[PATCH v3 3/4] pretty.c: refactor trailer logic to `format_set_trailers_options()`

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

From: Hariom Verma <hariom18599@gmail.com>

Refactored trailers formatting logic inside pretty.c to a new function
`format_set_trailers_options()`.

Also, introduced a code to get invalid trailer arguments. As we would
like to use same logic in ref-filter, it's nice to get invalid trailer
argument. This will allow us to print accurate 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>
---
 Hariom Verma via GitGitGadget |  0
 pretty.c                      | 83 ++++++++++++++++++++++-------------
 pretty.h                      | 11 +++++
 3 files changed, 64 insertions(+), 30 deletions(-)
 create mode 100644 Hariom Verma via GitGitGadget

diff --git a/Hariom Verma via GitGitGadget b/Hariom Verma via GitGitGadget
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/pretty.c b/pretty.c
index 2a3d46bf42..bd8d38e27b 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1147,6 +1147,55 @@ static int format_trailer_match_cb(const struct strbuf *key, void *ud)
 	return 0;
 }
 
+int format_set_trailers_options(struct process_trailer_options *opts,
+				struct string_list *filter_list,
+				struct strbuf *sepbuf,
+				const char **arg,
+				const char **err)
+{
+	for (;;) {
+		const char *argval;
+		size_t arglen;
+
+		if (**arg != ')') {
+			size_t vallen = strcspn(*arg, "=,)");
+			const char *valstart = xstrndup(*arg, vallen);
+			if (strcmp(valstart, "key") &&
+				strcmp(valstart, "separator") &&
+				strcmp(valstart, "only") &&
+				strcmp(valstart, "valueonly") &&
+				strcmp(valstart, "unfold")) {
+					*err = xstrdup(valstart);
+					return 1;
+				}
+			free((char *)valstart);
+		}
+		if (match_placeholder_arg_value(*arg, "key", arg, &argval, &arglen)) {
+			uintptr_t len = arglen;
+
+			if (!argval)
+				return 1;
+
+			if (len && argval[len - 1] == ':')
+				len--;
+			string_list_append(filter_list, argval)->util = (char *)len;
+
+			opts->filter = format_trailer_match_cb;
+			opts->filter_data = filter_list;
+			opts->only_trailers = 1;
+		} else if (match_placeholder_arg_value(*arg, "separator", arg, &argval, &arglen)) {
+			char *fmt = xstrndup(argval, arglen);
+			strbuf_expand(sepbuf, fmt, strbuf_expand_literal_cb, NULL);
+			free(fmt);
+			opts->separator = sepbuf;
+		} 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, "valueonly", arg, &opts->value_only))
+			break;
+	}
+	return 0;
+}
+
 static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 				const char *placeholder,
 				void *context)
@@ -1417,41 +1466,14 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		struct string_list filter_list = STRING_LIST_INIT_NODUP;
 		struct strbuf sepbuf = STRBUF_INIT;
 		size_t ret = 0;
+		const char *unused = NULL;
 
 		opts.no_divider = 1;
 
 		if (*arg == ':') {
 			arg++;
-			for (;;) {
-				const char *argval;
-				size_t arglen;
-
-				if (match_placeholder_arg_value(arg, "key", &arg, &argval, &arglen)) {
-					uintptr_t len = arglen;
-
-					if (!argval)
-						goto trailer_out;
-
-					if (len && argval[len - 1] == ':')
-						len--;
-					string_list_append(&filter_list, argval)->util = (char *)len;
-
-					opts.filter = format_trailer_match_cb;
-					opts.filter_data = &filter_list;
-					opts.only_trailers = 1;
-				} else if (match_placeholder_arg_value(arg, "separator", &arg, &argval, &arglen)) {
-					char *fmt;
-
-					strbuf_reset(&sepbuf);
-					fmt = xstrndup(argval, arglen);
-					strbuf_expand(&sepbuf, fmt, strbuf_expand_literal_cb, NULL);
-					free(fmt);
-					opts.separator = &sepbuf;
-				} 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, "valueonly", &arg, &opts.value_only))
-					break;
-			}
+			if (format_set_trailers_options(&opts, &filter_list, &sepbuf, &arg, &unused))
+				goto trailer_out;
 		}
 		if (*arg == ')') {
 			format_trailers_from_commit(sb, msg + c->subject_off, &opts);
@@ -1460,6 +1482,7 @@ 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 071f2fb8e4..cfe2e8b39b 100644
--- a/pretty.h
+++ b/pretty.h
@@ -6,6 +6,7 @@
 
 struct commit;
 struct strbuf;
+struct process_trailer_options;
 
 /* Commit formats */
 enum cmit_fmt {
@@ -139,4 +140,14 @@ const char *format_subject(struct strbuf *sb, const char *msg,
 /* Check if "cmit_fmt" will produce an empty output. */
 int commit_format_is_empty(enum cmit_fmt);
 
+/*
+ * Set values of fields in "struct process_trailer_options"
+ * according to trailers arguments.
+ */
+int format_set_trailers_options(struct process_trailer_options *opts,
+				struct string_list *filter_list,
+				struct strbuf *sepbuf,
+				const char **arg,
+				const char **err);
+
 #endif /* PRETTY_H */
-- 
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