Merge branch 'jk/diff-graph-cleanup'

Refactors a lot of repetitive code sequence from the graph drawing
code and adds it to the combined diff output.

* jk/diff-graph-cleanup:
  combine-diff.c: teach combined diffs about line prefix
  diff.c: use diff_line_prefix() where applicable
  diff: add diff_line_prefix function
  diff.c: make constant string arguments const
  diff: write prefix to the correct file
  graph: output padding for merge subsequent parents

4 files changed, 79 insertions, 114 deletions

diff --git a/combine-diff.c b/combine-diff.c
index 7f6187f9c..35d41cd56 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -526,7 +526,8 @@ static void show_line_to_eol(const char *line, int len, const char *reset)
 	       saw_cr_at_eol ? "\r" : "");
 }
 
-static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent,
+static void dump_sline(struct sline *sline, const char *line_prefix,
+		       unsigned long cnt, int num_parent,
 		       int use_color, int result_deleted)
 {
 	unsigned long mark = (1UL<<num_parent);
@@ -582,7 +583,7 @@ static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent,
 			rlines -= null_context;
 		}
 
-		fputs(c_frag, stdout);
+		printf("%s%s", line_prefix, c_frag);
 		for (i = 0; i <= num_parent; i++) putchar(combine_marker);
 		for (i = 0; i < num_parent; i++)
 			show_parent_lno(sline, lno, hunk_end, i, null_context);
@@ -614,7 +615,7 @@ static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent,
 			struct sline *sl = &sline[lno++];
 			ll = (sl->flag & no_pre_delete) ? NULL : sl->lost_head;
 			while (ll) {
-				fputs(c_old, stdout);
+				printf("%s%s", line_prefix, c_old);
 				for (j = 0; j < num_parent; j++) {
 					if (ll->parent_map & (1UL<<j))
 						putchar('-');
@@ -627,6 +628,7 @@ static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent,
 			if (cnt < lno)
 				break;
 			p_mask = 1;
+			fputs(line_prefix, stdout);
 			if (!(sl->flag & (mark-1))) {
 				/*
 				 * This sline was here to hang the
@@ -680,11 +682,13 @@ static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
 static void dump_quoted_path(const char *head,
 			     const char *prefix,
 			     const char *path,
+			     const char *line_prefix,
 			     const char *c_meta, const char *c_reset)
 {
 	static struct strbuf buf = STRBUF_INIT;
 
 	strbuf_reset(&buf);
+	strbuf_addstr(&buf, line_prefix);
 	strbuf_addstr(&buf, c_meta);
 	strbuf_addstr(&buf, head);
 	quote_two_c_style(&buf, prefix, path, 0);
@@ -696,6 +700,7 @@ static void show_combined_header(struct combine_diff_path *elem,
 				 int num_parent,
 				 int dense,
 				 struct rev_info *rev,
+				 const char *line_prefix,
 				 int mode_differs,
 				 int show_file_header)
 {
@@ -714,8 +719,8 @@ static void show_combined_header(struct combine_diff_path *elem,
 		show_log(rev);
 
 	dump_quoted_path(dense ? "diff --cc " : "diff --combined ",
-			 "", elem->path, c_meta, c_reset);
-	printf("%sindex ", c_meta);
+			 "", elem->path, line_prefix, c_meta, c_reset);
+	printf("%s%sindex ", line_prefix, c_meta);
 	for (i = 0; i < num_parent; i++) {
 		abb = find_unique_abbrev(elem->parent[i].sha1,
 					 abbrev);
@@ -734,11 +739,12 @@ static void show_combined_header(struct combine_diff_path *elem,
 			    DIFF_STATUS_ADDED)
 				added = 0;
 		if (added)
-			printf("%snew file mode %06o",
-			       c_meta, elem->mode);
+			printf("%s%snew file mode %06o",
+			       line_prefix, c_meta, elem->mode);
 		else {
 			if (deleted)
-				printf("%sdeleted file ", c_meta);
+				printf("%s%sdeleted file ",
+				       line_prefix, c_meta);
 			printf("mode ");
 			for (i = 0; i < num_parent; i++) {
 				printf("%s%06o", i ? "," : "",
@@ -755,16 +761,16 @@ static void show_combined_header(struct combine_diff_path *elem,
 
 	if (added)
 		dump_quoted_path("--- ", "", "/dev/null",
-				 c_meta, c_reset);
+				 line_prefix, c_meta, c_reset);
 	else
 		dump_quoted_path("--- ", a_prefix, elem->path,
-				 c_meta, c_reset);
+				 line_prefix, c_meta, c_reset);
 	if (deleted)
 		dump_quoted_path("+++ ", "", "/dev/null",
-				 c_meta, c_reset);
+				 line_prefix, c_meta, c_reset);
 	else
 		dump_quoted_path("+++ ", b_prefix, elem->path,
-				 c_meta, c_reset);
+				 line_prefix, c_meta, c_reset);
 }
 
 static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
@@ -782,6 +788,7 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 	struct userdiff_driver *userdiff;
 	struct userdiff_driver *textconv = NULL;
 	int is_binary;
+	const char *line_prefix = diff_line_prefix(opt);
 
 	context = opt->context;
 	userdiff = userdiff_find_by_path(elem->path);
@@ -901,7 +908,7 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 	}
 	if (is_binary) {
 		show_combined_header(elem, num_parent, dense, rev,
-				     mode_differs, 0);
+				     line_prefix, mode_differs, 0);
 		printf("Binary files differ\n");
 		free(result);
 		return;
@@ -962,8 +969,8 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 
 	if (show_hunks || mode_differs || working_tree_file) {
 		show_combined_header(elem, num_parent, dense, rev,
-				     mode_differs, 1);
-		dump_sline(sline, cnt, num_parent,
+				     line_prefix, mode_differs, 1);
+		dump_sline(sline, line_prefix, cnt, num_parent,
 			   opt->use_color, result_deleted);
 	}
 	free(result);
@@ -986,6 +993,7 @@ static void show_raw_diff(struct combine_diff_path *p, int num_parent, struct re
 {
 	struct diff_options *opt = &rev->diffopt;
 	int line_termination, inter_name_termination, i;
+	const char *line_prefix = diff_line_prefix(opt);
 
 	line_termination = opt->line_termination;
 	inter_name_termination = '\t';
@@ -995,7 +1003,10 @@ static void show_raw_diff(struct combine_diff_path *p, int num_parent, struct re
 	if (rev->loginfo && !rev->no_commit_id)
 		show_log(rev);
 
+
 	if (opt->output_format & DIFF_FORMAT_RAW) {
+		printf("%s", line_prefix);
+
 		/* As many colons as there are parents */
 		for (i = 0; i < num_parent; i++)
 			putchar(':');
@@ -1033,6 +1044,7 @@ void show_combined_diff(struct combine_diff_path *p,
 		       struct rev_info *rev)
 {
 	struct diff_options *opt = &rev->diffopt;
+
 	if (!p->len)
 		return;
 	if (opt->output_format & (DIFF_FORMAT_RAW |
@@ -1143,8 +1155,10 @@ void diff_tree_combined(const unsigned char *sha1,
 
 		if (show_log_first && i == 0) {
 			show_log(rev);
+
 			if (rev->verbose_header && opt->output_format)
-				putchar(opt->line_termination);
+				printf("%s%c", diff_line_prefix(opt),
+				       opt->line_termination);
 		}
 		diff_flush(&diffopts);
 	}
@@ -1172,7 +1186,8 @@ void diff_tree_combined(const unsigned char *sha1,
 
 		if (opt->output_format & DIFF_FORMAT_PATCH) {
 			if (needsep)
-				putchar(opt->line_termination);
+				printf("%s%c", diff_line_prefix(opt),
+				       opt->line_termination);
 			for (p = paths; p; p = p->next) {
 				if (p->len)
 					show_patch_diff(p, num_parent, dense,
diff --git a/diff.c b/diff.c
index 348f71b46..f441f6c7f 100644
--- a/diff.c
+++ b/diff.c
@@ -402,12 +402,7 @@ static void emit_line_0(struct diff_options *o, const char *set, const char *res
 	int nofirst;
 	FILE *file = o->file;
 
-	if (o->output_prefix) {
-		struct strbuf *msg = NULL;
-		msg = o->output_prefix(o, o->output_prefix_data);
-		assert(msg);
-		fwrite(msg->buf, msg->len, 1, file);
-	}
+	fputs(diff_line_prefix(o), file);
 
 	if (len == 0) {
 		has_trailing_newline = (first == '\n');
@@ -625,13 +620,7 @@ static void emit_rewrite_diff(const char *name_a,
 	char *data_one, *data_two;
 	size_t size_one, size_two;
 	struct emit_callback ecbdata;
-	char *line_prefix = "";
-	struct strbuf *msgbuf;
-
-	if (o && o->output_prefix) {
-		msgbuf = o->output_prefix(o, o->output_prefix_data);
-		line_prefix = msgbuf->buf;
-	}
+	const char *line_prefix = diff_line_prefix(o);
 
 	if (diff_mnemonic_prefix && DIFF_OPT_TST(o, REVERSE_DIFF)) {
 		a_prefix = o->b_prefix;
@@ -827,18 +816,14 @@ static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
 	int minus_first, minus_len, plus_first, plus_len;
 	const char *minus_begin, *minus_end, *plus_begin, *plus_end;
 	struct diff_options *opt = diff_words->opt;
-	struct strbuf *msgbuf;
-	char *line_prefix = "";
+	const char *line_prefix;
 
 	if (line[0] != '@' || parse_hunk_header(line, len,
 			&minus_first, &minus_len, &plus_first, &plus_len))
 		return;
 
 	assert(opt);
-	if (opt->output_prefix) {
-		msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
-		line_prefix = msgbuf->buf;
-	}
+	line_prefix = diff_line_prefix(opt);
 
 	/* POSIX requires that first be decremented by one if len == 0... */
 	if (minus_len) {
@@ -962,14 +947,10 @@ static void diff_words_show(struct diff_words_data *diff_words)
 	struct diff_words_style *style = diff_words->style;
 
 	struct diff_options *opt = diff_words->opt;
-	struct strbuf *msgbuf;
-	char *line_prefix = "";
+	const char *line_prefix;
 
 	assert(opt);
-	if (opt->output_prefix) {
-		msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
-		line_prefix = msgbuf->buf;
-	}
+	line_prefix = diff_line_prefix(opt);
 
 	/* special case: only removal */
 	if (!diff_words->plus.text.size) {
@@ -1105,6 +1086,16 @@ const char *diff_get_color(int diff_use_color, enum color_diff ix)
 	return "";
 }
 
+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;
+}
+
 static unsigned long sane_truncate_line(struct emit_callback *ecb, char *line, unsigned long len)
 {
 	const char *cp;
@@ -1145,13 +1136,7 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
 	const char *plain = diff_get_color(ecbdata->color_diff, DIFF_PLAIN);
 	const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
 	struct diff_options *o = ecbdata->opt;
-	char *line_prefix = "";
-	struct strbuf *msgbuf;
-
-	if (o && o->output_prefix) {
-		msgbuf = o->output_prefix(o, o->output_prefix_data);
-		line_prefix = msgbuf->buf;
-	}
+	const char *line_prefix = diff_line_prefix(o);
 
 	if (ecbdata->header) {
 		fprintf(ecbdata->opt->file, "%s", ecbdata->header->buf);
@@ -1475,16 +1460,11 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 	const char *reset, *add_c, *del_c;
 	const char *line_prefix = "";
 	int extra_shown = 0;
-	struct strbuf *msg = NULL;
 
 	if (data->nr == 0)
 		return;
 
-	if (options->output_prefix) {
-		msg = options->output_prefix(options, options->output_prefix_data);
-		line_prefix = msg->buf;
-	}
-
+	line_prefix = diff_line_prefix(options);
 	count = options->stat_count ? options->stat_count : data->nr;
 
 	reset = diff_get_color_opt(options, DIFF_RESET);
@@ -1736,12 +1716,7 @@ static void show_shortstats(struct diffstat_t *data, struct diff_options *option
 			dels += deleted;
 		}
 	}
-	if (options->output_prefix) {
-		struct strbuf *msg = NULL;
-		msg = options->output_prefix(options,
-				options->output_prefix_data);
-		fprintf(options->file, "%s", msg->buf);
-	}
+	fprintf(options->file, "%s", diff_line_prefix(options));
 	print_stat_summary(options->file, total_files, adds, dels);
 }
 
@@ -1755,12 +1730,7 @@ static void show_numstat(struct diffstat_t *data, struct diff_options *options)
 	for (i = 0; i < data->nr; i++) {
 		struct diffstat_file *file = data->files[i];
 
-		if (options->output_prefix) {
-			struct strbuf *msg = NULL;
-			msg = options->output_prefix(options,
-					options->output_prefix_data);
-			fprintf(options->file, "%s", msg->buf);
-		}
+		fprintf(options->file, "%s", diff_line_prefix(options));
 
 		if (file->is_binary)
 			fprintf(options->file, "-\t-\t");
@@ -1802,13 +1772,7 @@ static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
 {
 	unsigned long this_dir = 0;
 	unsigned int sources = 0;
-	const char *line_prefix = "";
-	struct strbuf *msg = NULL;
-
-	if (opt->output_prefix) {
-		msg = opt->output_prefix(opt, opt->output_prefix_data);
-		line_prefix = msg->buf;
-	}
+	const char *line_prefix = diff_line_prefix(opt);
 
 	while (dir->nr) {
 		struct dirstat_file *f = dir->files;
@@ -2058,15 +2022,10 @@ static void checkdiff_consume(void *priv, char *line, unsigned long len)
 	const char *reset = diff_get_color(data->o->use_color, DIFF_RESET);
 	const char *set = diff_get_color(data->o->use_color, DIFF_FILE_NEW);
 	char *err;
-	char *line_prefix = "";
-	struct strbuf *msgbuf;
+	const char *line_prefix;
 
 	assert(data->o);
-	if (data->o->output_prefix) {
-		msgbuf = data->o->output_prefix(data->o,
-			data->o->output_prefix_data);
-		line_prefix = msgbuf->buf;
-	}
+	line_prefix = diff_line_prefix(data->o);
 
 	if (line[0] == '+') {
 		unsigned bad;
@@ -2123,7 +2082,8 @@ static unsigned char *deflate_it(char *data,
 	return deflated;
 }
 
-static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two, char *prefix)
+static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two,
+				  const char *prefix)
 {
 	void *cp;
 	void *delta;
@@ -2184,7 +2144,8 @@ static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two, char
 	free(data);
 }
 
-static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two, char *prefix)
+static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two,
+			     const char *prefix)
 {
 	fprintf(file, "%sGIT binary patch\n", prefix);
 	emit_binary_diff_body(file, one, two, prefix);
@@ -2251,13 +2212,7 @@ static void builtin_diff(const char *name_a,
 	struct userdiff_driver *textconv_one = NULL;
 	struct userdiff_driver *textconv_two = NULL;
 	struct strbuf header = STRBUF_INIT;
-	struct strbuf *msgbuf;
-	char *line_prefix = "";
-
-	if (o->output_prefix) {
-		msgbuf = o->output_prefix(o, o->output_prefix_data);
-		line_prefix = msgbuf->buf;
-	}
+	const char *line_prefix = diff_line_prefix(o);
 
 	if (DIFF_OPT_TST(o, SUBMODULE_LOG) &&
 			(!one->mode || S_ISGITLINK(one->mode)) &&
@@ -2956,14 +2911,9 @@ static void fill_metainfo(struct strbuf *msg,
 {
 	const char *set = diff_get_color(use_color, DIFF_METAINFO);
 	const char *reset = diff_get_color(use_color, DIFF_RESET);
-	struct strbuf *msgbuf;
-	char *line_prefix = "";
+	const char *line_prefix = diff_line_prefix(o);
 
 	*must_show_header = 1;
-	if (o->output_prefix) {
-		msgbuf = o->output_prefix(o, o->output_prefix_data);
-		line_prefix = msgbuf->buf;
-	}
 	strbuf_init(msg, PATH_MAX * 2 + 300);
 	switch (p->status) {
 	case DIFF_STATUS_COPIED:
@@ -3900,12 +3850,8 @@ static void diff_flush_raw(struct diff_filepair *p, struct diff_options *opt)
 {
 	int line_termination = opt->line_termination;
 	int inter_name_termination = line_termination ? '\t' : '\0';
-	if (opt->output_prefix) {
-		struct strbuf *msg = NULL;
-		msg = opt->output_prefix(opt, opt->output_prefix_data);
-		fprintf(opt->file, "%s", msg->buf);
-	}
 
+	fprintf(opt->file, "%s", diff_line_prefix(opt));
 	if (!(opt->output_format & DIFF_FORMAT_NAME_STATUS)) {
 		fprintf(opt->file, ":%06o %06o %s ", p->one->mode, p->two->mode,
 			diff_unique_abbrev(p->one->sha1, opt->abbrev));
@@ -4175,12 +4121,7 @@ static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_fil
 static void diff_summary(struct diff_options *opt, struct diff_filepair *p)
 {
 	FILE *file = opt->file;
-	char *line_prefix = "";
-
-	if (opt->output_prefix) {
-		struct strbuf *buf = opt->output_prefix(opt, opt->output_prefix_data);
-		line_prefix = buf->buf;
-	}
+	const char *line_prefix = diff_line_prefix(opt);
 
 	switch(p->status) {
 	case DIFF_STATUS_DELETED:
@@ -4481,13 +4422,9 @@ void diff_flush(struct diff_options *options)
 
 	if (output_format & DIFF_FORMAT_PATCH) {
 		if (separator) {
-			if (options->output_prefix) {
-				struct strbuf *msg = NULL;
-				msg = options->output_prefix(options,
-					options->output_prefix_data);
-				fwrite(msg->buf, msg->len, 1, stdout);
-			}
-			putc(options->line_termination, options->file);
+			fprintf(options->file, "%s%c",
+				diff_line_prefix(options),
+				options->line_termination);
 			if (options->stat_sep) {
 				/* attach patch instead of inline */
 				fputs(options->stat_sep, options->file);
diff --git a/diff.h b/diff.h
index a47bae48d..76830e28b 100644
--- a/diff.h
+++ b/diff.h
@@ -174,6 +174,9 @@ const char *diff_get_color(int diff_use_color, enum color_diff ix);
 	diff_get_color((o)->use_color, ix)
 
 
+const char *diff_line_prefix(struct diff_options *);
+
+
 extern const char mime_boundary_leader[];
 
 extern void diff_tree_setup_paths(const char **paths, struct diff_options *);
diff --git a/graph.c b/graph.c
index 391a712e5..2a3fc5c0e 100644
--- a/graph.c
+++ b/graph.c
@@ -1227,6 +1227,16 @@ void graph_show_commit(struct git_graph *graph)
 	if (!graph)
 		return;
 
+	/*
+	 * When showing a diff of a merge against each of its parents, we
+	 * are called once for each parent without graph_update having been
+	 * called.  In this case, simply output a single padding line.
+	 */
+	if (graph_is_commit_finished(graph)) {
+		graph_show_padding(graph);
+		shown_commit_line = 1;
+	}
+
 	while (!shown_commit_line && !graph_is_commit_finished(graph)) {
 		shown_commit_line = graph_next_line(graph, &msgbuf);
 		fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);