Re: [PATCH v2] wt-status: using of wt_status_state_free_buffers

From: Rubén Justo <rjusto@gmail.com>
Date: Oct 8, 2022, 00:35 UTC
Message-ID: <b6be0af4-8b47-d89d-13fe-a307c0e96797@gmail.com>
In-Reply-To: <6ff29e96-7f8d-c354-dced-b1b363e54467@gmail.com>

In 2708ce62d2 (branch: sort detached HEAD based on a flag, 2021-01-07) a call to wt_status_state_free_buffers, responsible of freeing the resources that could be allocated in the local struct wt_status_state state, was eliminated.

That introduced a leak that occurs with "branch list" in a detached HEAD state. The number of leaks depends on the references to "refname" in --sort and --format. With defaults, 3 are leaked: default sort is by "refname" and default format needs two references of "refname": %(refname:lstrip=2) and %(refname:rstrip-2).

This doesn't leak:
    $ git branch --sort objectname --format '%(objectname)'

This leak once:
    $ git branch --sort refname --format '%(refname)'

This leak twice:
    $ git branch --sort refname --format '%(refname:lstrip=2)'

Note that each different "atom" is only resolved once (see ref-filter.c).

The call to wt_status_state_free_buffers was introduced in 962dd7ebc3 (wt-status: introduce wt_status_state_free_buffers(), 2020-09-27). Bring back that call in get_head_description.

Ævar Arnfjörð pointed out [1] that a similar leak is present in builtin/checkout.c:die_if_some_operation_in_progress(void), since c45f0f525de (switch: reject if some operation is in progress, 2019-03-29). The leak occurs once with "switch" while bisecting.

Lets call to wc_status_state_free_buffers() there too.

[1] 220926.86bkr24kjw.gmgdl@evledraar.gmail.com

Signed-off-by: Rubén Justo <rjusto@gmail.com>
---

Changes since v1:
	- Add details about the leak
	- Fix the leak in builtin/checkout.c

Range-diff:
1:  86b7803955 ! 1:  3fa1ddbb30 ref-filter.c: fix a leak in get_head_description
    @@ Commit message
         resources that could be allocated in the local struct wt_status_state
         state, was eliminated.
     
    +    That introduced a leak that occurs with "branch list" in a detached HEAD
    +    state.  The number of leaks depends on the references to "refname" in
    +    --sort and --format.  With defaults, 3 are leaked: default sort is by
    +    "refname" and default format needs two references of "refname",
    +    %(refname:lstrip=2) and %(refname:rstrip-2).
    +
    +    This doesn't leak:
    +        $ git branch --sort objectname --format '%(objectname)'
    +
    +    This leak once:
    +        $ git branch --sort refname --format '%(refname)'
    +
    +    This leak twice:
    +        $ git branch --sort refname --format '%(refname:lstrip=2)'
    +
    +    Note that each different "atom" is only resolved once (see ref-filter.c).
    +
         The call to wt_status_state_free_buffers was introduced in 962dd7ebc3
    -    (wt-status: introduce wt_status_state_free_buffers(), 2020-09-27).  This
    -    commit brings back that call in get_head_description.
    +    (wt-status: introduce wt_status_state_free_buffers(), 2020-09-27).
    +    Bring back that call in get_head_description.
    +
    +    Ævar Arnfjörð pointed out [1] that a similar leak is present in
    +    builtin/checkout.c:die_if_some_operation_in_progress(void), since
    +    c45f0f525de (switch: reject if some operation is in progress,
    +    2019-03-29).  The leak ocurrs once with checkout while bisecting.
    +
    +    Lets call to wc_status_state_free_buffers() there too.
    +
    +    [1] 220926.86bkr24kjw.gmgdl@evledraar.gmail.com
     
         Signed-off-by: Rubén Justo <rjusto@gmail.com>
     
    + ## builtin/checkout.c ##
    +@@ builtin/checkout.c: static void die_if_some_operation_in_progress(void)
    + 		      "or \"git worktree add\"."));
    + 	if (state.bisect_in_progress)
    + 		warning(_("you are switching branch while bisecting"));
    ++
    ++	wt_status_state_free_buffers(&state);
    + }
    + 
    + static int checkout_branch(struct checkout_opts *opts,
    +
      ## ref-filter.c ##
     @@ ref-filter.c: char *get_head_description(void)
      	} else

 builtin/checkout.c | 2 ++
 ref-filter.c       | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 2a132392fb..659dd5c430 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1470,6 +1470,8 @@ static void die_if_some_operation_in_progress(void)
 		      "or \"git worktree add\"."));
 	if (state.bisect_in_progress)
 		warning(_("you are switching branch while bisecting"));
+
+	wt_status_state_free_buffers(&state);
 }
 
 static int checkout_branch(struct checkout_opts *opts,
diff --git a/ref-filter.c b/ref-filter.c
index fd1cb14b0f..914908fac5 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -1722,6 +1722,8 @@ char *get_head_description(void)
 	} else
 		strbuf_addstr(&desc, _("(no branch)"));
 
+	wt_status_state_free_buffers(&state);
+
 	return strbuf_detach(&desc, NULL);
 }

-- 
2.32.0