
==1367==Hint: address points to the zero page.
#0 0x7ffff7a01a99 in EVP_MD_CTX_copy_ex (/nix/store/h1ydpxkw9qhjdxjpic1pdc2nirggyy6f-openssl-3.3.2/lib/libcrypto.so.3+0x201a99) (BuildId: 41746a580d39075fc85e8c8065b6c07fb34e97d4)
#1 0x555555ddde56 in openssl_SHA1_Clone ../sha1/openssl.h:40:2
#2 0x555555dce2fc in git_hash_sha1_clone_unsafe ../object-file.c:123:2
#3 0x555555c2d5f8 in hashfile_checkpoint ../csum-file.c:211:2
#4 0x555555b9905d in deflate_blob_to_pack ../bulk-checkin.c:286:4
#5 0x555555b98ae9 in index_blob_bulk_checkin ../bulk-checkin.c:362:15
#6 0x555555ddab62 in index_blob_stream ../object-file.c:2756:9
#7 0x555555dda420 in index_fd ../object-file.c:2778:9
#8 0x555555ddad76 in index_path ../object-file.c:2796:7
#9 0x555555e947f3 in add_to_index ../read-cache.c:771:7
#10 0x555555e954a4 in add_file_to_index ../read-cache.c:804:9
#11 0x5555558b5c39 in add_files ../builtin/add.c:355:7
#12 0x5555558b412e in cmd_add ../builtin/add.c:578:18
#13 0x555555b1f493 in run_builtin ../git.c:480:11
#14 0x555555b1bfef in handle_builtin ../git.c:740:9
#15 0x555555b1e6f4 in run_argv ../git.c:807:4
#16 0x555555b1b87a in cmd_main ../git.c:947:19
#17 0x5555561649e6 in main ../common-main.c:64:11
#18 0x7ffff742a1fb in __libc_start_call_main (/nix/store/65h17wjrrlsj2rj540igylrx7fqcd6vq-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: bf320110569c8ec2425e9a0c5e4eb7e97f1fb6e4)
#19 0x7ffff742a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/65h17wjrrlsj2rj540igylrx7fqcd6vq-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: bf320110569c8ec2425e9a0c5e4eb7e97f1fb6e4)
#20 0x555555772c84 in _start (git+0x21ec84)
==1367==Register values:
rax = 0x0000511000001080 rbx = 0x0000000000000000 rcx = 0x000000000000000c rdx = 0x0000000000000000
rdi = 0x0000000000000000 rsi = 0x0000507000000db0 rbp = 0x0000507000000db0 rsp = 0x00007fffffff5690
r8 = 0x0000000000000000 r9 = 0x0000000000000000 r10 = 0x0000000000000000 r11 = 0x00007ffff7a01a30
r12 = 0x0000000000000000 r13 = 0x00007fffffff6b38 r14 = 0x00007ffff7ffd000 r15 = 0x00005555563b9910
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/nix/store/h1ydpxkw9qhjdxjpic1pdc2nirggyy6f-openssl-3.3.2/lib/libcrypto.so.3+0x201a99) (BuildId: 41746a580d39075fc85e8c8065b6c07fb34e97d4) in EVP_MD_CTX_copy_ex
==1367==ABORTING
./test-lib.sh: line 1023: 1367 Aborted git $config add large1
error: last command exited with $?=134
not ok 4 - add with -c core.compression=0
Fix the issue by using the unsafe variant instead.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
|
|
One of the tests in t5616 asserts that git-fetch(1) with `--refetch`
triggers repository maintenance with the correct set of arguments. This
test is flaky and causes us to fail sometimes:
++ git -c protocol.version=0 -c gc.autoPackLimit=0 -c maintenance.incremental-repack.auto=1234 -C pc1 fetch --refetch origin
error: unable to open .git/objects/pack/pack-029d08823bd8a8eab510ad6ac75c823cfd3ed31e.pack: No such file or directory
fatal: unable to rename temporary file to '.git/objects/pack/pack-029d08823bd8a8eab510ad6ac75c823cfd3ed31e.pack'
fatal: could not finish pack-objects to repack local links
fatal: index-pack failed
error: last command exited with $?=128
The error message is quite confusing as it talks about trying to rename
a temporary packfile. A first hunch would thus be that this packfile
gets written by git-fetch(1), but removed by git-maintenance(1) while it
hasn't yet been finalized, which shouldn't ever happen. And indeed, when
looking closer one notices that the file that is supposedly of temporary
nature does not have the typical `tmp_pack_` prefix.
As it turns out, the "unable to rename temporary file" fatal error is a
red herring and the real error is "unable to open". That error is raised
by `check_collision()`, which is called by `finalize_object_file()` when
moving the new packfile into place. Because t5616 re-fetches objects, we
end up with the exact same pack as we already have in the repository. So
when the concurrent git-maintenance(1) process rewrites the preexisting
pack and unlinks it exactly at the point in time where git-fetch(1)
wants to check the old and new packfiles for equality we will see ENOENT
and thus `check_collision()` returns an error, which gets bubbled up by
`finalize_object_file()` and is then handled by `rename_tmp_packfile()`.
That function does not know about the exact root cause of the error and
instead just claims that the rename has failed.
This race is thus caused by b1b8dfde69 (finalize_object_file():
implement collision check, 2024-09-26), where we have newly introduced
the collision check.
By definition, two files cannot collide with each other when one of them
has been removed. We can thus trivially fix the issue by ignoring ENOENT
when opening either of the files we're about to check for collision.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
|
|
There's a race with LSan when spawning threads and one of the threads
calls die(). We worked around one such problem with index-pack in the
previous commit, but it exists in git-grep, too. You can see it with:
make SANITIZE=leak THREAD_BARRIER_PTHREAD=YesOnLinux
cd t
./t0003-attributes.sh --stress
which fails pretty quickly with:
==git==4096424==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 32 byte(s) in 1 object(s) allocated from:
#0 0x7f906de14556 in realloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:98
#1 0x7f906dc9d2c1 in __pthread_getattr_np nptl/pthread_getattr_np.c:180
#2 0x7f906de2500d in __sanitizer::GetThreadStackTopAndBottom(bool, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:150
#3 0x7f906de25187 in __sanitizer::GetThreadStackAndTls(bool, unsigned long*, unsigned long*, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:614
#4 0x7f906de17d18 in __lsan::ThreadStart(unsigned int, unsigned long long, __sanitizer::ThreadType) ../../../../src/libsanitizer/lsan/lsan_posix.cpp:53
#5 0x7f906de143a9 in ThreadStartFunc<false> ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:431
#6 0x7f906dc9bf51 in start_thread nptl/pthread_create.c:447
#7 0x7f906dd1a677 in __clone3 ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78
As with the previous commit, we can fix this by inserting a barrier that
makes sure all threads have finished their setup before continuing. But
there's one twist in this case: the thread which calls die() is not one
of the worker threads, but the main thread itself!
So we need the main thread to wait in the barrier, too, until all
threads have gotten to it. And thus we initialize the barrier for
num_threads+1, to account for all of the worker threads plus the main
one.
If we then test as above, t0003 should run indefinitely.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
|
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We sometimes get false positives from our linux-leaks CI job because of
a race in LSan itself. The problem is that one thread is still
initializing its stack in LSan's code (and allocating memory to do so)
while anothe thread calls die(), taking down the whole process and
triggering a leak check.
The problem is described in more detail in 993d38a066 (index-pack: spawn
threads atomically, 2024-01-05), which tried to fix it by pausing worker
threads until all calls to pthread_create() had completed. But that's
not enough to fix the problem, because the LSan setup code runs in the
threads themselves. So even though pthread_create() has returned, we
have no idea if all threads actually finished their setup before letting
any of them do real work.
We can fix that by using a barrier inside the threads themselves,
waiting for all of them to hit the start of their main function before
any of them proceed.
You can test for the race by running:
make SANITIZE=leak THREAD_BARRIER_PTHREAD=YesOnLinux
cd t
./t5309-pack-delta-cycles.sh --stress
which fails quickly before this patch, and should run indefinitely
without it.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
|
|
One thread primitive we don't yet support is a barrier: it waits for all
threads to reach a synchronization point before letting any of them
continue. This would be useful for avoiding the LSan race we see in
index-pack (and other places) by having all threads complete their
initialization before any of them start to do real work.
POSIX introduced a pthread_barrier_t in 2004, which does what we want.
But if we want to rely on it:
1. Our Windows pthread emulation would need a new set of wrapper
functions. There's a Synchronization Barrier primitive there, which
was introduced in Windows 8 (which is old enough for us to depend
on).
2. macOS (and possibly other systems) has pthreads but not
pthread_barrier_t. So there we'd have to implement our own barrier
based on the mutex and cond primitives.
Those are do-able, but since we only care about avoiding races in our
LSan builds, there's an easier way: make it a noop on systems without a
native pthread barrier.
This patch introduces a "maybe_thread_barrier" API. The clunky name
(rather than just using pthread_barrier directly) should hopefully clue
people in that on some systems it will do nothing. It's wired to a
Makefile knob which has to be triggered manually, and we enable it for
the linux-leaks CI jobs (since we know we'll have it there).
There are some other possible options:
- we could turn it on all the time for Linux systems based on uname.
But we really only care about it for LSan builds, and there is no
need to add extra code to regular builds.
- we could turn it on only for LSan builds. But that would break
builds on non-Linux platforms (like macOS) that otherwise should
support sanitizers.
- we could trigger only on the combination of Linux and LSan together.
This isn't too hard to do, but the uname check isn't completely
accurate. It is really about what your libc supports, and non-glibc
systems might not have it (though at least musl seems to).
So we'd risk breaking builds on those systems, which would need to
add a new knob. Though the upside would be that running local "make
SANITIZE=leak test" would be protected automatically.
And of course none of this protects LSan runs from races on systems
without pthread barriers. It's probably OK in practice to protect only
our CI jobs, though. The race is rare-ish and most leak-checking happens
through CI.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
|
|
This reverts commit 993d38a0669a8056d496797516e743e26b6b8b54.
That commit was trying to solve a race between LSan setting up the
threads stack and another thread calling exit(), by making sure that all
pthread_create() calls have finished before doing any work that might
trigger the exit().
But that isn't sufficient. The setup code actually runs in the
individual threads themselves, not in the spawning thread's call to
pthread_create(). So while it may have improved the race a bit, you can
still trigger it pretty quickly with:
make SANITIZE=leak
cd t
./t5309-pack-delta-cycles.sh --stress
Let's back out that failed attempt so we can try again.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
|
|
When storing output in test-results/, we usually give each numbered run
in a --stress set its own output file. But we don't do that for storing
LSan logs, so something like:
./t0003-attributes.sh --stress
will have many scripts simultaneously creating, writing to, and deleting
the test-results/t0003-attributes.leak directory. This can cause logs
from one run to be attributed to another, spurious failures when
creation and deletion race, and so on.
This has always been broken, but nobody noticed because it's rare to do
a --stress run with LSan (since the point is for the code to run quickly
many times in order to hit races). But if you're trying to find a race
in the leak sanitizing code, it makes sense to use these together.
We can fix it by using $TEST_RESULTS_BASE, which already incorporates
the stress job suffix.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
|
|
Signed-off-by: Peter Krefting <peter@softwolves.pp.se>
|
|
Signed-off-by: Jean-Noël Avila <jn.avila@free.fr>
|
