Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Add the capability to send smoke reports from the Git test suite.

Currently we only notice bugs in the test suite when it's run
manually. Bugs in Git that only occur on obscure platforms or setups
that the core developers aren't using can thus go unnoticed.

This series aims to change that. With it, anyone that's interested in
avoiding bitrot in Git can volunteer to run a smoke tester. A smoke
tester periodically compiles the latest version of Git, runs the test
suite, and submits a report to a central server indicating how the
test run went.

A smoke tester might run something like this in cron:

    #!/bin/sh
    cd ~/g/git
    git fetch
    for branch in maint master next pu; do
        git checkout origin/$i &&
        make clean all &&
        cd t &&
        make smoke_report
    done

The smoker might want to compile git with non-default flags, include
bisecting functionality or run the tests under valgrind. Doing that is
outside the scope of this patch, this just adds a report submission
mechanism. But including a canonical smoke runner is something we'll
want to include eventually.

What this does now is add smoke and smoke_report targets to t/Makefile
(this example only uses a few tests for demonstration):

    $ make clean smoke
    rm -f -r 'trash directory'.* test-results
    rm -f t????/cvsroot/CVSROOT/?*
    rm -f -r valgrind/bin
    rm -f .prove
    perl ./harness --git-version="1.7.2.1.173.gc9b40" \
                    --no-verbose \
                    --archive="test-results/git-smoke.tar.gz" \
                    t0000-basic.sh t0001-init.sh t0002-gitfile.sh t0003-attributes.sh t0004-unwritable.sh t0005-signals.sh t0006-date.sh
    t0000-basic.sh ....... ok
    t0001-init.sh ........ ok
    t0002-gitfile.sh ..... ok
    t0003-attributes.sh .. ok
    t0004-unwritable.sh .. ok
    t0005-signals.sh ..... ok
    t0006-date.sh ........ ok
    All tests successful.

    Test Summary Report
    -------------------
    t0000-basic.sh     (Wstat: 0 Tests: 46 Failed: 0)
      TODO passed:   5
    Files=7, Tests=134,  3 wallclock secs ( 0.06 usr  0.05 sys +  0.23 cusr  1.33 csys =  1.67 CPU)
    Result: PASS

    TAP Archive created at /home/avar/g/git/t/test-results/git-smoke.tar.gz

The smoke target uses TAP::Harness::Archive to aggregate the test
results into a tarball. The tarball contains two things, the output of
every test file that was run, and a metadata file:

Tarball contents:

    $ tar xzvf git-smoke.tar.gz
    t0004-unwritable.sh
    t0001-init.sh
    t0002-gitfile.sh
    t0005-signals.sh
    t0000-basic.sh
    t0003-attributes.sh
    t0006-date.sh
    meta.yml

A test report:

    $ cat t0005-signals.sh
    ok 1 - sigchain works
    # passed all 1 test(s)
    1..1

A metadata file:

    ---
    extra_properties:
    file_attributes:
      -
        description: t0000-basic.sh
        end_time: 1280437324.61398
        start_time: 1280437324.22186
      -
        description: t0001-init.sh
        end_time: 1280437325.12346
        start_time: 1280437324.62393
      -
        description: t0002-gitfile.sh
        end_time: 1280437325.29428
        start_time: 1280437325.13646
      -
        description: t0003-attributes.sh
        end_time: 1280437325.59678
        start_time: 1280437325.30565
      -
        description: t0004-unwritable.sh
        end_time: 1280437325.77376
        start_time: 1280437325.61003
      -
        description: t0005-signals.sh
        end_time: 1280437325.85426
        start_time: 1280437325.78727
      -
        description: t0006-date.sh
        end_time: 1280437326.2362
        start_time: 1280437325.86768
    file_order:
      - t0000-basic.sh
      - t0001-init.sh
      - t0002-gitfile.sh
      - t0003-attributes.sh
      - t0004-unwritable.sh
      - t0005-signals.sh
      - t0006-date.sh
    start_time: 1280437324
    stop_time: 1280437326

The "extra_properties" hash is where we'll stick Git-specific info,
like whether Git was compiled with gettext or the fallback regex
engine, and what branch we're compiling. Currently no metadata like
this is included.

The entire tarball is then submitted to a central smokebox at
smoke.git.nix.is. This is done with curl(1) via the "smoke_report"
target:

    $ make smoke_report
    curl \
                    -H "Expect: " \
                    -F project=Git \
                    -F architecture=x86_64 \
                    -F platform=Linux \
                    -F revision="1.7.2.1.173.gc9b40" \
                    -F report_file=@test-results/git-smoke.tar.gz \
                    http://smoke.git.nix.is/app/projects/process_add_report/1 \
            | grep -v ^Redirecting
      % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                     Dload  Upload   Total   Spent    Left  Speed
    100  117k  100    63  100  117k      3   6430  0:00:21  0:00:18  0:00:03     0
    Reported #8 added.

Reports are then made available on the smokebox via a web interface:

    http://smoke.git.nix.is/app/projects/smoke_reports/1

The smoke reports are also mirrored to a Git repository hosted on
GitHub:

    http://github.com/gitsmoke/smoke-reports

The Smolder SQLite database that contains metadata about the reports
is also made available:

    http://github.com/gitsmoke/smoke-database

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>

Add the capability to send smoke reports from the Git test suite.

Currently we only notice bugs in the test suite when it's run
manually. Bugs in Git that only occur on obscure platforms or setups
that the core developers aren't using can thus go unnoticed.

This series aims to change that. With it, anyone that's interested in
avoiding bitrot in Git can volunteer to run a smoke tester. A smoke
tester periodically compiles the latest version of Git, runs the test
suite, and submits a report to a central server indicating how the
test run went.

A smoke tester might run something like this in cron:

    #!/bin/sh
    cd ~/g/git
    git fetch
    for branch in maint master next pu; do
        git checkout origin/$i &&
        make clean all &&
        cd t &&
        make smoke_report
    done

The smoker might want to compile git with non-default flags, include
bisecting functionality or run the tests under valgrind. Doing that is
outside the scope of this patch, this just adds a report submission
mechanism. But including a canonical smoke runner is something we'll
want to include eventually.

What this does now is add smoke and smoke_report targets to t/Makefile
(this example only uses a few tests for demonstration):

    $ make clean smoke
    rm -f -r 'trash directory'.* test-results
    rm -f t????/cvsroot/CVSROOT/?*
    rm -f -r valgrind/bin
    rm -f .prove
    perl ./harness --git-version="1.7.2.1.173.gc9b40" \
                    --no-verbose \
                    --archive="test-results/git-smoke.tar.gz" \
                    t0000-basic.sh t0001-init.sh t0002-gitfile.sh t0003-attributes.sh t0004-unwritable.sh t0005-signals.sh t0006-date.sh
    t0000-basic.sh ....... ok
    t0001-init.sh ........ ok
    t0002-gitfile.sh ..... ok
    t0003-attributes.sh .. ok
    t0004-unwritable.sh .. ok
    t0005-signals.sh ..... ok
    t0006-date.sh ........ ok
    All tests successful.

    Test Summary Report
    -------------------
    t0000-basic.sh     (Wstat: 0 Tests: 46 Failed: 0)
      TODO passed:   5
    Files=7, Tests=134,  3 wallclock secs ( 0.06 usr  0.05 sys +  0.23 cusr  1.33 csys =  1.67 CPU)
    Result: PASS

    TAP Archive created at /home/avar/g/git/t/test-results/git-smoke.tar.gz

The smoke target uses TAP::Harness::Archive to aggregate the test
results into a tarball. The tarball contains two things, the output of
every test file that was run, and a metadata file:

Tarball contents:

    $ tar xzvf git-smoke.tar.gz
    t0004-unwritable.sh
    t0001-init.sh
    t0002-gitfile.sh
    t0005-signals.sh
    t0000-basic.sh
    t0003-attributes.sh
    t0006-date.sh
    meta.yml

A test report:

    $ cat t0005-signals.sh
    ok 1 - sigchain works
    # passed all 1 test(s)
    1..1

A metadata file:

    ---
    extra_properties:
    file_attributes:
      -
        description: t0000-basic.sh
        end_time: 1280437324.61398
        start_time: 1280437324.22186
      -
        description: t0001-init.sh
        end_time: 1280437325.12346
        start_time: 1280437324.62393
      -
        description: t0002-gitfile.sh
        end_time: 1280437325.29428
        start_time: 1280437325.13646
      -
        description: t0003-attributes.sh
        end_time: 1280437325.59678
        start_time: 1280437325.30565
      -
        description: t0004-unwritable.sh
        end_time: 1280437325.77376
        start_time: 1280437325.61003
      -
        description: t0005-signals.sh
        end_time: 1280437325.85426
        start_time: 1280437325.78727
      -
        description: t0006-date.sh
        end_time: 1280437326.2362
        start_time: 1280437325.86768
    file_order:
      - t0000-basic.sh
      - t0001-init.sh
      - t0002-gitfile.sh
      - t0003-attributes.sh
      - t0004-unwritable.sh
      - t0005-signals.sh
      - t0006-date.sh
    start_time: 1280437324
    stop_time: 1280437326

The "extra_properties" hash is where we'll stick Git-specific info,
like whether Git was compiled with gettext or the fallback regex
engine, and what branch we're compiling. Currently no metadata like
this is included.

The entire tarball is then submitted to a central smokebox at
smoke.git.nix.is. This is done with curl(1) via the "smoke_report"
target:

    $ make smoke_report
    curl \
                    -H "Expect: " \
                    -F project=Git \
                    -F architecture=x86_64 \
                    -F platform=Linux \
                    -F revision="1.7.2.1.173.gc9b40" \
                    -F report_file=@test-results/git-smoke.tar.gz \
                    http://smoke.git.nix.is/app/projects/process_add_report/1 \
            | grep -v ^Redirecting
      % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                     Dload  Upload   Total   Spent    Left  Speed
    100  117k  100    63  100  117k      3   6430  0:00:21  0:00:18  0:00:03     0
    Reported #8 added.

Reports are then made available on the smokebox via a web interface:

    http://smoke.git.nix.is/app/projects/smoke_reports/1

The smoke reports are also mirrored to a Git repository hosted on
GitHub:

    http://github.com/gitsmoke/smoke-reports

The Smolder SQLite database that contains metadata about the reports
is also made available:

    http://github.com/gitsmoke/smoke-database

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Among the many attempts to microproject #8, this seemed to be the
most "done" among the table based ones; I however tend to think
that the original with minimum refactoring would be easier to read.

* pw/branch-config-message:
  install_branch_config(): simplify verbose messages logic

# Conflicts:
# 	branch.c

Memory sanitizer (msan) is detecting a use of an uninitialized variable
(`size`) in `read_attr_from_index`:

    ==2268==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x5651f3416504 in read_attr_from_index git/attr.c:868:11
    #1 0x5651f3415530 in read_attr git/attr.c
    #2 0x5651f3413d74 in bootstrap_attr_stack git/attr.c:968:6
    #3 0x5651f3413d74 in prepare_attr_stack git/attr.c:1004:2
    #4 0x5651f3413d74 in collect_some_attrs git/attr.c:1199:2
    #5 0x5651f3413144 in git_check_attr git/attr.c:1345:2
    #6 0x5651f34728da in convert_attrs git/convert.c:1320:2
    #7 0x5651f3473425 in would_convert_to_git_filter_fd git/convert.c:1373:2
    #8 0x5651f357a35e in index_fd git/object-file.c:2630:34
    #9 0x5651f357aa15 in index_path git/object-file.c:2657:7
    #10 0x5651f35db9d9 in add_to_index git/read-cache.c:766:7
    #11 0x5651f35dc170 in add_file_to_index git/read-cache.c:799:9
    #12 0x5651f321f9b2 in add_files git/builtin/add.c:346:7
    #13 0x5651f321f9b2 in cmd_add git/builtin/add.c:565:18
    #14 0x5651f321d327 in run_builtin git/git.c:474:11
    #15 0x5651f321bc9e in handle_builtin git/git.c:729:3
    #16 0x5651f321a792 in run_argv git/git.c:793:4
    #17 0x5651f321a792 in cmd_main git/git.c:928:19
    #18 0x5651f33dde1f in main git/common-main.c:62:11

The issue exists because `size` is an output parameter from
`read_blob_data_from_index`, but it's only modified if
`read_blob_data_from_index` returns non-NULL. The read of `size` when
calling `read_attr_from_buf` unconditionally may read from an
uninitialized value. `read_attr_from_buf` checks that `buf` is non-NULL
before reading from `size`, but by then it's already too late: the
uninitialized read will have happened already. Furthermore, there's no
guarantee that the compiler won't reorder things so that it checks
`size` before checking `!buf`.

Make the call to `read_attr_from_buf` conditional on `buf` being
non-NULL, ensuring that `size` is not read if it's never set.

Signed-off-by: Kyle Lippincott <spectral@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

It was recently reported that concurrent reads and writes may cause the
reftable backend to segfault. The root cause of this is that we do not
properly keep track of reftable readers across reloads.

Suppose that you have a reftable iterator and then decide to reload the
stack while iterating through the iterator. When the stack has been
rewritten since we have created the iterator, then we would end up
discarding a subset of readers that may still be in use by the iterator.
The consequence is that we now try to reference deallocated memory,
which of course segfaults.

One way to trigger this is in t5616, where some background maintenance
jobs have been leaking from one test into another. This leads to stack
traces like the following one:

  + git -c protocol.version=0 -C pc1 fetch --filter=blob:limit=29999 --refetch origin
  AddressSanitizer:DEADLYSIGNAL
  =================================================================
  ==657994==ERROR: AddressSanitizer: SEGV on unknown address 0x7fa0f0ec6089 (pc 0x55f23e52ddf9 bp
0x7ffe7bfa1700 sp 0x7ffe7bfa1700 T0)
  ==657994==The signal is caused by a READ memory access.
      #0 0x55f23e52ddf9 in get_var_int reftable/record.c:29
      #1 0x55f23e53295e in reftable_decode_keylen reftable/record.c:170
      #2 0x55f23e532cc0 in reftable_decode_key reftable/record.c:194
      #3 0x55f23e54e72e in block_iter_next reftable/block.c:398
      #4 0x55f23e5573dc in table_iter_next_in_block reftable/reader.c:240
      #5 0x55f23e5573dc in table_iter_next reftable/reader.c:355
      #6 0x55f23e5573dc in table_iter_next reftable/reader.c:339
      #7 0x55f23e551283 in merged_iter_advance_subiter reftable/merged.c:69
      #8 0x55f23e55169e in merged_iter_next_entry reftable/merged.c:123
      #9 0x55f23e55169e in merged_iter_next_void reftable/merged.c:172
      #10 0x55f23e537625 in reftable_iterator_next_ref reftable/generic.c:175
      #11 0x55f23e2cf9c6 in reftable_ref_iterator_advance refs/reftable-backend.c:464
      #12 0x55f23e2d996e in ref_iterator_advance refs/iterator.c:13
      #13 0x55f23e2d996e in do_for_each_ref_iterator refs/iterator.c:452
      #14 0x55f23dca6767 in get_ref_map builtin/fetch.c:623
      #15 0x55f23dca6767 in do_fetch builtin/fetch.c:1659
      #16 0x55f23dca6767 in fetch_one builtin/fetch.c:2133
      #17 0x55f23dca6767 in cmd_fetch builtin/fetch.c:2432
      #18 0x55f23dba7764 in run_builtin git.c:484
      #19 0x55f23dba7764 in handle_builtin git.c:741
      #20 0x55f23dbab61e in run_argv git.c:805
      #21 0x55f23dbab61e in cmd_main git.c:1000
      #22 0x55f23dba4781 in main common-main.c:64
      #23 0x7fa0f063fc89 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
      #24 0x7fa0f063fd44 in __libc_start_main_impl ../csu/libc-start.c:360
      #25 0x55f23dba6ad0 in _start (git+0xadfad0) (BuildId: 803b2b7f59beb03d7849fb8294a8e2145dd4aa27)

While it is somewhat awkward that the maintenance processes survive
tests in the first place, it is totally expected that reftables should
work alright with concurrent writers. Seemingly they don't.

The only underlying resource that we need to care about in this context
is the reftable reader, which is responsible for reading a single table
from disk. These readers get discarded immediately (unless reused) when
calling `reftable_stack_reload()`, which is wrong. We can only close
them once we know that there are no iterators using them anymore.

Prepare for a fix by converting the reftable readers to be refcounted.

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

It was recently reported that concurrent reads and writes may cause the
reftable backend to segfault. The root cause of this is that we do not
properly keep track of reftable readers across reloads.

Suppose that you have a reftable iterator and then decide to reload the
stack while iterating through the iterator. When the stack has been
rewritten since we have created the iterator, then we would end up
discarding a subset of readers that may still be in use by the iterator.
The consequence is that we now try to reference deallocated memory,
which of course segfaults.

One way to trigger this is in t5616, where some background maintenance
jobs have been leaking from one test into another. This leads to stack
traces like the following one:

  + git -c protocol.version=0 -C pc1 fetch --filter=blob:limit=29999 --refetch origin
  AddressSanitizer:DEADLYSIGNAL
  =================================================================
  ==657994==ERROR: AddressSanitizer: SEGV on unknown address 0x7fa0f0ec6089 (pc 0x55f23e52ddf9 bp
0x7ffe7bfa1700 sp 0x7ffe7bfa1700 T0)
  ==657994==The signal is caused by a READ memory access.
      #0 0x55f23e52ddf9 in get_var_int reftable/record.c:29
      #1 0x55f23e53295e in reftable_decode_keylen reftable/record.c:170
      #2 0x55f23e532cc0 in reftable_decode_key reftable/record.c:194
      #3 0x55f23e54e72e in block_iter_next reftable/block.c:398
      #4 0x55f23e5573dc in table_iter_next_in_block reftable/reader.c:240
      #5 0x55f23e5573dc in table_iter_next reftable/reader.c:355
      #6 0x55f23e5573dc in table_iter_next reftable/reader.c:339
      #7 0x55f23e551283 in merged_iter_advance_subiter reftable/merged.c:69
      #8 0x55f23e55169e in merged_iter_next_entry reftable/merged.c:123
      #9 0x55f23e55169e in merged_iter_next_void reftable/merged.c:172
      #10 0x55f23e537625 in reftable_iterator_next_ref reftable/generic.c:175
      #11 0x55f23e2cf9c6 in reftable_ref_iterator_advance refs/reftable-backend.c:464
      #12 0x55f23e2d996e in ref_iterator_advance refs/iterator.c:13
      #13 0x55f23e2d996e in do_for_each_ref_iterator refs/iterator.c:452
      #14 0x55f23dca6767 in get_ref_map builtin/fetch.c:623
      #15 0x55f23dca6767 in do_fetch builtin/fetch.c:1659
      #16 0x55f23dca6767 in fetch_one builtin/fetch.c:2133
      #17 0x55f23dca6767 in cmd_fetch builtin/fetch.c:2432
      #18 0x55f23dba7764 in run_builtin git.c:484
      #19 0x55f23dba7764 in handle_builtin git.c:741
      #20 0x55f23dbab61e in run_argv git.c:805
      #21 0x55f23dbab61e in cmd_main git.c:1000
      #22 0x55f23dba4781 in main common-main.c:64
      #23 0x7fa0f063fc89 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
      #24 0x7fa0f063fd44 in __libc_start_main_impl ../csu/libc-start.c:360
      #25 0x55f23dba6ad0 in _start (git+0xadfad0) (BuildId: 803b2b7f59beb03d7849fb8294a8e2145dd4aa27)

While it is somewhat awkward that the maintenance processes survive
tests in the first place, it is totally expected that reftables should
work alright with concurrent writers. Seemingly they don't.

The only underlying resource that we need to care about in this context
is the reftable reader, which is responsible for reading a single table
from disk. These readers get discarded immediately (unless reused) when
calling `reftable_stack_reload()`, which is wrong. We can only close
them once we know that there are no iterators using them anymore.

Prepare for a fix by converting the reftable readers to be refcounted.

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

It was recently reported that concurrent reads and writes may cause the
reftable backend to segfault. The root cause of this is that we do not
properly keep track of reftable readers across reloads.

Suppose that you have a reftable iterator and then decide to reload the
stack while iterating through the iterator. When the stack has been
rewritten since we have created the iterator, then we would end up
discarding a subset of readers that may still be in use by the iterator.
The consequence is that we now try to reference deallocated memory,
which of course segfaults.

One way to trigger this is in t5616, where some background maintenance
jobs have been leaking from one test into another. This leads to stack
traces like the following one:

  + git -c protocol.version=0 -C pc1 fetch --filter=blob:limit=29999 --refetch origin
  AddressSanitizer:DEADLYSIGNAL
  =================================================================
  ==657994==ERROR: AddressSanitizer: SEGV on unknown address 0x7fa0f0ec6089 (pc 0x55f23e52ddf9 bp
0x7ffe7bfa1700 sp 0x7ffe7bfa1700 T0)
  ==657994==The signal is caused by a READ memory access.
      #0 0x55f23e52ddf9 in get_var_int reftable/record.c:29
      #1 0x55f23e53295e in reftable_decode_keylen reftable/record.c:170
      #2 0x55f23e532cc0 in reftable_decode_key reftable/record.c:194
      #3 0x55f23e54e72e in block_iter_next reftable/block.c:398
      #4 0x55f23e5573dc in table_iter_next_in_block reftable/reader.c:240
      #5 0x55f23e5573dc in table_iter_next reftable/reader.c:355
      #6 0x55f23e5573dc in table_iter_next reftable/reader.c:339
      #7 0x55f23e551283 in merged_iter_advance_subiter reftable/merged.c:69
      #8 0x55f23e55169e in merged_iter_next_entry reftable/merged.c:123
      #9 0x55f23e55169e in merged_iter_next_void reftable/merged.c:172
      #10 0x55f23e537625 in reftable_iterator_next_ref reftable/generic.c:175
      #11 0x55f23e2cf9c6 in reftable_ref_iterator_advance refs/reftable-backend.c:464
      #12 0x55f23e2d996e in ref_iterator_advance refs/iterator.c:13
      #13 0x55f23e2d996e in do_for_each_ref_iterator refs/iterator.c:452
      #14 0x55f23dca6767 in get_ref_map builtin/fetch.c:623
      #15 0x55f23dca6767 in do_fetch builtin/fetch.c:1659
      #16 0x55f23dca6767 in fetch_one builtin/fetch.c:2133
      #17 0x55f23dca6767 in cmd_fetch builtin/fetch.c:2432
      #18 0x55f23dba7764 in run_builtin git.c:484
      #19 0x55f23dba7764 in handle_builtin git.c:741
      #20 0x55f23dbab61e in run_argv git.c:805
      #21 0x55f23dbab61e in cmd_main git.c:1000
      #22 0x55f23dba4781 in main common-main.c:64
      #23 0x7fa0f063fc89 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
      #24 0x7fa0f063fd44 in __libc_start_main_impl ../csu/libc-start.c:360
      #25 0x55f23dba6ad0 in _start (git+0xadfad0) (BuildId: 803b2b7f59beb03d7849fb8294a8e2145dd4aa27)

While it is somewhat awkward that the maintenance processes survive
tests in the first place, it is totally expected that reftables should
work alright with concurrent writers. Seemingly they don't.

The only underlying resource that we need to care about in this context
is the reftable reader, which is responsible for reading a single table
from disk. These readers get discarded immediately (unless reused) when
calling `reftable_stack_reload()`, which is wrong. We can only close
them once we know that there are no iterators using them anymore.

Prepare for a fix by converting the reftable readers to be refcounted.

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The incremental MIDX bitmap work was done prior to 9d4855e
(midx-write: fix leaking buffer, 2024-09-30), and causes test failures
in t5334 in a post-9d4855eef3 world.

The leak looks like:

    Direct leak of 264 byte(s) in 1 object(s) allocated from:
        #0 0x7f6bcd87eaca in calloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:90
        #1 0x55ad1428e8a4 in xcalloc wrapper.c:151
        #2 0x55ad14199e16 in prepare_midx_bitmap_git pack-bitmap.c:742
        #3 0x55ad14199447 in open_midx_bitmap_1 pack-bitmap.c:507
        #4 0x55ad14199cca in open_midx_bitmap pack-bitmap.c:704
        #5 0x55ad14199d44 in open_bitmap pack-bitmap.c:717
        #6 0x55ad14199dc2 in prepare_bitmap_git pack-bitmap.c:733
        #7 0x55ad1419e496 in test_bitmap_walk pack-bitmap.c:2698
        #8 0x55ad14047b0b in cmd_rev_list builtin/rev-list.c:629
        #9 0x55ad13f71cd6 in run_builtin git.c:487
        #10 0x55ad13f72132 in handle_builtin git.c:756
        #11 0x55ad13f72380 in run_argv git.c:826
        #12 0x55ad13f728f4 in cmd_main git.c:961
        #13 0x55ad1407d3ae in main common-main.c:64
        #14 0x7f6bcd5f0c89 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
        #15 0x7f6bcd5f0d44 in __libc_start_main_impl ../csu/libc-start.c:360
        #16 0x55ad13f6ff90 in _start (git+0x1ef90) (BuildId: 3e63cdd415f1d185b21da3035cb48332510dddce)

, and is a result of us not freeing the resources corresponding to the
bitmap's base layer, if one was present.

Rectify that leak by calling the newly-introduced free_bitmap_index()
function on the base layer to ensure that its resources are also freed.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

When trying to resolve a revision query like "HEAD~~~~~", our call
pattern looks something like:

  - object-name.c::get_oid_with_context()
  - object-name.c::get_oid_1()
  - object-name.c::get_nth_ancestor()
  - object-name.c::get_oid_1()
  - ...

With `get_nth_ancestor()` and `get_oid_1()` mutually recurring, popping
one '~' off of the revision query for each round of the recursion.

Since this recursive behavior is unbounded, having too many "~"'s
contained in a revision query will cause us to blow the stack.
Generating a message like this when compiled under SANITIZE=address:

    $ valgrind git rev-parse "HEAD$(perl -e "print \"~\" x 1000000000000")"
    ==597453== Memcheck, a memory error detector
    ==597453== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al.
    ==597453== Using Valgrind-3.19.0 and LibVEX; rerun with -h for copyright info
    ==597453== Command: /home/ttaylorr/local/bin/git.compile diff HEAD~~~~~~~~~~~~[...]
    ==597453==
    AddressSanitizer:DEADLYSIGNAL
    =================================================================
    ==597453==ERROR: AddressSanitizer: stack-overflow on address 0x7fffdd838ff8 (pc 0x7f2726082748 bp 0x7fffdd839110 sp 0x7fffdd839000 T0)
        #0 0x7f2726082748 in __asan::GetTLSFakeStack() ../../../../src/libsanitizer/asan/asan_fake_stack.cpp:176
        #1 0x7f2726082748 in GetFakeStackFast ../../../../src/libsanitizer/asan/asan_fake_stack.cpp:193
        #2 0x7f27260833de in OnMalloc ../../../../src/libsanitizer/asan/asan_fake_stack.cpp:207
        #3 0x7f27260833de in __asan_stack_malloc_1 ../../../../src/libsanitizer/asan/asan_fake_stack.cpp:256
        #4 0x563f9077d9d8 in get_nth_ancestor /home/ttaylorr/src/git/object-name.c:1087
        #5 0x563f9077e957 in get_oid_1 /home/ttaylorr/src/git/object-name.c:1295
        git#6 0x563f9077da64 in get_nth_ancestor /home/ttaylorr/src/git/object-name.c:1092
        #7 0x563f9077e957 in get_oid_1 /home/ttaylorr/src/git/object-name.c:1295
        git#8 0x563f9077da64 in get_nth_ancestor /home/ttaylorr/src/git/object-name.c:1092
        [...]
        git#247 0x563f9077e957 in get_oid_1 /home/ttaylorr/src/git/object-name.c:1295
        git#248 0x563f9077da64 in get_nth_ancestor /home/ttaylorr/src/git/object-name.c:1092

    SUMMARY: AddressSanitizer: stack-overflow ../../../../src/libsanitizer/asan/asan_fake_stack.cpp:176 in __asan::GetTLSFakeStack()
    ==597453==ABORTING

(Note that the actual stack is much deeper. GDB reports that the bottom
of the stack looks something like the following):

    #54866 0x0000555555c6d3bf in get_oid_with_context_1 (repo=0x5555563849a0 <the_repo>, name=0x7fffffff4be5 "HEAD", '~' <repeats 196 times>..., flags=128, prefix=0x0, oid=0x7ffff5713d40, oc=0x7ffff5713d90) at object-name.c:1947
    #54867 0x0000555555c6e2fa in get_oid_with_context (repo=0x5555563849a0 <the_repo>, str=0x7fffffff4be5 "HEAD", '~' <repeats 196 times>..., flags=128, oid=0x7ffff5713d40, oc=0x7ffff5713d90) at object-name.c:2096
    #54868 0x0000555555d8eed8 in handle_revision_arg_1 (arg_=0x7fffffff4be5 "HEAD", '~' <repeats 196 times>..., revs=0x7ffff5b000d0, flags=0, revarg_opt=0) at revision.c:2174
    #54869 0x0000555555d8f1a9 in handle_revision_arg (arg=0x7fffffff4be5 "HEAD", '~' <repeats 196 times>..., revs=0x7ffff5b000d0, flags=0, revarg_opt=0) at revision.c:2189
    #54870 0x0000555555d97ca9 in setup_revisions (argc=2, argv=0x7fffffff4970, revs=0x7ffff5b000d0, opt=0x0) at revision.c:2932
    #54871 0x00005555557d6a63 in cmd_diff (argc=2, argv=0x7fffffff4970, prefix=0x0) at builtin/diff.c:502
    #54872 0x00005555557367bf in run_builtin (p=0x5555561c4c30 <commands+816>, argc=2, argv=0x7fffffff4970) at git.c:469
    #54873 0x000055555573716b in handle_builtin (argc=2, argv=0x7fffffff4970) at git.c:723
    #54874 0x000055555573785a in run_argv (argcp=0x7ffff56028b0, argv=0x7ffff56028e0) at git.c:787
    #54875 0x0000555555738626 in cmd_main (argc=2, argv=0x7fffffff4970) at git.c:922
    #54876 0x00005555559d3fdd in main (argc=3, argv=0x7fffffff4968) at common-main.c:62

Fortunately, we can impose a limit on the maximum recursion depth we're
willing to accept when resolving queries like the above without
significantly impeding users. This patch sets the limit at 4096, though
we could probably increase that limit depending on the size of each
frame.

The limit introduced here is large enough that any reasonable query
should still run to completion, but small enough that if the frame size
were to significantly increase, our protection would still be effective.

The change here is straightforward: each call to get_nth_ancestor()
increases a counter, and then decrements that counter before returning.

The diff is a little noisy since there are a handful of return paths
from `get_nth_ancestor()`, all of which need to decrement the depth
variable.

Since this is a local-only exploit, a user would have to be tricked into
running such a query by an adversary. Even if they were successfully
tricked into running the malicious query, the blast radius is limited to
a local stack overflow, which does not have meaningful paths to remote
code execution, arbitrary memory reads, or any more grave security
concerns.

Reported-by: Carlos Andrés Ramírez Cataño <antaigroupltda@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>

This one is a little bit more curious. In t6112, we have a test that
exercises the `git rev-list --filter` option with invalid filters. We
execute git-rev-list(1) via `test_must_fail`, which means that we check
for leaks even though Git exits with an error code. This causes the
following leak:

    Direct leak of 27 byte(s) in 1 object(s) allocated from:
        #0 0x5555555e6946 in realloc.part.0 lsan_interceptors.cpp.o
        #1 0x5555558fb4b6 in xrealloc wrapper.c:137:8
        #2 0x5555558b6e06 in strbuf_grow strbuf.c:112:2
        #3 0x5555558b7550 in strbuf_add strbuf.c:311:2
        #4 0x5555557c1a88 in strbuf_addstr strbuf.h:310:2
        #5 0x5555557c1d4c in parse_list_objects_filter list-objects-filter-options.c:261:3
        #6 0x555555885ead in handle_revision_pseudo_opt revision.c:2899:3
        #7 0x555555884e20 in setup_revisions revision.c:3014:11
        #8 0x5555556c4b42 in cmd_rev_list builtin/rev-list.c:588:9
        #9 0x5555555ec5e3 in run_builtin git.c:483:11
        #10 0x5555555eb1e4 in handle_builtin git.c:749:13
        #11 0x5555555ec001 in run_argv git.c:819:4
        #12 0x5555555eaf94 in cmd_main git.c:954:19
        #13 0x5555556fd569 in main common-main.c:64:11
        #14 0x7ffff7ca714d in __libc_start_call_main (.../lib/libc.so.6+0x2a14d)
        #15 0x7ffff7ca7208 in __libc_start_main@GLIBC_2.2.5 (.../libc.so.6+0x2a208)
        #16 0x5555555ad064 in _start (git+0x59064)

This leak is valid, as we call `die()` and do not clean up the memory at
all. But what's curious is that this is the only leak reported, because
we don't clean up any other allocated memory, either, and I have no idea
why the leak sanitizer treats this buffer specially.

In any case, we can work around the leak by shuffling things around a
bit. Instead of calling `gently_parse_list_objects_filter()` and dying
after we have modified the filter spec, we simply do so beforehand. Like
this we don't allocate the buffer in the error case, which makes the
reported leak go away.

It's not pretty, but it manages to make t6112 leak free.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

In 1b9e9be (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>

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>

This one is a little bit more curious. In t6112, we have a test that
exercises the `git rev-list --filter` option with invalid filters. We
execute git-rev-list(1) via `test_must_fail`, which means that we check
for leaks even though Git exits with an error code. This causes the
following leak:

    Direct leak of 27 byte(s) in 1 object(s) allocated from:
        #0 0x5555555e6946 in realloc.part.0 lsan_interceptors.cpp.o
        #1 0x5555558fb4b6 in xrealloc wrapper.c:137:8
        #2 0x5555558b6e06 in strbuf_grow strbuf.c:112:2
        #3 0x5555558b7550 in strbuf_add strbuf.c:311:2
        #4 0x5555557c1a88 in strbuf_addstr strbuf.h:310:2
        #5 0x5555557c1d4c in parse_list_objects_filter list-objects-filter-options.c:261:3
        git#6 0x555555885ead in handle_revision_pseudo_opt revision.c:2899:3
        #7 0x555555884e20 in setup_revisions revision.c:3014:11
        git#8 0x5555556c4b42 in cmd_rev_list builtin/rev-list.c:588:9
        git#9 0x5555555ec5e3 in run_builtin git.c:483:11
        git#10 0x5555555eb1e4 in handle_builtin git.c:749:13
        git#11 0x5555555ec001 in run_argv git.c:819:4
        git#12 0x5555555eaf94 in cmd_main git.c:954:19
        git#13 0x5555556fd569 in main common-main.c:64:11
        git#14 0x7ffff7ca714d in __libc_start_call_main (.../lib/libc.so.6+0x2a14d)
        git#15 0x7ffff7ca7208 in __libc_start_main@GLIBC_2.2.5 (.../libc.so.6+0x2a208)
        git#16 0x5555555ad064 in _start (git+0x59064)

This leak is valid, as we call `die()` and do not clean up the memory at
all. But what's curious is that this is the only leak reported, because
we don't clean up any other allocated memory, either, and I have no idea
why the leak sanitizer treats this buffer specially.

In any case, we can work around the leak by shuffling things around a
bit. Instead of calling `gently_parse_list_objects_filter()` and dying
after we have modified the filter spec, we simply do so beforehand. Like
this we don't allocate the buffer in the error case, which makes the
reported leak go away.

It's not pretty, but it manages to make t6112 leak free.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

This one is a little bit more curious. In t6112, we have a test that
exercises the `git rev-list --filter` option with invalid filters. We
execute git-rev-list(1) via `test_must_fail`, which means that we check
for leaks even though Git exits with an error code. This causes the
following leak:

    Direct leak of 27 byte(s) in 1 object(s) allocated from:
        #0 0x5555555e6946 in realloc.part.0 lsan_interceptors.cpp.o
        #1 0x5555558fb4b6 in xrealloc wrapper.c:137:8
        #2 0x5555558b6e06 in strbuf_grow strbuf.c:112:2
        #3 0x5555558b7550 in strbuf_add strbuf.c:311:2
        #4 0x5555557c1a88 in strbuf_addstr strbuf.h:310:2
        #5 0x5555557c1d4c in parse_list_objects_filter list-objects-filter-options.c:261:3
        git#6 0x555555885ead in handle_revision_pseudo_opt revision.c:2899:3
        #7 0x555555884e20 in setup_revisions revision.c:3014:11
        git#8 0x5555556c4b42 in cmd_rev_list builtin/rev-list.c:588:9
        git#9 0x5555555ec5e3 in run_builtin git.c:483:11
        git#10 0x5555555eb1e4 in handle_builtin git.c:749:13
        git#11 0x5555555ec001 in run_argv git.c:819:4
        git#12 0x5555555eaf94 in cmd_main git.c:954:19
        git#13 0x5555556fd569 in main common-main.c:64:11
        git#14 0x7ffff7ca714d in __libc_start_call_main (.../lib/libc.so.6+0x2a14d)
        git#15 0x7ffff7ca7208 in __libc_start_main@GLIBC_2.2.5 (.../libc.so.6+0x2a208)
        git#16 0x5555555ad064 in _start (git+0x59064)

This leak is valid, as we call `die()` and do not clean up the memory at
all. But what's curious is that this is the only leak reported, because
we don't clean up any other allocated memory, either, and I have no idea
why the leak sanitizer treats this buffer specially.

In any case, we can work around the leak by shuffling things around a
bit. Instead of calling `gently_parse_list_objects_filter()` and dying
after we have modified the filter spec, we simply do so beforehand. Like
this we don't allocate the buffer in the error case, which makes the
reported leak go away.

It's not pretty, but it manages to make t6112 leak free.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>

When trying to create a Unix socket in a path that exceeds the maximum
socket name length we try to first change the directory into the parent
folder before creating the socket to reduce the length of the name. When
this fails we error out of `unix_sockaddr_init()` with an error code,
which indicates to the caller that the context has not been initialized.
Consequently, they don't release that context.

This leads to a memory leak: when we have already populated the context
with the original directory that we need to chdir(3p) back into, but
then the chdir(3p) into the socket's parent directory fails, then we
won't release the original directory's path. The leak is exposed by
t0301, but only via Meson with `meson setup -Dsanitize=leak`:

    Direct leak of 129 byte(s) in 1 object(s) allocated from:
        #0 0x5555555e85c6 in realloc.part.0 lsan_interceptors.cpp.o
        #1 0x55555590e3d6 in xrealloc ../wrapper.c:140:8
        #2 0x5555558c8fc6 in strbuf_grow ../strbuf.c:114:2
        #3 0x5555558cacab in strbuf_getcwd ../strbuf.c:605:3
        #4 0x555555923ff6 in unix_sockaddr_init ../unix-socket.c:65:7
        #5 0x555555923e42 in unix_stream_connect ../unix-socket.c:84:6
        #6 0x55555562a984 in send_request ../builtin/credential-cache.c:46:11
        #7 0x55555562a89e in do_cache ../builtin/credential-cache.c:108:6
        #8 0x55555562a655 in cmd_credential_cache ../builtin/credential-cache.c:178:3
        #9 0x555555700547 in run_builtin ../git.c:480:11
        #10 0x5555556ff0e0 in handle_builtin ../git.c:740:9
        #11 0x5555556ffee8 in run_argv ../git.c:807:4
        #12 0x5555556fee6b in cmd_main ../git.c:947:19
        #13 0x55555593f689 in main ../common-main.c:64:11
        #14 0x7ffff7a2a1fb in __libc_start_call_main (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #15 0x7ffff7a2a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #16 0x5555555ad1d4 in _start (git+0x591d4)

    DEDUP_TOKEN: ___interceptor_realloc.part.0--xrealloc--strbuf_grow--strbuf_getcwd--unix_sockaddr_init--unix_stream_connect--send_request--do_cache--cmd_credential_cache--run_builtin--handle_builtin--run_argv--cmd_main--main--__libc_start_call_main--__libc_start_main@GLIBC_2.2.5--_start
    SUMMARY: LeakSanitizer: 129 byte(s) leaked in 1 allocation(s).

Fix this leak.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

We don't free the result of `remote_default_branch()`, leading to a
memory leak. This leak is exposed by t9211, but only when run with Meson
via `meson setup -Dsanitize=leak`:

    Direct leak of 5 byte(s) in 1 object(s) allocated from:
        #0 0x5555555cfb93 in malloc (scalar+0x7bb93)
        #1 0x5555556b05c2 in do_xmalloc ../wrapper.c:55:8
        #2 0x5555556b06c4 in do_xmallocz ../wrapper.c:89:8
        #3 0x5555556b0656 in xmallocz ../wrapper.c:97:9
        #4 0x5555556b0728 in xmemdupz ../wrapper.c:113:16
        #5 0x5555556b07a7 in xstrndup ../wrapper.c:119:9
        #6 0x5555555d3a4b in remote_default_branch ../scalar.c:338:14
        #7 0x5555555d20e6 in cmd_clone ../scalar.c:493:28
        #8 0x5555555d196b in cmd_main ../scalar.c:992:14
        #9 0x5555557c4059 in main ../common-main.c:64:11
        #10 0x7ffff7a2a1fb in __libc_start_call_main (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #11 0x7ffff7a2a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #12 0x555555592054 in _start (scalar+0x3e054)

    DEDUP_TOKEN: __interceptor_malloc--do_xmalloc--do_xmallocz--xmallocz--xmemdupz--xstrndup--remote_default_branch--cmd_clone--cmd_main--main--__libc_start_call_main--__libc_start_main@GLIBC_2.2.5--_start
    SUMMARY: LeakSanitizer: 5 byte(s) leaked in 1 allocation(s).

As the `branch` variable may contain a string constant obtained from
parsing command line arguments we cannot free the leaking variable
directly. Instead, introduce a new `branch_to_free` variable that only
ever gets assigned the allocated string and free that one to plug the
leak.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

When trying to create a Unix socket in a path that exceeds the maximum
socket name length we try to first change the directory into the parent
folder before creating the socket to reduce the length of the name. When
this fails we error out of `unix_sockaddr_init()` with an error code,
which indicates to the caller that the context has not been initialized.
Consequently, they don't release that context.

This leads to a memory leak: when we have already populated the context
with the original directory that we need to chdir(3p) back into, but
then the chdir(3p) into the socket's parent directory fails, then we
won't release the original directory's path. The leak is exposed by
t0301, but only when running tests in a directory hierarchy whose path
is long enough to make the socket name length exceed the maximum socket
name length:

    Direct leak of 129 byte(s) in 1 object(s) allocated from:
        #0 0x5555555e85c6 in realloc.part.0 lsan_interceptors.cpp.o
        #1 0x55555590e3d6 in xrealloc ../wrapper.c:140:8
        #2 0x5555558c8fc6 in strbuf_grow ../strbuf.c:114:2
        #3 0x5555558cacab in strbuf_getcwd ../strbuf.c:605:3
        #4 0x555555923ff6 in unix_sockaddr_init ../unix-socket.c:65:7
        #5 0x555555923e42 in unix_stream_connect ../unix-socket.c:84:6
        #6 0x55555562a984 in send_request ../builtin/credential-cache.c:46:11
        #7 0x55555562a89e in do_cache ../builtin/credential-cache.c:108:6
        #8 0x55555562a655 in cmd_credential_cache ../builtin/credential-cache.c:178:3
        #9 0x555555700547 in run_builtin ../git.c:480:11
        #10 0x5555556ff0e0 in handle_builtin ../git.c:740:9
        #11 0x5555556ffee8 in run_argv ../git.c:807:4
        #12 0x5555556fee6b in cmd_main ../git.c:947:19
        #13 0x55555593f689 in main ../common-main.c:64:11
        #14 0x7ffff7a2a1fb in __libc_start_call_main (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #15 0x7ffff7a2a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #16 0x5555555ad1d4 in _start (git+0x591d4)

    DEDUP_TOKEN: ___interceptor_realloc.part.0--xrealloc--strbuf_grow--strbuf_getcwd--unix_sockaddr_init--unix_stream_connect--send_request--do_cache--cmd_credential_cache--run_builtin--handle_builtin--run_argv--cmd_main--main--__libc_start_call_main--__libc_start_main@GLIBC_2.2.5--_start
    SUMMARY: LeakSanitizer: 129 byte(s) leaked in 1 allocation(s).

Fix this leak.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

We don't free the result of `remote_default_branch()`, leading to a
memory leak. This leak is exposed by t9211, but only when run with Meson
with the `-Db_sanitize=leak` option:

    Direct leak of 5 byte(s) in 1 object(s) allocated from:
        #0 0x5555555cfb93 in malloc (scalar+0x7bb93)
        #1 0x5555556b05c2 in do_xmalloc ../wrapper.c:55:8
        #2 0x5555556b06c4 in do_xmallocz ../wrapper.c:89:8
        #3 0x5555556b0656 in xmallocz ../wrapper.c:97:9
        #4 0x5555556b0728 in xmemdupz ../wrapper.c:113:16
        #5 0x5555556b07a7 in xstrndup ../wrapper.c:119:9
        #6 0x5555555d3a4b in remote_default_branch ../scalar.c:338:14
        #7 0x5555555d20e6 in cmd_clone ../scalar.c:493:28
        #8 0x5555555d196b in cmd_main ../scalar.c:992:14
        #9 0x5555557c4059 in main ../common-main.c:64:11
        #10 0x7ffff7a2a1fb in __libc_start_call_main (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #11 0x7ffff7a2a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #12 0x555555592054 in _start (scalar+0x3e054)

    DEDUP_TOKEN: __interceptor_malloc--do_xmalloc--do_xmallocz--xmallocz--xmemdupz--xstrndup--remote_default_branch--cmd_clone--cmd_main--main--__libc_start_call_main--__libc_start_main@GLIBC_2.2.5--_start
    SUMMARY: LeakSanitizer: 5 byte(s) leaked in 1 allocation(s).

As the `branch` variable may contain a string constant obtained from
parsing command line arguments we cannot free the leaking variable
directly. Instead, introduce a new `branch_to_free` variable that only
ever gets assigned the allocated string and free that one to plug the
leak.

It is unclear why the leak isn't flagged when running the test via our
Makefile.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>