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pack-objects: lazily set up "struct rev_info", don't leak 

In the preceding [1] (pack-objects: move revs out of
get_object_list(), 2022-03-22) the "repo_init_revisions()" was moved
to cmd_pack_objects() so that it unconditionally took place for all
invocations of "git pack-objects".

We'd thus start leaking memory, which is easily reproduced in
e.g. git.git by feeding e83c516331 (Initial revision of "git", the
information manager from hell, 2005-04-07) to "git pack-objects";

    $ echo e83c516331 | ./git pack-objects initial
    [...]
	==19130==ERROR: LeakSanitizer: detected memory leaks

	Direct leak of 7120 byte(s) in 1 object(s) allocated from:
	    #0 0x455308 in __interceptor_malloc (/home/avar/g/git/git+0x455308)
	    #1 0x75b399 in do_xmalloc /home/avar/g/git/wrapper.c:41:8
	    #2 0x75b356 in xmalloc /home/avar/g/git/wrapper.c:62:9
	    #3 0x5d7609 in prep_parse_options /home/avar/g/git/diff.c:5647:2
	    #4 0x5d415a in repo_diff_setup /home/avar/g/git/diff.c:4621:2
	    #5 0x6dffbb in repo_init_revisions /home/avar/g/git/revision.c:1853:2
	    #6 0x4f599d in cmd_pack_objects /home/avar/g/git/builtin/pack-objects.c:3980:2
	    #7 0x4592ca in run_builtin /home/avar/g/git/git.c:465:11
	    #8 0x457d81 in handle_builtin /home/avar/g/git/git.c:718:3
	    #9 0x458ca5 in run_argv /home/avar/g/git/git.c:785:4
	    #10 0x457b40 in cmd_main /home/avar/g/git/git.c:916:19
	    #11 0x562259 in main /home/avar/g/git/common-main.c:56:11
	    #12 0x7fce792ac7ec in __libc_start_main csu/../csu/libc-start.c:332:16
	    #13 0x4300f9 in _start (/home/avar/g/git/git+0x4300f9)

	SUMMARY: LeakSanitizer: 7120 byte(s) leaked in 1 allocation(s).
	Aborted

Narrowly fixing that commit would have been easy, just add call
repo_init_revisions() right before get_object_list(), which is
effectively what was done before that commit.

But an unstated constraint when setting it up early is that it was
needed for the subsequent [2] (pack-objects: parse --filter directly
into revs.filter, 2022-03-22), i.e. we might have a --filter
command-line option, and need to either have the "struct rev_info"
setup when we encounter that option, or later.

Let's just change the control flow so that we'll instead set up the
"struct rev_info" only when we need it. Doing so leads to a bit more
verbosity, but it's a lot clearer what we're doing and why.

An earlier version of this commit[3] went behind
opt_parse_list_objects_filter()'s back by faking up a "struct option"
before calling it. Let's avoid that and instead create a blessed API
for this pattern.

We could furthermore combine the two get_object_list() invocations
here by having repo_init_revisions() invoked on &pfd.revs, but I think
clearly separating the two makes the flow clearer. Likewise
redundantly but explicitly (i.e. redundant v.s. a "{ 0 }") "0" to
"have_revs" early in cmd_pack_objects().

While we're at it add parentheses around the arguments to the OPT_*
macros in in list-objects-filter-options.h, as we need to change those
lines anyway. It doesn't matter in this case, but is good general
practice.

1. https://lore.kernel.org/git/619b757d98465dbc4995bdc11a5282fbfcbd3daa.1647970119.git.gitgitgadget@gmail.com
2. https://lore.kernel.org/git/97de926904988b89b5663bd4c59c011a1723a8f5.1647970119.git.gitgitgadget@gmail.com
3. https://lore.kernel.org/git/patch-1.1-193534b0f07-20220325T121715Z-avarab@gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Ævar Arnfjörð Bjarmason 2022-03-28 17:43:18 +02:00 committed by Junio C Hamano
parent 8ba221e245
commit 5cb28270a1
3 changed files with 48 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
builtin/pack-objects.c
View File

@ -3857,6 +3857,21 @@ static int option_parse_unpack_unreachable(const struct option *opt,
return 0;
}
struct po_filter_data {
unsigned have_revs:1;
struct rev_info revs;
};
static struct list_objects_filter_options *po_filter_revs_init(void *value)
{
struct po_filter_data *data = value;
repo_init_revisions(the_repository, &data->revs, NULL);
data->have_revs = 1;
return &data->revs.filter;
}
int cmd_pack_objects(int argc, const char **argv, const char *prefix)
{
int use_internal_rev_list = 0;
@ -3867,7 +3882,7 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
int rev_list_index = 0;
int stdin_packs = 0;
struct string_list keep_pack_list = STRING_LIST_INIT_NODUP;
struct rev_info revs;
struct po_filter_data pfd = { .have_revs = 0 };
struct option pack_objects_options[] = {
OPT_SET_INT('q', "quiet", &progress,
@ -3954,7 +3969,7 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
&write_bitmap_index,
N_("write a bitmap index if possible"),
WRITE_BITMAP_QUIET, PARSE_OPT_HIDDEN),
OPT_PARSE_LIST_OBJECTS_FILTER(&revs.filter),
OPT_PARSE_LIST_OBJECTS_FILTER_INIT(&pfd, po_filter_revs_init),
OPT_CALLBACK_F(0, "missing", NULL, N_("action"),
N_("handling for missing objects"), PARSE_OPT_NONEG,
option_parse_missing_action),
@ -3973,8 +3988,6 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
read_replace_refs = 0;
repo_init_revisions(the_repository, &revs, NULL);
sparse = git_env_bool("GIT_TEST_PACK_SPARSE", -1);
if (the_repository->gitdir) {
prepare_repo_settings(the_repository);
@ -4076,7 +4089,7 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
if (!rev_list_all || !rev_list_reflog || !rev_list_index)
unpack_unreachable_expiration = 0;
if (revs.filter.choice) {
if (pfd.have_revs && pfd.revs.filter.choice) {
if (!pack_to_stdout)
die(_("cannot use --filter without --stdout"));
if (stdin_packs)
@ -4152,7 +4165,12 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
add_unreachable_loose_objects();
} else if (!use_internal_rev_list) {
read_object_list_from_stdin();
} else if (pfd.have_revs) {
get_object_list(&pfd.revs, rp.nr, rp.v);
} else {
struct rev_info revs;
repo_init_revisions(the_repository, &revs, NULL);
get_object_list(&revs, rp.nr, rp.v);
}
cleanup_preferred_base();

4
list-objects-filter-options.c
View File

@ -285,6 +285,10 @@ int opt_parse_list_objects_filter(const struct option *opt,
const char *arg, int unset)
{
struct list_objects_filter_options *filter_options = opt->value;
opt_lof_init init = (opt_lof_init)opt->defval;
if (init)
filter_options = init(opt->value);
if (unset || !arg)
list_objects_filter_set_no_filter(filter_options);

24
list-objects-filter-options.h
View File

@ -104,13 +104,31 @@ void parse_list_objects_filter(
struct list_objects_filter_options *filter_options,
const char *arg);
/**
* The opt->value to opt_parse_list_objects_filter() is either a
* "struct list_objects_filter_option *" when using
* OPT_PARSE_LIST_OBJECTS_FILTER().
*
* Or, if using no "struct option" field is used by the callback,
* except the "defval" which is expected to be an "opt_lof_init"
* function, which is called with the "opt->value" and must return a
* pointer to the ""struct list_objects_filter_option *" to be used.
*
* The OPT_PARSE_LIST_OBJECTS_FILTER_INIT() can be used e.g. the
* "struct list_objects_filter_option" is embedded in a "struct
* rev_info", which the "defval" could be tasked with lazily
* initializing. See cmd_pack_objects() for an example.
*/
int opt_parse_list_objects_filter(const struct option *opt,
const char *arg, int unset);
typedef struct list_objects_filter_options *(*opt_lof_init)(void *);
#define OPT_PARSE_LIST_OBJECTS_FILTER_INIT(fo, init) \
{ OPTION_CALLBACK, 0, "filter", (fo), N_("args"), \
N_("object filtering"), 0, opt_parse_list_objects_filter, \
(intptr_t)(init) }
#define OPT_PARSE_LIST_OBJECTS_FILTER(fo) \
OPT_CALLBACK(0, "filter", fo, N_("args"), \
N_("object filtering"), \
opt_parse_list_objects_filter)
OPT_PARSE_LIST_OBJECTS_FILTER_INIT((fo), NULL)
/*
* Translates abbreviated numbers in the filter's filter_spec into their