Re: [PATCH v2 0/3] diff: build parseopts array on demand

["René Scharfe" <l.s.r@web.de>]

Am 01.12.2022 um 17:54 schrieb Ævar Arnfjörð Bjarmason:
>
> On Thu, Dec 01 2022, René Scharfe wrote:
>
>> Calling repo_init_revisions() and release_revisions() in that order
>> leaks the memory allocated for the parseopts array in the embedded
>> struct diff_options member.  Get rid of that leak by reducing the
>> lifetime of that array.
>>
>> Original patch:
>> https://lore.kernel.org/git/4fd82dc6-e0f8-0638-5b10-16bfef39a171@web.de/
>>
>> Submitted separately from that thread because it's independent enough.
>>
>> Change since v1:
>> - Actually remove the parseopts member.  Its removal got lost during
>>   refactoring in v1.  Thank you for spotting that, Junio!
>>
>>   diff: factor out add_diff_options()
>>   diff: let prep_parse_options() return parseopt array
>>   diff: remove parseopts member from struct diff_options
>>
>>  builtin/range-diff.c |  2 +-
>>  diff-no-index.c      |  3 +--
>>  diff.c               | 26 +++++++++++++++-----------
>>  diff.h               |  2 +-
>>  4 files changed, 18 insertions(+), 15 deletions(-)
>>
>> Range-Diff gegen v1:
>> 1:  630f95320f = 1:  4dc8b2632b diff: factor out add_diff_options()
>> 2:  4b56fa795c = 2:  10903d355e diff: let prep_parse_options() return parseopt array
>> 3:  7e54e4370a ! 3:  24bd18ae79 diff: remove parseopts member from struct diff_options
>>     @@ diff.c: void diff_free(struct diff_options *options)
>>       }
>>
>>       void diff_flush(struct diff_options *options)
>>     +
>>     + ## diff.h ##
>>     +@@ diff.h: struct diff_options {
>>     + 	unsigned color_moved_ws_handling;
>>     +
>>     + 	struct repository *repo;
>>     +-	struct option *parseopts;
>>     + 	struct strmap *additional_path_headers;
>>     +
>>     + 	int no_free;
>
> This looks good to me. Would you mind running the tests with:
>
> 	GIT_TEST_PASSING_SANITIZE_LEAK=check GIT_TEST_SANITIZE_LEAK_LOG=true make SANITIZE=leak
>
> And then marking up the ones that now pass with
> TEST_PASSES_SANITIZE_LEAK=true. I think it's all except one of these
> (one isn't marked on "master", I forget which one):
>
> 	Test Summary Report
> 	-------------------
> 	t1022-read-tree-partial-clone.sh                 (Wstat: 256 Tests: 1 Failed: 0)
> 	  Non-zero exit status: 1
> 	t2012-checkout-last.sh                           (Wstat: 256 Tests: 22 Failed: 0)
> 	  Non-zero exit status: 1
> 	t3210-pack-refs.sh                               (Wstat: 256 Tests: 30 Failed: 0)
> 	  Non-zero exit status: 1
> 	t4053-diff-no-index.sh                           (Wstat: 256 Tests: 19 Failed: 0)
> 	  Non-zero exit status: 1
> 	t5554-noop-fetch-negotiator.sh                   (Wstat: 256 Tests: 1 Failed: 0)
> 	  Non-zero exit status: 1
> 	t5613-info-alternate.sh                          (Wstat: 256 Tests: 13 Failed: 0)
> 	  Non-zero exit status: 1
> 	t6021-rev-list-exclude-hidden.sh                 (Wstat: 256 Tests: 42 Failed: 0)
> 	  Non-zero exit status: 1
> 	t6415-merge-dir-to-symlink.sh                    (Wstat: 256 Tests: 24 Failed: 0)
> 	  Non-zero exit status: 1
> 	t7403-submodule-sync.sh                          (Wstat: 256 Tests: 18 Failed: 0)
> 	  Non-zero exit status: 1
> 	t7504-commit-msg-hook.sh                         (Wstat: 256 Tests: 30 Failed: 0)
> 	  Non-zero exit status: 1
> 	t9115-git-svn-dcommit-funky-renames.sh           (Wstat: 256 Tests: 12 Failed: 0)
> 	  Non-zero exit status: 1
> 	t9146-git-svn-empty-dirs.sh                      (Wstat: 256 Tests: 14 Failed: 0)
> 	  Non-zero exit status: 1
> 	t9160-git-svn-preserve-empty-dirs.sh             (Wstat: 256 Tests: 12 Failed: 0)
> 	  Non-zero exit status: 1
>
> I.e. this makes a lot more tests pass leak-free, yay!

With -rc1 (i.e. without this series) I get:

t1022-read-tree-partial-clone.sh                 (Wstat: 256 Tests: 1 Failed: 0)
  Non-zero exit status: 1
t2016-checkout-patch.sh                          (Wstat: 256 Tests: 16 Failed: 0)
  Non-zero exit status: 1
t2012-checkout-last.sh                           (Wstat: 256 Tests: 22 Failed: 0)
  Non-zero exit status: 1
t4023-diff-rename-typechange.sh                  (Wstat: 256 Tests: 4 Failed: 0)
  Non-zero exit status: 1
t4053-diff-no-index.sh                           (Wstat: 256 Tests: 19 Failed: 0)
  Non-zero exit status: 1
t4058-diff-duplicates.sh                         (Wstat: 256 Tests: 16 Failed: 0)
  Non-zero exit status: 1
t4205-log-pretty-formats.sh                      (Wstat: 256 Tests: 21 Failed: 0)
  Non-zero exit status: 1
  Parse errors: No plan found in TAP output
t5406-remote-rejects.sh                          (Wstat: 256 Tests: 3 Failed: 0)
  Non-zero exit status: 1
t5507-remote-environment.sh                      (Wstat: 256 Tests: 5 Failed: 0)
  Non-zero exit status: 1
t5554-noop-fetch-negotiator.sh                   (Wstat: 256 Tests: 1 Failed: 0)
  Non-zero exit status: 1
t6001-rev-list-graft.sh                          (Wstat: 256 Tests: 14 Failed: 0)
  Non-zero exit status: 1
t6021-rev-list-exclude-hidden.sh                 (Wstat: 256 Tests: 42 Failed: 0)
  Non-zero exit status: 1
t6401-merge-criss-cross.sh                       (Wstat: 256 Tests: 4 Failed: 0)
  Non-zero exit status: 1
t6407-merge-binary.sh                            (Wstat: 256 Tests: 3 Failed: 0)
  Non-zero exit status: 1
t6415-merge-dir-to-symlink.sh                    (Wstat: 256 Tests: 24 Failed: 0)
  Non-zero exit status: 1
t7006-pager.sh                                   (Wstat: 256 Tests: 109 Failed: 0)
  Non-zero exit status: 1
t7008-filter-branch-null-sha1.sh                 (Wstat: 256 Tests: 6 Failed: 0)
  Non-zero exit status: 1
t7504-commit-msg-hook.sh                         (Wstat: 256 Tests: 30 Failed: 0)
  Non-zero exit status: 1
t7517-per-repo-email.sh                          (Wstat: 256 Tests: 16 Failed: 0)
  Non-zero exit status: 1
t7605-merge-resolve.sh                           (Wstat: 256 Tests: 4 Failed: 0)
  Non-zero exit status: 1

There is some overlap with your results, but also several differences.
I wonder why so many more tests appear to be leak-free for me.  I used
Debian clang version 11.0.1-2.

In any case it seems we need to update the marks before we can
attribute which tests are made leak-free by any new patches.

The TAP error in t4205-log-pretty-formats.sh is fixed by the following
patch, but I can't explain it:

diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index e448ef2928..0404491d6e 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -156,7 +156,7 @@ test_expect_success 'NUL termination with --reflog --pretty=oneline' '
 	for r in $revs
 	do
 		git show -s --pretty=oneline "$r" >raw &&
-		cat raw | lf_to_nul || exit 1
+		cat raw | lf_to_nul || return 1
 	done >expect &&
 	# the trailing NUL is already produced so we do not need to
 	# output another one

> To nitpick a bit: I didn't find that splitting this up into three
> patches helped to read it, e.g. 2/3 adds code that promptly goes away in
> 3/3.
>
> I also wondered why add two API functions for this, instead of just
> teaching the "prep options" to concat passed-in options with the user
> options?

Only add_diff_options() is exported.

get_diff_parseopts() is more flexible than a function that concatenates.
Callers can choose the order, or not concatenate at all.

An inter-diff would have been nice.  Let's see if I can find the
relevant parts.

> That also avoids a parse_options_dup(). I.e. with that squashed
> in the whole thing is:
>
>  builtin/range-diff.c |  2 +-
>  diff-no-index.c      |  3 +--
>  diff.c               | 19 ++++++++-----------
>  diff.h               |  3 ++-
>  4 files changed, 12 insertions(+), 15 deletions(-)
>
> diff --git a/builtin/range-diff.c b/builtin/range-diff.c
> index e2a74efb42a..8fcd6663b89 100644
> --- a/builtin/range-diff.c
> +++ b/builtin/range-diff.c
> @@ -47,7 +47,7 @@ int cmd_range_diff(int argc, const char **argv, const char *prefix)
>
>  	repo_diff_setup(the_repository, &diffopt);
>
> -	options = parse_options_concat(range_diff_options, diffopt.parseopts);
> +	options = add_diff_parseopts(range_diff_options, &diffopt);
>  	argc = parse_options(argc, argv, prefix, options,
>  			     builtin_range_diff_usage, PARSE_OPT_KEEP_DASHDASH);
>
> diff --git a/diff-no-index.c b/diff-no-index.c
> index 18edbdf4b59..efac1d38b38 100644
> --- a/diff-no-index.c
> +++ b/diff-no-index.c
> @@ -255,8 +255,7 @@ int diff_no_index(struct rev_info *revs,
>  	};
>  	struct option *options;
>
> -	options = parse_options_concat(no_index_options,
> -				       revs->diffopt.parseopts);
> +	options = add_diff_parseopts(no_index_options, &revs->diffopt);
>  	argc = parse_options(argc, argv, revs->prefix, options,
>  			     diff_no_index_usage, 0);
>  	if (argc != 2) {
> diff --git a/diff.c b/diff.c
> index 1054a4b7329..e186fc91802 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -4615,8 +4615,6 @@ static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
>  	builtin_checkdiff(name, other, attr_path, p->one, p->two, o);
>  }
>
> -static void prep_parse_options(struct diff_options *options);
> -
>  void repo_diff_setup(struct repository *r, struct diff_options *options)
>  {
>  	memcpy(options, &default_diff_options, sizeof(*options));
> @@ -4662,8 +4660,6 @@ void repo_diff_setup(struct repository *r, struct diff_options *options)
>
>  	options->color_moved = diff_color_moved_default;
>  	options->color_moved_ws_handling = diff_color_moved_ws_default;
> -
> -	prep_parse_options(options);
>  }
>
>  static const char diff_status_letters[] = {
> @@ -4821,8 +4817,6 @@ void diff_setup_done(struct diff_options *options)
>  			options->filter = ~filter_bit[DIFF_STATUS_FILTER_AON];
>  		options->filter &= ~options->filter_not;
>  	}
> -
> -	FREE_AND_NULL(options->parseopts);
>  }
>
>  int parse_long_opt(const char *opt, const char **argv,
> @@ -5419,7 +5413,8 @@ static int diff_opt_rotate_to(const struct option *opt, const char *arg, int uns
>  	return 0;
>  }
>
> -static void prep_parse_options(struct diff_options *options)
> +struct option *add_diff_parseopts(struct option *useropts,
> +				  struct diff_options *options)

You rename add_diff_options() to add_diff_parseopts().  OK.

>  {
>  	struct option parseopts[] = {
>  		OPT_GROUP(N_("Diff output format options")),
> @@ -5689,22 +5684,25 @@ static void prep_parse_options(struct diff_options *options)
>  		OPT_END()
>  	};
>
> -	ALLOC_ARRAY(options->parseopts, ARRAY_SIZE(parseopts));
> -	memcpy(options->parseopts, parseopts, sizeof(parseopts));
> +	return parse_options_concat(useropts, parseopts);

You bring back the concatenate from my demo patch.

>  }
>
>  int diff_opt_parse(struct diff_options *options,
>  		   const char **av, int ac, const char *prefix)
>  {
> +	struct option no_options[] = { OPT_END() };
> +	struct option *diff_parseopts = add_diff_parseopts(no_options, options);

This kinda open-codes parse_options_dup().  The reduced flexibility of
the concatenating variant is easily worked around here and it avoids the
need for slightly awkward manual concatenation.

Well, the get_diff_parseopts() variant feels cleaner, but baking the
concat in is simpler overall.

> +
>  	if (!prefix)
>  		prefix = "";
>
> -	ac = parse_options(ac, av, prefix, options->parseopts, NULL,
> +	ac = parse_options(ac, av, prefix, diff_parseopts, NULL,
>  			   PARSE_OPT_KEEP_DASHDASH |
>  			   PARSE_OPT_KEEP_UNKNOWN_OPT |
>  			   PARSE_OPT_NO_INTERNAL_HELP |
>  			   PARSE_OPT_ONE_SHOT |
>  			   PARSE_OPT_STOP_AT_NON_OPTION);
> +	free(diff_parseopts);
>
>  	return ac;
>  }
> @@ -6513,7 +6511,6 @@ void diff_free(struct diff_options *options)
>  	diff_free_file(options);
>  	diff_free_ignore_regex(options);
>  	clear_pathspec(&options->pathspec);
> -	FREE_AND_NULL(options->parseopts);
>  }
>
>  void diff_flush(struct diff_options *options)
> diff --git a/diff.h b/diff.h
> index fd33caeb25d..56704d3de22 100644
> --- a/diff.h
> +++ b/diff.h
> @@ -394,7 +394,6 @@ struct diff_options {
>  	unsigned color_moved_ws_handling;
>
>  	struct repository *repo;
> -	struct option *parseopts;
>  	struct strmap *additional_path_headers;
>
>  	int no_free;
> @@ -539,6 +538,8 @@ int git_diff_ui_config(const char *var, const char *value, void *cb);
>  #define diff_setup(diffopts) repo_diff_setup(the_repository, diffopts)
>  #endif
>  void repo_diff_setup(struct repository *, struct diff_options *);
> +struct option *add_diff_parseopts(struct option *useropts,
> +				  struct diff_options *options);
>  int diff_opt_parse(struct diff_options *, const char **, int, const char *);
>  void diff_setup_done(struct diff_options *);
>  int git_config_rename(const char *var, const char *value);