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revisions API: have release_revisions() release "mailmap"

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Extend the the release_revisions() function so that it frees the
"mailmap" in the "struct rev_info".

The log family of functions now calls the clear_mailmap() function
added in fa8afd18e5a (revisions API: provide and use a
release_revisions(), 2021-09-19), allowing us to whitelist some tests
with "TEST_PASSES_SANITIZE_LEAK=true".

Unfortunately having a pointer to a mailmap in "struct rev_info"
instead of an embedded member that we "own" get a bit messy, as can be
seen in the change to builtin/commit.c.

When we free() this data we won't be able to tell apart a pointer to a
"mailmap" on the heap from one on the stack. As seen in
ea57bc0d41 (log: add --use-mailmap option, 2013-01-05) the "log"
family allocates it on the heap, but in the find_author_by_nickname()
code added in ea16794e43 (commit: search author pattern against
mailmap, 2013-08-23) we allocated it on the stack instead.

Ideally we'd simply change that member to a "struct string_list
mailmap" and never free() the "mailmap" itself, but that would be a
much larger change to the revisions API.

We have code that needs to hand an existing "mailmap" to a "struct
rev_info", while we could change all of that, let's not go there
now.

The complexity isn't in the ownership of the "mailmap" per-se, but
that various things assume a "rev_info.mailmap == NULL" means "doesn't
want mailmap", if we changed that to an init'd "struct string_list
we'd need to carefully refactor things to change those assumptions.

Let's instead always free() it, and simply declare that if you add
such a "mailmap" it must be allocated on the heap. Any modern libc
will correctly panic if we free() a stack variable, so this should be
safe going forward.

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
2022-04-13 22:01:46 +02:00
committed by Junio C Hamano
parent e966fc5a89
commit a52f07afcb
7 changed files with 16 additions and 3 deletions
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5
builtin/commit.c
View File

@ -1100,7 +1100,6 @@ static const char *find_author_by_nickname(const char *name)
struct rev_info revs;
struct commit *commit;
struct strbuf buf = STRBUF_INIT;
struct string_list mailmap = STRING_LIST_INIT_NODUP;
const char *av[20];
int ac = 0;
@ -1111,7 +1110,8 @@ static const char *find_author_by_nickname(const char *name)
av[++ac] = buf.buf;
av[++ac] = NULL;
setup_revisions(ac, av, &revs, NULL);
revs.mailmap = &mailmap;
revs.mailmap = xmalloc(sizeof(struct string_list));
string_list_init_nodup(revs.mailmap);
read_mailmap(revs.mailmap);
if (prepare_revision_walk(&revs))
@ -1122,7 +1122,6 @@ static const char *find_author_by_nickname(const char *name)
ctx.date_mode.type = DATE_NORMAL;
strbuf_release(&buf);
format_commit_message(commit, "%aN <%aE>", &buf, &ctx);
clear_mailmap(&mailmap);
release_revisions(&revs);
return strbuf_detach(&buf, NULL);
}