@matheusbsbs / matheus-bagliano / commits / e95e481f9e

merge-recursive: avoid losing output and leaking memory holding that output

If opt->buffer_output is less than 2, then merge_trees(), merge_recursive(), and merge_recursive_generic() are all supposed to flush the opt->obuf output buffer to stdout and release any memory it holds. merge_trees() did not do this. Move the logic that handles this for merge_recursive_internal() to merge_finalize() so that all three methods handle this requirement. Note that this bug didn't cause any problems currently, because there are only two callers of merge_trees() right now (a git grep for 'merge_trees(' is misleading because builtin/merge-tree.c also defines a 'merge_tree' function that is unrelated), and only one of those is called with buffer_output less than 2 (builtin/checkout.c), but it set opt->verbosity to 0, for which there is only currently one non-error message that would be shown: "Already up to date!". However, that one message can only occur when the merge is utterly trivial (the merge base tree exactly matches the merge tree), and builtin/checkout.c already attempts a trivial merge via unpack_trees() before falling back to merge_trees(). Also, if opt->buffer_output is 2, then the caller is responsible to handle showing any output in opt->obuf and for free'ing it. This requirement might be easy to overlook, so add a comment to merge-recursive.h pointing it out. (There are currently two callers that set buffer_output to 2, both in sequencer.c, and both of which handle this correctly.) Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Elijah Newren committed Aug 17, 2019 at 11:41 UTC e95e481f9e6e4dfe62380ccc8a47acf446403a94

2 files changed +5 -4

merge-recursive.c

+3 -3

@@ -3598,9 +3598,6 @@ static int merge_recursive_internal(struct merge_options *opt,

3598 commit_list_insert(h1, &(*result)->parents);

3599 commit_list_insert(h2, &(*result)->parents->next);

3600 }

3601 - flush_output(opt);

3602 - if (!opt->call_depth && opt->buffer_output < 2)

3603 - strbuf_release(&opt->obuf);

3601 return clean;

3602 }

3603

@@ -3620,6 +3617,9 @@ static int merge_start(struct merge_options *opt, struct tree *head)

3617

3618 static void merge_finalize(struct merge_options *opt)

3619 {

3620 + flush_output(opt);

3621 + if (!opt->call_depth && opt->buffer_output < 2)

3622 + strbuf_release(&opt->obuf);

3623 if (show(opt, 2))

3624 diff_warn_rename_limit("merge.renamelimit",

3625 opt->needed_rename_limit, 0);

merge-recursive.h

+2 -1

@@ -38,7 +38,8 @@ struct merge_options {

38 /* console output related options */

39 int verbosity;

40 unsigned buffer_output; /* 1: output at end, 2: keep buffered */

41 - struct strbuf obuf; /* output buffer */

41 + struct strbuf obuf; /* output buffer; if buffer_output == 2, caller

42 + * must handle and call strbuf_release */

44 /* miscellaneous control options */

45 const char *subtree_shift;