[PATCH v4 3/5] ref-filter: change parsing function error handling

[Olga Telezhnaya <olyatelezhnaya@gmail.com>]

Continue removing die() calls from ref-filter formatting logic,
so that it could be used by other commands.

Change the signature of parse_ref_filter_atom() by adding
strbuf parameter for error message.
The function returns the position in the used_atom[] array
(as before) for the given atom, or -1 to signal an error (there
could be more negative error codes further if necessary).
Upon failure, error message is appended to the strbuf.

Signed-off-by: Olga Telezhnaia <olyatelezhnaya@gmail.com>
---
 ref-filter.c | 36 ++++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/ref-filter.c b/ref-filter.c
index d120360104806..2313a33f0baa4 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -397,7 +397,8 @@ struct atom_value {
  * Used to parse format string and sort specifiers
  */
 static int parse_ref_filter_atom(const struct ref_format *format,
-				 const char *atom, const char *ep)
+				 const char *atom, const char *ep,
+				 struct strbuf *err)
 {
 	const char *sp;
 	const char *arg;
@@ -406,8 +407,10 @@ static int parse_ref_filter_atom(const struct ref_format *format,
 	sp = atom;
 	if (*sp == '*' && sp < ep)
 		sp++; /* deref */
-	if (ep <= sp)
-		die(_("malformed field name: %.*s"), (int)(ep-atom), atom);
+	if (ep <= sp) {
+		strbuf_addf(err, _("malformed field name: %.*s"), (int)(ep-atom), atom);
+		return -1;
+	}
 
 	/* Do we have the atom already used elsewhere? */
 	for (i = 0; i < used_atom_cnt; i++) {
@@ -432,8 +435,10 @@ static int parse_ref_filter_atom(const struct ref_format *format,
 			break;
 	}
 
-	if (ARRAY_SIZE(valid_atom) <= i)
-		die(_("unknown field name: %.*s"), (int)(ep-atom), atom);
+	if (ARRAY_SIZE(valid_atom) <= i) {
+		strbuf_addf(err, _("unknown field name: %.*s"), (int)(ep-atom), atom);
+		return -1;
+	}
 
 	/* Add it in, including the deref prefix */
 	at = used_atom_cnt;
@@ -725,17 +730,21 @@ int verify_ref_format(struct ref_format *format)
 
 	format->need_color_reset_at_eol = 0;
 	for (cp = format->format; *cp && (sp = find_next(cp)); ) {
+		struct strbuf err = STRBUF_INIT;
 		const char *color, *ep = strchr(sp, ')');
 		int at;
 
 		if (!ep)
 			return error(_("malformed format string %s"), sp);
 		/* sp points at "%(" and ep points at the closing ")" */
-		at = parse_ref_filter_atom(format, sp + 2, ep);
+		at = parse_ref_filter_atom(format, sp + 2, ep, &err);
+		if (at < 0)
+			die("%s", err.buf);
 		cp = ep + 1;
 
 		if (skip_prefix(used_atom[at].name, "color:", &color))
 			format->need_color_reset_at_eol = !!strcmp(color, "reset");
+		strbuf_release(&err);
 	}
 	if (format->need_color_reset_at_eol && !want_color(format->use_color))
 		format->need_color_reset_at_eol = 0;
@@ -2154,13 +2163,15 @@ int format_ref_array_item(struct ref_array_item *info,
 
 	for (cp = format->format; *cp && (sp = find_next(cp)); cp = ep + 1) {
 		struct atom_value *atomv;
+		int pos;
 
 		ep = strchr(sp, ')');
 		if (cp < sp)
 			append_literal(cp, sp, &state);
-		get_ref_atom_value(info,
-				   parse_ref_filter_atom(format, sp + 2, ep),
-				   &atomv);
+		pos = parse_ref_filter_atom(format, sp + 2, ep, error_buf);
+		if (pos < 0)
+			return -1;
+		get_ref_atom_value(info, pos, &atomv);
 		if (atomv->handler(atomv, &state, error_buf))
 			return -1;
 	}
@@ -2215,7 +2226,12 @@ static int parse_sorting_atom(const char *atom)
 	 */
 	struct ref_format dummy = REF_FORMAT_INIT;
 	const char *end = atom + strlen(atom);
-	return parse_ref_filter_atom(&dummy, atom, end);
+	struct strbuf err = STRBUF_INIT;
+	int res = parse_ref_filter_atom(&dummy, atom, end, &err);
+	if (res < 0)
+		die("%s", err.buf);
+	strbuf_release(&err);
+	return res;
 }
 
 /*  If no sorting option is given, use refname to sort as default */

--
https://github.com/git/git/pull/466