[PATCH v2 2/3] pretty.c: capture invalid trailer argument

["Hariom Verma via GitGitGadget" <gitgitgadget@gmail.com>]

From: Hariom Verma <hariom18599@gmail.com>

As we would like to use this same logic in ref-filter, it's nice to
get invalid trailer argument. This will allow us to print precise
error message, while using `format_set_trailers_options()` in
ref-filter.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Heba Waly <heba.waly@gmail.com>
Signed-off-by: Hariom Verma <hariom18599@gmail.com>
---
 pretty.c | 18 ++++++++++++++----
 pretty.h |  3 ++-
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/pretty.c b/pretty.c
index bb6a3c634ac..b5fa7944389 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1152,12 +1152,17 @@ int format_set_trailers_options(struct process_trailer_options *opts,
 				struct string_list *filter_list,
 				struct strbuf *sepbuf,
 				struct strbuf *kvsepbuf,
-				const char **arg)
+				const char **arg,
+				char **invalid_arg)
 {
 	for (;;) {
 		const char *argval;
 		size_t arglen;
 
+		if(**arg == ')') {
+			break;
+		}
+
 		if (match_placeholder_arg_value(*arg, "key", arg, &argval, &arglen)) {
 			uintptr_t len = arglen;
 
@@ -1186,8 +1191,11 @@ int format_set_trailers_options(struct process_trailer_options *opts,
 		} else if (!match_placeholder_bool_arg(*arg, "only", arg, &opts->only_trailers) &&
 			   !match_placeholder_bool_arg(*arg, "unfold", arg, &opts->unfold) &&
 			   !match_placeholder_bool_arg(*arg, "keyonly", arg, &opts->key_only) &&
-			   !match_placeholder_bool_arg(*arg, "valueonly", arg, &opts->value_only))
-			break;
+			   !match_placeholder_bool_arg(*arg, "valueonly", arg, &opts->value_only)) {
+			size_t invalid_arg_len = strcspn(*arg, ",)");
+			*invalid_arg = xstrndup(*arg, invalid_arg_len);
+			return 1;
+		}
 	}
 	return 0;
 }
@@ -1464,12 +1472,13 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		struct strbuf sepbuf = STRBUF_INIT;
 		struct strbuf kvsepbuf = STRBUF_INIT;
 		size_t ret = 0;
+		char *unused = NULL;
 
 		opts.no_divider = 1;
 
 		if (*arg == ':') {
 			arg++;
-			if (format_set_trailers_options(&opts, &filter_list, &sepbuf, &kvsepbuf, &arg))
+			if (format_set_trailers_options(&opts, &filter_list, &sepbuf, &kvsepbuf, &arg, &unused))
 				goto trailer_out;
 		}
 		if (*arg == ')') {
@@ -1479,6 +1488,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 	trailer_out:
 		string_list_clear(&filter_list, 0);
 		strbuf_release(&sepbuf);
+		free((char *)unused);
 		return ret;
 	}
 
diff --git a/pretty.h b/pretty.h
index 7369cf7e148..d902cdd70a9 100644
--- a/pretty.h
+++ b/pretty.h
@@ -151,6 +151,7 @@ int format_set_trailers_options(struct process_trailer_options *opts,
 			struct string_list *filter_list,
 			struct strbuf *sepbuf,
 			struct strbuf *kvsepbuf,
-			const char **arg);
+			const char **arg,
+			char **invalid_arg);
 
 #endif /* PRETTY_H */
-- 
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