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The `%w(width,indent1,indent2)` formatting directive can be used to
rewrap text to a specific width and is designed after git-shortlog(1)'s
`-w` parameter. While the three parameters are all stored as `size_t`
internally, `strbuf_add_wrapped_text()` accepts integers as input. As a
result, the casted integers may overflow. As these now-negative integers
are later on passed to `strbuf_addchars()`, we will ultimately run into
implementation-defined behaviour due to casting a negative number back
to `size_t` again. On my platform, this results in trying to allocate
9000 petabyte of memory.
Fix this overflow by using `cast_size_t_to_int()` so that we reject
inputs that cannot be represented as an integer.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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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
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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>
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When verifying the ownership of the Git directory, we sometimes would
like to say a bit more about it, e.g. when using a platform-dependent
code path (think: Windows has the permission model that is so different
from Unix'), but only when it is a appropriate to actually say
something.
To allow for that, collect that information and hand it back to the
caller (whose responsibility it is to show it or not).
Note: We do not actually fill in any platform-dependent information yet,
this commit just adds the infrastructure to be able to do so.
Based-on-an-idea-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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* maint-2.35:
Git 2.35.4
Git 2.34.4
Git 2.33.4
Git 2.32.3
Git 2.31.4
Git 2.30.5
setup: tighten ownership checks post CVE-2022-24765
git-compat-util: allow root to access both SUDO_UID and root owned
t0034: add negative tests and allow git init to mostly work under sudo
git-compat-util: avoid failing dir ownership checks if running privileged
t: regression git needs safe.directory when using sudo
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* maint-2.34:
Git 2.34.4
Git 2.33.4
Git 2.32.3
Git 2.31.4
Git 2.30.5
setup: tighten ownership checks post CVE-2022-24765
git-compat-util: allow root to access both SUDO_UID and root owned
t0034: add negative tests and allow git init to mostly work under sudo
git-compat-util: avoid failing dir ownership checks if running privileged
t: regression git needs safe.directory when using sudo
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* maint-2.33:
Git 2.33.4
Git 2.32.3
Git 2.31.4
Git 2.30.5
setup: tighten ownership checks post CVE-2022-24765
git-compat-util: allow root to access both SUDO_UID and root owned
t0034: add negative tests and allow git init to mostly work under sudo
git-compat-util: avoid failing dir ownership checks if running privileged
t: regression git needs safe.directory when using sudo
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* maint-2.32:
Git 2.32.3
Git 2.31.4
Git 2.30.5
setup: tighten ownership checks post CVE-2022-24765
git-compat-util: allow root to access both SUDO_UID and root owned
t0034: add negative tests and allow git init to mostly work under sudo
git-compat-util: avoid failing dir ownership checks if running privileged
t: regression git needs safe.directory when using sudo
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* maint-2.31:
Git 2.31.4
Git 2.30.5
setup: tighten ownership checks post CVE-2022-24765
git-compat-util: allow root to access both SUDO_UID and root owned
t0034: add negative tests and allow git init to mostly work under sudo
git-compat-util: avoid failing dir ownership checks if running privileged
t: regression git needs safe.directory when using sudo
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* maint-2.30:
Git 2.30.5
setup: tighten ownership checks post CVE-2022-24765
git-compat-util: allow root to access both SUDO_UID and root owned
t0034: add negative tests and allow git init to mostly work under sudo
git-compat-util: avoid failing dir ownership checks if running privileged
t: regression git needs safe.directory when using sudo
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"sudo git foo" used to consider a repository owned by the original
user a safe one to access; it now also considers a repository owned
by root a safe one, too (after all, if an attacker can craft a
malicious repository owned by root, the box is 0wned already).
* cb/path-owner-check-with-sudo-plus:
git-compat-util: allow root to access both SUDO_UID and root owned
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Previous changes introduced a regression which will prevent root for
accessing repositories owned by thyself if using sudo because SUDO_UID
takes precedence.
Loosen that restriction by allowing root to access repositories owned
by both uid by default and without having to add a safe.directory
exception.
A previous workaround that was documented in the tests is no longer
needed so it has been removed together with its specially crafted
prerequisite.
Helped-by: Johanness Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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A new bug() and BUG_if_bug() API is introduced to make it easier to
uniformly log "detect multiple bugs and abort in the end" pattern.
* ab/bug-if-bug:
cache-tree.c: use bug() and BUG_if_bug()
receive-pack: use bug() and BUG_if_bug()
parse-options.c: use optbug() instead of BUG() "opts" check
parse-options.c: use new bug() API for optbug()
usage.c: add a non-fatal bug() function to go with BUG()
common-main.c: move non-trace2 exit() behavior out of trace2.c
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Preliminary code refactoring around transport and bundle code.
* ds/bundle-uri:
bundle.h: make "fd" version of read_bundle_header() public
remote: allow relative_url() to return an absolute url
remote: move relative_url()
http: make http_get_file() external
fetch-pack: move --keep=* option filling to a function
fetch-pack: add a deref_without_lazy_fetch_extended()
dir API: add a generalized path_match_flags() function
connect.c: refactor sending of agent & object-format
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Introduce a filesystem-dependent mechanism to optimize the way the
bits for many loose object files are ensured to hit the disk
platter.
* ns/batch-fsync:
core.fsyncmethod: performance tests for batch mode
t/perf: add iteration setup mechanism to perf-lib
core.fsyncmethod: tests for batch mode
test-lib-functions: add parsing helpers for ls-files and ls-tree
core.fsync: use batch mode and sync loose objects by default on Windows
unpack-objects: use the bulk-checkin infrastructure
update-index: use the bulk-checkin infrastructure
builtin/add: add ODB transaction around add_files_to_cache
cache-tree: use ODB transaction around writing a tree
core.fsyncmethod: batched disk flushes for loose-objects
bulk-checkin: rebrand plug/unplug APIs as 'odb transactions'
bulk-checkin: rename 'state' variable and separate 'plugged' boolean
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Add a bug() function to use in cases where we'd like to indicate a
runtime BUG(), but would like to defer the BUG() call because we're
possibly accumulating more bug() callers to exhaustively indicate what
went wrong.
We already have this sort of facility in various parts of the
codebase, just in the form of ad-hoc re-inventions of the
functionality that this new API provides. E.g. this will be used to
replace optbug() in parse-options.c, and the 'error("BUG:[...]' we do
in a loop in builtin/receive-pack.c.
Unlike the code this replaces we'll log to trace2 with this new bug()
function (as with other usage.c functions, including BUG()), we'll
also be able to avoid calls to xstrfmt() in some cases, as the bug()
function itself accepts variadic sprintf()-like arguments.
Any caller to bug() can follow up such calls with BUG_if_bug(),
which will BUG() out (i.e. abort()) if there were any preceding calls
to bug(), callers can also decide not to call BUG_if_bug() and leave
the resulting BUG() invocation until exit() time. There are currently
no bug() API users that don't call BUG_if_bug() themselves after a
for-loop, but allowing for not calling BUG_if_bug() keeps the API
flexible. As the tests and documentation here show we'll catch missing
BUG_if_bug() invocations in our exit() wrapper.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Change the exit() wrapper added in ee4512ed481 (trace2: create new
combined trace facility, 2019-02-22) so that we'll split up the trace2
logging concerns from wanting to wrap the "exit()" function itself for
other purposes.
This makes more sense structurally, as we won't seem to conflate
non-trace2 behavior with the trace2 code. I'd previously added an
explanation for this in 368b5843158 (common-main.c: call exit(), don't
return, 2021-12-07), that comment is being adjusted here.
Now the only thing we'll do if we're not using trace2 is to truncate
the "code" argument to the lowest 8 bits.
We only need to do that truncation on non-POSIX systems, but in
ee4512ed481 that "if defined(__MINGW32__)" code added in
47e3de0e796 (MinGW: truncate exit()'s argument to lowest 8 bits,
2009-07-05) was made to run everywhere. It might be good for clarify
to narrow that down by an "ifdef" again, but I'm not certain that in
the interim we haven't had some other non-POSIX systems rely the
behavior. On a POSIX system taking the lowest 8 bits is implicit, see
exit(3)[1] and wait(2)[2]. Let's leave a comment about that instead.
1. https://man7.org/linux/man-pages/man3/exit.3.html
2. https://man7.org/linux/man-pages/man2/wait.2.html
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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With a recent update to refuse access to repositories of other
people by default, "sudo make install" and "sudo git describe"
stopped working. This series intends to loosen it while keeping
the safety.
* cb/path-owner-check-with-sudo:
t0034: add negative tests and allow git init to mostly work under sudo
git-compat-util: avoid failing dir ownership checks if running privileged
t: regression git needs safe.directory when using sudo
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Add a path_match_flags() function and have the two sets of
starts_with_dot_{,dot_}slash() functions added in
63e95beb085 (submodule: port resolve_relative_url from shell to C,
2016-04-15) and a2b26ffb1a8 (fsck: convert gitmodules url to URL
passed to curl, 2020-04-18) be thin wrappers for it.
As the latter of those notes the fsck version was copied from the
initial builtin/submodule--helper.c version.
Since the code added in a2b26ffb1a8 was doing really doing the same as
win32_is_dir_sep() added in 1cadad6f658 (git clone <url>
C:\cygwin\home\USER\repo' is working (again), 2018-12-15) let's move
the latter to git-compat-util.h is a is_xplatform_dir_sep(). We can
then call either it or the platform-specific is_dir_sep() from this
new function.
Let's likewise change code in various other places that was hardcoding
checks for "'/' || '\\'" with the new is_xplatform_dir_sep(). As can
be seen in those callers some of them still concern themselves with
':' (Mac OS classic?), but let's leave the question of whether that
should be consolidated for some other time.
As we expect to make wider use of the "native" case in the future,
define and use two starts_with_dot_{,dot_}slash_native() convenience
wrappers. This makes the diff in builtin/submodule--helper.c much
smaller.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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bdc77d1d685 (Add a function to determine whether a path is owned by the
current user, 2022-03-02) checks for the effective uid of the running
process using geteuid() but didn't account for cases where that user was
root (because git was invoked through sudo or a compatible tool) and the
original uid that repository trusted for its config was no longer known,
therefore failing the following otherwise safe call:
guy@renard ~/Software/uncrustify $ sudo git describe --always --dirty
[sudo] password for guy:
fatal: unsafe repository ('/home/guy/Software/uncrustify' is owned by someone else)
Attempt to detect those cases by using the environment variables that
those tools create to keep track of the original user id, and do the
ownership check using that instead.
This assumes the environment the user is running on after going
privileged can't be tampered with, and also adds code to restrict that
the new behavior only applies if running as root, therefore keeping the
most common case, which runs unprivileged, from changing, but because of
that, it will miss cases where sudo (or an equivalent) was used to change
to another unprivileged user or where the equivalent tool used to raise
privileges didn't track the original id in a sudo compatible way.
Because of compatibility with sudo, the code assumes that uid_t is an
unsigned integer type (which is not required by the standard) but is used
that way in their codebase to generate SUDO_UID. In systems where uid_t
is signed, sudo might be also patched to NOT be unsigned and that might
be able to trigger an edge case and a bug (as described in the code), but
it is considered unlikely to happen and even if it does, the code would
just mostly fail safely, so there was no attempt either to detect it or
prevent it by the code, which is something that might change in the future,
based on expected user feedback.
Reported-by: Guy Maurel <guy.j@maurel.de>
Helped-by: SZEDER Gábor <szeder.dev@gmail.com>
Helped-by: Randall Becker <rsbecker@nexbridge.com>
Helped-by: Phillip Wood <phillip.wood123@gmail.com>
Suggested-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Build fix.
* bc/csprng-mktemps:
git-compat-util: really support openssl as a source of entropy
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Git for Windows has defaulted to core.fsyncObjectFiles=true since
September 2017. We turn on syncing of loose object files with batch mode
in upstream Git so that we can get broad coverage of the new code
upstream.
We don't actually do fsyncs in the most of the test suite, since
GIT_TEST_FSYNC is set to 0. However, we do exercise all of the
surrounding batch mode code since GIT_TEST_FSYNC merely makes the
maybe_fsync wrapper always appear to succeed.
Signed-off-by: Neeraj Singh <neerajsi@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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* ns/core-fsyncmethod:
configure.ac: fix HAVE_SYNC_FILE_RANGE definition
core.fsyncmethod: correctly camel-case warning message
core.fsync: fix incorrect expression for default configuration
core.fsync: documentation and user-friendly aggregate options
core.fsync: new option to harden the index
core.fsync: add configuration parsing
core.fsync: introduce granular fsync control infrastructure
core.fsyncmethod: add writeout-only mode
wrapper: make inclusion of Windows csprng header tightly scoped
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05cd988dce5 (wrapper: add a helper to generate numbers from a CSPRNG,
2022-01-17), configure openssl as the source for entropy in NON-STOP
but doesn't add the needed header or link options.
Since the only system that is configured to use openssl as a source
of entropy is NON-STOP, add the header unconditionally, and -lcrypto
to the list of external libraries.
An additional change is required to make sure a NO_OPENSSL=1 build
will be able to work as well (tested on Linux with a modified value
of CSPRNG_METHOD = openssl), and the more complex logic that allows
for compatibility with APPLE_COMMON_CRYPTO or allowing for simpler
ways to link (without libssl) has been punted for now.
Reported-by: Randall Becker <rsbecker@nexbridge.com>
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Add some global trace2 statistics for the number of fsyncs performed
during the lifetime of a Git process.
These stats are printed as part of trace2_cmd_exit_fl, which is
presumably where we might want to print any other cross-cutting
statistics.
Signed-off-by: Neeraj Singh <neerajsi@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Replace core.fsyncObjectFiles with two new configuration variables,
core.fsync and core.fsyncMethod.
* ns/core-fsyncmethod:
core.fsync: documentation and user-friendly aggregate options
core.fsync: new option to harden the index
core.fsync: add configuration parsing
core.fsync: introduce granular fsync control infrastructure
core.fsyncmethod: add writeout-only mode
wrapper: make inclusion of Windows csprng header tightly scoped
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* maint-2.34:
Git 2.34.2
Git 2.33.2
Git 2.32.1
Git 2.31.2
GIT-VERSION-GEN: bump to v2.33.1
Git 2.30.3
setup_git_directory(): add an owner check for the top-level directory
Add a function to determine whether a path is owned by the current user
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* maint-2.33:
Git 2.33.2
Git 2.32.1
Git 2.31.2
GIT-VERSION-GEN: bump to v2.33.1
Git 2.30.3
setup_git_directory(): add an owner check for the top-level directory
Add a function to determine whether a path is owned by the current user
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* maint-2.32:
Git 2.32.1
Git 2.31.2
Git 2.30.3
setup_git_directory(): add an owner check for the top-level directory
Add a function to determine whether a path is owned by the current user
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* maint-2.31:
Git 2.31.2
Git 2.30.3
setup_git_directory(): add an owner check for the top-level directory
Add a function to determine whether a path is owned by the current user
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* maint-2.30:
Git 2.30.3
setup_git_directory(): add an owner check for the top-level directory
Add a function to determine whether a path is owned by the current user
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This function will be used in the next commit to prevent
`setup_git_directory()` from discovering a repository in a directory
that is owned by someone other than the current user.
Note: We cannot simply use `st.st_uid` on Windows just like we do on
Linux and other Unix-like platforms: according to
https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/stat-functions
this field is always zero on Windows (because Windows' idea of a user ID
does not fit into a single numerical value). Therefore, we have to do
something a little involved to replicate the same functionality there.
Also note: On Windows, a user's home directory is not actually owned by
said user, but by the administrator. For all practical purposes, it is
under the user's control, though, therefore we pretend that it is owned
by the user.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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mingw-w64's pthread_unistd.h had a bug that mistakenly (because there is
no support for the *lockfile() functions required[1]) defined
_POSIX_THREAD_SAFE_FUNCTIONS and that was being worked around since
3ecd153a3b (compat/mingw: support MSys2-based MinGW build, 2016-01-14).
The bug was fixed in winphtreads, but as a side effect, leaves the
reentrant functions from time.h no longer visible and therefore breaks
the build.
Since the intention all along was to avoid using the fallback functions,
formalize the use of POSIX by setting the corresponding feature flag and
compile out the implementation for the fallback functions.
[1] https://unix.org/whitepapers/reentrant.html
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Acked-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This commit introduces the `core.fsyncMethod` configuration
knob, which can currently be set to `fsync` or `writeout-only`.
The new writeout-only mode attempts to tell the operating system to
flush its in-memory page cache to the storage hardware without issuing a
CACHE_FLUSH command to the storage controller.
Writeout-only fsync is significantly faster than a vanilla fsync on
common hardware, since data is written to a disk-side cache rather than
all the way to a durable medium. Later changes in this patch series will
take advantage of this primitive to implement batching of hardware
flushes.
When git_fsync is called with FSYNC_WRITEOUT_ONLY, it may fail and the
caller is expected to do an ordinary fsync as needed.
On Apple platforms, the fsync system call does not issue a CACHE_FLUSH
directive to the storage controller. This change updates fsync to do
fcntl(F_FULLFSYNC) to make fsync actually durable. We maintain parity
with existing behavior on Apple platforms by setting the default value
of the new core.fsyncMethod option.
Signed-off-by: Neeraj Singh <neerajsi@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Including NTSecAPI.h in git-compat-util.h causes build errors in any
other file that includes winternl.h. NTSecAPI.h was included in order to
get access to the RtlGenRandom cryptographically secure PRNG. This
change scopes the inclusion of ntsecapi.h to wrapper.c, which is the only
place that it's actually needed.
The build breakage is due to the definition of UNICODE_STRING in
NtSecApi.h:
#ifndef _NTDEF_
typedef LSA_UNICODE_STRING UNICODE_STRING, *PUNICODE_STRING;
typedef LSA_STRING STRING, *PSTRING ;
#endif
LsaLookup.h:
typedef struct _LSA_UNICODE_STRING {
USHORT Length;
USHORT MaximumLength;
#ifdef MIDL_PASS
[size_is(MaximumLength/2), length_is(Length/2)]
#endif // MIDL_PASS
PWSTR Buffer;
} LSA_UNICODE_STRING, *PLSA_UNICODE_STRING;
winternl.h also defines UNICODE_STRING:
typedef struct _UNICODE_STRING {
USHORT Length;
USHORT MaximumLength;
PWSTR Buffer;
} UNICODE_STRING;
typedef UNICODE_STRING *PUNICODE_STRING;
Both definitions have equivalent layouts. Apparently these internal
Windows headers aren't designed to be included together. This is
an oversight in the headers and does not represent an incompatibility
between the APIs.
Signed-off-by: Neeraj Singh <neerajsi@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Remove the "else" branches of the HAVE_VARIADIC_MACROS macro, which
have been unconditionally omitted since 765dc168882 (git-compat-util:
always enable variadic macros, 2021-01-28).
Since were always omitted, anyone trying to use a compiler without
variadic macro support to compile a git since version
git v2.31.0 or later would have had a compilation error. 10 months
across a few releases since then should have been enough time for
anyone who cared to run into that and report the issue.
In addition to that, for anyone unsetting HAVE_VARIADIC_MACROS we've
been emitting extremely verbose warnings since at least
ee4512ed481 (trace2: create new combined trace facility,
2019-02-22). That's because there is no such thing as a
"region_enter_printf" or "region_leave_printf" format, so at least
under GCC and Clang everything that includes trace.h (almost every
file) emits a couple of warnings about that.
There's a large benefit to being able to have a hard dependency rely
on variadic macros, the code surrounding usage.c is hard to maintain
if we need to write two implementations of everything, and by relying
on "__FILE__" and "__LINE__" along with "__VA_ARGS__" we can in the
future make error(), die() etc. log where they were called from. We've
also recently merged d67fc4bf0ba (Merge branch 'bc/require-c99',
2021-12-10) which further cements our hard dependency on C99.
So let's delete the fallback code, and update our CodingGuidelines to
note that we depend on this. The added bullet-point starts with
lower-case for consistency with other bullet-points in that section.
The diff in "trace.h" is relatively hard to read, since we need to
retain the existing API docs, which were comments on the code used if
HAVE_VARIADIC_MACROS was not defined.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Change a comment added in e208f9cc757 (make error()'s constant return
value more visible, 2012-12-15). It's not correct that this is GCC-ism
anymore, it's code that uses standard C99 features.
The comment being changed here pre-dates the HAVE_VARIADIC_MACROS
define, which we got in e05bed960d3 (trace: add 'file:line' to all
trace output, 2014-07-12).
The original implementation of an error() macro) in e208f9cc757 used a
GCC-ism with the paste operator (see the commit message for mention of
it), but that was dropped later by 9798f7e5f9 (Use __VA_ARGS__ for all
of error's arguments, 2013-02-08), giving us the C99-portable version
we have now.
While we could remove the __GNUC__ define here, it might cause issues
for other compilers or static analysis systems, so let's not. See
87fe5df365 (inline constant return from error() function, 2014-05-06)
for one such issue.
See also e05bed960d3 (trace: add 'file:line' to all trace output,
2014-07-12) for another comment about GNUC's handling of __VA_ARGS__.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The build procedure has been taught to notice older version of zlib
and enable our replacement uncompress2() automatically.
* ab/auto-detect-zlib-compress2:
compat: auto-detect if zlib has uncompress2()
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Pick a better random number generator and use it when we prepare
temporary filenames.
* bc/csprng-mktemps:
wrapper: use a CSPRNG to generate random file names
wrapper: add a helper to generate numbers from a CSPRNG
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We have a copy of uncompress2() implementation in compat/ so that we
can build with an older version of zlib that lack the function, and
the build procedure selects if it is used via the NO_UNCOMPRESS2
$(MAKE) variable. This is yet another "annoying" knob the porters
need to tweak on platforms that are not common enough to have the
default set in the config.mak.uname file.
Attempt to instead ask the system header <zlib.h> to decide if we
need the compatibility implementation. This is a deviation from the
way we have been handling the "compatiblity" features so far, and if
it can be done cleanly enough, it could work as a model for features
that need compatibility definition we discover in the future. With
that goal in mind, avoid expedient but ugly hacks, like shoving the
code that is conditionally compiled into an unrelated .c file, which
may not work in future cases---instead, take an approach that uses a
file that is independently compiled and stands on its own.
Compile and link compat/zlib-uncompress2.c file unconditionally, but
conditionally hide the implementation behind #if/#endif when zlib
version is 1.2.9 or newer, and unconditionally archive the resulting
object file in the libgit.a to be picked up by the linker.
There are a few things to note in the shape of the code base after
this change:
- We no longer use NO_UNCOMPRESS2 knob; if the system header
<zlib.h> claims a version that is more cent than the library
actually is, this would break, but it is easy to add it back when
we find such a system.
- The object file compat/zlib-uncompress2.o is always compiled and
archived in libgit.a, just like a few other compat/ object files
already are.
- The inclusion of <zlib.h> is done in <git-compat-util.h>; we used
to do so from <cache.h> which includes <git-compat-util.h> as the
first thing it does, so from the *.c codes, there is no practical
change.
- Until objects in libgit.a that is already used gains a reference
to the function, the reftable code will be the only one that
wants it, so libgit.a on the linker command line needs to appear
once more at the end to satisify the mutual dependency.
- Beat found a trick used by OpenSSL to avoid making the
conditionally-compiled object truly empty (apparently because
they had to deal with compilers that do not want to see an
effectively empty input file). Our compat/zlib-uncompress2.c
file borrows the same trick for portabilty.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Helped-by: Beat Bolli <dev+git@drbeat.li>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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There are many situations in which having access to a cryptographically
secure pseudorandom number generator (CSPRNG) is helpful. In the
future, we'll encounter one of these when dealing with temporary files.
To make this possible, let's add a function which reads from a system
CSPRNG and returns some bytes.
We know that all systems will have such an interface. A CSPRNG is
required for a secure TLS or SSH implementation and a Git implementation
which provided neither would be of little practical use. In addition,
POSIX is set to standardize getentropy(2) in the next version, so in the
(potentially distant) future we can rely on that.
For systems which lack one of the other interfaces, we provide the
ability to use OpenSSL's CSPRNG. OpenSSL is highly portable and
functions on practically every known OS, and we know it will have access
to some source of cryptographically secure randomness. We also provide
support for the arc4random in libbsd for folks who would prefer to use
that.
Because this is a security sensitive interface, we take some
precautions. We either succeed by filling the buffer completely as we
requested, or we fail. We don't return partial data because the caller
will almost never find that to be a useful behavior.
Specify a makefile knob which users can use to specify one or more
suitable CSPRNGs, and turn the multiple string options into a set of
defines, since we cannot match on strings in the preprocessor. We allow
multiple options to make the job of handling this in autoconf easier.
The order of options is important here. On systems with arc4random,
which is most of the BSDs, we use that, since, except on MirBSD and
macOS, it uses ChaCha20, which is extremely fast, and sits entirely in
userspace, avoiding a system call. We then prefer getrandom over
getentropy, because the former has been available longer on Linux, and
then OpenSSL. Finally, if none of those are available, we use
/dev/urandom, because most Unix-like operating systems provide that API.
We prefer options that don't involve device files when possible because
those work in some restricted environments where device files may not be
available.
Set the configuration variables appropriately for Linux and the BSDs,
including macOS, as well as Windows and NonStop. We specifically only
consider versions which receive publicly available security support
here. For the same reason, we don't specify getrandom(2) on Linux,
because CentOS 7 doesn't support it in glibc (although its kernel does)
and we don't want to resort to making syscalls.
Finally, add a test helper to allow this to be tested by hand and in
tests. We don't add any tests, since invoking the CSPRNG is not likely
to produce interesting, reproducible results.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Code clean-up to hide vreportf() from public API.
* ab/usage-die-message:
config API: use get_error_routine(), not vreportf()
usage.c + gc: add and use a die_message_errno()
gc: return from cmd_gc(), don't call exit()
usage.c API users: use die_message() for error() + exit 128
usage.c API users: use die_message() for "fatal :" + exit 128
usage.c: add a die_message() routine
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