[PATCH v2 02/13] sparse-checkout: pass string literals directly to add_pattern()
- From
Jeff King <peff@peff.net>
- Date
- Jun 4, 2024, 10:13 UTC
- Message-ID
- <20240604101310.GB1304593@coredump.intra.peff.net>
- In-Reply-To
- <20240604100814.GA1304520@coredump.intra.peff.net>
The add_pattern() function takes a pattern string, but neither makes a copy of it nor takes ownership of the memory. So it is the caller's responsibility to make sure the string hangs around as long as the pattern_list which references it.
There are a few cases in sparse-checkout where we use string literal patterns by stuffing them into a strbuf, detaching the buffer, and then passing the result into add_pattern(). This creates a leak when the pattern_list is eventually cleared, since we don't retain a copy of the detached buffer to free.
But we can observe that the whole strbuf dance is unnecessary. The point was presumably[1] to satisfy the lifetime requirement of the string. But string literals have static duration; we can count on them lasting for the whole program.
So we can fix the leak by just passing them directly. And as a bonus, that simplifies the code. The leaks can be seen in t7002, which drops from 25 leaks to 22 with this patch. It also makes t3602 and t1090 leak-free.
In the long run, we will also want to clean up this (undocumented!) memory lifetime requirement of add_pattern(). But that can come in a later patch; passing the string literals directly will be the right thing either way.
[1] The code in question comes from 416adc8711 (sparse-checkout: update
working directory in-process for 'init', 2019-11-21) and 99dfa6f970
(sparse-checkout: use in-process update for disable subcommand,
2019-11-21), but I didn't see anything in their commit messages or
on the list explaining the strbufs.Signed-off-by: Jeff King <peff@peff.net> --- builtin/sparse-checkout.c | 11 +++-------- t/t1090-sparse-checkout-scope.sh | 1 + t/t3602-rm-sparse-checkout.sh | 1 + 3 files changed, 5 insertions(+), 8 deletions(-)
diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c index 8747191484..7c17ed238c 100644 --- a/builtin/sparse-checkout.c +++ b/builtin/sparse-checkout.c @@ -442,7 +442,6 @@ static int sparse_checkout_init(int argc, const char **argv, const char *prefix) char *sparse_filename; int res; struct object_id oid; - struct strbuf pattern = STRBUF_INIT; static struct option builtin_sparse_checkout_init_options[] = { OPT_BOOL(0, "cone", &init_opts.cone_mode, @@ -493,10 +492,8 @@ static int sparse_checkout_init(int argc, const char **argv, const char *prefix) return 0; } - strbuf_addstr(&pattern, "/*"); - add_pattern(strbuf_detach(&pattern, NULL), empty_base, 0, &pl, 0); - strbuf_addstr(&pattern, "!/*/"); - add_pattern(strbuf_detach(&pattern, NULL), empty_base, 0, &pl, 0); + add_pattern("/*", empty_base, 0, &pl, 0); + add_pattern("!/*/", empty_base, 0, &pl, 0); pl.use_cone_patterns = init_opts.cone_mode; return write_patterns_and_update(&pl); @@ -893,7 +890,6 @@ static int sparse_checkout_disable(int argc, const char **argv, OPT_END(), }; struct pattern_list pl; - struct strbuf match_all = STRBUF_INIT; /* * We do not exit early if !core_apply_sparse_checkout; due to the @@ -919,8 +915,7 @@ static int sparse_checkout_disable(int argc, const char **argv, pl.use_cone_patterns = 0; core_apply_sparse_checkout = 1; - strbuf_addstr(&match_all, "/*"); - add_pattern(strbuf_detach(&match_all, NULL), empty_base, 0, &pl, 0); + add_pattern("/*", empty_base, 0, &pl, 0); prepare_repo_settings(the_repository); the_repository->settings.sparse_index = 0; diff --git a/t/t1090-sparse-checkout-scope.sh b/t/t1090-sparse-checkout-scope.sh index 3a14218b24..da0e7714d5 100755 --- a/t/t1090-sparse-checkout-scope.sh +++ b/t/t1090-sparse-checkout-scope.sh @@ -6,6 +6,7 @@ GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME TEST_CREATE_REPO_NO_TEMPLATE=1 +TEST_PASSES_SANITIZE_LEAK=true . ./test-lib.sh test_expect_success 'setup' ' diff --git a/t/t3602-rm-sparse-checkout.sh b/t/t3602-rm-sparse-checkout.sh index 08580fd3dc..fcdefba48c 100755 --- a/t/t3602-rm-sparse-checkout.sh +++ b/t/t3602-rm-sparse-checkout.sh @@ -2,6 +2,7 @@ test_description='git rm in sparse checked out working trees' +TEST_PASSES_SANITIZE_LEAK=true . ./test-lib.sh test_expect_success 'setup' "
-- 2.45.2.807.g3b5fadc4da