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>

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>

find_cfg_ent() allocates a struct reflog_expire_entry_option via
FLEX_ALLOC_MEM and inserts it into a linked list in the
reflog_expire_options structure. The entries in this list are never
freed, resulting in a leak in cmd_reflog_expire and the gc reflog expire
maintenance task:

Direct leak of 39 byte(s) in 1 object(s) allocated from:
    #0 0x7ff975ee6883 in calloc (/lib64/libasan.so.8+0xe6883)
    #1 0x0000010edada in xcalloc ../wrapper.c:154
    #2 0x000000df0898 in find_cfg_ent ../reflog.c:28
    #3 0x000000df0898 in reflog_expire_config ../reflog.c:70
    #4 0x00000095c451 in configset_iter ../config.c:2116
    #5 0x0000006d29e7 in git_config ../config.h:724
    #6 0x0000006d29e7 in cmd_reflog_expire ../builtin/reflog.c:205
    #7 0x0000006d504c in cmd_reflog ../builtin/reflog.c:419
    #8 0x0000007e4054 in run_builtin ../git.c:480
    #9 0x0000007e4054 in handle_builtin ../git.c:746
    #10 0x0000007e8a35 in run_argv ../git.c:813
    #11 0x0000007e8a35 in cmd_main ../git.c:953
    #12 0x000000441e8f in main ../common-main.c:9
    #13 0x7ff9754115f4 in __libc_start_call_main (/lib64/libc.so.6+0x35f4)
    #14 0x7ff9754116a7 in __libc_start_main@@GLIBC_2.34 (/lib64/libc.so.6+0x36a7)
    #15 0x000000444184 in _start (/home/jekeller/libexec/git-core/git+0x444184)

Close this leak by adding a reflog_clear_expire_config() function which
iterates the linked list and frees its elements. Call it upon exit of
cmd_reflog_expire() and reflog_expire_condition().

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

find_cfg_ent() allocates a struct reflog_expire_entry_option via
FLEX_ALLOC_MEM and inserts it into a linked list in the
reflog_expire_options structure. The entries in this list are never
freed, resulting in a leak in cmd_reflog_expire and the gc reflog expire
maintenance task:

Direct leak of 39 byte(s) in 1 object(s) allocated from:
    #0 0x7ff975ee6883 in calloc (/lib64/libasan.so.8+0xe6883)
    #1 0x0000010edada in xcalloc ../wrapper.c:154
    #2 0x000000df0898 in find_cfg_ent ../reflog.c:28
    #3 0x000000df0898 in reflog_expire_config ../reflog.c:70
    #4 0x00000095c451 in configset_iter ../config.c:2116
    #5 0x0000006d29e7 in git_config ../config.h:724
    #6 0x0000006d29e7 in cmd_reflog_expire ../builtin/reflog.c:205
    #7 0x0000006d504c in cmd_reflog ../builtin/reflog.c:419
    #8 0x0000007e4054 in run_builtin ../git.c:480
    #9 0x0000007e4054 in handle_builtin ../git.c:746
    #10 0x0000007e8a35 in run_argv ../git.c:813
    #11 0x0000007e8a35 in cmd_main ../git.c:953
    #12 0x000000441e8f in main ../common-main.c:9
    #13 0x7ff9754115f4 in __libc_start_call_main (/lib64/libc.so.6+0x35f4)
    #14 0x7ff9754116a7 in __libc_start_main@@GLIBC_2.34 (/lib64/libc.so.6+0x36a7)
    #15 0x000000444184 in _start (/home/jekeller/libexec/git-core/git+0x444184)

Close this leak by adding a reflog_clear_expire_config() function which
iterates the linked list and frees its elements. Call it upon exit of
cmd_reflog_expire() and reflog_expire_condition().

Add a basic test which covers this leak. While at it, cover the
functionality from commit commit 3cb22b8 (Per-ref reflog expiry
configuration, 2008-06-15). We've had this support for years, but lacked
any tests.

Co-developed-by: Jeff King <peff@peff.net>
Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

When performing auto-maintenance we check whether commit graphs need to
be generated by counting the number of commits that are reachable by any
reference, but not covered by a commit graph. This search is performed
by iterating through all references and then doing a depth-first search
until we have found enough commits that are not present in the commit
graph.

This logic has a memory leak though:

  Direct leak of 16 byte(s) in 1 object(s) allocated from:
      #0 0x55555562e433 in malloc (git+0xda433)
      #1 0x555555964322 in do_xmalloc ../wrapper.c:55:8
      #2 0x5555559642e6 in xmalloc ../wrapper.c:76:9
      #3 0x55555579bf29 in commit_list_append ../commit.c:1872:35
      #4 0x55555569f160 in dfs_on_ref ../builtin/gc.c:1165:4
      #5 0x5555558c33fd in do_for_each_ref_iterator ../refs/iterator.c:431:12
      #6 0x5555558af520 in do_for_each_ref ../refs.c:1828:9
      #7 0x5555558ac317 in refs_for_each_ref ../refs.c:1833:9
      #8 0x55555569e207 in should_write_commit_graph ../builtin/gc.c:1188:11
      #9 0x55555569c915 in maintenance_is_needed ../builtin/gc.c:3492:8
      #10 0x55555569b76a in cmd_maintenance ../builtin/gc.c:3542:9
      #11 0x55555575166a in run_builtin ../git.c:506:11
      #12 0x5555557502f0 in handle_builtin ../git.c:779:9
      #13 0x555555751127 in run_argv ../git.c:862:4
      #14 0x55555575007b in cmd_main ../git.c:984:19
      #15 0x5555557523aa in main ../common-main.c:9:11
      #16 0x7ffff7a2a4d7 in __libc_start_call_main (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x2a4d7) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)
      #17 0x7ffff7a2a59a in __libc_start_main@GLIBC_2.2.5 (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x2a59a) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)
      #18 0x5555555f0934 in _start (git+0x9c934)

The root cause of this memory leak is our use of `commit_list_append()`.
This function expects as parameters the item to append and the _tail_ of
the list to append. This tail will then be overwritten with the new tail
of the list so that it can be used in subsequent calls. But we call it
with `commit_list_append(parent->item, &stack)`, so we end up losing
everything but the new item.

This issue only surfaces when counting merge commits. Next to being a
memory leak, it also shows that we're in fact miscounting as we only
respect children of the last parent. All previous parents are discarded,
so their children will be disregarded unless they are hit via another
reference.

While crafting a test case for the issue I was puzzled that I couldn't
establish the proper border at which the auto-condition would be
fulfilled. As it turns out, there's another bug: if an object is at the
tip of any reference we don't mark it as seen. Consequently, if it is
reachable via any other reference, we'd count that object twice.

Fix both of these bugs so that we properly count objects without leaking
any memory.

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

In the next commit we are about to move the packfile store into the ODB
source so that we have one store per source. This will lead to a memory
leak in the following commit when reading data from a submodule via
git-grep(1):

  Direct leak of 192 byte(s) in 1 object(s) allocated from:
    #0 0x55555562e726 in calloc (git+0xda726)
    #1 0x555555964734 in xcalloc ../wrapper.c:154:8
    #2 0x555555835136 in load_multi_pack_index_one ../midx.c:135:2
    #3 0x555555834fd6 in load_multi_pack_index ../midx.c:382:6
    #4 0x5555558365b6 in prepare_multi_pack_index_one ../midx.c:716:17
    #5 0x55555586c605 in packfile_store_prepare ../packfile.c:1103:3
    #6 0x55555586c90c in packfile_store_reprepare ../packfile.c:1118:2
    #7 0x5555558546b3 in odb_reprepare ../odb.c:1106:2
    #8 0x5555558539e4 in do_oid_object_info_extended ../odb.c:715:4
    #9 0x5555558533d1 in odb_read_object_info_extended ../odb.c:862:8
    #10 0x5555558540bd in odb_read_object ../odb.c:920:6
    #11 0x55555580a330 in grep_source_load_oid ../grep.c:1934:12
    #12 0x55555580a13a in grep_source_load ../grep.c:1986:10
    #13 0x555555809103 in grep_source_is_binary ../grep.c:2014:7
    #14 0x555555807574 in grep_source_1 ../grep.c:1625:8
    #15 0x555555807322 in grep_source ../grep.c:1837:10
    #16 0x5555556a5c58 in run ../builtin/grep.c:208:10
    #17 0x55555562bb42 in void* ThreadStartFunc<false>(void*) lsan_interceptors.cpp.o
    #18 0x7ffff7a9a979 in start_thread (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x9a979) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)
    #19 0x7ffff7b22d2b in __GI___clone3 (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x122d2b) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)

The root caues of this leak is the way we set up and release the
submodule:

  1. We use `repo_submodule_init()` to initialize a new repository. This
     repository is stored in `repos_to_free`.

  2. We now read data from the submodule repository.

  3. We then call `repo_clear()` on the submodule repositories.

  4. `repo_clear()` calls `odb_free()`.

  5. `odb_free()` calls `odb_free_sources()` followed by `odb_close()`.

The issue here is the 5th step: we call `odb_free_sources()` _before_ we
call `odb_close()`. But `odb_free_sources()` already frees all sources,
so the logic that closes them in `odb_close()` now becomes a no-op. As a
consequence, we never explicitly close sources at all.

Fix the leak by closing the store before we free the sources.

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

When pushing to a set of remotes using a nickname for the group, the
client initializes the connection to each remote, talks to the
remote and reads and parses capabilities line, and holds the
capabilities in a file-scope static variable server_capabilities_v1.

There are a few other such file-scope static variables, and these
connections cannot be parallelized until they are refactored to a
structure that keeps track of active connections.

Which is *not* the theme of this patch ;-)

For a single connection, the server_capabilities_v1 variable is
initialized to NULL (at the program initialization), populated when
we talk to the other side, used to look up capabilities of the other
sdie possible multiple times, and the memory is held by the variable
until program exit, without leaking.  When talking to multiple remotes,
however, the server capabilities from the second connection overwrites
without freeing the one from the first connection, which leaks.

    ==1080970==ERROR: LeakSanitizer: detected memory leaks

    Direct leak of 421 byte(s) in 2 object(s) allocated from:
	#0 0x5615305f849e in strdup (/home/gitster/g/git-jch/bin/bin/git+0x2b349e) (BuildId: 54d149994c9e85374831958f694bd0aa3b8b1e26)
	#1 0x561530e76cc4 in xstrdup /home/gitster/w/build/wrapper.c:43:14
	#2 0x5615309cd7fa in process_capabilities /home/gitster/w/build/connect.c:243:27
	#3 0x5615309cd502 in get_remote_heads /home/gitster/w/build/connect.c:366:4
	#4 0x561530e2cb0b in handshake /home/gitster/w/build/transport.c:372:3
	#5 0x561530e29ed7 in get_refs_via_connect /home/gitster/w/build/transport.c:398:9
	#6 0x561530e26464 in transport_push /home/gitster/w/build/transport.c:1421:16
	#7 0x561530800bec in push_with_options /home/gitster/w/build/builtin/push.c:387:8
	#8 0x5615307ffb99 in do_push /home/gitster/w/build/builtin/push.c:442:7
	#9 0x5615307fe926 in cmd_push /home/gitster/w/build/builtin/push.c:664:7
	#10 0x56153065673f in run_builtin /home/gitster/w/build/git.c:506:11
	#11 0x56153065342f in handle_builtin /home/gitster/w/build/git.c:779:9
	#12 0x561530655b89 in run_argv /home/gitster/w/build/git.c:862:4
	#13 0x561530652cba in cmd_main /home/gitster/w/build/git.c:984:19
	#14 0x5615308dda0a in main /home/gitster/w/build/common-main.c:9:11
	#15 0x7f051651bca7 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16

    SUMMARY: AddressSanitizer: 421 byte(s) leaked in 2 allocation(s).

Free the capablities data for the previous server before overwriting
it with the next server to plug this leak.

The added test fails without the freeing with SANITIZE=leak; I
somehow couldn't get it fail reliably with SANITIZE=leak,address
though.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

When pushing to a set of remotes using a nickname for the group, the
client initializes the connection to each remote, talks to the
remote and reads and parses capabilities line, and holds the
capabilities in a file-scope static variable server_capabilities_v1.

There are a few other such file-scope static variables, and these
connections cannot be parallelized until they are refactored to a
structure that keeps track of active connections.

Which is *not* the theme of this patch ;-)

For a single connection, the server_capabilities_v1 variable is
initialized to NULL (at the program initialization), populated when
we talk to the other side, used to look up capabilities of the other
side possibly multiple times, and the memory is held by the variable
until program exit, without leaking.  When talking to multiple remotes,
however, the server capabilities from the second connection overwrites
without freeing the one from the first connection, which leaks.

    ==1080970==ERROR: LeakSanitizer: detected memory leaks

    Direct leak of 421 byte(s) in 2 object(s) allocated from:
	#0 0x5615305f849e in strdup (/home/gitster/g/git-jch/bin/bin/git+0x2b349e) (BuildId: 54d149994c9e85374831958f694bd0aa3b8b1e26)
	#1 0x561530e76cc4 in xstrdup /home/gitster/w/build/wrapper.c:43:14
	#2 0x5615309cd7fa in process_capabilities /home/gitster/w/build/connect.c:243:27
	#3 0x5615309cd502 in get_remote_heads /home/gitster/w/build/connect.c:366:4
	#4 0x561530e2cb0b in handshake /home/gitster/w/build/transport.c:372:3
	#5 0x561530e29ed7 in get_refs_via_connect /home/gitster/w/build/transport.c:398:9
	#6 0x561530e26464 in transport_push /home/gitster/w/build/transport.c:1421:16
	#7 0x561530800bec in push_with_options /home/gitster/w/build/builtin/push.c:387:8
	#8 0x5615307ffb99 in do_push /home/gitster/w/build/builtin/push.c:442:7
	#9 0x5615307fe926 in cmd_push /home/gitster/w/build/builtin/push.c:664:7
	#10 0x56153065673f in run_builtin /home/gitster/w/build/git.c:506:11
	#11 0x56153065342f in handle_builtin /home/gitster/w/build/git.c:779:9
	#12 0x561530655b89 in run_argv /home/gitster/w/build/git.c:862:4
	#13 0x561530652cba in cmd_main /home/gitster/w/build/git.c:984:19
	#14 0x5615308dda0a in main /home/gitster/w/build/common-main.c:9:11
	#15 0x7f051651bca7 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16

    SUMMARY: AddressSanitizer: 421 byte(s) leaked in 2 allocation(s).

Free the capablities data for the previous server before overwriting
it with the next server to plug this leak.

The added test fails without the freeing with SANITIZE=leak; I
somehow couldn't get it fail reliably with SANITIZE=leak,address
though.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

When performing auto-maintenance we check whether commit graphs need to
be generated by counting the number of commits that are reachable by any
reference, but not covered by a commit graph. This search is performed
by iterating through all references and then doing a depth-first search
until we have found enough commits that are not present in the commit
graph.

This logic has a memory leak though:

  Direct leak of 16 byte(s) in 1 object(s) allocated from:
      #0 0x55555562e433 in malloc (git+0xda433)
      #1 0x555555964322 in do_xmalloc ../wrapper.c:55:8
      #2 0x5555559642e6 in xmalloc ../wrapper.c:76:9
      #3 0x55555579bf29 in commit_list_append ../commit.c:1872:35
      #4 0x55555569f160 in dfs_on_ref ../builtin/gc.c:1165:4
      #5 0x5555558c33fd in do_for_each_ref_iterator ../refs/iterator.c:431:12
      #6 0x5555558af520 in do_for_each_ref ../refs.c:1828:9
      #7 0x5555558ac317 in refs_for_each_ref ../refs.c:1833:9
      #8 0x55555569e207 in should_write_commit_graph ../builtin/gc.c:1188:11
      #9 0x55555569c915 in maintenance_is_needed ../builtin/gc.c:3492:8
      #10 0x55555569b76a in cmd_maintenance ../builtin/gc.c:3542:9
      #11 0x55555575166a in run_builtin ../git.c:506:11
      #12 0x5555557502f0 in handle_builtin ../git.c:779:9
      #13 0x555555751127 in run_argv ../git.c:862:4
      #14 0x55555575007b in cmd_main ../git.c:984:19
      #15 0x5555557523aa in main ../common-main.c:9:11
      #16 0x7ffff7a2a4d7 in __libc_start_call_main (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x2a4d7) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)
      #17 0x7ffff7a2a59a in __libc_start_main@GLIBC_2.2.5 (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x2a59a) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)
      #18 0x5555555f0934 in _start (git+0x9c934)

The root cause of this memory leak is our use of `commit_list_append()`.
This function expects as parameters the item to append and the _tail_ of
the list to append. This tail will then be overwritten with the new tail
of the list so that it can be used in subsequent calls. But we call it
with `commit_list_append(parent->item, &stack)`, so we end up losing
everything but the new item.

This issue only surfaces when counting merge commits. Next to being a
memory leak, it also shows that we're in fact miscounting as we only
respect children of the last parent. All previous parents are discarded,
so their children will be disregarded unless they are hit via another
reference.

While crafting a test case for the issue I was puzzled that I couldn't
establish the proper border at which the auto-condition would be
fulfilled. As it turns out, there's another bug: if an object is at the
tip of any reference we don't mark it as seen. Consequently, if it is
reachable via any other reference, we'd count that object twice.

Fix both of these bugs so that we properly count objects without leaking
any memory.

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

It is possible to hit a memory leak when reading data from a submodule
via git-grep(1):

  Direct leak of 192 byte(s) in 1 object(s) allocated from:
    #0 0x55555562e726 in calloc (git+0xda726)
    #1 0x555555964734 in xcalloc ../wrapper.c:154:8
    #2 0x555555835136 in load_multi_pack_index_one ../midx.c:135:2
    #3 0x555555834fd6 in load_multi_pack_index ../midx.c:382:6
    #4 0x5555558365b6 in prepare_multi_pack_index_one ../midx.c:716:17
    #5 0x55555586c605 in packfile_store_prepare ../packfile.c:1103:3
    #6 0x55555586c90c in packfile_store_reprepare ../packfile.c:1118:2
    #7 0x5555558546b3 in odb_reprepare ../odb.c:1106:2
    #8 0x5555558539e4 in do_oid_object_info_extended ../odb.c:715:4
    #9 0x5555558533d1 in odb_read_object_info_extended ../odb.c:862:8
    #10 0x5555558540bd in odb_read_object ../odb.c:920:6
    #11 0x55555580a330 in grep_source_load_oid ../grep.c:1934:12
    #12 0x55555580a13a in grep_source_load ../grep.c:1986:10
    #13 0x555555809103 in grep_source_is_binary ../grep.c:2014:7
    #14 0x555555807574 in grep_source_1 ../grep.c:1625:8
    #15 0x555555807322 in grep_source ../grep.c:1837:10
    #16 0x5555556a5c58 in run ../builtin/grep.c:208:10
    #17 0x55555562bb42 in void* ThreadStartFunc<false>(void*) lsan_interceptors.cpp.o
    #18 0x7ffff7a9a979 in start_thread (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x9a979) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)
    #19 0x7ffff7b22d2b in __GI___clone3 (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x122d2b) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)

The root caues of this leak is the way we set up and release the
submodule:

  1. We use `repo_submodule_init()` to initialize a new repository. This
     repository is stored in `repos_to_free`.

  2. We now read data from the submodule repository.

  3. We then call `repo_clear()` on the submodule repositories.

  4. `repo_clear()` calls `odb_free()`.

  5. `odb_free()` calls `odb_free_sources()` followed by `odb_close()`.

The issue here is the 5th step: we call `odb_free_sources()` _before_ we
call `odb_close()`. But `odb_free_sources()` already frees all sources,
so the logic that closes them in `odb_close()` now becomes a no-op. As a
consequence, we never explicitly close sources at all.

Fix the leak by closing the store before we free the sources.

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

When performing auto-maintenance we check whether commit graphs need to
be generated by counting the number of commits that are reachable by any
reference, but not covered by a commit graph. This search is performed
by iterating through all references and then doing a depth-first search
until we have found enough commits that are not present in the commit
graph.

This logic has a memory leak though:

  Direct leak of 16 byte(s) in 1 object(s) allocated from:
      #0 0x55555562e433 in malloc (git+0xda433)
      #1 0x555555964322 in do_xmalloc ../wrapper.c:55:8
      #2 0x5555559642e6 in xmalloc ../wrapper.c:76:9
      #3 0x55555579bf29 in commit_list_append ../commit.c:1872:35
      #4 0x55555569f160 in dfs_on_ref ../builtin/gc.c:1165:4
      #5 0x5555558c33fd in do_for_each_ref_iterator ../refs/iterator.c:431:12
      #6 0x5555558af520 in do_for_each_ref ../refs.c:1828:9
      #7 0x5555558ac317 in refs_for_each_ref ../refs.c:1833:9
      #8 0x55555569e207 in should_write_commit_graph ../builtin/gc.c:1188:11
      #9 0x55555569c915 in maintenance_is_needed ../builtin/gc.c:3492:8
      #10 0x55555569b76a in cmd_maintenance ../builtin/gc.c:3542:9
      #11 0x55555575166a in run_builtin ../git.c:506:11
      #12 0x5555557502f0 in handle_builtin ../git.c:779:9
      #13 0x555555751127 in run_argv ../git.c:862:4
      #14 0x55555575007b in cmd_main ../git.c:984:19
      #15 0x5555557523aa in main ../common-main.c:9:11
      #16 0x7ffff7a2a4d7 in __libc_start_call_main (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x2a4d7) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)
      #17 0x7ffff7a2a59a in __libc_start_main@GLIBC_2.2.5 (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x2a59a) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)
      #18 0x5555555f0934 in _start (git+0x9c934)

The root cause of this memory leak is our use of `commit_list_append()`.
This function expects as parameters the item to append and the _tail_ of
the list to append. This tail will then be overwritten with the new tail
of the list so that it can be used in subsequent calls. But we call it
with `commit_list_append(parent->item, &stack)`, so we end up losing
everything but the new item.

This issue only surfaces when counting merge commits. Next to being a
memory leak, it also shows that we're in fact miscounting as we only
respect children of the last parent. All previous parents are discarded,
so their children will be disregarded unless they are hit via another
reference.

While crafting a test case for the issue I was puzzled that I couldn't
establish the proper border at which the auto-condition would be
fulfilled. As it turns out, there's another bug: if an object is at the
tip of any reference we don't mark it as seen. Consequently, if it is
the tip of or reachable via another ref, we'd count that object multiple
times.

Fix both of these bugs so that we properly count objects without leaking
any memory.

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

It is possible to hit a memory leak when reading data from a submodule
via git-grep(1):

  Direct leak of 192 byte(s) in 1 object(s) allocated from:
    #0 0x55555562e726 in calloc (git+0xda726)
    #1 0x555555964734 in xcalloc ../wrapper.c:154:8
    #2 0x555555835136 in load_multi_pack_index_one ../midx.c:135:2
    #3 0x555555834fd6 in load_multi_pack_index ../midx.c:382:6
    #4 0x5555558365b6 in prepare_multi_pack_index_one ../midx.c:716:17
    #5 0x55555586c605 in packfile_store_prepare ../packfile.c:1103:3
    #6 0x55555586c90c in packfile_store_reprepare ../packfile.c:1118:2
    #7 0x5555558546b3 in odb_reprepare ../odb.c:1106:2
    #8 0x5555558539e4 in do_oid_object_info_extended ../odb.c:715:4
    #9 0x5555558533d1 in odb_read_object_info_extended ../odb.c:862:8
    #10 0x5555558540bd in odb_read_object ../odb.c:920:6
    #11 0x55555580a330 in grep_source_load_oid ../grep.c:1934:12
    #12 0x55555580a13a in grep_source_load ../grep.c:1986:10
    #13 0x555555809103 in grep_source_is_binary ../grep.c:2014:7
    #14 0x555555807574 in grep_source_1 ../grep.c:1625:8
    #15 0x555555807322 in grep_source ../grep.c:1837:10
    #16 0x5555556a5c58 in run ../builtin/grep.c:208:10
    #17 0x55555562bb42 in void* ThreadStartFunc<false>(void*) lsan_interceptors.cpp.o
    #18 0x7ffff7a9a979 in start_thread (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x9a979) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)
    #19 0x7ffff7b22d2b in __GI___clone3 (/nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6+0x122d2b) (BuildId: cddea92d6cba8333be952b5a02fd47d61054c5ab)

The root caues of this leak is the way we set up and release the
submodule:

  1. We use `repo_submodule_init()` to initialize a new repository. This
     repository is stored in `repos_to_free`.

  2. We now read data from the submodule repository.

  3. We then call `repo_clear()` on the submodule repositories.

  4. `repo_clear()` calls `odb_free()`.

  5. `odb_free()` calls `odb_free_sources()` followed by `odb_close()`.

The issue here is the 5th step: we call `odb_free_sources()` _before_ we
call `odb_close()`. But `odb_free_sources()` already frees all sources,
so the logic that closes them in `odb_close()` now becomes a no-op. As a
consequence, we never explicitly close sources at all.

Fix the leak by closing the store before we free the sources.

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