[PATCH v3 23/24] merge-recursive: add sanity checks for relevant merge_options

[Elijah Newren]

There are lots of options that callers can set, yet most have a limited
range of valid values, some options are meant for output (e.g.
opt->obuf, which is expected to start empty), and callers are expected
to not set opt->priv.  Add several sanity checks to ensure callers
provide sane values.

Signed-off-by: Elijah Newren <new...@gmail.com>
---
 merge-recursive.c | 23 +++++++++++++++++++++++
 merge-recursive.h |  2 +-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 647b1f25c3..bc0da608c4 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -3620,6 +3620,29 @@ static int merge_start(struct merge_options *opt, struct 
tree *head)
 {
        struct strbuf sb = STRBUF_INIT;
 
+       /* Sanity checks on opt */
+       assert(opt->repo);
+
+       assert(opt->branch1 && opt->branch2);
+
+       assert(opt->detect_renames >= -1 &&
+              opt->detect_renames <= DIFF_DETECT_COPY);
+       assert(opt->detect_directory_renames >= MERGE_DIRECTORY_RENAMES_NONE &&
+              opt->detect_directory_renames <= MERGE_DIRECTORY_RENAMES_TRUE);
+       assert(opt->rename_limit >= -1);
+       assert(opt->rename_score >= 0 && opt->rename_score <= MAX_SCORE);
+
+       assert(opt->xdl_opts >= 0);
+       assert(opt->recursive_variant >= MERGE_VARIANT_NORMAL &&
+              opt->recursive_variant <= MERGE_VARIANT_THEIRS);
+
+       assert(opt->verbosity >= 0 && opt->verbosity <= 5);
+       assert(opt->buffer_output >= 0 && opt->buffer_output <= 2);
+       assert(opt->obuf.len == 0);
+
+       assert(opt->priv == NULL);
+
+       /* Sanity check on repo state; index must match head */
        if (repo_index_has_changes(opt->repo, head, &sb)) {
                err(opt, _("Your local changes to the following files would be 
overwritten by merge:\n  %s"),
                    sb.buf);
diff --git a/merge-recursive.h b/merge-recursive.h
index 978847e672..d201ee80fb 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -27,7 +27,7 @@ struct merge_options {
        } detect_directory_renames;
        int rename_limit;
        int rename_score;
-       int show_rename_progress;
+       int show_rename_progress : 1;
 
        /* xdiff-related options (patience, ignore whitespace, ours/theirs) */
        long xdl_opts;
-- 
2.23.0.rc2.32.g2123e9e4e4