pretty: Initialize notes if %N is used

When using git log --pretty='%N' without an explicit --show-notes, git
would segfault. This patches fixes this behaviour by loading the needed
notes datastructures if --pretty is used and the format contains %N.
When --pretty='%N' is used together with --no-notes, %N won't be
expanded.

This is an extension to a proposed patch by Jeff King.

Signed-off-by: Johannes Gilger <heipei@hackvalue.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 36 insertions, 4 deletions

diff --git a/pretty.c b/pretty.c
index 6ba3da89b..7cb3a2af5 100644
--- a/pretty.c
+++ b/pretty.c
@@ -775,10 +775,13 @@ static size_t format_commit_one(struct strbuf *sb, const char *placeholder,
 		}
 		return 0;	/* unknown %g placeholder */
 	case 'N':
-		format_display_notes(commit->object.sha1, sb,
-			    git_log_output_encoding ? git_log_output_encoding
-						    : git_commit_encoding, 0);
-		return 1;
+		if (c->pretty_ctx->show_notes) {
+			format_display_notes(commit->object.sha1, sb,
+				    git_log_output_encoding ? git_log_output_encoding
+							    : git_commit_encoding, 0);
+			return 1;
+		}
+		return 0;
 	}
 
 	/* For the rest we have to parse the commit header. */
@@ -855,6 +858,35 @@ static size_t format_commit_item(struct strbuf *sb, const char *placeholder,
 	return consumed + 1;
 }
 
+static size_t userformat_want_item(struct strbuf *sb, const char *placeholder,
+				   void *context)
+{
+	struct userformat_want *w = context;
+
+	if (*placeholder == '+' || *placeholder == '-')
+		placeholder++;
+
+	switch (*placeholder) {
+	case 'N':
+		w->notes = 1;
+		break;
+	}
+	return 0;
+}
+
+void userformat_find_requirements(const char *fmt, struct userformat_want *w)
+{
+	struct strbuf dummy = STRBUF_INIT;
+
+	if (!fmt) {
+		if (!user_format)
+			return;
+		fmt = user_format;
+	}
+	strbuf_expand(&dummy, user_format, userformat_want_item, w);
+	strbuf_release(&dummy);
+}
+
 void format_commit_message(const struct commit *commit,
 			   const char *format, struct strbuf *sb,
 			   const struct pretty_print_context *pretty_ctx)