Merge branch 'jk/output-prefix-cleanup'

Code clean-up.

* jk/output-prefix-cleanup:
  diff: store graph prefix buf in git_graph struct
  diff: return line_prefix directly when possible
  diff: return const char from output_prefix callback
  diff: drop line_prefix_length field
  line-log: use diff_line_prefix() instead of custom helper

diff-lib.c

@@ -701,7 +701,7 @@ int index_differs_from(struct repository *r,
 	return (has_changes != 0);
 }
 
-static struct strbuf *idiff_prefix_cb(struct diff_options *opt UNUSED, void *data)
+static const char *idiff_prefix_cb(struct diff_options *opt UNUSED, void *data)
 {
 	return data;
 }
@@ -716,7 +716,7 @@ void show_interdiff(const struct object_id *oid1, const struct object_id *oid2,
 	opts.output_format = DIFF_FORMAT_PATCH;
 	opts.output_prefix = idiff_prefix_cb;
 	strbuf_addchars(&prefix, ' ', indent);
-	opts.output_prefix_data = &prefix;
+	opts.output_prefix_data = prefix.buf;
 	diff_setup_done(&opts);
 
 	diff_tree_oid(oid1, oid2, "", &opts);

diff.c

@@ -2317,12 +2317,9 @@ const char *diff_get_color(int diff_use_color, enum color_diff ix)
 
 const char *diff_line_prefix(struct diff_options *opt)
 {
-	struct strbuf *msgbuf;
-	if (!opt->output_prefix)
-		return "";
-
-	msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
-	return msgbuf->buf;
+	return opt->output_prefix ?
+		opt->output_prefix(opt, opt->output_prefix_data) :
+		"";
 }
 
 static unsigned long sane_truncate_line(char *line, unsigned long len)
@@ -5400,7 +5397,6 @@ static int diff_opt_line_prefix(const struct option *opt,
 
 	BUG_ON_OPT_NEG(unset);
 	options->line_prefix = optarg;
-	options->line_prefix_length = strlen(options->line_prefix);
 	graph_setup_line_prefix(options);
 	return 0;
 }

diff.h

@@ -94,7 +94,7 @@ typedef void (*add_remove_fn_t)(struct diff_options *options,
 typedef void (*diff_format_fn_t)(struct diff_queue_struct *q,
 		struct diff_options *options, void *data);
 
-typedef struct strbuf *(*diff_prefix_fn_t)(struct diff_options *opt, void *data);
+typedef const char *(*diff_prefix_fn_t)(struct diff_options *opt, void *data);
 
 #define DIFF_FORMAT_RAW		0x0001
 #define DIFF_FORMAT_DIFFSTAT	0x0002
@@ -274,7 +274,6 @@ struct diff_options {
 	const char *single_follow;
 	const char *a_prefix, *b_prefix;
 	const char *line_prefix;
-	size_t line_prefix_length;
 
 	/**
 	 * collection of boolean options that affects the operation, but some do

graph.c

@@ -76,10 +76,7 @@ static void graph_show_line_prefix(const struct diff_options *diffopt)
 	if (!diffopt || !diffopt->line_prefix)
 		return;
 
-	fwrite(diffopt->line_prefix,
-	       sizeof(char),
-	       diffopt->line_prefix_length,
-	       diffopt->file);
+	fputs(diffopt->line_prefix, diffopt->file);
 }
 
 static const char **column_colors;
@@ -312,22 +309,28 @@ struct git_graph {
 	 * stored as an index into the array column_colors.
 	 */
 	unsigned short default_column_color;
+
+	/*
+	 * Scratch buffer for generating prefixes to be used with
+	 * diff_output_prefix_callback().
+	 */
+	struct strbuf prefix_buf;
 };
 
-static struct strbuf *diff_output_prefix_callback(struct diff_options *opt, void *data)
+static const char *diff_output_prefix_callback(struct diff_options *opt, void *data)
 {
 	struct git_graph *graph = data;
-	static struct strbuf msgbuf = STRBUF_INIT;
 
 	assert(opt);
 
-	strbuf_reset(&msgbuf);
+	if (!graph)
+		return opt->line_prefix;
+
+	strbuf_reset(&graph->prefix_buf);
 	if (opt->line_prefix)
-		strbuf_add(&msgbuf, opt->line_prefix,
-			   opt->line_prefix_length);
-	if (graph)
-		graph_padding_line(graph, &msgbuf);
-	return &msgbuf;
+		strbuf_addstr(&graph->prefix_buf, opt->line_prefix);
+	graph_padding_line(graph, &graph->prefix_buf);
+	return graph->prefix_buf.buf;
 }
 
 static const struct diff_options *default_diffopt;
@@ -397,6 +400,7 @@ struct git_graph *graph_init(struct rev_info *opt)
 	 * The diff output prefix callback, with this we can make
 	 * all the diff output to align with the graph lines.
 	 */
+	strbuf_init(&graph->prefix_buf, 0);
 	opt->diffopt.output_prefix = diff_output_prefix_callback;
 	opt->diffopt.output_prefix_data = graph;
 
@@ -412,6 +416,7 @@ void graph_clear(struct git_graph *graph)
 	free(graph->new_columns);
 	free(graph->mapping);
 	free(graph->old_mapping);
+	strbuf_release(&graph->prefix_buf);
 	free(graph);
 }
 

line-log.c

@@ -900,16 +900,6 @@ static void print_line(const char *prefix, char first,
 		fputs("\\ No newline at end of file\n", file);
 }
 
-static const char *output_prefix(struct diff_options *opt)
-{
-	if (opt->output_prefix) {
-		struct strbuf *sb = opt->output_prefix(opt, opt->output_prefix_data);
-		return sb->buf;
-	} else {
-		return "";
-	}
-}
-
 static void dump_diff_hacky_one(struct rev_info *rev, struct line_log_data *range)
 {
 	unsigned int i, j = 0;
@@ -919,7 +909,7 @@ static void dump_diff_hacky_one(struct rev_info *rev, struct line_log_data *rang
 	struct diff_ranges *diff = &range->diff;
 
 	struct diff_options *opt = &rev->diffopt;
-	const char *prefix = output_prefix(opt);
+	const char *prefix = diff_line_prefix(opt);
 	const char *c_reset = diff_get_color(opt->use_color, DIFF_RESET);
 	const char *c_frag = diff_get_color(opt->use_color, DIFF_FRAGINFO);
 	const char *c_meta = diff_get_color(opt->use_color, DIFF_METAINFO);
@@ -1014,7 +1004,7 @@ out:
  */
 static void dump_diff_hacky(struct rev_info *rev, struct line_log_data *range)
 {
-	const char *prefix = output_prefix(&rev->diffopt);
+	const char *prefix = diff_line_prefix(&rev->diffopt);
 
 	fprintf(rev->diffopt.file, "%s\n", prefix);
 

log-tree.c

@@ -922,12 +922,7 @@ int log_tree_diff_flush(struct rev_info *opt)
 			 * diff/diffstat output for readability.
 			 */
 			int pch = DIFF_FORMAT_DIFFSTAT | DIFF_FORMAT_PATCH;
-			if (opt->diffopt.output_prefix) {
-				struct strbuf *msg = NULL;
-				msg = opt->diffopt.output_prefix(&opt->diffopt,
-					opt->diffopt.output_prefix_data);
-				fwrite(msg->buf, msg->len, 1, opt->diffopt.file);
-			}
+			fputs(diff_line_prefix(&opt->diffopt), opt->diffopt.file);
 
 			/*
 			 * We may have shown three-dashes line early

range-diff.c

@@ -480,7 +480,7 @@ static void patch_diff(const char *a, const char *b,
 	diff_flush(diffopt);
 }
 
-static struct strbuf *output_prefix_cb(struct diff_options *opt UNUSED, void *data)
+static const char *output_prefix_cb(struct diff_options *opt UNUSED, void *data)
 {
 	return data;
 }
@@ -508,7 +508,7 @@ static void output(struct string_list *a, struct string_list *b,
 	opts.flags.suppress_hunk_header_line_count = 1;
 	opts.output_prefix = output_prefix_cb;
 	strbuf_addstr(&indent, "    ");
-	opts.output_prefix_data = &indent;
+	opts.output_prefix_data = indent.buf;
 	diff_setup_done(&opts);
 
 	/*